Journal of Ethnopharmacology 78 (2001) 119 – 127 Evaluation of extracts of the root of Landolphia owerrience for antibacterial activity M.I. Okeke a , C.U. Iroegbu a, *, E.N. Eze a , A.S. Okoli a , C.O. Esimone b a Department of Microbiology, Uniersity of Nigeria, Nsukka, Enugu State, Nigeria b Department of Pharmaceutics, Uniersity of Nigeria, Nsukka, Enugu State, Nigeria Received 10 May 2000; received in revised form 4 June 2001; accepted 29 June 2001 Abstract Ethanolic and aqueous (cold and hot) extracts of Landolphia owerrience root parts (whole-root, root-bark and root-wood) were tested for activity against ten bacterial strains using agar-well diffusion and macro-broth dilution methods, respectively. The ethanolic extracts of the whole-root and root-wood were active against 100 and 80% of the test organisms, respectively. Ethanolic and aqueous extracts of the root-bark were moderately active while the aqueous (cold and hot) extracts of the root-wood exhibited little or no activity. Out of the nine extracts prepared, 66.7% were active against Staphylococcus aureus ATCC 12600, 55.6% variously against each of Pseudomonas aeruginosa ATCC 10145 and local clinical isolates of P. aeruginosa, S. aureus, Escherichia coli and Salmonella typhi, 44.4% against Proteus sp., 33.3% against Bacillus subtilis ATCC 6051 and 22.2% against E. coli ATCC 11775. The agar-well-determined MIC values for the ethanolic whole-root extract (0.78 – 50 mg/ml) were higher (indicating lower activity) than the corresponding macro-broth-determined values (0.39 – 50 mg/ml) probably because of slow diffusion rates of the active constituents of the extract in agar. On the other hand, the differences could be due to the effects of DMSO used to dissolve the ethanolic extracts in the agar-well diffusion tests. Similar discrepancies in the MIC values detectable with the two test methods were apparent in the root-wood extract and the control drug, Gentamycin, except that in the latter the agar-well-determined MIC values (0.125 – 8.0 g/ml) were lower than the macro-broth-determined values (0.125 – 64 g/ml). The strong activity of the ethanolic extracts against known etiologic agents of diseases traditionally treated with L. owerrience root of similar preparations provides scientific justification for the use of the herb in ethnomedical practice in Nigeria. © 2001 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Landolphia owerrience ; Root parts; Antibacterial activity; Ethnomedicine; Nigeria www.elsevier.com/locate/jethpharm 1. Introduction Landolphia owerrience, family Apocynaceae, (Igbo: Utu ) has widely varied applications in Nigerian folk medicine. Many herbalists have claimed to use the leaves and stem-bark as a colic and in treatment of venereal diseases (Watt and Breyer-Brandwijk, 1962; Ebi and Ofoefule, 1997). The whole root, root-bark and root-stem have also been reported to be effective in treatment of wound infections and various gastrointes- tinal disorders, including diarrhoea, food poisoning, constipation and typhoid fever. Most of the folkloric claims agree in the traditional use of the herb for treatment of diseases of known bacterial aetiology. However, except for the report of Ebi and Ofoefule (1997) that a methanolic extract of the leaves exhibited anti-microbial properties, there is apparently no scien- tific report on the antibacterial properties of the plant. Such lack of scientific knowledge has often constituted a major constraint to consideration of the use of tradi- tional herbal remedies in conjunction with or as an affordable alternative to orthodox medical treatment. This work is part of a comprehensive project to evaluate the therapeutic potentials of Nigerian herbs with a view to conserving and developing them and exploring their potential to application in orthodox medical practice. Thus, the extracts of root parts of L. owerrience were quantitatively evaluated for activity against ten bacterial strains, including four from the American Type Culture Collection (ATCC); one serotyped local Salmonella strain and five other local clinical isolates. * Corresponding author. 0378-8741/01/$ - see front matter © 2001 Elsevier Science Ireland Ltd. All rights reserved. PII:S0378-8741(01)00307-5