Phytochemical characterization, antioxidant and alpha- and beta-glucosidase inhibitory potential of Satureja khuzestanica leaf traditional herbal preparations

Satureja khuzestanica Jamzad is a popular herbal medicine among the nomadic inhabitants of southwestern Iran as a dental anesthetic and oral antiseptic [1]. Essential oil composition has been already determined and carvacrol identified as the main constituent [2]. Different biological studies were performed using the essential oil but studies related to quality; safety and efficacy of the leaf traditional herbal preparations (THPs, infusion and decoction) were scarce. Hereby results concerning the chemical characterization together with antioxidant and α- and β-glucosidase inhibitory potential of these THPs are presented. Chemical analyses were performed using different phytochemical methods, including TLC, LC-UV/DAD and preparative CC. The THPs total phenolic content was also determined. α- and β-glucosidase inhibitory activity and DPPH free radical scavenging potential were evaluated by bioautographic method [3, 4]. This last activity was also evaluated by spectrophotometry. Results of the TLC and LC-UV/DAD screening were consistent with presence of phenolic compounds, namely phenolic acids, flavonoids (flavones) and condensed tannins. Bioautographic analyses revealed the presence of free radical scavengers as well as α- and β-glucosidase inhibitors in both THPs and also in infusion liquid-liquid (L-L) partition fractions. Among all, 3 compounds of the ethyl acetate infusion L-L fraction were isolated and identified as cirsilineol, diosmetin and 6-hydroxyluteolin 7,3'-dimethyl ether according to UV, 1 H-NMR and 13C-NMR spectral data in comparison with the literature. In conclusion, non-volatile compounds like flavones and phenolic acid derivatives were detected and quantified for the first time in S. khuzestanica leaf and might be responsible for the antioxidant/anti-inflammatory and anti-diabetic activities traditionally referred to this medicinal plant.