Antibacterial, antioxidant, and phytochemical analysis of Piper longum fruit extracts against multi-drug resistant non-typhoidal Salmonella strains in vitro

Most bacteria are becoming resistant to almost all of the currently recommended drugs, leading to difficulty in their treatment. The present study focused on evaluating the therapeutic potential of Piper longum fruit extracts in terms of bactericidal, antioxidant and phytochemical evaluation by conducting antibacterial sensitivity tests against four multidrug-resistant Salmonella strains (Salmonella enterica subsp. arizonae, Salmonella Newport, Salmonella enterica ser. Typhi, and Salmonella enterica ser. Paratyphi) obtained from the Institute of Microbial Technology (IMTECH), Chandigarh. The Agar Well Diffusion method and the Minimum Inhibitory concentration (MIC) methods were performed to implement the anti-sensitivity test of crude extracts of the plant. The present study showed that the MIC of the P. longum  was between 0.25-0.0625mg/ml, which was lowest in the aqueous extract at 0.5mg/100µl, and the highest in the methanol extract (1mg/100µl). The Minimum Bactericidal Concentration (MBC) was lowest in aqueous (0.5mg/100µl) and highest in methanol plant extract (1mg/100µl). The methanol extract had the maximum antibacterial potency, whereas the aqueous extract had the lowest. The antioxidant capacity of the plant extracts was determined using a DPPH assay. Methanol plant extract revealed the highest antioxidant power (81.92%) and the lowest was found in the aqueous extract (62.84%). The GC-MS approach identified active bioingredients, important botanicals including caryophyllene, eicosane, and piperazine (potent antibacterial agent) as naphthyridine (having antimicrobial, anticancer, and anti-inflammatory activities), among others. The unique aspect of the study was the effectiveness of P. longum against Salmonella strains that are resistant to multiple antibiotics. This suggests that P. longum can be a great source of novel antibacterial compound for the development of herbal formulations.