Topical Administration of Tannin Promotes Healing Rate in a Rabbit Model of Dermatitis

Background: Contact dermatitis is a common clinical problem, affecting approximately 15% of adults, with both allergic and irritant variants being prevalent. While such corticosteroid therapies are effective, the risk of side effects increases with prolonged use. Tannins, natural polyphenolic compounds with established anti-inflammatory and antioxidant properties, have become potential options for skin some skin diseases. Objective: The present study aimed to assess the potential of topically applied tannin extract of pomegranate peel in the acceleration of healing of experimentally induced dermatitis in a rabbit model and to compare its effectiveness with that of conventional corticosteroid therapy (mometasone). Methods: Twenty male New Zealand White rabbits were divided into four groups (n=5/group): dermatitis, tannin-treated group, mometasone-treated group and vehicle-treated group. The mode of acute dermatitis was induced by topical administration of 0.5% sodium lauryl sulfate (SLS). The treatments were topically applied twice a day for 14 days. Clinical findings (itching or scratching), wound surface, and erythema/edema were assessed. Biochemical readouts of inflammation (IL-1β, TNF-α), oxidative stress (malonaldehyde (MDA), superoxide dismutase (SOD)) and anti-oxidant (catalase) were measured by ELISA and colorimetric assays. Results: On day 14, the healing rate was 91% for the tannin group, similar to the mometasone group (95%), and significantly higher when compared untreated group (26%) (p < 0.01). Gallate of tannin significantly decreased the levels of erythema, edema, IL-1β, TNF-α, MDA and increased the activities of SOD. Re-epithelialization was shorter in the tannin group (10 ± 3 days) compared with control cases. Conclusions: The present study has shown that topically applied tannin promotes wound healing, reduces inflammation and increases antioxidant biomarkers in rabbits with contact dermatitis. The efficacy of tannins was similar to that of mometasone. Tannins could be a promising natural nonsteroidal alternative for the treatment of inflammatory skin disease. However, further research is needed to evaluate the most appropriate dosing, develop new formulations, and assess long-term safety.