Chemical composition and biological activity of pennyroyal (Mentha pulegium L.) grown in Turkey

The chemical composition of the pennyroyal (Mentha pulegium L.) essential oil and extracts, grown in Turkey has been determined. The major components of essential oil (0.37%) obtained by hydrodistillation was found to be oxygenated monoterpenes cis-piperitone epoxide (32.04%) and piperitenone oxide (31.90%). Extracts obtained with 95 and 70% ethanol were also obtained from the pennyroyal leaves which determined the total polyphenol content expressed in gallic acid equivalents (GAE) per gram dry extract weight (dw) and the total flavonoid content expressed as quercetin equivalent (QE) per gram dw. Their content in the extract with 95% ethanol is 20.62 mg GAE/g dw and 5.92 QE/g dw respectively, and in the extract with 70% ethanol 32.55 mg GAE/g dw and 7.75 QE/g dw respectively. The antioxidant activity of the pennyroyal extracts was determined by the method of 2,2-diphenyl-1-picrylhydra-zyl (DPPH) and a modified method of cupric reducing antioxidant capacity (CUPRAC). The antioxidant activity of 95% ethanol extract is 557.74 mM Trolox® equivalent (TE)/g dw (CUPRAC) and 242.36 mM TE/g dw (DPPH). The 70% ethanol extract showed higher levels of antioxidant activity, the highest being reported in the CUPRAC method (1100.61 mM TE/g dw). The dry leaves are also determined for their content of chlorophyll and carotenoids.