In-vitro wound healing activities of carica papaya leaves extract on human skin fibroblast cell line

Abstract

Wound healing is a critical issue that has a significant impact on one’s quality of life. It imposed a costly burden on individuals and the healthcare system because it necessitates extended hospitalisation and death in severe cases. With the rising cost of antibiotics and the emergence of bacterial resistance, more medical practitioners are turning to traditional medicine for solutions. Carica papaya (C. papaya) is a wellknown plant with various pharmacological activities, including antioxidant and wound healing properties. However, to date, the lack of scientific evidence has been investigated on the efficiency of the solvents towards C. papaya leaves extract as a potential wound healer, its underlying mechanism, and in silico approach with the putative phenolic compounds. The present study was aimed to explore in vitro wound healing activities of C. papaya leaves extract and its fraction on human skin fibroblast cells. The study included cell viability, cell proliferation, scratch assay, and collagen synthesis. Different solvents (methanol, ethanol, aqueous) of crude extracts were screened. The best crude extract of C. papaya leaves was further subjected to a bioassay-guided fractionation using the solid-phase extraction method to ascertain the best fraction. Further investigation was conducted to evaluate the possible mechanism involved using the best extract and fraction, including the gene expression analysis by quantitative real-time polymerase chain reaction (qRT-PCR), cell cycle analysis, and MMP-1 production. The best extract and fraction were screened for their phytoconstituents using high performance liquid chromatography (HPLC) whilst in silico approach was carried out to assess inhibition of glycogen synthase kinase 3-B (GSK3-B), a specific biomarker for wound healing. The results showed that the methanolic extract of C. papaya leaves and Fraction 2 (Fr II) possessed a significant antioxidant potential and wound healing properties compared to other extracts and fractions. The methanolic extract and Fr II significantly stimulated the highest migration rate on HSF cells at 15.6 p,g/mL (p < 0.05) after 48 h with no cytotoxicity observed at the highest concentration. The qRT-PCR analysis suggested that wound healing activities of the best extract and fraction were strongly associated with activation of the Wnt/B-catenin signalling pathway, which involved the upregulated expression of genes AXIN2, TGF-pi, and CTNBB1 after 48 h (p < 0.05). The results also indicated the raised of MMP-1 synthesis upon treatment as compared to control. Furthermore, cell cycle analysis was significantly increased during the G2/M phase, indicating that C. papaya leaves extract and Fr II gradually reinvigorated cell division for wound closure. HPLC analysis identified phenolic compounds of gallic acid, caffeic acid, p-coumaric acid, catechin, and quercetin in various concentrations. Molecular docking results found that quercetin and catechin exhibited the most promising activity among the phenolic compounds detected based on the lowest binding energy and inhibition constant of GSK3-B than the standard drug, nitrofurazone. The findings suggested that the C. papaya leaves extract and its fraction exhibited wound healing by activating the Wnt/B-catenin-dependent signalling pathway. This work provides a significant endeavour in promoting C. papaya as an option to treat wounds.