Isolation of potential liver x receptor alpha agonist and antioxidant compounds from Hypericum microcalycinum Boiss. & Heldr.

Abstract

Background and Aims: Hypericum microcalycinum Boiss. & Heldr. is used for inflammatory diseases in Anatolia. The involvement of liver X receptors (LXRs) and free radicals in inflammatory diseases, activation of LXRs, and high radical contents in cancerous tissue and organs prompted us to determine the radical scavenging and LXRα agonist activity of aqueous fraction of methanol extract and fractions of H. microcalycinum along with the isolation studies from active fractions. Methods: Isolation studies were carried out on chromatographic techniques. DPPH, NO, and SO radical scavenging activity methods were used for the determination of antioxidant activity, and a LXRE reporter gene assay was used for the determination of LXRα agonist activity. Results: While the extract showed weak LXRα agonist activity, phenolic compounds- rich fractions showed moderate activity. DPPH radical scavenging capacities of the extract and some fractions seemed to be very high as well as some isolated compounds. Bioactivity- guided studies resulted in the isolation of catechin (1), epicatechin (2), apigenin-8-C-(2-O-acetyl)- glucopyranoside (3), quercetin-3-O-β-glucopyranoside (4), quercetin-3-O-β-arabinopyranoside (5), kaempferol-3-O-βarabinopyranoside (6), luteolin-8-C-β-glucopyranoside (orientin) (7). Conclusion: According to our results, compounds 1, 2, 4, and 5 may be responsible for the anti-inflammatory effects of H. microcalycinum as a function of LXRα agonist and free radical scavenging effects.