Antioxidant, antibacterial, and antimutagenic activity of Piper nigrum seeds extracts

Piper nigrum is a widely used plant in traditional remedies and known for its numerous biological properties. However, fraction-based antioxidant activity and their antimutagenic potential are not yet fully investigated. Different extracts of the seeds P. nigrum were obtained by sequential extraction in different solvents. All extracts were evaluated for antibacterial and antioxidant activities using different methods. The most active fraction was analyzed for antimutagenic activity using the Ames Salmonella test. The antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) was found to be more prominent compared to ESβL producing Klebsiella pneumoniae isolates. The MIC values were found to be lower against MRSA than K. pneumoniae. The extract showing highest antioxidant activity (methanol extract) was further tested for antimutagenic activity both against direct and indirect-acting mutagens. A varying level of antimutagenic activity was shown by methanol extract at highest tested concentration (200 µg/plate). Alkaloids, phenols, and flavonoids were detected as major class of compounds in methanol extract. Gas chromatography-mass spectrometry (GC–MS) analysis showed the presence of various phytocompounds. Based on molecular docking of two major active phytocompounds (piperine and copaene), they were found to interact at the minor groove of DNA. Molecular dynamics (MD) simulation revealed that both the ligands were quite stable with DNA under physiological conditions. The ability of phytocompounds to interact with DNA might be reducing the interaction of mutagens and could be one of the possible mechanism of anti-mutagenic activity of P. nigrum extract. This study highlights the antioxidant and antimutagenic potential of Piper nigrum. The role of phytocompounds present in the bioactive extract is needed to be explored further for herbal drug research