BackgroundThe global burden of bacterial infections is high and has been further aggravated by increasing resistance to antibiotics. In the search for novel antibacterials, three medicinal plants: Peperomia vulcanica, Peperomia fernandopoioana (Piperaceae) and Scleria striatinux (Cyperaceae), were investigated for antibacterial activity and toxicity.MethodsCrude extracts of these plants were tested by the disc diffusion method against six bacterial test organisms followed by bio-assay guided fractionation, isolation and testing of pure compounds. The minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations were measured by the microdilution method. The acute toxicity of the active extracts and cytotoxicity of the active compound were performed in mice and mammalian cells, respectively.ResultsThe diameter of the zones of inhibition (DZI) of the extracts ranged from 7–13 mm on Escherichia coli and Staphylococcus aureus of which the methylene chloride:methanol [1:1] extract of Scleria striatinux recorded the highest activity (DZI = 13 mm). Twenty-nine pure compounds were screened and one, Okundoperoxide, isolated from S. striatinux, recorded a DZI ranging from 10–19 mm on S. aureus. The MICs and MBCs indicated that the Peperomias had broad-spectrum bacteriostatic activity. Toxicity tests showed that Okundoperoxide may have a low risk of toxicity with an LC50 of 46.88 μg/mL.ConclusionsThe antibacterial activity of these plants supports their use in traditional medicine. The pure compound, Okundoperoxide, may yield new antibacterial lead compounds following medicinal chemistry exploration.
Chemical investigation of the methanol crude extract of dried flower buds of Syzygium aromaticum (Myrtaceae) resulted in the isolation of seven known compounds; oleanolic acid (1), lignoceric acid (2), β-sitosterol (3), heneicosanoic acid (4), 5-hydroxy-7-methoxy-2-methylchromone (5), 5-hydroxy-7-methoxy-2,8-dimethylchromone (6) and vanillin (7). Their structures were elucidated using one-dimensional NMR spectroscopy and comparison with literature data. The crude extract, and compounds 1-6, revealed significant anticonvulsant activities against seizures induced by picrotoxin, pentylenetetrazole and bicuculline, respectively in mice. Compound 3 produced 100% protection, compound 2, and 5; on the other hand, each offered 83.33%, while the lowest protection came from compounds 1, 4, and 6 (16.66 – 50 00 %). This is the first report on the anticonvulsant activity of these isolated compounds, and the first report on the isolation of compounds 2, 4, 5, 6, and 7 from Syzygium aromaticum.
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