In vitro Antioxidant and Antimycobacterial Activity of Seeds of Piper longum Linn: A comparative Study

Piper longum, belonging to the family Piperaceae, have been reported to have pharmacological and clinical importance. The present study was undertaken to compare the in vitro antioxidant and antimycobacterial activity of chloroform, ethyl-acetate, hexane, ethanol, hydro-ethanol and aqueous extracts of seeds of Piper longum in order to establish the most active extract for further study. All the six extracts were screened for antioxidant activity using in vitro screening models viz. scavenging activity of DPPH radical, nitric oxide, hydroxyl radical; reductive ability and ABTS assay. Ascorbic acid served as reference standard. The extracts were also screened for antimycobacterial activities against M. smegmatis in order to authenticate the folklore claims of its use against non tuberculous bacteria. Various plant secondary metabolites were found to be present in the extracts in different proportions. Mycobacterium smegmatis (non-tuberculous bacteria) was found to be sensitive against chloroform (PC), ethanol (PE), ethyl-acetate (PEA) and hexane (PH) extracts. The mean minimum inhibitory concentration (MIC) of different extracts were in the increasing order of PC>PE=PH>PEA. MIC of PC, PH, PE, PEA was found to be 8, 16, 16 and 32 mg/mL, respectively and minimum bactericidal concentration (MBC) was calculated as 20.23, 33.43, 36.23 and 64.09 mg/mL, respectively. Chloroform extract of Piper longum (PC) showed the highest in vitro antioxidant activity as well as antimycobacterial activity.