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-g1ucoside, quercetin-3-O-[beta -D-glucosyl[1[right wards]2]-O- beta -D-glucoside], quercetin-3- O-[beta -D-glucosyl[1[right wards]3]-O- beta -D-glucoside] and kaempferol-3-O-[beta -D-glucosyl[1[right wards]2]-[[6'''p-coumaroyl]- beta -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 Enterohemorrhagic E. coli [EHEC] strain was more sensitive to dichloromethane and n-butanol extracts