Anti-inflammatory Activities of 6β-Acetoxy-7α-hydroxyroyleanone from Taiwania cryptomerioides Hayata ex Vivo and in Vivo

Abstract

Excess production of nitric oxide (NO) by inducible NO synthase (iNOS) in activated macrophages is linked to acute and chronic inflammation. Thus, it would be valuable to develop inhibitors of NO production and/or iNOS for potential therapeutic use. This study investigated the anti-inflammatory effects of 6β-acetoxy-7α-hydroxyroyleanone (AHR), a compound isolated from the bark of Taiwania cryptomerioides Hayata, using lipopolysaccharide (LPS)-stimulated mouse macrophage (RAW 264.7) ex vivo and carrageenan (Carr)-induced mouse paw edema model in vivo. When RAW 264.7 macrophages were treated with different concentrations of AHR (0, 0.31, 0.62, 1.25, and 2.50 μg/mL) together with LPS (100 ng/mL), a significant concentration-dependent inhibition of NO production was detected. Western blotting revealed that AHR blocked protein expression of iNOS and cyclooxygenase-2 (COX-2) in LPS-stimulated RAW 264.7 macrophages, significantly. In the anti-inflammatory test, AHR (1.25 and 2.50 mg/kg) decreased paw edema at 4 and 5 h after λ-carrageenan (Carr) administration and increased the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) in the liver tissue. It was also demonstrated that AHR significantly attenuated the malondialdehyde (MDA) level in the edema paw at 5 h after Carr injection. AHR (0.62, 1.25, and 2.50 mg/kg) decreased the NO levels on both edema paw and serum at 5 h after Carr injection. Also, AHR diminished the serum tumor necrosis factor (TNF-α) at 5 h after Carr injection. Western blotting revealed that AHR (2.50 mg/kg) decreased Carr-induced iNOS and COX-2 expressions at 5 h in the edema paw. An intraperitoneal (ip) injection treatment with AHR also diminished neutrophil infiltration into sites of inflammation, as did indomethacin (Indo). The anti-inflammatory activities of AHR might be related to the decrease in the levels of MDA, iNOS, and COX-2 in the edema paw and to the increase in the activities of CAT, SOD, and GPx in the liver through the suppression of TNF-α and NO.