Studies on antioxidant and antibacterial activities of crude extracts of Plantago lanceolata leaves

In this study, three different antioxidant activity quantification methods: 2,2-diphenyl-1-picrylhydrazyl radical scavenging (DPPH), reducing power, FRAP and peroxide value determination including total phenolic, TP, total flavonoid, TF assays of crude leaf extracts of Plantago lanceolata were carried out. The extracts showed significant activities in all antioxidant assays in a concentration dependent manner. The crude extracts were found to possess higher ferric reducing activity ranging from 336.58±0.052 mgAAE/100g (90% methanol) to 172.94±0.032 mgAAE/100g (petroleum ether) and DPPH activity varied from 90.6% (90% methanol) to 36.04% (petroleum ether). Strong correlation of TPC with AEACDPPH and AEACFRAP (R2 = 0.9033 and R2 = 0.8538 respectively) implied that compounds in the extract were proficient to scavenge the DPPH free radical and reducing ferric ions into ferrous ions. Moreover, peroxide values of the extracts were obtained and varied from 19.8 meq/kg (90% methanol) to 379 meq/kg(petroleum ether) and 3.1meq/kg (90% methanol) to 119 meq/kg (petroleum ether) at 70 oC and room temperature respectively. Therefore, P. lanceolata leaf extracts as compared to the control showed effective activity in delaying oxidation of the oil. Antimicrobial capacity evaluation of crude extracts against different gram-positive and gram-negative organisms was also evaluated and a higher degree of antimicrobial activity was observed of crude extracts with MIC and MBC values in the range of 6.25 to 25% were also observed for the crude extracts.