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Therapeutic Potential of Plants as Anti-microbials for Drug Discovery.
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PMID:  18955349     Owner:  NLM     Status:  In-Data-Review    
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The uses of traditional medicinal plants for primary health care have steadily increased worldwide in recent years. Scientists are in search of new phytochemicals that could be developed as useful anti-microbials for treatment of infectious diseases. Currently, out of 80% of pharmaceuticals derived from plants, very few are now being used as anti-microbials. Plants are rich in a wide variety of secondary metabolites that have found anti-microbial properties. This review highlights the current status of traditional medicine, its contribution to modern medicine, recent trends in the evaluation of anti-microbials with a special emphasis upon some tribal medicine, in vitro and in vivo experimental design for screening, and therapeutic efficacy in safety and human clinical trails for commercial outlet. Many of these commercially available compounds are crude preparations administered without performing human clinical trials. Recent methods are useful to standardize the extraction for scientific investigation of new phytochemicals and anti-microbials of traditionally used plants. It is concluded that once the local ethnomedical preparations of traditional sources are scientifically evaluated before dispensing they should replace existing drugs commonly used for the therapeutic treatment of infection. This method should be put into practice for future investigations in the field of ethnopharmacology, phytochemistry, ethnobotany and other biological fields for drug discovery.
Authors:
Ramar Perumal Samy; Ponnampalam Gopalakrishnakone
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Publication Detail:
Type:  Journal Article     Date:  2008-06-24
Journal Detail:
Title:  Evidence-based complementary and alternative medicine : eCAM     Volume:  7     ISSN:  1741-4288     ISO Abbreviation:  Evid Based Complement Alternat Med     Publication Date:  2010 Sep 
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Created Date:  2011-05-11     Completed Date:  -     Revised Date:  -    
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Nlm Unique ID:  101215021     Medline TA:  Evid Based Complement Alternat Med     Country:  United States    
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Languages:  eng     Pagination:  283-94     Citation Subset:  -    
Affiliation:
Venom and Toxin Research Programme, Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore - 117597.
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Journal ID (nlm-ta): Evid Based Complement Alternat Med
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ISSN: 1741-427X
ISSN: 1741-4288
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Received Day: 12 Month: 4 Year: 2007
Accepted Day: 18 Month: 4 Year: 2008
Print publication date: Month: 9 Year: 2010
Electronic publication date: Day: 24 Month: 6 Year: 2008
Volume: 7 Issue: 3
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PubMed Id: 18955349
DOI: 10.1093/ecam/nen036
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Therapeutic Potential of Plants as Anti-microbials for Drug Discovery
Ramar Perumal Samy
Ponnampalam Gopalakrishnakone
Venom and Toxin Research Programme, Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore – 117597
Correspondence: For reprints and all correspondence: Prof. P. Gopalakrishnakone, Venom and Toxin Research Programme, Department of Anatomy, Yong Loo Lin School of Medicine, MD 10, 4 Medical Drive, National University of Singapore, Singapore – 117597. Tel: +65 - 65163207; Fax: +65 - 67787643; E-mail: antgopal@nus.edu.sg

Introduction

Primitive people have used plants to cure a variety of human ailments. Even today, 85% of Indians use higher plants as effective anti-microbials for the treatment of various diseases (1). A large number of anti-microbial agents derived from traditional medicinal plants are available for treating various diseases caused by micro-organisms (2). They are used to eliminate the infecting micro-organisms. The therapeutically useful novel agents should inhibit the germs and exhibit greater selective toxicity towards the infecting germ than the host cells (3). The mode of action for plant-derived agent should target biochemical features of the invading pathogens that are not possessed by the normal host cell. Some of the factors important for anti-microbial treatment include methods such as sensitivity of the infecting micro-organism to a particular agent (4). Side-effects of the plant-derived agent can be tested relative to direct toxicity upon animal cells because of their close association with human tissues or cells. So, we attempt to summarize information linked to plant extracts/chemical substances for the effective treatment of certain bacterial and fungal diseases. We also discuss the obvious necessity for new anti-microbial agents in various therapy regimens.

Recent Trends in the Evaluation of Anti-microbials

Anti-bacterial screening of traditional medicinal plants has been the source of innumerable therapeutic agents (Figs 1 and 2). In the area of antibiotics, random screening as a tool of discovering new biologically active molecules has been most productive. Chemotaxonomic considerations and target-directed screening also play a crucial role. For a successful outcome the main requirement is access to a large number of compounds/extracts that must be well screened (5). Ethanol extracts of 78 traditional medicinal plants from India are used for treating infectious diseases and show bacterial and fungal activity at 1.6 mg/ml (6). The 50% ethanol extracts of 285 plant materials were screened for 61 biological activities and revealed effective anti-bacterial, and a wide range of pharmacological, activities (7). Anti-microbial and phytochemical studies revealed 45 Indian medicinal plants effective against multi-drug- resistant bacteria (8). These results suggest the presence of either good anti-bacterial potency or the high concentration of an active principle in the extract. Plant extracts were screened phytochemically and 20% of the species yielded positive reactions for alkaloids, 25% species contained steroids/triterpenoids and 45% of species possessed saponins (9). Those plants with anti-bacterial effects are rich in polyphenolic substances such as tannins, catechins, alkaloids, steriods and polyphenolic acids. The anti-bacterial activity also could be due to various chemical components and the presence of essential oils in adequate concentrations, which damage micro-organisms (10). The insolubility of essential oils and non-polar extracts make it very difficult for them to be used in an aqueous medium during the study of anti-microbial activity (4). A great number of factors can influence the results such as the extraction method, volume of media, culture composition and incubation temperature. However, the recent advanced method of bioautographic TLC assays makes it possible to localize anti-microbial activity on a chromatogram (11); while bioassay-guided fractions led to the isolation of compounds (12).


Anti-microbial Compounds from Plants

Traditional medicinal plants have an almost maximum ability to synthesize aromatic substances, most of which are phenols or their oxygen-substituted derivatives (13). Most of these are secondary metabolites, of which 12 000 plant-derived agents have been isolated in the recent past. Many of these substances serve as plant defense mechanisms against invasion by micro-organisms (Table 1), insects and herbivores. Some of the plant substances such as terpenoids are responsible for odor (quinones and tannins) plus pigment of the plant. Many compounds are responsible for plant flavor (e.g. the terpenoid capsaicin from chili peppers), and some of the same herbs and spices used by humans to season food yield useful medicinal compounds. The useful major groups of anti-microbial phytochemicals can be divided into several categories that include alkaloids, flavones (flavonoids, flavonols, Quinones), essential oils, lectins, polypeptides, phenolics, polyphenols, tannins and terpenoids.

Alkaloids

Heterocylic nitrogen compounds are called alkaloids. The first medically useful alkaloid was morphine, isolated in 1805 from Paver somniferum (opium poppy) (27). The name morphine comes form the Greek word Morpheus, which means ‘god of dreams’. Codeine and heroin are both derivatives of morphine. Diterpenoid alkaloids, isolated from the plants of the Ranunculaceae family, are commonly found to have anti-microbial properties. Bioassay-guided isolation studies done on the root extract of Polyalthia longifolia shows that it possesses significant anti-bacterial activity led to the isolation of three new alkaloids pendulamine A, pendulamine B and penduline along with stigmasterol 3-O-beta-D-glucoside, allantoin, the known diterpenoid kolavenic acid and the azafluorene alkaloid isoursuline. Compound pendulamine A and pendulamine B were found to be active. Micro-organism inhibition concentrations, abbreviated as MICs, are ∼0.02–20 μg against bacteria (12). The seed pods of Erythrina latissima yielded erysotrine, erysodine, syringaresinol, vanillic acid and a new erythrina alkaloid, (+)-10,11-dioxoerysotrine that was lethal to brine shrimp. 2-(5′-Hydroxy-3′-methoxy phenyl)-6-hydroxy-5-methoxybenzofuran has strong anti-microbial activity against yeast spores (28). Ethanol extracts of the Guatteria multivenia root have furnished known alkaloids such as liriodenine, lysicamine, lanuginosine, guadiscine and O-methylpallidine. Lanuginosine possesses weak inhibitory effects against fungi and liriodenine was found to have anti-microbial activity against both bacteria and Candida albicans (29). Pyrrolizidine alkaloids (Heliotropium subulatum) extracts showed anti-microbial activity against both fungal and bacterial species (3). Alkaloids isolated (Schizozygia coffaeoides) using bioassay-guided fractionation was isoschizogaline, schizogynine and indoline that were subsequently shown to be the most active anti-fungal compounds (30). The anti-microbial berberine alkaloid isolated from Mahonia aquifolium was active against bacteria (31). For the anti-microbial components of berberin from Hydrastis canadensis, change in the lipophilicity of protoberberinium salts caused by modification of the substituents appears to influence the anti-bacterial activity. Both berberine and palmatine exhibited the greatest anti-bacterial activity (32). Biologically active carbazole alkaloids (from Murraya koenigii) showed mosquitocidal and anti-microbial activites, as well as exhibited topoisomerase I and II inhibition activities (33).

Flavones, Flavonoids and Flavonols

Flavones are phenolic structures containing one carbonyl group. They are hydroxlated phenolic substances that occur as C6–C3 units linked to an aromatic ring. Flavonoids are known to be synthesized by plants in response to microbial infection (34) and are effective anti-microbial substances against a wide array of micro-organisms. Anti-microbial flavonoids have been reported from E. latissima (28). Dimethoxyflavone and bonducellin were isolated from the aerial parts of Caesalpinia pulcherrima. Isobonducellin was found to be a homoisoflavanoid containing a cis (Z)-double bond possessing anti-microbial activity (35). Compounds of C. pulcherrima with anti-viral activities were derived from the flavonoid of quercetin (36). Moreover, the flavonoids, acacetin-7-o-β-D-galactopyranoside of C. morifolium was found to be active as towards HIV (37). A wide variety of flavonoids, sesquiterpenoid alcohols, triterpenoids and quinic acid caffeates product from plants may also be useful as anti-microbials (38). The activity is probably due to their ability to form a complex with extra-cellular and soluble proteins, which then binds to bacterial cell wall. More lipophilic flavonoids may also disrupt microbial membranes (39). Flavonoids lacking hydroxyl groups on their β-rings are more active against micro-organisms and the microbial target is the membrane with –OH groups (40).

Essential Oils and Terpenoids

The anti-microbial properties of aromatic volatile oils from medicinal, as well as other edible, plants have been recognized since antiquity. Essential oil, which is used as a food flavoring agent, possesses a broad spectrum of anti-microbial activities attributed to the high content of phenolic derivatives such as carvacrol and thymol. Some essential oils are used for systemic and superficial fungal infections and further exploration reveals a broad spectrum effect against other pathogenic manifestations that include malignancy (41). Moreover, fragrance of plants is associated with essential oils. This oil consists of secondary metabolities which are highly enriched in compounds based on an isoprene structure. They are called terpenes and occur as diterpenes, triterpenes, tetraterpenes as well as hemiterpenes and sesquiterpenes. When the compounds contain additional elements, usually oxygen, they are termed as terpenes. Terpenenes or terpenoids are active against bacteria (29). Nearly 60% of all essential oil derivatives possess inhibitory effects upon fungi while 39% inhibited bacteria (40). The seeds of Nigella sativa Linn. (Ranunculaceae) contain active constituents, e.g. volatile oil and thymoquinone showed protection against nephrotoxicity and hepatotoxicity induced by either disease or chemicals. The seed oil has anti-inflammatory, analgesic, anti-pyretic, anti-microbial and anti-neoplastic activity (42). Petroleum ether extract of Melicope indica afforded two unusual pentacyclic triterpenes and the ubiquitous steroids, stigmasterol and sitosterol (43). Pentacyclic tritepenes were isolated from Combretum imberbe that are novel glycosidic derivatives (hydroxyimberbic acid). Terminalia stuhlmannii Engl. stem bark yielded two glycosides of hydroxyimberbic acid, several of which had anti-bacterial activity. Imberbic acid showed potent activity against Mycobacterium fortuitum and Staphylococcus aureus (44). New cycloartane-type triterpenes isolated from the aerial parts of Acalypha communis exhibited moderate anti-microbial activity (MIC 8 and 32 µg/ml) against vancomycin-resistant enterococci. Compounds tested in an in vivo model did not provide protection to mice infected with S. aureus (45). Friedelin, epifriedelinol, β-amyrin, β-sitosterol, β-sitosterol 3-β-D-glucopyranoside and naringin isolated from the methanol extract of dried rhizome from Drynaria quercifolia showed concentration-dependent broad spectrum of anti-bacterial activity (46). Andrographolide, neoandrographolide and andrographiside (Fig. 1) are the diterpene lactone of Andrographis paniculata (king of bitter) possesses liver protection under various experimental conditions (47). It showed weak anti-microbial activity against bacteria and viruses. Asiaticoide and hypaphorine (Fig. 1) are the mixture of pentacyclic triterpene of Centella asiatica. Topical and oral applications of asiaticoside improved wound healing in guinea pigs (1 mg/kg dose) (48). Tinosporaside and columbin are diterpenes and cordifolioside (Fig. 1) is a sesquiterpene glucoside of Tinospora cordifolia as reported (49). An ether extract of the aerial part of T. cordifolia inhibited the growth of M. tuberculosis at 1 : 50 000 dilutions (50). The mechanism of action of terpenes is not fully understood but it is speculated to involve membrane disruption by the lipophilic compounds.

Lectins and Polypeptides

The active compounds can be grouped into two major classes: anti-microbial proteins and a wide variety of non-protein compounds. Their distribution is often tissue specific (51) and they are usually found in cells located at the external layers of plant tissues, thus suggesting that these compounds would be the first line of defense against a pathogen attack. An anti-microbial compound of 316 Da, present in the soluble fraction of strawberry (Fragaria ananassa) leaves shows in vitro activity against bacterial and fungal plant pathogens (52). An anti-microbial protein (WjAMP-1) purified from leaves of Wasabia japonica showed anti-microbial activity against both fungi and bacteria (53). Oleanolic acid (C. paraguariensis Burk, Fabaceae) from an Argentinean legume was found active against Bacillus subtilis and S. aureus with MICs 64 µg/ml (54). Peptides that are inhibitory to micro-organisms were first reported in 1942. Peptides called cathelicidins represent an important native component of innate host defense in mice and provide protection against necrotic skin infection caused by Streptococcus (55). They are often positively charged and contain disulfide bonds (56).The mechanism of action may be ion channel formation in the microbial membrane or competitive inhibition of adhesion of microbial proteins to host polysaccharide receptors (57). Diverse application has been demonstrated for anti-microbial peptides as anti-infective agents. The broad spectrum activity displayed by anti-microbial peptides is considered a ‘chemical condom’ against HIV infection and Herpes simplex virus (58).

Polyphenols and Phenolics

Some of the simplest bioactive phytochemicals consist of a single substituted phenolic ring. Cinnamic and caffeic acids are common representatives of a wide group of phenylpropane-derived compounds that are in the highest oxidation state. The common traditional medicinal plants have such compounds that are effective against bacteria (59). Phenolic compounds possessing a C3 side chain at a lower level of oxidation and containing no oxygen are classified as an essential oil and reported as anti-microbials. Coumarins are phenolic substances made of fused benzene and α-pyrone rings (60). Several coumarins have anti-microbial properties and anti-viral effects reported in 1954 (61). Anti-microbial properties of phenolic compounds (Finnish berries) active against pathogenic bacteria exhibited different sensitivities towards phenolics. These properties can be utilized in functional food development and for food preservation (62). Phenols are toxic to mico-organisms because of the sites and numbers of hydroxyl groups on the phenol groups, which is all related to their relative toxicity of micro-organism. There is evidence that highly oxidized phenols possess more inhibitory action (63). The mechanism responsible for phenolic toxicity to micro-organisms includes enzyme inhibition by the oxidized compounds, possibly through reaction with sulfydryl groups or through more non-specific interactions with proteins (64). Polyphenols which can form heavy soluble complexes with proteins may bind to bacterial adhesions thereby disturbing the availability of receptor on the cell surface.

Tannins

Tannins are generally descriptive of a group of polymeric phenolic substances capable of tanning leather or precipitating gelatin from solutions, the property known as astringency. Their molecular weights range from 500 to 3000 Da (55) and are found in almost every plant parts: bark, leaf, root, wood and fruit. They form two groups, hydrolysable and condensed tannins based on gallic acid. The first group is usually found as multiple esters with D-glucose, while the more numerous condensed tannins are derived from flavonoid monomers. Tannins (tannic acid) are water-soluble polyphenols that are present in many plant foods (65). Polyphenols (Tea) and many tannin components have been suggested to be anti-carcinogenic. The anti-microbial activities of tannins are well documented. The growth of many fungi, yeasts, bacteria and viruses were inhibited by tannins. Tannic acid and propyl gallate inhibit food borne, aquatic and off-flavor-producing micro-organisms. Their anti-microbial properties seemed to be associated with the hydrolysis of an ester linkage between gallic acid and polyols hydrolyzed after the ripening of many edible fruits. Tannins in these fruits thus serve as a natural defense mechanism against microbial infections. The anti-microbial property of tannic acid can also be used in food processing to increase the shelf-life of certain foods, such as catfish fillets. Tannin components of epicatechin and catechin (Vaccinium vitis-idaea L.) showed strong anti-microbial activity against bacteria and fungi. Such anti-microbial activity could potentially be used as a possible alternative for the treatment of periodontal diseases (66). Eucaglobulin is a new complex of gallotannin and monoterpene of leaves of Eucalyptus globulus possessing anti-bacterial effects (67). Methanol extracts of T. citrina fruit yielded known tannins such as corilagin, punicalagin and chebulagic acid that were tested for anti-microbial action (68). Arjunolic acid, ethyl gallate, flavone, ellagic acid and gallic acid are the active constituents of T. arjuna (Fig. 1). Macrocyclic structures of bioactive ellagiannins (gluconic acid core) and oligomeric ellagitannins have been found in species of Myrtaceae and Elaeagnaceae and they too possess anti-bacterial activity against Helicobacter pylori (69). Proanthocyanidins (condensed tannins) and hydrolyzable tannins are the two major classes of tannins. Proanthocyanidins are flavonoid polymers, the most common type of tannin found in forage legumes (70). Hydrolyzable tannins are polymers of gallic and ellagic acid esterified to a core molecule of Phyllanthus emblica (Fig. 1). Phyllanthin and hypophyllanthin are lignans of P. niruri (Fig. 1) that enhance cytotoxic response against multi-drug-resistant cells (71). The mode of anti-microbial action of tannins and their ability to inactivate microbial adhesins, enzymes and cell envelop transport proteins also have been studied.

Mixtures

The neem (Azadirachta indica), verasingam pattai (Zanthoxylum limonella), Indian babool (Acacia nilotica) stick are widely used as tooth brushes by various tribes throughout India, Africa and Nigeria. The neem (A. indica), traditionally used as medicine, and in particular the stem bark extract showed activity against various Candida species. The minimum fungicidal concentrations ranged from 0.06 to >8 mg/ml (72). Anti-bacterial effects of neem mouthwash have been tested over a period of 2 months against salivary levels of Streptococcus mutans, Lactobacillus species and S. mutans. They were all inhibited by neem-based mouth washes (73). The active component of the Nigerian chewing stick (Fagara zanthoxyloides) was found to consist of various alkaloids (74). Ayurvedic practitioners rely on plant extracts, both single and mixed combination, for the preparation. The preparations are used to treat a wide range of human, as well as animal, ailments (75). Cleistanthus collinus is known as oduvanthalai (Nillipalai) in India and all parts of this plant are highly poisonous. Various extracts of this plant yield a multitude of compounds that include glycosides, arylnathalene lignan lactones such as cleistanthin A and B, collinusin and oduvin found to have anti-microbial activities (76). Strawberry extracts were strong inhibitors of Salmonella bacteria. The dried flower-heads of Chrysanthemum moriforium are an oriental drug as well as a popular herbal tea in China, which has been used for the treatment of eye diseases in Japan. They have been found to possess anti-bacterial, anti-fungal, anti-viral and anti-inflammatory activities (77).


Experimental Designs for Extraction

Traditional healers prepare a wide range of healing juices, crude extracts, paste and tincture from various herbs by using a water extract. Water or alcohol (methanol/ethanol) are mainly used for a large number of crude extract/library preparations (dry powder soaking or suspension, mechanical shaker, distillation of essential oils), sequential grinding (alkaloids, steroids, triterpenoids), gradial centrifugation (lectins and polypeptides) and acid hydrolysis (phenols) for a specific time frame. A variety of extractants are used for their ability to solubilize anti-microbials and also other factors from plants. This particular study provided a more standardized extraction method for a wide variety of plants (78). The crude extracts or mixtures of compound-rich residues are used for the initial screening of plants for anti-microbial activities. In many reports, methanol or ethanol are used for alkaloid extraction; acetone for flavonoids and steroids, hexane, diethyl ether and chloroform for fat soluble oils, wax, lipids and esters; dichloromethane for terpenoids, ethyl acetate for esters, ethanol for sterols, polyphenols, tannins and water for the water soluble components like glycosides, polysaccharides, polypeptides and lectins, which are most effective against pathogens. TLC, other chromatography separations (79) and several solvent systems are used for the elution of enormous water and organic solvent (Fig. 3) soluble anti-microbial compounds (Table 2). Diverse analytical spectral devices are often used for the identification and structural characterization of active components from plants (Fig. 4). However, the water medium is the most suitable for the treatment point of view in humans/animals.


Efficacy for In vitro Studies

Several plants used for the treatment of various infections have some in vitro activity against pathogenic Gram-positive bacteria. In our findings, the popular use of Tragia involucrata as a traditional medicine for the treatment of scabies and skin infection was documented in India. The most promising T. involucrata and its extracts (organic and water) exhibited marked and/or broad spectrum activity especially towards Gram-negative and -positive bacteria. These results suggested the presence of good anti-microbial potency and a high concentration of active principles that were proven useful for wound healing in a rat model. Anti-inflammatory properties and safety of extracts were also evaluated. Effective inhibition is due to the high content of active principles in the extract. Whereas, among catechins (a constituent of green tea) and pyrogallol (Holmskioldia sanguinea Retz) (89), as well as other anti-fungal compounds like ginger (Zingiber officinale Roscoe) were found active against human pathogens (90). The use of natural remedies for the treatment of viral diseases has a long history in traditional systems of medicines. An extract of Ribes nigram has been used as an ingredient in a variety of food and folk medicines in Japan. The extract has activity which inhibits virus replication in cells, due to the inhibition of protein synthesis among infected cells from the very early stage of infection (91). Anti-protozoal and cytotoxic activities were also reported (92).


Need to Explore New Anti-microbials

This review highlights some of the important medicinal plants used for traditional medicine and the medicinal information was obtained from various traditional healers or medical practitioners in the Hilly areas in India. Tribal healers in most countries, where traditional ethnomedical treatment is frequently used, provide instructions to local people as how to prepare medicine from the plants (93). They keep no records and the information is mainly passed on verbally from generation to generation (94). World Health Organization (WHO) has shown great interest in documenting the use of medicinal plants from tribes in different parts of the world (95). Many developing countries have intensified their efforts in documenting the ethnomedical data on medicinal plants. Moreover, an unexplored reservoir of phytochemical information is being rapidly destroyed by deforestation. About 10–20% of all plant species become extinct and above all, there is a continuing threat and pressure upon the existing plants by fast-growing industrialization and commercial exploitation of pharmaceutical industry (96). However, the medicinal plants are an important health resource in all the regions of India and particularly among the primitive communities (97). Though a vast number of plants have not been studied for their anti-microbial properties these may become new sources of plants for anti-microbial activity. There is a need for further collaborative biological screening of plant extracts in single, or combination, form. Phytochemicals derived from plant products are quite effective in controlling the growth of micro-organism. The recent approaches of bioautography assay (11) and high-throughput screening methods are the most suitable method to detect the anti-microbial component present in the extract. With the current trend on increasing awareness in traditional medicine, the plant-derived agents have been attracting much interest as natural alternatives to synthetic compounds because microbes slowly develop resistance against antibiotics. Scientists are trying to tap the pharmaceutical and food values of these many unidentified plants. It is believed that the plants (traditional medicine) will be a major source of new chemicals and raw materials for the pharmaceutical industry.


Conclusions

From the above studies, it is concluded that the traditional plants may represent new sources of anti-microbials with stable, biologically active components that can establish a scientific base for the use of plants in modern medicine. These local ethnomedical preparations and prescriptions of plant sources should be scientifically evaluated and then disseminated properly. The knowledge that primitive people used plants gives a clear idea about the unclear botanical preparation of traditional sources of medicinal plants. These can be extended for future investigation into the field of pharmacology, phytochemistry, ethnobotany and other biological actions for drug discovery.

In addition, folklorist, pharmacologist, phytochemists and ethnobotanists are investigating plants for anti-microbials. Several plant-based chemicals have shown potential inhibitory action on a wide range of micro-organism in vitro experiment. Although tannins, polyphenols (98), oils (99) and others were identified as the effective component for the bacterial damaging or killing action in the in vitro system, many of these compounds failed in human clinical trails to determine their therapeutic effectiveness.

We concluded that well-designed bioassay-guided isolation and studying anti-microbial effect should be able to complete this task. In the past 20 years, several studies proving the extract or chemicals derived from plant extracts were reported. These studies indicated that extracts contain interesting biopharmaceutical substances (anti-microbials) that have attracted significant scientific attention. More detailed investigation at molecular, cellular levels, suitable animal models and human clinical studies are necessary to elucidate anti-microbial and other biological activities.


Acknowledgements

The authors would like to thank Dr Bradley G. Stiles, Integrated Toxicology, US Army Medical Research Institute of Infectious Disease, Fort Detrick, Maryland 21702-5011, USA for his evaluation and correction of the manuscript.


References
1. Kamboj VP. Herbal medicineCurr SciYear: 200078359
2. Jain SK. Ethnobotany and research on medicinal plants in IndiaCiba Found SympYear: 1994185153647736852
3. Craig WA. Pharmacokinetics/pharmacodynamic parameters: rationale for antibacterial dosing of mice and menClin Infect DisYear: 1998261129455502
4. Pellecure S,Allegrini J,Buochberg S. Huiles essenticlles bactericides et fongicidesRevue del l Institute Pasteur de LyonYear: 1976913559
5. Ali-Shtayeh MS,Yaghmour RMR,Faidi YR,Salem K,Al-Nuri MA. Antimicrobial activity of 20 plants used in folkloric medicine in the PalestinianJ EthnopharmacolYear: 199860265719613839
6. Valsaraj R,Pushpangadan P,Smitt UW,Adsersen A,Nyman U. Antimicrobial screening of selected medicinal plants from IndiaJ EthnopharmacolYear: 19975875839406894
7. Smith RA,Calviello CM,Der Marderosian A,Palmer ME. Evaluation of antibacterial activity of belizea plants: an improved methodPharm BiolYear: 200038259
8. Ahmad I,Beg AZ. Antimicrobial and phytochemical studies on 45 Indian medicinal plants against multi-drug resistant human pathogensJ EthnopharmacolYear: 2001741132311167029
9. Arthur HR. A phytochemical survey of some of plants of North BornewJ Pharm PharmacolYear: 19546667213118519
10. Deininger R. Neves aus der Terpenf or schung. Excerpta phytotherapeutikaLectures of the Medical CongressYear: 1984BerlinFirma Klosterfrau, Koln2431
11. Martini N,Eloff JN. The preliminary isolation of several antibacterial compounds from Combretum erythrophyllum (Combretaceae)J EthnopharmacolYear: 199862255639849638
12. Faizi S,Khan RA,Azher S,Khan SA,Tauseef S,Ahmad A. New antimicrobial alkaloids from the roots of Polyalthia longifolia var. pendulaPlanta MedicaYear: 200369350512709903
13. Geissman TA. Florkin M,Stotz EHFlavonoid compounds, tannins, lignins and related compoundsPyrrole Pigments, Isoprenoid Compounds and Phenolic Plant ConstituentsYear: 19639New YorkElsevier2653
14. Feresin GE,Tapia A,Gimenez A,Ravelo AG,Zacchino S,Sortino M,et al. Constituents of the Argentinian medicinal plant Baccharis grisebachii and their antimicrobial activityJ EthnopharmacolYear: 200389738014522435
15. Abo KA,Adeyemi AA. Seasonal accumulation of anthraquinones in leaves of cultivated Cassia podocarpa Guill et PerrAfr J Med SciYear: 2002311713
16. Lee-Huang S,Zhang L,Huang PL,Chang YT,Huang PL. Anti-HIV activity of olive leaf extract (OLE) and modulation of host cell gene expression by HIV-1 infection and OLE treatmentBiochem Biophys Res CommunYear: 200330710293712878215
17. Chainani-Wu N. Safety and anti-inflammatory activity of curcumin: a component of tumeric (Curcuma longa)J Altern Complement MedYear: 20039161812676044
18. Salgueiro LR,Cavaleiro C,Pinto E,Pina-Vaz C,Rodrigues AG,Palmeira A,et al. Chemical composition and antifungal activity of the essential oil of Origanum virens on Candida speciesPlanta MedicaYear: 20036987187414598221
19. Viljoen A,van Vuuren S,Ernst E,Klepser M,Demirci B,Baser H,et al. Osmitopsis asteriscoides (Asteraceae)-the antimicrobial activity and essential oil composition of a Cape-Dutch remedyJ EthnopharmacolYear: 2003881374312963133
20. Martins AP,Salgueiro LR,Goncalves MJ,Proenca da Cunha A,Vila R,Canigueral S. Essential oil composition and antimicrobial activity of Santiria trimera barkPlanta MedicaYear: 20036977912567287
21. Gören AC,Zhou BN,Kingston DGI. Cytotoxic and DNA damaging activity of some aporphine alkaloids from Stephania dinklageiPlanta MedicaYear: 200369867814598219
22. Olila D,Odyek O,Opuda-Asibo J. Antibacterial and antifungal activities of extracts of Zanthoxylum chalybeum and Warburgia ugandensis, Ugandan medicinal plantsAfr Health SciYear: 20012667212789119
23. Lau CW,Yao XQ,Chen ZY,Ko WH,Huang Y. Cardiovascular actions of berberineCardiovasc Drug RevYear: 2001192344411607041
24. Mahady GB,Pendland SL,Yun GS,Lu ZZ,Stoia A. Ginger (Zingiber officinale Roscoe) and the gingerols inhibit the growth of Cag A+ strains of Helicobacter pyloriAnticancer ResYear: 200323369970214666666
25. Ammon HP. Boswellic acids (components of frankincense) as the active principle in treatment of chronic inflammatory diseasesWien Med WochenschrYear: 2001152373812244881
26. Narwal S,Balasubrahmanyam A,Sadhna P,Kapoor H,Lodha ML. A systemic resistance inducing antiviral protein with N-glycosidase activity from Bougainvillea xbuttiana leavesIndian J Exp BiolYear: 200139600312562026
27. Fessenden RJ,Fessenden JS. Organic ChemistryYear: 19822ndBoston, MAWillard Grant Press139
28. Wanjala CC,Juma BF,Bojase G,Gashe BA,Majinda RR. Erythrinaline alkaloids and antimicrobial flavonoids from Erythrina latissimaPlanta MedicaYear: 200268640212143000
29. Ahamd AA,Mahmoud AA,Williams HJ,Scott AI,Reibebspies JH,Mabry TJ. New sesquiterpene α-methylene lactones from the Egyptian plants Jasonia candicansJ Nat ProdYear: 1993561276808229012
30. Kariba RM,Houghton PJ,Yenesew A. Antimicrobial activities of a new schizozygane indoline alkaloid from Schizozygia coffaeoides and the revised structure of isoschizogalineJ Nat ProdYear: 200265566911975502
31. Cernakova M,Kostalova D. Antimicrobial activity of berberine-a constituent of Mahonia aquifoliumFolia MicrobiolYear: 200247375812422513
32. Iwasa K,Nanba H,Lee DU,Kang SI. Structure-activity relationships of protoberberines having antimicrobial activityPlanta MedicaYear: 199864748519933992
33. Ramsewak RS,Nair MG,Strasburg GM,DeWitt DL,Nitiss JL. Biologically active carbazole alkaloids from Murraya koenigiiJ Agri Food ChemYear: 1999474447
34. Dixon RA,Dey PM,Lamb CJ. Phytoalexins: enzymology and molecular biologyAdv EnzymolYear: 1983551696353887
35. Srinivas KV,Koteswara Rao Y,Mahender I,Das B,Rama Krishna KV,Hara Kishore K,et al. Flavanoids from Caesalpinia pulcherrimaPhytochemistryYear: 2003637899312877920
36. Chiang LC,Cheng HY,Liu MC,Chiang W,Lin CC. In vitro anti-herpes simplex viruses and anti-adenoviruses activity of twelve traditionally used medicinal plants in TaiwanBiol Pharm BullYear: 2003261600414600409
37. Hu CQ,Chen K,Shi Q,Kilkuskie RE,Cheng YC,Lee KH. Anti-AIDS agents, 10. Acacetin-7-o-β-D-galactopyranoside, an anti-HIV principle from Chrysanthemum morifolium and a structure-activity correlation with some related flavonoidsJ Nat ProdYear: 19945742518158164
38. Hu L,Chen Z. Sesquiterpenoid alcohols from Chrysanthemum morifoliumPhytochemistryYear: 199744128790
39. Tsuchiya H,Sato M,Miyazaki T,Fujiwara S,Tanigaki S,Ohyama M,et al. Comparative study on the antibacterial activity of phytochemical flavanones against methicillin-resistant Staphylococcus aureusJ. EthnopharmacolYear: 19965027348778504
40. Chaurasia SC,Vyas KK. In vitro effect of some volatile oil against Phytophtora parasitica var. piperinaJ Res Indian Med Yoga HomeopathYear: 19971246
41. Manohar V,Ingram C,Gray J. Antifungal activities of origanum oil againstCandida albicans. Mol Cell BiochemYear: 20012281117
42. Ali BH,Blunden G. Pharmacological and toxicological properties of Nigella sativaPhytother ResYear: 20031729930512722128
43. Farruque R,Chowdhury R,Sohrab MH,Hasan CM,Rashid MA. Triterpene constituents from the leaves of Melicope indicaPharmazieYear: 2003585182012889540
44. Katerere DR,Gray AI,Nash RJ,Waigh RD. Antimicrobial activity of pentacyclic triterpenes isolated from African CombretaceaePhytochemistryYear: 20036381812657301
45. Gutierrez-Lugo MT,Singh MP,Maiese WM,Timmermann BN. New antimicrobial cycloartane triterpenes from Acalypha communisJ Nat ProdYear: 200265872512088430
46. Ramesh N,Viswanathan MB,Saraswathy A,Balakrishna K,Brindha P,Lakshmanaperumalsamy P. Phytochemical and antimicrobial studies on Drynaria quercifoliaFitoterapiaYear: 200172934611731121
47. Visen PKS,Shukla B,Patnaik GK. Andrographolide protects rat hepatocytes against paracetamol-induced damageJ EthnopharmacolYear: 19934013168133653
48. Maquart FX,Bellon G,Gillery P,Wegrowski Y,Borel JP. Stimulation of collagen synthesis in fibroblast cultures by a triterpene extracted from Centella asiaticaConnect Tissue ResYear: 199024107202354631
49. Handa SS. Indian Herbal PhamacopoeiaYear: 1998IMumbai, IndiaIndian Drug Manufacturer's Association 102-B1589
50. Sampson JH,Raman A,Karlsen G,Navsaria H,Leigh IM. In vitro keratinocyte antiproliferant effect of Centella asiatica extract and triterpenoid saponinsPhytomedicineYear: 20018230511417919
51. Price KR,Johnson IT,Fenwick GR. The chemistry and biological significance of saponins in foods and feeding stuffCrit Rev Food Sci NutrYear: 198726271353308321
52. Filippone MP,Diaz Ricci J,Mamani de Marchese A,Farias RN,Castagnaro A. Isolation and purification of a 316 Da performed compounds from strawberry (Fragaria ananassa) leaves active against plant pathogensFEBS LettYear: 1999459115810508928
53. Kiba A,Saitoh H,Nishihara M,Omiya K,Yamamura S. C-terminal domain of a hevein-like protein from Wasabia japonica has potent antimicrobial activityPlant Cell PhysiolYear: 20034429630312668776
54. Woldemichael GM,Singh MP,Maiese WM,Timmermann BN. Constituents of antibacterial extract of Caesalpinia paraguariensis BurkZ NaturforschYear: 200358705
55. Nizet V,Ohtake T,Lauth X,Trowbridge J,Rudisill J,Dorschner RA,et al. Innate antimicrobial peptide protects the skin from invasive bacterial infectionNatureYear: 2001414454711719807
56. Zhang Y,Lewis K. Fabatins: new antimicrobial plant peptidesFEMS Microbiol LettYear: 199714959649103978
57. Sharon N,Ofek I. Mirelman DMannose specific bacterial surface lectinsMicrobial Lectins and AgglutininsYear: 1986New YorkJohn Wiley & Sons, Inc.5582
58. Yasin B,Pang M,Turner JS,Cho Y,Dinh NN,Waring AJ,et al. Evaluation of the inactivation of infectious herpes simplex virus by host-defense peptidesEur J Clin Microbiol Infect DisYear: 2001191879410795591
59. Brantner A,Males Z,Pepeljnjak S,Antolic A. Antimicrobial activity of Paliurus spina-christi MillJ EthnopharmacolYear: 199652119228735457
60. Okennedy R,Thornes RDCoumarins: biology, applications and mode of action.Year: 1997New YorkJohn Wiley & Sons, Inc
61. Berkada B. Preliminary report on warfarin for the treatment of herbes simplexJ Irish Collect Physiol SurgYear: 197822Suppl 256
62. Puupponen-Pimia R,Nohynek L,Meier C,Kahkonen M,Heinonen M,Hopia A,et al. Antimicrobial properties of phenolic compounds from berriesJ Appl MicrobiolYear: 20019049450711309059
63. Urs NRR,Dunleavy JM. Enhancement of the bactericidal activity of a peroxidase system by phenolic compounds (Xanthomonas phaseoli var. sojensis, soybeans)PhytopathologyYear: 19756568690
64. Mason TL,Wasserman BP. Inactivation of red beet betaglucan synthase by native oxidized phenolic compoundsPhytochemistryYear: 1987262197202
65. Scalbert A. Antimicrobial properties of tanninsPhytochemistryYear: 199130387583
66. Ho KY,Tsai CC,Huang JS,Chen CP,Lin TC,Lin CC. Antimicrobial activity of tannin components from Vaccinium vitis-idaea LJ Pharm PharmacolYear: 2001531879111273014
67. Hou AJ,Liu YZ,Yang H,Lin ZW,Sun HD. Hydrolyzable tannins and related polyphenols from Eucalyptus globulusJ Asian Nat Prod ResYear: 200022051211256694
68. Burapadaja S,Bunchoo A. Antimicrobial activity of tannins from Terminalia citrinaPlanta MedicaYear: 19956136567480186
69. Yoshida T,Hatano T,Ito H. Chemistry and function of vegetable polyphenols with high molecular weightsBiofactorsYear: 200013121511237170
70. Reed JD. Nutritional toxicology of tannins and related polyphenols in forage legumesJ Animal SciYear: 199573151628
71. Somanabandhu A,Nitayangkura S,Mahidol C,Ruchirawat S,Likhitwitayawuid K,Shieh HL,et al. 1H- and 13C-NMR assignments of phyllanthin and hypophyllanthin: lignans that enhance cytotoxic responses with cultured multidrug-resistant cellsJ Nat ProdYear: 19935623398385184
72. Fabry W,Okemo P,Ansorg R. Fungistatic and fungicidal activity of east African medicinal plantsMycosesYear: 19963967708786762
73. Vanka A,Tandon S,Rao SR,Udupa N,Ramkumar P. The effect of indigenous Neem Azadirachta indica [correction of (Adirachta indica)] mouth wash on Streptococcus mutans and lactobacilli growthIndian J Dent ResYear: 2001121334411808064
74. Odebiyi OO,Sofowora EA. Antimicrobial alkaloids from a Nigerian chewing stick (Fagara zanthoxyloides)Planta MedicaYear: 1979362047482432
75. Kumar O,Singh B. Effect of Ayurvedic liver stimulants on live weight gain of broilers in North Eastern regionIndian J Animal ResYear: 19922615
76. Satyanarayana P,Subramanyam P,Koteswara RP. Chemical constitutents of Cleistanthus collinus roots. IndianJ Pharm SciYear: 198446956
77. Dian ZYDC. The Dictionary of Chines MedicineYear: 1997ShanghaiShanghai Science and Technique Press2008
78. Eloff JN. It is possible to use herbarium specimens to screen for antibacterial components in some plantsJ EthnopharmacolYear: 1999673556010617072
79. Harbone JB. Phytochemical Methods. A Guide to Modern Techniques of Plant AnalysisYear: 1998LondonChapman and Hall1302
80. Afolayan AJ,Meyer JJM. The antimicrobial activity of 3, 5, 7-trihydroxyflavon isolated from the shoots of Helichrysum aureonitensJ EthnopharmacolYear: 199757177819292410
81. Seca AM,Silva AM,Silvestre AJ,Cavaleiro JA,Domingues FM,Pascoal-Neto C. Lignanamides and other phenolic constituents from the bark of kenaf (Hibiscus cannabinus)PhytochemistryYear: 20015812192311738411
82. Ayafor JF,Tchuendem HK,Nyasse B. Novel bioactive diterpenoids from Aframomum aulacocarposJ Nat ProdYear: 199457917237964787
83. Perrett S,Whitefield PJ,Sanderson L,Bartlett A. The plant molluscide Millettia thonningii (Leguminosae) as a topical antischistosomal agentJ EthnopharmacolYear: 19954749547564421
84. Perumal Samy R,Ignacimuthu S,Sen A. Screening of thirty-four Indian medicinal plants for antibacterial propertiesJ EthnopharmacolYear: 199862173829741889
85. Zhang Z,ElSohly HN,Jacob MR,Pasco DS,Walker LA,Clark AM. New sesquiterpenoids from the root of Guatteria multiveniaJ Nat ProdYear: 200265856912088427
86. Kunle O,Okogun J,Egamana E,Emojevwe E,Shok M. Antimicrobial activity of various extracts and carvacrol from Lippia multiflora leaf extractPhytomedicineYear: 200310596112622465
87. Kaul TN,Middletown Jr,Ogra PL. Antiviral effect of flavonoids on human virusesJ Med VirolYear: 1985157192981979
88. De Pasquale R,Germano MP,Keita A,Sanogo R,Iauk L. Antiulcer activity ofPteleopsis subersa. J EthnopharmacolYear: 199547558
89. Hirasawa M,Takada K. Multiple effects of green tea catechin on the antifungal activity of antimycotics against Candida albicansJ Antimicrob ChemotherYear: 20034615
90. Ficker C,Smith ML,Akpagana K,Gbeassor M,Zhang J,Durst T,et al. Bioassay-guided isolation and identification of antifungal compounds from gingerPhytother ResYear: 20031789790213680820
91. Suzutani T,Ogasawara M,Yoshida I,Azuma M,Knox YM. Anti-herpesvirus activity of an extract of Ribes nigrum LPhytother ResYear: 2003176091312820226
92. Camacho MR,Kirby GC,Warhurst DC,Croft SL,Phillipson JD. Oxoaporphine alkaloids and quinones from Stephania dinklagei and evaluation of their antiprotozoal activitiesPlanta MedicaYear: 2000664788010909274
93. John D. One hundred useful raw drugs of the Kani tribes of Trivandrum forest division, KeralaInt J Crude Drug ResYear: 1984221739
94. Puspangadan P,Atal CK. Ethnomedico-botanical investigation in Kerala I. Some primitive tribals of Western Ghats and their herbal medicineJ EthnopharmacolYear: 19841159776471881
95. Dev S. Ethnotherapeutics and modern drug development: The potential of AyurvedaCurr SciYear: 19977390928
96. Vogel HG. Similarities between various systems of traditional medicine. Considerations for the future of ethnopharmacologyJ EthnopharmacolYear: 199135179901809825
97. Khan M,Schneider B,Wassilew SW,Splanemann V. Experimental study of the effect of raw materials of the neem tree and neem extracts on dermatophytes, yeasts and moldsZ HautkrYear: 1988634995023407264
98. Biradar YS,Jagatap S,Khandelwal KR,Singhania SS. Exploring of antimicrobial activity of Triphala Mashi - an Ayurvedic formulationEvid Based Complement Alternat MedYear: 200851071318317557
99. Vukovic N,Milosevic T,Sukdolak S,Solujic S. Antimicrobial activities of essential oil and methanol extract ofTeucrium montanum. Evid Based Complement Alternat MedYear: 200741720

Figures

[Figure ID: F1]
Figure 1. 

Some of the folk medicinal plants and its various parts used as therapeutic potential in Southern Tamil nadu, Western Ghats of India. (a and c) Seed with flower of Andrographics paniculata Wallichi ex Nees (Acanthaceae), (b) fruit of Strychnos nux-vomica L. (Loganiaceae), (d) Euphorbia hirta L. (Euphorbiaceae), (e) whole plant of Ocimum sanctum L. (Lamiaceae) and (f) inflorescence of Ocimum sanctum L.



[Figure ID: F2]
Figure 2. 

Some of the folk medicinal plants and its various parts used as therapeutic potential in Southern Tamil nadu, Western Ghats of India. (a) Cardiospermum halicaccabum L. (Sapindaceae), (b) Aloe vera Mill. (Liliaceae), (c) Vitex negundo L. (Verbenaceae), (d) Phyllanthus amarus (Euphorbiaceae) (e) Cathranthus roseus (L) and (f) Mimosa pudica L. (Mimosaceae).



[Figure ID: F3]
Figure 3. 

Flow chart for the various sequential protocols involved for the purification, characterization and structural derivation of medicinal plants and their bioactive compounds. Various fractions, i.e. HF: hexane fraction; PEF: petroleum ether fraction; DCM: dichrloromethane fraction; ETA: ethyl acetate fraction; MF: methanol fraction; CHL: chloroform fraction; WA: water and ACE: acetone fraction.



[Figure ID: F4]
Figure 4. 

Structure of common anti-microbial compounds from the popularly used traditional medicinal plants.



Tables
[TableWrap ID: T1] Table 1. 

Some of the traditional medicinal plants and their class of anti-microbial compounds


Scientific names Parts/solvents Class Compounds Mechanism of traditional medicine References
Baccharis grisebachii Hieron (Asteraceae) Resinous exudate Diterpenes, p-coumaric acid derivatives, flavones 3-Prenyl-p-coumaric acid and 3,5-diprenyl-p-coumaric acid Argentinian traditional medicine showed activity towards dermatophytes and bacteria (MICs 50,100 and 125 µg/ml). Feresin et al. (14)
Cassia podocarpa Guill et Perr. (Caesalpiniaceae) Leaf and flower Glycosides Anthraquinone glycosides, anthraquinones, free aglycone Optimum laxative activity and reduced toxicity. Abo and Adeyemi (15)
Chrysanthemum morifolium Ramat. (Compositae) Flowers Flavonoids Apigenin 7-O-β-D-glucurnoide Glucuronide showed strong HIV-1 integrase inhibitory activity in a cell culture assay using HIV-IIIIB-infected MT-4 cells. Lee-Huang et al. (16)
Curcuma longa L. (Zingiberaceae) Rhizome Flavonoids Curcumin and curminoids A number of different molecules involved in inflammation that are inhibited by curcumin including lipo-oxygenase, phosphopolipase and elastase. Chainani-Wu (17)
Origanum virens L. (Lamiaceae) Aerial parts Essential oil Carvacrol (68.1%), γ-terpinene (9.9%) and p-cymene (4.5%) Anti-fungal activity against Candida species. The fungicidal effect is primarily due to an extensive lesion of the membrane. Salgueiro et al. (18)
Osmitopsis asteriscoides L. (Asteraceae) Essential oil Cineole and camphor, Camphor and 1,8-cineole Anti-microbial activity (0.5–2% v/v) synergistic effect is presented as a possible explanation for the traditional use for chest pain in South Africa. Viljoen et al. (19)
Santiria trimera (Oliv.) Aubrev. (Burseraceae) Bark Essential oil monoterpenes β-Pinene (20.0%), α-pinene (66.6%) Plant widely used by the traditional healers, anti-microbial activity (MIC 1.11–0.71 µg/ml). Martins et al. (20)
Stephania dinklagei Engl. (Menispermaceae) Ethanol extract Aporphine alkaloids Liriodenine, corydine, isocorydine, atherospermidine, stephalagine and dehydrostephalagine Liriodenine showed strong cytotoxic activity while corydine and atherospermidine showed DNA damaging activity. Gören et al. (21)
Warburgia ugandensis Sprague (Canellaceae) Zanthoxylum chalybeum Engl. (Rutaceae) Seed Alkaloid Skimmianine Ugandan plants showed anti-microbial activity by agar well assay and anti-fungal activity. Its mode of action is unclear from these results. Olila et al. (22)
Hydrastis canadensis L. (Ranunculaceae) Whole plant Alkaloid Berberine-etrahydroberberine and 8-oxoberberine Chinese herb-exhibited vasodilator activity has been attributed to multiple cellular mechanisms. And its derivatives are attributed to the blockade of K+ channels [delayed rectifier and K (ATP)] and stimulation of Na+–Ca (2+) exchanger. Lau et al. (23)
Zingiber officinale Rosc (Gingiberaceae) Rhizome Polyphenolics 6-,8-,10-gingerol and 6-shogoal The gingerols inhibit the growth of H. pylori CagA+ strains in vitro at 6.25–50 µg/ml. Mahady et al. (24)
Boswellia serrata Roxb. (Burseraceae) Gum resin Pentacyclic triterpenes Boswellic acids Boswellic acids inhibit the leukotriene biosynthesis in neutrophilic granulocytes by a non-redox, non-competitive inhibition of 5-lipoxygenase. Ammon (25)
Bougainvillea xbuttiana (Nyctaginaceae) Leaf Proteins Lysine The inhibitor showed N-glycosidase activity on 25S rRNA of tobacco ribosomes, which interfered with virus multiplication through ribosome interaction. Narwal et al. (26)

[TableWrap ID: T2] Table 2. 

Different types of organic solvents are used for the extraction of active compounds


Acetone Chloroform Diethyl ether Ethanol Hexane Methanol Petroleum ether Water
Flavonols (80), alkaloids (33), naphthol, glucoside (81), Terpenoids (82), flavonoids (83), steroids (74), ursolic acid Alkaloids, terpenoids, fatty acids (84) Alkaloid (22), tannins, flavonol, terpenoid, sesquiterpenes (85), sterols, polyphenols, aporphine alkaloids (21) Carvacrol (86), carvacrol (86) Terpenoids, flavonnes, polyphenols, tannins (68) Proanthocyanidin (69), tannins (70) Anthrocyanins (87), tannins (61), saponins (88), glygosides (74)


Article Categories:
  • Reviews

Keywords: ethnopharmacology, human clinical trails, phytochemicals, secondary metabolites, traditional medicine.

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