Antioxidant and anti-inflammatory activities of durian and rambutan

Durian (Durio zibethinus murr.) and rambutan (Nephelium lappaceum) are popular exotic fruits grown and consumed in Southeast Asia. Two economically important cultivars of durian and rambutan were studied to assess their antioxidant and anti-inflammatory activities. Nondifferentiated U937 monocyte-like cells were pre-treated with non-toxic doses of ethanol extract from fruit pulp prior to inducing oxidative stress with H2O2. Antioxidant capacity of fruit extracts was measured from the suppressive effect on reactive oxygen species (ROS) formation. Anti-inflammatory activity of non-toxic extracts doses also was assessed by measuring secretion of cyto/chemokines into medium of lipopolysaccharide-induced differentiated U937 cells treated with fruit extracts. Durian extracts were more potent at suppressing ROS formation and decreasing secretion of tumor necrosis factor alpha (TNF-α) and interleukin-8 (IL-8) than rambutan extracts. The extract from the Monthong cultivar of durian possessed greater antioxidant and anti-inflammatory activities than that prepared from the Chanee cultivar. Extract from the cultivar Sichompu of rambutan inhibited ROS formation but the extract from Rongrien had no significant activity. Both rambutan cultivars inhibited secretion of TNF-α, but not IL-8 secretion. The results indicate that durian pulp has greater potential for the development of functional foods than rambutan. An in vivo study is now needed to confirm these biological activities.