Assessment of cholinesterase and tyrosinase inhibitory and antioxidant properties of Viscum album L. samples collected from different host plants and its two principal substances

In the current study, the aqueous, dichloromethane, and methanol extracts of 12 samples of Viscum album L. collected on different host plants as well as two isolated compounds [syringin (VA-1) and 5,7-dimethoxyflavanone-4′-O-[5′′′-O-trans-cinnamoyl-β-d-apiofuranosyl]-β-d-glucopyranoside (VA-2)] were tested against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and tryosinase (TYRO) enzymes at 2000 μg/mL by ELISA microtiter plate assays. Antioxidant activity of the extracts and compounds was evaluated by six in vitro methods [2,2-diphenyl-1-picrylhydrazyl (DPPH), N,N-dimethyl-p-phenylendiamine (DMPD), and nitric oxide radical scavenging assays, metal-chelation capacity, ferric-(FRAP), and phosphomolibdenum-reducing antioxidant power (PRAP)]. Total phenolic and flavonoid contents of the extracts were determined using Folin-Ciocaltaeu's and AlCl3 reagents, respectively. None of the extracts had any marked inhibition against tyrosinase, while they exerted a low inhibition against AChE and BChE at 200 μg/mL. The aqueous and methanol extracts displayed a strong antioxidant activity in DPPH and DMPD radical quenching tests as well as FRAP and metal-chelation capacity assays.