Flavonol Glycosides from Convolvulus supinus and Their Antioxidant Activity

Abstract

Convolvulus is a fairly large genus with 250 species, almost cosmopolitan in distribution 1. Various biological activities such as anticancer [2], antinociceptive [3], antidiarrhea [4], and antifungal [5] have been reported for Convolvulus species, which are characterized by the presence of phenolic compounds and alkaloids [6–9]. Algerian flora is represented by 17 species [10]. We have been interested in the phytochemical study and antioxidant activity of the endemic species Convolvulus supinus Coss. & Kralik (Convolvulaceae). Aerial parts (1.5 kg) of Convolvulus supinus were macerated in a methanolic solution (80%) at room temperature. The extract was concentracted under low pressure, diluted with water, and filtered, then successively extracted with dichloromethane, ethyl acetate, and n-butanol. The butanolic extract (12 g) was column chromatographed on polyamid SC 6 , eluting with toluene–methanol with increasing polarity. A total of 103 fractions was obtained and combined into 19 main fractions (according to the number, color, and R f of the sports). Fraction F-9 was separated by column chromatography on silica gel and eluted with an isocratic system of EtOAc–MeOH–H 2 O (10:1:0.5) to afford compounds 1 and 2. Fraction F-14 was subjected to column chromatography on silica gel and eluted with an isocratic system of EtOAc–MeOH–H 2 O (10:1:1.5) to yield compound 3. These compounds were identified by the use of spectral methods: UV, 1 H NMR, and 13 C NMR in addition to acid hydrolysis.