Development of Topical Oral Anti-Inflammatory Gel Containing Zanthoxylum limonella seed Extracted: A Preclinical Study

Background: This study aims to investigate the stability of Zanthoxylum limonella Alston. seed (ZL) at various storage temperatures and anti-inflammatory activity of the topical oral gel (ZG) in a preclinical study.

Methods: The seed was stored in 2 different conditions: accelerated condition (50 °C, 70 °C and 90 °C) over 96 h and long-term condition (4 °C, 25 °C and 50 °C) over 6 months. Anti-inflammatory activity of the topical oral in rats was observed by using croton oil ear edema and oral punch wound healing.

Results: High storage temperature decreased the total phenolic content of ZL extract which the rate of degradation followed zero-order kinetic. In the long term condition, ZL stored at 50°C generated free radical while at 4 °C and 25 °C found the non-significant difference from the initial. The rate of release and permeation of phenolic content detected in receptor medium of the ZL into a mucoadhesive gel was 0.11 and 0.47 µg/cm2/h with no lag time indicated the fast release and permeation. The anti-inflammatory study suggests an effective dose of 10% of ZG which accelerated the wound size and reduced erythema compared to blank gel (p<0.001) and similar to FG (p=0.8) since the third day of treatment. The anti-inflammatory and wound healing activity of the ZG demonstrated re-epithelialized and wound closure, as supported by results of histopathology.

Conclusion: The topical oral gel contained the Zanthoxylum limonella seed extracts in the preclinical of rats was proved usefulness as an alternative topical oral product.