Antimicrobial Activities of the Extracts and Fractions of Allanblackia floribunda
ABSTRACT Allanblackia floribunda is a tree employed in Nigeria and other countries to treat skin disease and other microbial diseases. The ethanol extract, n-hexane, chloroform, ethyl acetate and butanol fractions of the leaves, stem bark and root bark were evaluated for antimicrobial activities against Staphylococcus aureus NCIB 8588, Bacillus subtilis NCIB 3610, Escherichia coli NCIB 86, Proteus vulgaris NCIB 67, Pseudomonas aeruginosa NCIB 950, Klebsiella pneumoniae NCIB 418, Candida albicans and Aspergilus flavus , using agar diffusion method to validate the ethnobotanical uses of the plant. Among the extracts, the ethanol extract of the leaf gave the most significant antibacterial activity. However, no extract showed antifungal activity. Generally, the fractions obtained from the extracts elicited better activity, including antifungal activity against C. albicans . The highest inhibitory effect was exhibited by leaf extract against Ps. aeruginosa NCIB 950, while the ethyl acetate fraction of the stem bark gave the least inhibitory effect against B. subtilis NCIB 3610. The plant extract and fractions produced inhibition zone range between 5 and 35 mm.
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ABSTRACT: Allanblackia floribunda Oliver (Guttiferae) is an African medicinal plant used traditionally to treat a variety of ailments. We investigated the antitumor, radical scavenging, antimycobacterial, antibacterial and antifungal activities of the root bark extract of A. floribunda and three isolated phenolics, namely 1,7-dihydroxyxanthone (1), morelloflavone (2) and 7'-O-glucoside of morelloflavone (3). The 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging assay was used for antioxidant tests, while crown gall tumor assay was used for assay of antitumor activity. The p-iodonitrotetrazolium chloride (INT) colorimetry and Microplate Alamar Blue Assay (MABA) were used for antimicrobial investigations. Moderate tumor reducing activity was observed with the extract, while better activities were recorded with compounds 2 and 3. The antimycobacterial and antitumor activities of the extract are being reported for the first time. The DPPH radical scavenging test showed that all the studied samples were able to scavenge more than 50% of the free radical, with compound 3 showing the best inhibitory activity (IC(50) of 49.08 µg/mL). Compounds 1 to 3 prevented the growth of Mycobacterium smegmatis and both extract and compound 2 were active on M. tuberculosis. The lowest MIC value for the extract (9.76 μg/mL) was recorded against Enterobacter aerogenes while the corresponding value for the compounds (4.88 µg/mL) was obtained with compound 2 on Trichophyton rubrum. The overall results of the present work provide baseline information for the potential use of the root bark extract of A. floribunda as an antimicrobial, antitumor and antioxidant phytomedicine.Pharmaceutical Biology 01/2011; 49(1):57-65. · 1.21 Impact Factor