New 5-Methyl-4-Hydroxycoumarin Polyketide Derivatives from Gerbera Delavayi with Anti-Inflammatory Activity

Abstract

Five new 5-methyl-4-hydroxycoumarin polyketide derivatives (MPDs), delavayicoumarins A-E (1–5), were isolated from the whole plants of Gerbera delavayi. Among them, compounds 1–3 are the common monoterpene polyketide coumarins (MPCs), while 4 is a modified MPC with both the lactone ring contracted to a five-membered furan ring and a carboxyl at C-3, and 5 is an unusual phenylpropanoid polyketide coumarin, featuring a phenylpropanoid unit at C-3. The planar structures were elucidated by spectroscopic methods and biosynthetic arguments, and the absolute configurations of 1–3 were confirmed by calculated electronic circular dichroism (ECD) experiment. Furthermore, compounds 1–3 were tested for the nitric oxide (NO) inhibitory activity by using lipopolysaccharide (LPS)-induced RAW 264.7 cells in vitro. The results showed that compounds 1–3 remarkably inhibited NO production at the concentration of 10.0 μμμM, exhibiting that they have significant anti-inflammatory activity.

Keywords: Gerbera delavayi, 5-Methyl-4-hydroxycoumarin polyketide derivatives, Monoterpene polyketide coumarins, Phenylpropanoid polyketide coumarin, Anti-inflammatory activity