The effect of Indian costus (Saussurea lappa) extract on the healing of chemically induced oral ulcer in rats: in vitro and in vivo study with histological evaluation

Abstract

Background: Saussurea lappa ( S. lappa ) is a plant known for anti-inflammatory, antimicrobial, antioxidant, and anti-ulcer properties, yet its potential in oral-ulcer healing remains underexplored. This study evaluates the effects of S. lappa extract on oral ulcers using in vitro and in vivo models. Methods: Rat tongue epithelial cells received hydroethanolic (70% v/v) S. lappa extract (0–100 µg/mL) for 24, 48, or 72 h; viability (MTT) yielded EC50 at each timepoint. The extract was high-performance liquid chromatography-fingerprinted (costunolide and dehydrocostus lactone). A lipopolysaccharide (LPS) model (1 µg/mL, 48 h) was then treated with EC50 doses; dexamethasone 2.5 µM served as drug-positive control (PC). Interleukin-6 (IL-6; pg/mL) was measured by enzyme-linked immunosorbent assay. A scratch assay assessed 72-h closure. In vivo , 27 male rats were allocated to naïve ( n = 3), PC ( n = 12), and S. lappa ( n = 12) groups, with Days 7 and 14 endpoints ( n = 6 each). Histology evaluated re-epithelialization and collagen area. Results: S. lappa showed no cytotoxicity across the tested range. It significantly reduced IL-6 versus LPS-only at all timepoints (analysis of variance/Tukey, P < 0.01); at EC50 (72 h), IL-6 did not differ from dexamethasone 2.5 µM ( P > 0.05). The extract enhanced in vitro wound closure (higher relative wound density; lower gap width/area). In vivo, S. lappa- treated ulcers showed greater collagen deposition, improved re-epithelialization, and lower ulcer scores than controls at Days 7 and 14. Conclusion: S. lappa shows wound-healing and anti-inflammatory activity; future studies incorporating functional and molecular endpoints are warranted to establish effect magnitude and mechanisms.