New abietane diterpenes from <i>Origanum vulgare</i> exhibiting lipase inhibitory activity

Many herbs and spices have been reported to exhibit various biological activities, including antioxidant effects, antimicrobial activity, and antitumor activity; consequently, they are expected to contain novel bioactive compounds. In this study, anti-obesity agents were identified in several herbs and spices by screening for inhibitors of lipase, a key enzyme involved in lipid digestion. The extract of Origanum vulgare (oregano) demonstrated considerable lipase inhibitory activity. The active constituents from this plant were isolated by subjecting the oregano extract to several separation protocols, including SiO2 gel column chromatography and reversed-phase high-performance liquid chromatography. The purification process was guided by lipase inhibitory activity, affording origanone A (1) and origanone B (2) as novel abietane diterpenes. Notably, these compounds exhibited moderate lipase inhibitory activity. These findings indicate the potential of oregano and its active constituents as functional food ingredients for regulating lipid levels and obesity.