Buddleja species play a minor role in the ethnopharmacology of several areas of the world where they are indigenous. Phytochemical investigation of the genus has been somewhat neglected but a picture is emerging of the type of constituents which are present in reasonable quantities, namely iridoid and flavonoid glycosides. Many of the uses of Buddleja in folk medicine such as a topical antiseptic and a diuretic can be partially explained at least by the known biological activity of compounds identical or similar to those found in the genus. Other reputed uses are, as yet, without explantation due to the incomplete state of knowledge of the chemistry and, to an even greater extent, the pharmacology of Buddleja.
Extracts of six selected Malaysian plants with a reputation of usefulness in treating diabetes were examined for alpha-amylase inhibition using an in vitro model. Inhibitory activity studied by two different protocols (with and without pre-incubation) showed that Phyllanthus amarus hexane extract had alpha-amylase inhibitory properties. Hexane and dichloromethane extracts of Anacardium occidentale, Lagerstroemia speciosa, Averrhoa bilimbiPithecellobium jiringa and Parkia speciosa were not active when tested without pre-incubation. Extraction and fractionation of Phyllanthus amarus hexane extract led to the isolation of dotriacontanyl docosanoate, triacontanol and a mixture of oleanolic acid and ursolic acid. Dotriacontanyl docosanoate and the mixture of oleanolic acid and ursolic acid are reported from this plant species for the first time. All compounds were tested in the alpha-amylase inhibition assay and the results revealed that the oleanolic acid and ursolic acid (2:1) mixture was a potent alpha-amylase inhibitor with IC(50)=2.01 microg/ml (4.41 microM) and that it contributes significantly to the alpha-amylase inhibition activity of the extract. Three pure pentacyclic triterpenoids, oleanolic acid, ursolic acid and lupeol were shown to inhibit alpha-amylase.
Dichloromethane extracts of the stembark and root of Oroxylum indicum were found to have antimicrobial activities against Gram positive bacteria (Bacillus subtilis and Staphylococcus aureus), Gramnegative bacteria (Escherichia coli and Pseudomonas aeruginosa) and a yeast (Candida albicans). Bioassay-guided chromatographic fractionation led to the isolation of flavonoids (bacailein and chrysin) and a naphthoquinone, lapachol. Lapachol was found active against the Gram-positive bacteria, 5 μg giving a zone of inhibition equivalent to that shown by 5 μg streptomycin, whereas 5 μg chrysin gave inhibition zones of equal size to 5 μg streptomycin against Candida albicans and Pseudomonas aeruginosa. The inhibitory activity of lapachol from O. indicum root against soya 5-lipoxygenase (IC(50) 0.79 μg/ml) was equivalent to that of the positive control fisetin (IC(50) 0.97 μg/ml) and 50 μg/ml of the dichloromethane extract of the rootbark gave 100% inhibition of leukocyte lipoxygenase. These activities might indicate an antiinflammatory effect for the dichloromethane extract, mainly due to the lapachol content.
Dichloromethane extracts of the root bark and stem bark of Kigelia pinnata collected from Zimbabwe exhibited antitrypanosomal activity against Trypanosoma brucei brucei in vitro. Activity-guided fractionation led to the isolation of four naphthoquinones from both the root and stem bark of the plant. The compounds were identified as 2-(1-hydroxyethyl)-naphtho[2,3-b]furan-4,9-quinone (1), isopinnatal (2), kigelinol (3), and isokigelinol (4). Subsequently, the compounds were assessed for antitrypanosomal activity against T. brucei brucei and T. brucei rhodesiense bloodstream form trypomastigotes in vitro. Compound 1 with a furanonaphthoquinone structure was found to possess pronounced activity against both parasites with IC50 values of 0.12 and 0.045 microM, respectively, although it was less active than the standard drug pentamidine. Compounds 2, 3, and 4 also exhibited activity against the parasites, although to a lesser extent. The activities of the compounds were further assessed by comparison with the cytotoxic activities obtained against KB cell lines.
Eurycomanone is a cytotoxic compound found in Eurycoma longifolia Jack. Previous studies had noted the cytotoxic effect against various cancer cell lines. The aim of this study is to investigate the cytotoxicity against human hepato carcinoma cell in vitro and the mode of action. The cytotoxicity of eurycomanone was evaluated using MTT assay and the mode of cell death was detected by Hoechst 33258 nuclear staining and flow cytometry with Annexin-V/propidium iodide double staining. The protein expression Bax, Bcl-2, p53 and cytochrome C were studied by flow cytometry using a spesific antibody conjugated fluorescent dye to confirm the up-regulation of p53 and Bax in cancer cells.