Optimized extraction based on the terpenoids of Heterotrigona itama propolis and their antioxidative and anti-inflammatory activities

Terpenoids are the main components of stingless bee propolis, their biological activities have not been fully quantified and investigated. In this study, the single-factor design and response surface methodology were applied to optimize the terpenoids extraction process in Heterotrigona itama (also called H. itama) propolis. Furthermore, the in vitro antioxidant and anti-inflammatory activities of terpenoid-rich extract were evaluated. The results showed with 95% ethanol/5% water, a material-liquid extraction yield of 1:30 g/ml, and extraction 72 hr for three extractions, the highest terpenoids content in H. itama propolis of 46.44 ± 0.07%. The H. itama propolis terpenoid-rich extract showed relative low antioxidant effect but inhibited inflammatory response by decreasing the inflammatory mediators iNOS, IL-1β, IL-10, and increasing the antioxidant mediators HO-1. This study provided experimental parameters for the terpenoids optimal extraction from H. itama propolis and revealed their strong anti-inflammatory activity. PRACTICAL APPLICATIONS: H. itama stingless propolis is a newly founded stingless bee propolis type recently. H. itama stingless propolis has abundant terpenoids, however, scant information were provided regarding its extraction optimization. In this study, we investigated and obtained the optimal extract parameters of terpenoids in H. itama propolis，and demonstrated their strong anti-inflammatory activities; however, their antioxidant activities are relatively low. This study provided theoretical basis for the usage of H. itama stingless propolis in industry.

Keywords: Heterotrigona itama propolis; anti-inflammatory; antioxidant; optimal extraction; terpenoids.