Effectiveness of Chitosan-Curcumin Preparation in Management of Oral and Gastric Ulcers in Experimental Animals

Abstract

Curcumin, a lipophilic polyphenol extracted from the rhizomes of Curcuma longa Linn, has been reported to exert a variety of therapeutic properties including antioxidant, anti-inflammatory, antiulcer and wound healing. However, its limitations for further clinical use include its poor aqueous solubility, low bioavailability, large oral daily dosing and frequent drug administration. Chitosan is a well-known polysaccharide biopolymer with bioadhesive and drug penetration enhancing properties that could be beneficial in enhancing the substantivity in the oral and gastric mucosa, including the bioavailability through the gastric mucosa of curcumin. Its anti-oxidant, anti-inflammatory and ulcer-healing properties could also enhance the antiulcer efficacy of curcumin. Accordingly, a chitosan-curcumin preparation was developed and evaluated for its efficacy and mechanisms of antiulcer action in management of oral and gastric ulcers in experimental animals. An oral chitosan-curcumin mixture used for gastric ulcers was prepared using 0.1 M acetic acid as a solvent. The developed mixture was a uniform yellowed-color mixture with an optimal gastric pH range. Using a rat model, a chitosan-curcumin mixture with a combination ratio of curcumin (20 mg) and chitosan (150 mg) was superior to curcumin, chitosan or a standard antiulcer agent (lansoprazole) in prevention and treatment of acute gastric ulcers induced by non-steroidal anti- inflammatory drug (indomethacin). Interestingly, once-daily administration of an oral chitosan-curcumin mixture exerted comparable ulcer healing efficacy to twice-daily administration of curcumin, chitosan or a standard lansoprazole in treating acetic acid- induced chronic gastric ulcer in which the pathological aspects and healing process highly resembles a human chronic gastric ulcer. The pharmacological investigation on in vitro antioxidant and anti-inflammatory activities including in vivo antioxidant, anti-inflammatory, antisecretory and gastric mucus producing activities in rats indicated that an oral chitosan-curcumin mixture possessed a lower potent antisecretory activity than lansoprazole but exerted the highest gastric mucus producing, anti-oxidant and anti-inflammatory activities among curcumin, chitosan and lansoprazole. RT-PCR and real time RT-PCR (qRT-PCR) analysis on the expression of COX and NOS in the gastric ulcerated tissue revealed that a chitosan- curcumin mixture exerted anti-inflammatory activity through a down-regulation of pro-inflammatory COX-2 and iNOS expression including an up-regulation of cytoprotective eNOS expression, antisecretory activity through an up-regulation of cytoprotective COX-1 and nNOS expression and gastric mucus producing activity through an up-regulation of cytoprotective COX-1 and nNOS expression. A topical chitosan-curcumin mouthwash used for oral ulcers was prepared by dissolving 0.1 g of curcumin in a co-solvent system composed of 0.5 g of chitosan in 1% acetic acid solution and 40 ml of polyethylene glycol 400. The developed mouthwash was a clear solution with an optimum pH range to use in the human oral cavity. Its oral ulcer healing efficacy was evaluated on acetic acid-induced buccal mucosal ulcer in hamsters of which pathophysiologic ulcer phase is similar to that of radiation or chemotherapy-induced oral ulcers. The application of the mouthwash twice a day for 7 consecutive days significantly decreased the ulcer severity (p<0.05) with a better ulcer healing efficacy than those of a standard 0.15% benzydamine mouthwash with histological evidences on its beneficial effects of complete epithelization, wound contraction and tissue remodelling. An oral chitosan-curcumin mixture also exerted a comparable histological healing score to that of a topical chitosan-curcumin mouthwash. Additionally, the scratch wound healing assay demonstrated that a chitosan- curcumin mixture, curcumin and chitosan had comparable efficacy in stimulating HGF human gingival fibroblast cell and AGS human gastric epithelial cell proliferation and migration.The potential pharmacological findings obtained from the present studies indicated the benefit of a chitosan-curcumin preparation with a low dose of curcumin and low frequent drug administration as a potential alternative in management of gastric ulcer and oral ulcer. It is important to recognize that both curcumin and chitosan possess a potent down-regulation of iNOS and COX expression, therefore, a chitosan-curcumin preparation can exert the opposing effects of prevention and exacerbation of ulcer or ulcer healing and ulcer relapse depending on the dose-effect relationship.