Fatty Acid Composition, Antioxidant, Anticholinesterase and Tyrosinase Inhibitory Activities of Four Serratula Species from Anatolia

Serratula L. (Astareceae) rich in ecdysteroid, phytoecdysteroids and flavonoids some have various biological activities including antibacterial and antitumor. The fatty acid profiles of four Serratula species were investigated by using GC and GC-MS techniques. Palmitic, oleic, linoleic and linolenic acids were found to be the main fatty acids. The unsaturation percentage was between 27.24-50.47%. The antioxidant activity of the extracts was determined by using four complementary tests; namely, beta-carotene-linoleic acid, DPPH center dot scavenging, CUPRAC and ferrous-ions chelating assays. The methanol extract of S. lasiocephala showed the highest activity in beta-carotene-linoleic acid, DPPH center dot scavenging and CUPRAC assays, while the hexane extract of S. radiata exhibited the best metal chelating activity. In addition, total phenolic and total flavonoid contents in the extracts were determined as pyrocatechol and quercetin equivalents, respectively. The in vitro anticholinesterase activity of extracts were tested against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) which are the key enzymes taking place in pathogenesis of Alzheimer's disease. Besides, the extracts were tested in vitro against tyrosinase enzyme which is associated with melanin hyperpigmentation. Except the hexane extracts of S. radiata and S. lasiocephala, the extracts showed moderate inhibition against AChE and BChE, while the only hexane extract of S. erucifolia and methanol extract of S. radiata exhibited tyrosinase inhibitory activity.