Immune-Enhancing Effect of Ethanol Extract of Rambutan (Nephelium lappaceum L.) Fruit Peel on phagocytosis index, Paw Edema Formation, and Antibody Titer in Mice

Abstract

Rambutan (Nephelium lappaceum L.) fruit peel contains flavonoids, phenolic compounds, and other phytoconstituents with health benefits and immunomodulatory effects. This study investigated the immunomodulatory effect of ethanol extract of rambutan peel (EERP) in mice using the carbon clearance method to evaluate innate/non-specific immune responses and delayed-type hypersensitivity (DTH). The antibody titer test was used to assess adaptive/specific immune responses. The experimental animals (mice) were divided into six groups. Group I (negative control) received oral doses of CMC-Na, while II and III received stimuno and prednisolone as positive control drugs. Groups IV-VI (test groups) were treated with 50, 100, and 200 mg/kg of EERP, respectively. The phagocytosis index value was obtained by the carbon clearance method using carbon suspension as an antigen. The percentage of paw edema was obtained by DTH test using SRBC (sheep red blood cells) as antigen. The secondary antibody titer was obtained using an antibody titer test using SRBC as an antigen by hemagglutination methods. The results showed that EERP at a dose of 100 mg/kg showed a greater immunostimulant effect than 50 and 200 mg/kg based on phagocytic index value 1.63±0.08, and increasing percentage of paw edema 53.77±14.87 % equivalent with positive control Stimuno. EERP dose of 200 mg/kg could boost the humoral immune response by increasing secondary antibody titers (1:2048). Phytochemical screening revealed that EERP contained saponin, flavonoid, and phenolic compounds. These findings showed that the EERP is a potential immunostimulant by increasing the phagocytic index, cellular inflammation and humoral immune responses.