Evaluation of the wound healing, anti-inflammatory, and antimicrobial activity of isovanillin by using an animal model
Authors: Abbas Aqsa , Mehmood Malik Hassan Hassan , Muhammad faqir , Siddique Rida , Kamran Abdul Abdul malik 
Published: October 2022

Abstract
Oxidative stress-induced uncontrolled inflammation is the hallmark of non-healing or chronic wounds. A vast number of chronic wound healing modalities involve the utilization of antioxidants for their free radical scavenging and inflammation curtailing properties. Based on the pharmacological profile of its isomer and the reported antioxidant potential of isovanillin, the present study is aimed to investigate the wound healing and anti-inflammatory activity of isovanillin using in vivo models. Among isomers of vanillin, o-vanillin has shown better pharmacological activity and isovanillin has also been reported for its promising pharmacological role as an antioxidant, antispasmodic and antidiarrheal compound. For evaluation of antioxidant, antimicrobial, wound healing, anti-inflammatory, and anti-angiogenic potential of isovanillin in excision wound model and burn wound models. ELIZA test was used for the estimation of antioxidant and inflammatory parameters. Analgesic activity was assessed by carrageenan induced paw edema, xylene induced ear edema, acetic acid induced writhing test. Antimicrobial activity was evaluated by disc diffusion Antioxidant of isovanillin was assesed with an IC50 value of 30.29 ± 1.86 µg/ml using by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. In wound healing (excision and burn wound) models isovanillin assisted dose-dependent wound contraction and re-epithelialization. There was no significant difference (p > 0.05) when % wound contraction of isovanillin (10% ointment) was compared to the standard treatment group. Isovanillin-treated animals showed complete re-epithelialization, reduced inflammatory cells, and development of hair follicles on histopathological analysis of skin samples, Furthermore elevation of enzymatic antioxidants such as CAT and SOD in liver tissues along with marked (p < 0.05) decrease in IL-6 and TNF-α was observed. To investigate the anti-inflammatory activity two models of acute edema were used. In the carrageenan-induced paw edema model, isovanillin exhibited significant anti-inflammatory activity up to 6 hours, while maximum % inhibition of edema was achieved at the 6th hour (p > 0.05) as compared to indomethacin (10 mg/kg). Anti-inflammatory activity in xylene-induced ear edema shown by isovanillin (10mg/kg) was comparable (p < 0.05) in comparison to dexamethasone. Analgesic activity assessed by acetic acid-induced abdominal writhing in rats showed comparable % inhibition of writhes compared to indomethacin (10 mg/kg). Antimicrobial activity evaluated by disc diffusion showed clear zone of inhibitions by isovanillin against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and pseudomonas aeruginosa. Based on our investigation, it was concluded that isovanillin possesses antimicrobial, wound healing, and anti-inflammatory activity mediated by upregulation of antioxidant enzymes and downregulation of pro-inflammatory cytokines (IL-6 and TNF-α).