Phytochemical Profiling, LC-MS Analysis, Anti-Melanogenic and Anti-Diabetic Potentials of an Unexplored Plant: <em>Euryops abrotanifolius</em>

Euryops abrotanifolius, commonly known as mountain resin bush, belongs to the Asteraceae family. Ethno-medicinally, it is used to treat chest ailments and as a general tonic for managing high blood pressure and diabetes. This research investigated the qualitative and quantitative metabolite profiling of methanolic extract from E. abrotanifolius using LC-MS and NMR and evaluates its anti-melanogenic and anti-diabetic potential as there has been no report on the phytochemistry as well as the mentioned inhibitory assays despite reports on some of its traditional uses. The air-dried plant material was macerated in 80 % aqueous methanol and fractionated with hexane, dichloromethane (DCM), ethyl acetate (EtOAc) and butanol (BuOH). LC-MS analysis led to the identification of 22 compounds in the methanolic extract. Additionally, three compounds were isolated for the first time from the plant and identified as ligularenolide (1), franchetianone B (2) and 1α-senecioyloxy-10β -hydroxyeremophil-7(11)-en-8α, 12-olide (3). The methanolic extract and the EtOAc soluble fraction showed favourable inhibitory activities against tyrosinase with IC50 values of 34.52 µg/mL and 53.26 µg/mL respectively, whereas the isolated compounds did not show any significant tyrosinase inhibitory activity. Despite reports of the plant being used traditionally for treating diabetes, the α-glucosidase and α-amylase inhibitory activities of the extracts and the isolated compounds did not substantiate this claim.