Structurally diverse abietane diterpenoids from the whole plants of Salvia przewalskii Maxim. With anti-inflammatory activity

Abstract

Using bioactivity guidance, eight previously undescribed abietane diterpenoids (1–8), were isolated from the whole plants of Salvia przewalskii Maxim. along with seven known analogues (9–15). Their structures were elucidated by extensive spectroscopic analyses, quantum chemical calculations, and single crystal X-ray diffraction. Among them, compound 1, an abietane diterpenoid bearing unique C-20 m-cymen-8-ol monoterpenoid moiety, was the first example of the adduct between a monocyclic monoterpenoid and an abietane diterpenoid connected by ester bond within the Salvia genus. The plausible biosynthetic pathways of 1–8 were proposed. All isolates were tested for their inhibitory activity towards the LPS-induced NO production in RAW 264.7 cells. Compounds 3, 5, 6 and 9 significantly inhibited nitric oxide (NO) production in RAW264.7 cells, which also could suppress the release of pro-inflammatory factors (TNF-α, IL-1β and IL-6). The key structure-activity relationships of these abietane-type diterpenes for anti-inflammatory effects have been summarized.