Protective Effects of Ethanol Extract and Bioaccessible Fraction of Centella asiatica against IL-1β-Induced Inflammation and Oxidative Stress in Human Intestinal Caco-2 Cells

Abstract

Pro-inflammatory mediators and free radicals play a critical role in the pathogenesis of several chronic diseases. This study aims to investigate the anti-inflammatory and antioxidant effects of ethanol extracts (CAE) and bioaccessible fraction from simulated gastrointestinal digestion of C. asiatica (BFC) leaves on IL-1β induced inflammation and oxidative stress Caco-2 cells. Triterpenoids and flavonoids were found in CAE and BFC from HPLC analysis. Triterpenoids in CAE and BFC were asiatic acid (421 and 185 µg/g dry weight of freeze-dried, respectively) and madecassic acid (583 and 285 µg/g dry weight of freeze-dried, respectively). Flavonoids in CAE and BFC were quercetin (1,632 and 987 µg/g dry weight of freeze-dried, respectively) and kaempferol (749 and 427 µg/g dry weight of freeze-dried, respectively). Caco-2 cells were treated with CAE at concentration 250-1000 µg/ml or BFC for 4 h prior to induce with 10 ng/ml IL-1β for another 24 h. The results showed that pre-treatment Caco-2 cells with CAE significantly (p<0.05) decreased pro-inflammatory mediators concentration (IL-6, IL-8 and TNF-α) and ROS formation in a dose-dependent manner. Moreover, the BFC significantly (p<0.05) decreased IL-1β induced pro-inflammatory mediators (IL-6, IL-8 and TNF-α) levels and ROS formation. These results showed that both CAE and BFC have anti-inflammatory and antioxidant activities in intestinal cells. This implies that C. asiatica leaves even after digestion still retains anti-inflammatory and antioxidant activities. However, these biological functions of C. asiatica leaves should be further investigated in animals and humans.