Bioassay-guided discovery of antibacterial agents: in vitro screening of Peperomia vulcanica, Peperomia fernandopoioana and Scleria striatinux

• Published in: Annals of clinical microbiology and antimicrobials 2012-05, Vol.11 (1), p.10-10, Article 10
• Main Authors: Mbah, James A, Ngemenya, Moses N, Abawah, Ashime Louis, Babiaka, Smith B, Nubed, Lina N, Nyongbela, Kennedy D, Lemuh, Njimoh Dieudonne, Efange, Simon M N
• Format: Article
• Language: English
• Subjects: Animals; Anti-Bacterial Agents - isolation & purification; Anti-Bacterial Agents - pharmacology; Anti-Bacterial Agents - toxicity; Antibacterial agents; Antibacterial compound; Bacterial infections; Biological Assay; Cell Line; Cells; Cyperaceae - chemistry; Disk Diffusion Antimicrobial Tests; Drug Discovery; Drug resistance in microorganisms; Drug Resistance, Multiple, Bacterial; Drug therapy; Escherichia coli; Female; Gram-Negative Bacteria - drug effects; Gram-Negative Bacteria - growth & development; Gram-Positive Bacteria - drug effects; Gram-Positive Bacteria - growth & development; Health aspects; Infection; Lead compounds; Lethal Dose 50; Male; Materia medica, Vegetable; Medicinal plants; Medicine, Botanic; Medicine, Herbal; Methanol; Methylene Chloride; Mice; Mice, Inbred BALB C; Peperomia - chemistry; Plant extracts; Plant Extracts - isolation & purification; Plant Extracts - pharmacology; Plant Extracts - toxicity; Resistance; Sesquiterpenes - isolation & purification; Sesquiterpenes - toxicity; Toxicity
• ISSN: 1476-0711; 1476-0711
• DOI: 10.1186/1476-0711-11-10

The 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. Crude 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. The 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. The 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.