Antioxidant and anti-inflammatory effects of Orthosiphon aristatus and its bioactive compounds

Orthosiphon aristatus (Blume) Miq., which can be used as a food ingredient, is grown throughout Southeast Asia and Australia. O. aristatus is frequently used for the treatment of renal inflammation, kidney stones and dysuria. The focus of the current work was to study the antioxidant and anti-inflammatory effects of methanol, ethanol and water extracts from O. aristatus (abbreviated as MEOA, EEOA and WEOA, respectively). The evaluation of antioxidant activity was determined by total phenolics, Trolox equivalent antioxidant capacity (TEAC), oxygen-radical absorbance capacity (ORAC) and cellular antioxidant activity (CAA) assays. These assays demonstrated a relatively high antioxidant activity for MEOA and EEOA. These results revealed that EEOA had the most prominent inhibitory effect on lipopolysaccharide (LPS)-stimulated nitric oxide (NO), prostaglandin E(2) (PGE(2)) and intracellular reactive oxygen species (ROS) production in RAW 264.7 cells. A high performance liquid chromatography profile indicated that MEOA and EEOA contained both ursolic acid and oleanolic acid. Moreover, ursolic acid significantly reduced NO production in LPS-stimulated RAW 264.7 cells. Both EEOA and ursolic acid inhibited LPS-stimulated protein and mRNA expression of both inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in these cells. These results demonstrate that EEOA and its bioactive compound, ursolic acid, suppress LPS-induced NO and PGE(2) production by inhibiting ROS generation, along with reducing expression of iNOS and COX-2 in RAW 264.7 cells.