Anti-Inflammatory Investigations of Extracts of Zanthoxylum rhetsa

Zanthoxylum rhetsa has been consumed in the diet in northern Thailand and also used as a medicament in ancient scripture for arthropathies. Thus, this study aimed to evaluate the activity of various extracts from differential parts of Z. rhetsa via inhibition of inflammatory mediators (NO, TNF-α, and PGE(2)) in RAW264.7 macrophages. The chemical composition in active extracts was also analyzed by GC/MS. The parts of this plant studied were whole fruits (F), pericarp (P), and seed (O). The methods of extraction included maceration in hexane, 95% ethanol and 50% ethanol, boiling in water, and water distillation. The results demonstrated that the hexane and 95% ethanolic extract from pericarp (PH and P95) and seed essential oil (SO) were the most active extracts. PH and P95 gave the highest inhibition of NO production with IC(50) as 11.99 ± 1.66 μg/ml and 15.33 ± 1.05 μg/ml, respectively, and they also showed the highest anti-inflammatory effect on TNF-α with IC(50) as 36.08 ± 0.55 μg/ml and 34.90 ± 2.58 μg/ml, respectively. PH and P95 also showed the highest inhibitory effect on PGE(2) but less than SO with IC(50) as 13.72 ± 0.81 μg/ml, 12.26 ± 0.71 μg/ml, and 8.61 ± 2.23 μg/ml, respectively. 2,3-Pinanediol was the major anti-inflammatory compound analyzed in PH (11.28%) and P95 (19.82%) while terpinen-4-ol constituted a major anti-inflammatory compound in SO at 35.13%. These findings are the first supportive data for ethnomedical use for analgesic and anti-inflammatory activity in acute (SO) and chronic (PH and P95) inflammation.