Kaempferia galanga L. alleviates the expression of COX-2 and NF-kappaB-p65 in the oral mucosa ulcer of Wistar rats and exhibits no irritation toward the vascular membrane of chicken eggs and the skin of albino rabbits

Abstract

The global incidence of recurrent aphthous stomatitis in 2018 reached 5–66 % of the population, while in Indonesia 8 %. Moreover, the prevalence of oral mucosal fibrosis and recurrent aphthous stomatitis among male doctors and nurses in China was 21.24 % and 24.27 %, respectively. Our previous study has shown that the ethanol extract of Kaempferia galanga L. rhizome (EKGR) revealed an accelerated wound-healing effect in the oral mucosa ulcer of Wistar rats. This study aims to explore the effects of EKGR on the expression of NF-kappaB-p65 and COX-2 in the tongue tissue of male Wistar rats by Western blot analysis and immunohistochemistry technique, its safety towards the vascular membrane of the egg chorioallantoic membrane, and its single-dose application on the skin of male rabbits. The rats were randomly assigned into 7 groups: the normal control; the negative control; the positive control (treated with triamcinolone acetonide); and 4 treatment groups of EKGR (0.5 %; 1 %; 2 %; 4 %). Western blot and immunohistochemistry methods were used to measure the expression of NF-kappaB-p65 and COX-2. The hen's egg test-chorioallantoic membrane assay was employed to predict the safety of EKGR towards the vascular membrane. Moreover, the effect of 200 mg/kg BW EKGR application on the dorsal skin of male albino rabbits was also evaluated. EKGR inhibits the expression of NF-kappaB-p65 and COX-2 as proven by WB and IHC results. In the HET-CAM assay, all concentrations of EKGR do not induce irritation responses, which elicits the safety of EKGR. The administration of EKGR causes mild irritation to the dorsal skin of male rabbits but does not induce erythema and edema, no significant changes in BW, no toxic effects on organ macroscopic examination or histopathology, and does not induce abnormalities in the hematological profile of male albino rabbits. EKGR has confirmed its anti-inflammatory activity by suppressing the expression of COX-2 and NF-kappaB-p65 in the oral mucosa ulcer of Wistar rats. EKGR is safe as it does not exhibit irritating potential and harmful effects.