Phytochemical investigation, antioxidant and wound healing activities of Citrullus colocynthis (bitter apple)

Objective: To undertake metabolite profiling of various plant parts of Citrullus colocynthis, and assess antioxidant and wound healing activities of fractions for therapeutical applications. Methods: Extracts from leaves, stem, root, fruit pulp and seeds were analyzed using gas chromatography-mass spectrometry and high performance liquid chromatography. Variation in antioxidant potential was assayed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay. The extract with highest antioxidant potential was subjected on in-vivo wound healing activity using excision wound model. Results: Metabolite profiling of Citrullus colocynthis identified 70 chemically diverse metabolites from different plant parts by using a combination of GC-MS and HPLC. Concentration of colocynthin, a principal active secondary metabolite, ranged from 3.15 mg/g dry weight to 242.00 mg/g dry weight, the lowest being in leaves and highest in fruit pulp. DPPH radical scavenging activity of free radical (IC50) ranged from 196.44 mu g/mL in fruit pulp to 413.33 mu g/mL in leaves tissues. Significant wound contraction and increase in hydroxyproline content of granulation tissue were observed with ointment formulated from methanolic extract of fruit pulp. Conclusions: The study indicates that the methanol extract of Citrullus colocynthis fruit pulp when applied topically may promote wound contraction in rat model attributable to the accumulation of colocynthin. The high quantity of colocynthin (242.00 mg/g dry weight) and substantial concentration of 2,4-di-tert butyl phenol (3.2%), squalene (4.2%) and delta-tocopherol (2.5%) make this plant to provide new opportunities for development of medicinal, nutraceutical and dietary supplements with optimized functionality.