Structural elucidation of two intricate polycyclic polyprenylated acylphloroglucinols using quantum chemical calculations and their hypoglycemic activities

Abstract

Compounds 1-2, the rare examples of polycyclic polyprenylated acylphloroglucinols (PPAPs) with unique 6/5/7 and 6/6 ring systems possessing unprecedented 2, 3, 12-trioxatricyclo-[5.3.1.15,11] dodecane and bicyclo-[4.4.0] decane, respectively, were isolated from the fruits of Garcinia bracteata and Garcinia multiflora, respectively. Their structures and absolute configurations were elucidated by the combination of gauge-independent atomic orbital (GIAO) NMR calculations and electronic circular dichroism (ECD) calculations. Furthermore, the hypoglycemic activity of 1 was assayed by the insulin resistance (IR)-HepG2 cell model. The results showed that compound 1 at the concentrations of 2, 4, and 6 μM could significantly promote glucose uptake dose-dependently and improve glucose metabolism disorder. Taken together, these findings suggested 1 could be a promising candidate for the treatment of diabetes mellitus.

Keywords

• Polycyclic polyprenylated acylphloroglucinols
• Garcinia bracteata
• Garcinia multiflora
• GIAO NMR calculations
• Hypoglycemic activity