Chemical characterization, antioxidant capacity and antimicrobial activity against food related microorganisms of essential oil from Mentha requienii Bentham

Mentha requienii Bentham (M. requienii) is an endemic Sardinian-Corsican species described for the first time by Valsecchi in the late 1983. It is a species that acts as a link between M. pulegium and a small group of mint species that grows in Australia and New Zealand. M. requienii is considered a paleoendemism because of its morphological isolation and lack of clear similarities with other species of the genus (Valsecchi et al. 1983). It grows wild in wet places along water-courses, rocky ravines, meadows, extending in particular areas submontane and montane and is one of the two Mentha species (M. gattefossei and M. requienii) that need special attention from the conservation point. The main components of the essential oil produced by M. requieni Bentham are similar to the main components of the so called ‘pennyroyal oil’ that is produced by M. pulegium. The chemical composition of both mints essential oils is complex with pulegone, as the dominant component (73-77%) in their chemical compositions. Despite the great number of studies of the more common M. pulegium, little is known as regard of the antimicrobial and antioxidant activity of the essential oil extracted from M. requienii. Previous studies (Chessa et al. 2012) evidenced very good activities against pool of moulds and Aspergillus fumigatus, and fairly high in Rhotodorula spp., Candida albicans, Fusarium spp. and Alternaria spp. In view of the above, herein we studied the essential oil of wild M. requienii collected in Sardinia. The essential oil was submitted to GC-MS and GC-FID analysis in order to obtain qualitative and quantitative data. Its antioxidant activity has been evaluated by means of two protocols namely, DPPH and ABST assays. Furthermore the antimicrobial activity of essential oil from M. requienii was assayed against foodborne microorganisms. The results were finally compared to those obtained on the essential oil extracted from M. pulegium collected in Sardinia. Our results suggest that essential oil from M. requienii is a promising natural additive to preserve food.