Antibacterial, antioxidant, anti-cholinesterase potential and flavonol glycosides of Biscutella raphanifolia (Brassicaceae)

Abstract

Different extracts of the aerial parts of Biscutella raphanifolia (Brassicaceae), which has not been the subject of any study, were screened for the phytochemical content, anti-microbial, antioxidant and anti-cholinesterase activities. We used four methods to identify the antioxidant activity namely, ABTS(.+), DPPH. scavenging, CUPRAC and ferrousions chelating methods. Since there is a relationship between antioxidants and cholinesterase enzyme inhibitors, we used two methods to determine the in vitro anti-cholinesterase activity by the use of the basic enzymes that occur in causing Alzheimer's disease: acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The extracts were also tested in vitro antimicrobial activity against various bacteria. The phytochemical study of B. raphanifolia afforded four flavonol glycosides; namely, quercetin-3-O-beta-D-glucoside, quercetin-3-O[beta-D-glucosyl(1 -> 2)-O-beta-D-glucoside], quercetin-30-[beta-D-glucosyl(1-6)-0-beta-D-glucoside] and kaempferol-3-04,6-D-glucosyl(1--2)-k6'"p-coumaroy1)-fl-D-glucoside], being isolated here for the first time from Biscutella raphanifolia and the genus. The ethyl acetate extract showed the highest activity in ABTS.+, DPPH" and CUPRAC assays, while the petroleum ether extract demonstrated optimum efficiency metal chelating activity. The dicloromethane and petroleum ether extracts showed a mild inhibition against AChE and BChE. However, the petroleum ether extract showed a good antibacterial activity against the pathovars Enteropathogenic E. coli (EPEC), Enterotoxigenic E. coli (ETEC) and Enterococcus feacalis, whereas the Entero hemorrhagic E. coli (EHEC) strain was more sensitive to dichloromethane and n-butanol extracts.