Bioactivity based phytochemical studies on Scutellaria salviifolia Benth.

Genus Scutellaria (Lamiaceae), is widespread in all over the world, has 25 taxa in Turkey. Among them 14 taxa are endemic [1,2]. Scutellaria species and their active principles possess antitumor, anti-angiogenesis, hepatoprotective, antioxidant, anticonvulsant, antibacterial, and antiviral activities [1]. In this study, endemic S. salviifolia aqueous extract is evaluated for its liver X receptors (LXRs) ligand activity using a LXRα luciferase reporter assay, antioxidant activity on DPPH, NO, SO radicals and cytotoxic activity against HEp-2 cell line. LXRs play role in de novo synthesis of cholesterol, excretion and detoxification of bile acids, or lipids, glucose homeostasis, neurological functions and inflammation. Recent discoveries found LXRs could regulate tumor growth in a variety of cancer cell lines [3]. Since the extract showed potent LXRα agonistic activity, it was subjected to polyamide column for fractionation of active compounds. The extract and fractions were tested for their antioxidant and cytotoxic activities. Flavonoid-rich fractions (Frs. D-E) were found to be the most active fractions in the both test systems. IC₅₀ values of Frs. D-E were determined as 116 and 33 µg/mL for cytotoxic and 20 – 202 µg/mL for antioxidant activities, respectively. The active fractions were applied to serial column chromatografies to give compounds 1 (apigenin), 2 (luteolin-7-O-β-glucopyranoside) and 3 (apigenin-7-O-β-glucopyranoside) in pure form. Studies on active constituents are still in progress.

Acknowledgements: This study was supported by TUBITAK (2211-C) and Hacettepe University (014-D08 301 001).

References:

[1] Shang X et al. The genus Scutellaria an ethnopharmacological and phytochemical review. J Ethnopharmacol 2010; 128: 279 – 313

[2] Cicek M. Revision of Turkish Scutellaria L. (Lamiaceae) Genus. Ankara University PhD Thesis 2008

[3] Zhang W et al. Liver X receptor activation induces apoptosis of melanoma cell through caspase pathway. Cancer Cell International 2014; 14: 16