Phytochemical analysis and in vitro biological activity of three Hypericum species from the Canary Islands (H. reflexum, H. canariense and H. grandifolium)

In the present work we carried out a phytochemical and biological investigation on three Hypericum species, i.e. H. reflexum, H. canariense and H. grandifolium, from the Canary Islands where they are traditionally used as diuretic, wound healing, vermifuge, sedative and antidepressive agents. The polar extracts of the top flowering aerial parts, prepared by Soxhlet apparatus using a methanol-acetone (1:1) extracting mixture, were analysed by HPLC-DAD and HPLC-MS for the content of 8 biomarkers such as hypericin, hyperforin, chlorogenic acid, rutin, hyperoside, isoquercitrin, quercitrin and quercetin, whereas the hydrodistilled essential oils were analysed by GC-FID and GC-MS. The three Hypericum species resulted different in both polar and volatile constituents, being H. reflexum the only one endowed with a small amount of naphtodianthrones (hypericin and pseudohypericin), and containing high levels of chlorogenic acid, rutin and volatile mono- and sesquiterpenes. After chemical characterization, all products were in vitro biologically assayed for antiproliferative activity on human tumor cell lines by MTT assay, for antioxidant potential by DPPH, ABTS and FRAP assays, and for antimicrobial activity by the agar disc diffusion and microdilution methods. Results revealed interesting bioactivities and differences between polar extracts and essential oils, with the former being endowed with significant antioxidant activity and the latter with comparable inhibition effects on the tumor cells (A375, MDA-MB 231 and HCT 116) to that of cisplatin.