Improving the bioactivity of medicinal plants using gamma radiation: Thymus vulgaris L. infusions as a case-study

The bioactive compounds present in medicinal plants have shown beneficiai effects in the prevention of various diseases due to their capacity to act positively in several biological mechanisms [1] with reduced adverse effects [2]. The aim of this work was to evaluate the effects of gamma radiation processing, at doses of 1 and 10 kGy, on antioxidant activity and phenolic composition of a medicinal plant used m traditional medicine - fhymus vulgaris L., and the results compared with the contrai sample (O kGy). After plants processing, an infusion was prepared, from irradiated and non-irradiated samples to evaluate antioxidant properties through: free radicais scavenging activity, reducing power and inhibition of lipid peroxidation in brain cell homogenates (TBARS assay) methods. And phenolic compounds were analysed by HPLC-DAD-ESI/MS. Com"paring'the results obtained for contrai (O kGy) and irradiated samples (at 1 and 10 kGy), it was evident that gamma irradiation at the dose of 10 kGy improved free radical scavenging actiyity, reducing power and lipid peroxidation inhibition capacity of the infusions (lower values of EÇso). RegardFng phenolics, thirteen compounds were detected in the infusions prepared either from irradiated or non-irradiated samples. However, the global phenolic profile was not changed. In this way, gamma radiation could be considered as a suitable treatment to be used in dried plants in particular, to improve bioactive properties of Thymus vulgaris L. related to its phenolic composition [3].Foundation for Science and Technology (FCT, Portugal) for financiai support to CIMO (PEst-OE/AGR/UI0690/2013), CTN (RECI/AAG-TEC/0400/2012), REQUIMTE (UID/QUI/50006/2013 - POCI/01/0145/ FERDER/007265) and L. Barms grant (BPD/107855/2015). The auíhors are also grateful to "MaisEn/as - Aromáticas e Medicinais" company for pmvidiry lhe samples.N/