African Journal of Biotechnology Vol. 6 (14), pp. 1690-1696, 18 July 2007 Available online at http://www.academicjournals.org/AJB ISSN 1684–5315 © 2007 Academic Journals Full Length Research Paper Preliminary phytochemical and antimicrobial screening of 50 medicinal plants from Nigeria D. Kubmarawa1*, G. A. Ajoku2, N. M. Enwerem3 and D. A. Okorie4 1 Department of Chemistry, Federal University of Technology, P. M. B. 2076, Yola, Adamawa State, Nigeria. Department of Pharmaceutical Microbiology, National Institute for Pharmaceutical Research and Development Abuja, Nigeria. 3 Department of Medicinal Plant Research and Traditional Medicine, National Institute for Pharmaceutical Research and Development, Abuja, Nigeria. 4 Department of Chemistry, University of Ibadan, Ibadan, Nigeria. 2 Accepted 15 June, 2007 Ethanolic extracts of 50 plant species were screened for their antimicrobial activity against Bacillus subtilis, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. The results indicated that of the 50 plant extracts, 28 plant extracts inhibited the growth of one or more test pathogens. Four plant extracts showed a broad spectrum of antimicrobial activity. Phytochemical investigation revealed the presence of tannins, saponins, alkaloids, glycosides, flavonoids and essential oils. Key words: Medicinal plant, antimicrobial activity, phytochemical, ethnomedicinal. INTRODUCTION Medicinal plants represent a rich source form which antimicrobial agents may be obtained. Plants are used medicinally in different countries and are a source of many potent and powerful drugs (Srivastava et al., 1996). The interest in the scientific investigation of these 50 medicinal plants from Nigeria is based on the claims of their effective use for the treatment of many diseases. Therefore, research into the effects of these local medicinal plants is expected to enhance the use of these plants against diseases caused by the test pathogens. However, most of these plants used in folk medicine have not been screened for their antimicrobial activity. The active principles of many drugs found in plants are secondary metabolites (Ghani, 1990; Dobelis, 1993). Therefore, basic phytochemical investigation of these extracts for their major phytoconstituents is also vital. In the present study, the ethanolic extracts from 50 medicinal plants were screened for phytochemical constituents and antimicrobial activity against Staphylococus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Candida *Corresponding author. E-mail: dkubmarawa@yahoo.com albicans and Escherichia coli. MATERIALS AND METHODS Plant material Plants used for this study were collected in July 2001 at Riji in Adamawa State of Nigeria. All the plants were identified at Forestry Research Institute, Ibadan where their voucher specimens are deposited (Table 1). Preparation of plant extracts The plant materials were dried at room temperature and then powdered using a grinder. A sample (200 g) of each powdered plant material was soaked in ethanol (200 ml) for 24 h. At the end of the extraction, each extract was filtered using Whatman filter paper. The filtrate was concentrated in vacuum at 30oC and stored at 4oC until further use. Phytochemical screening Phytochemical screening for major constituents was undertaken using standard qualitative methods as described by Odebiyi and Sofowora (1990) and Fadeyi et al. (1989). The plant extracts were Kubmarawa et al. 1691 Table 1. Phytochemical analysis of 50 medicinal plants. S/N 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12 13 14 15 Plant specie, voucher specimen number and family Acacia albida Del F.H.I. 36998 MIMOSOIDEAE Acadia nitolica (Gull & Par) Kuntze F.H.I. 51743 MIMOSOIDEAE Acacia sebriana DC F.H.I. 55744 MIMOSOIDEAE Acacia Senegal (Linn) Wild F.H.I. 93790 MIMOSOIDEAE Acacia tortilis (Forssk) Hayne F.H.I. 23330 MIMOSOIDEAE Adansonia digitata Linn F.H.I. 89479 BAMBACACEAE Afromosia laxiflora Ex. BAK F.H.I. 50890 PAPILIONOIDEAE Afzelia africana sm F.H.I. 40391 CAESALPINIOIDEAE Amblygonocarpus andogenesis (Welv ex. div) F.H.I. 43238 MIMOSOIDEAE Anogeissus leiocarpus DC F.H.I. 16303 COMBRETACEAE Anona senegalensis Pers F.H.I. 66372 COMBRETACEAE Aristolochia albida Ducha F.H.I. 96082 ARISTOLOCHIACEAE Balanites aegyptiaca Ducha F.H.I. 94010 BALAITACEAE Boswellia dalzielii Hutch F.H.I. 42474 BURSERACEAE Butyrospermum paradoxum (Gaertn.f.) F.H.I. 83524 SAPOTACEAE Phytocompounds Part used Traditional use S G T F A V SB Skin infections - - - - - + SB Sore throat - - + - - + RT Swellings + - + - - - SP Cough + + + - + + SB Cough + + + + + + AP Diarrhoea - - - - - - SB Tuberculosis + + - - - - RT Dysentry - - - - - - SB Breast cancer + + - - - - SB Diarrhoea and dysentery - - - + + - RT Tooth ache + - - - - - RT Malaria - - - + - - RT Swellings + - + - - + LF Laxative + + - + - + SB Diarrhoeae + + - - + - 1692 Afr. J. Biotechnol. Table 1. Contd. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. Callotropis procera R. Br. F.H.I. 83524 ASCLEPIADACEAE Cardiospermum grandiflorum Swantz F.H.I. 57861 SAPINDACEAE Ceiba pentandra (L.) F.H.I. 54404 BOMBACACEAE Combtretum mole R.Br. ex. G. DON F.H.I. 57804 COMBRETACEAE Commiphora kerstingii Engl F.H.I. 24484 BURSERACEAE Cyperus esculentus L. F.H.I. 94028 CYPERACEAE Danillia olivera (Rolf) Hutch & DALZ F.H.I. 46301 CAESALPINIOIDEAE Detarium macrocarpum Guill & part F.H.I. 95105 CAESALPINIOIDEAE Dichostachys cinera (Linn.) F.H.I. 28867 MIMOSOIDEAE Drospyros mespiliformis Ex A.DC F.H.I. 99329 EBENACEAE Ficus abotifolia (miq) miq F.H.I. 35928 MORACEAE Ficus platyphylla Del F.H.I. 37878 MORACEAE Ficus polita Vahl F.H.I. 12197 MORACEAE Ficus sycomorus Linn F.H.I. 106574 MORACEAE Ficus thoningii Blume F.H.I. 62204 MORACEAE LF Anti-scorpion bite + - + - + + FR Abortion - - - - - + AP Chest pain + - + - + + SB Diarrhoea + - + - - + SB Laxative + - + - - + TB Eye infection - - - - - + AP Tuberculosis + - - - + + SB Wound infection - - - - - + AP Chest pain + - + - - + SB Back pain - - + + - - SB Whitlow - - + - + + SB Tuberculosis + - - + + + SB Swellings + - - + - - SB Cough - + + + - + SB Sore throat + - - - - + Kubmarawa et al. 1693 Table 1. Contd. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40 41. 42. 43. 44. 45. Grewia venusta FRES F.H.I. 56066 TILIACEAE Haematotaphis barteri Hook F.H.I. 106576 ANACARDIACEAE Heeria insignis(Del) Kuntze F.H.I. 106581 ANARCARDIACEAE Isorberlinia doka Craib & Stapf F.H.I. 101396 CAESALPINIOIDEAE Isoberlinia tomentosa (Harms) Craib & Stapf F.H.I. 106578 CAESALPINIOIDEAE Jatropha curcas L. F.H.I. 99933 EUPHORBIACEAE Khaya senegalensis (Desr.) A. Juss F.H.I. 59961 MILLACEAE Nauclea diderichii (Dewild & Th. Dur) Merril F.H.I. 57253 RUBIACEAE Nauclea latifolia (Dewild & Th. Dur) merrill RUBIACEAE Parkia clapertonia Keay F.H.I. 18238 MIMOSOIDEAE Piliostigma reticulatum (DC.) Hochst F.H.I. 62529 CAESALPINIOIDEAE Sterculia setigera Del F.H.I. 88356 STERCULACEAE Strychnos spinosa Lam F.H.I. 35401 LOGANIACEAE Syzigium guineense DC F.H.I. 47959 MYRTACEAE Tamarindus indica Linn F.H.I. 10658 CAESALPINIOIDEAE SB Diarrhoeae + + + + + + AP Cancer - - + + - + FR Antivenom + - - - - - SB Cough + - - + + + SB Laxative - - - - - - RT Gonorrhoeae - - - - - - SB Skin infection + + - + - + SB Malaria - - - - - - SB Stomach ache + - - - - - SB Stomach ache - - - + - - RT Jaundice + - + + - - SB Diarrhoea + - - + + + SB Swellings + - - - - - AP Tuberculosis - - + + - + SB Sore throat + + - + - - 1694 Afr. J. Biotechnol. Table 1. Contd. 46. 47. 48. 49. 50. Terminalia avicenoides GULL & PARR F.H.I. 10462 COMBRETACEAE Vernonia amygdalina Del F.H.I. 31597 COMPOSITAE Vitex doniana SWEET F.H.I. 106580 VERBENACEAE Ximenia Americana Linn. F.H.I. 66336 OCACACEAE Zizyphus mauritiana Lam F.H.I. 94010 RHAMNACEAE RT Swellings + + + - + + LF Stomach ache - - - - - - SB Eye infection + - + - - + LF Tuberculosis - - + - - + SB Wound infection + + - + - - S =Saponins, G = glycosides, T = tannins, F = flavonoids, A = alkaloids, V= volatile oil, RT = roots, AP = aerial parts, LF = leaf, SB = stem bark, FR = fruits and TB = tubers. screened for the presence of glycosides, alkaloids, tannins, flavonoids, saponins and essential oils. Test organisms The strains used for the investigation were: B. subtilis, (NCTC 8236) E. coli, (ATCC 9637) S. aureus (ATCC 13709) P. aeruginosa (ATCC 27853) C. albicans (ATCC 10231) Antimicrobial activity The Agar dilution method was used to determine the antimicrobial activity. The nutrient agar used to dilute the sample solution to required concentration was inoculated by surface streaking using a wire loop with test organisms. The plates were kept overnight in the incubator at 37oC and observed for growth inhibition. Plates that had growth of the test organism inhibited at 2.0 mg/ml were further diluted in order to determine the minimum inhibitory concentrations (MIC). Minimum inhibitory concentration (MIC) The minimum inhibitory concentration (MIC) was observed after incubation at 37oC for 24 h. a 1:20 dilution was prepared in normal saline from the overnight culture of each test organism containing approximately 5 x 107 to 9 x 107 cfu/ml of nutrient broth before inoculation. The lowest concentration of the sample required to inhibit the growth of the test organism was recorded for each organism as the minimum inhibitory concentration (MIC). The extracts were dissolved in dimethyl sulfoxide (DMSO). RESULTS AND DISCUSSION Preliminary phytochemical investigation revealed the presence of saponins, glycosides, tannins, alkaloids, volatile oils and flavonoids, as indicated in Table 1. The results showed that Grewia venusta and Acacia tortilis demonstrated the presence of all phytocompounds tested. The presence of some of these compounds has been demonstrated previously by other researchers. For example, the presence of alkaloids in the stem bark of Sterculia setigera, and the absence of tannins in the stem bark of S. setigera has been demonstrated (El-kheir and Salim, 1980; Tona et al., 1998). Similarly the absence of alkaloids in the stem bark of Nauclea latifolia has also being demonstrated (El-kheir and Salim, 1980; Tona et al., 1998). However some of the results obtained are not in agreement with the previous findings. For example alkaloids were found to be absent in the stem bark of Anogeisus leiocarpus which is contrary to the findings of Baowa et al. (1978) and Atal et al. (1978). This might be due to climatic and environmental factors. The crude extracts of 50 medicinal plants were screened for their antimicrobial activity. Among the 50 plants tested 28 plants showed antimicrobial activity (Table 2). The minimum inhibitory concentration of 0.065 mg/ml was observed with crude extract of Anona seneglensis against B. subtilis. S. aureus was inhibited by nine plant extracts. The bacteria were most inhibited by the extract of A. tortilis, Afromosia laxiflora and Terminalia avicennoides at MIC values of 0.25 mg/ml. Similarly, E. coli were inhibited by nine plant extracts. A. tortilis and A. leiocarpus inhibited the growth of all of the microorganisms. These plant extracts have the broadest spectrum of inhibition. Similarly, A. laxilflora inhibited the growth of all the bacteria tested, except the fungus C. albicans. The antimicrobial activity of some of these plants has been studied previously. The ethanol extracts of the stem bark of Acacia albida (Legrand et al., 1988) was found to Kubmarawa et al. Table 2. Antimicrobial activities of the 50 medicinal plants. S/No. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45 46. 47. 48. 49. 50. Plant species Acacia albida Acacia nilotica Acacia sebriana Acacia Senegal Acacia tortilis Adansonia digitata Afromosia laxiflora Afzelia africana Amblygonocarpus andogenesis Anogeissus leiocarpus Anona senegalensis Aristolochia albida Balanites aegyptiaca Boswellia dalzielii Butyrospermum paradoxum Callotropis procera Cardiospermum grandiflorum Ceiba pentandra Combretum mole Commiphora kerstingii Cyperus esculentus Danillia olivera Detarium macrocarpum Dichostachys cinera Drospyros mespiliformis Ficus abotifolia Ficus platyphylla Ficus polita Ficus sycomorus Ficus thoningii Grewia venusta Haemtotaphis barteri Heeria insignis Isoberlinia doka Isoberlinia tomentosa Jatropha curcas Khaya senegalensis Nauclea diderichii Nauclea latifolia Parkia clapertonia Piliostigma reticulatum Sterculia setigera Strychnos spinosa Sysigium quineense Tamarindus indica Terminalia avicenoides Vernonia amygdalina Vitex doniana Ximenia Americana Zizyphus mauritiana Ca 0.50 0.50 0.25 0.125 2.0 1.0 1.0 1.0 2.0 - MIC (mg/ml) Sa Ps Bs 0.50 1.0 2.0 2.0 2.0 2.0 0.25 2.0 2.0 0.25 2.0 0.25 2.0 0.50 2.0 1.0 0.0635 1.0 0.50 1.0 0.50 0.50 1.0 2.0 0.50 1.0 0.50 1.0 1.0 0.50 1.0 0.50 2.0 0.50 0.50 2.0 1.0 1.0 0.25 2.0 1.0 2.0 0.50 2.0 2.0 1.0 0.50 Ec 2.0 2.0 1.0 1.0 0.50 2.0 1.0 1.0 1.0 1.0 2.0 2.0 - - = No activity, M.I.C. = minimum inhibitory concentration, Ca = Candida albicans (ATCC 10231), Sa = Staphlococcus aureus (ATCC 13709), Ps = Pseudomonas aeruginosa (ATCC 27853), Ec = Escherichia coli (ATCC 9637), and Bs = Bacillus subtilis (NCTC 8236). 1695 1696 Afr. J. Biotechnol. inhibit the growth of S. aureus and B. subtilis. The present finding on the extracts of A. albida is in agreement with the previous workers. Also, the ethanol extracts the root of Balanites aegyptiaca (Liu and Nakanishi, 1982) and the aerial parts of Danillia olivera (Awachic and Ugwu, 1997) was found to inhibit the growth of B. subtilis, while in the present study, both the extracts indicated no activity. These differences might also be attributed to the changes in environmental conditions. The results obtained indicated the existence of antimicrobial compounds in the crude ethanolic extracts of these plants and some showed a good correlation between the reported use of these plants in traditional medicine against infectious diseases. For example the inhibition of E. coli by the extract of A. leiocarpus, Botrychium paradoxum, Commiphora kerstingii, Ficus thoningii and G. venusta has justified their use for the treatment of diarrhea and dysentery in the traditional medicine. Conclusions This study is a preliminary evaluation of antimicrobila activity of the plants. It indicates that several plants have the potential to generate novel metabolites. The crude extracts demonstrating anticandidal activity could result in the discovery of novel anticandidal agents. Similarly the plants demonstrating broad spectra of activity may help to discover new chemical classes of antibiotics that could serve as selective agents for the maintenance of health. REFERENCES Atal CK, Srivastava JB, Wali BK, Chakravarty RB, Dhawan BN, Rastong KP (1978). Screening of Indian Plants for Biological activity part III, Indian J. Exp. Biol. 16: 330-349. Awachic PIA, Ugwu, FO (1997). 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