Isolation and anticancer, anthelminthic, and antiviral (HIV) activity of acylphloroglucinols, and regioselective synthesis of empetrifranzinans from Hypericum roeperianum

Abstract

From the ethno-medicinally used leaves of Hypericum roeperianum we isolated a new tricyclic acylphloroglucinol (1), a new tetracyclic acylphloroglucinol (2), and a new prenylated bicyclic acylphloroglucinol (3) together with four known prenylated (4-7) and three known tetracyclic acylphloroglucinol derivatives (8-10). Structure elucidation was based on UV, IR, [α]D(25), 1D- and 2D-NMR experiments. Furthermore, empetrifranzinans A (8) and C (9) were synthesized regioselectively in only two steps. The isolated compounds were evaluated for their cytotoxicity against PC-3 and HT-29 cancer cell lines as well as antibacterial and anthelmintic activities. They were also tested in cell-based assays for cytotoxicity against MT-4 cells and for anti-HIV activity in infected MT-4 cells. Significant anthelmintic activity against Caenorhabditis elegans was exhibited by compound 7 (3-geranyl-1-(2'-methylbutanoyl)-phloroglucinol), which might provide a new lead.

Keywords: (1)H NMR profile guided isolation; Acylphloroglucinol synthesis; Empetrifranzinans; H. riparium; Hypericaceae; Madeleinol; Metabolic profiling; Natural products.