Antimicrobial and antiplasmodial activities of a quaternary compound from Ritchiea capparoides var. longipedicellata.

UNLABELLED: The leaves of Ritchiea capparoides var. longipedicellata (Capparidaceae) is used in ethnomedicine in South-Western Nigeria to treat infectious and parasitic diseases. This study was aimed at identifying the compound(s) that are responsible for the antimicrobial and antiplasmodial activities of the leaves and also to contribute to the chemistry of the plant species. A 70 % aqueous ethanolic extract of the leaves of R. longipedicellata was subjected to repeated liquid chromatographic methods on silica gel, Lobar RP-18 column and Sephadex LH-20 to isolate a Draggendorf positive compound. The compound was identified by (1)H and (13)C NMR, ultra-violet spectroscopy and polarimetry. The antimicrobial activity of the compound was evaluated using the microbroth dilution method while the antiplasmodial activity was carried out according to Trager and Jenson (1976). The minimum inhibitory concentration (MIC) was expressed in mg/ml. The isolated compound, leavoisomer of stachydrine, inhibited the growth of Escherichia coli NCTC 8196 and Staphylococcus aureus NCTC 6571 at the MIC of 5 mg/ml. In the anti-malaria assay, the compound had inhibitory activity with the concentration required to cause 100% lethality being 0.667 mg/ml. CONCLUSION: The antibacterial and antiparasitic effects of quaternary ammonium compounds are well documented. However, this study is the first report of the presence and biological activities of this compound in this plant species which may justify the ethnomedicinal uses of the leaves.

Antimicrobial and Antioxidant Activities of Some Nigerian Medicinal Plants

Ten Nigerian plants suggested from their ethnomedical uses to possess antimicrobial and antioxidant activities were studied for their anti-microbial and anti-oxidant properties. Antimicrobial activity was tested against Escherichia coli NCTC 10418, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Candida albicans, Candida pseudotropicalis and Trichophyton rubrum (clinical isolate). Trichilia heudelotti leaf extract showed both antibacterial and antifungal activities and was the most active against all the strains of bacteria tested. Boerhavia diffusa, Markhamia tomentosa and T. heudelotti leaf extracts inhibited the gram negative bacteria E.coli and P. aeruginosa strains whereas those of M. tomentosa, T. heudelotti and Sphenoceutrum jollyamum root inhibited at least one of the fungi tested. At a concentration of 312 µg/ml, hexane and chloroform fractions of T. heudelotti extract inhibited 6 and 14% of the fifty mult-idrug resistant bacteria isolates from clinical infectins, respectively. At ≤ 5mg/ml, the CHCl3 (64%) and aqueous (22%) fractions of T. heudelotti and those of CHCl3 (34%) and EtOAC (48%) of M. tomentosa gave the highest inhibition that was stronger than their corresponding methanol extracts. The corresponding EC50 of the extracts on M. acuminata, T. heudelotti, E. senegalensis and M. tomentosa were 4.00, 6.50, 13.33, and 16.50 ig/ml using the TLC staining and 1,1-dipheyl-2-picry-hydrazyl (DPPH) free radical scavenging assay. Therefore, leaf extracts of M. tomentosa and T. heudelotti, especially the latter, possess strong antimicrobial and antioxidant activities and should be further investigated. These activities justified the ethnomedical uses of these plants

Antimicrobial and antioxidant activities of some Nigerian medicinal plants.

Ten Nigerian plants suggested from their ethnomedical uses to possess antimicrobial and antioxidant activities were studied for their anti-microbial and anti-oxidant properties. Antimicrobial activity was tested against Escherichia coli NCTC 10418, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Candida albicans, Candida pseudotropicalis and Trichophyton rubrum (clinical isolate). Trichilia heudelotti leaf extract showed both antibacterial and antifungal activities and was the most active against all the strains of bacteria tested. Boerhavia diffusa, Markhamia tomentosa and T. heudelotti leaf extracts inhibited the gram negative bacteria E. coli and P. aeruginosa strains whereas those of M. tomentosa, T. heudelotti and Sphenoceutrum jollyamum root inhibited at least one of the fungi tested. At a concentration of 312 microg/ml, hexane and chloroform fractions of T. heudelotti extract inhibited 6 and 14% of the fifty multi-drug resistant bacteria isolates from clinical infections, respectively. At < or = 5 mg/ml, the CHCl(3) (64%) and aqueous (22%) fractions of T. heudelotti and those of CHCl(3) (34%) and EtOAC (48%) of M. tomentosa gave the highest inhibition that was stronger than their corresponding methanol extracts. The corresponding EC(50) of the extracts on M. acuminata, T. heudelotti, E. senegalensis and M. tomentosa were 4.00, 6.50, 13.33, and 16.50 ig/ml using the TLC staining and 1,1-dipheyl-2-picry-hydrazyl (DPPH) free radical scavenging assay. Therefore, leaf extracts of M. tomentosa and T. heudelotti, especially the latter, possess strong antimicrobial and antioxidant activities and should be further investigated. These activities justified the ethnomedical uses of these plants.