Antioxidant, antibacterial activity, and phytochemical characterization of Carica papaya flowers

Background Carica papaya is an eminent medicinal plant used all over the world to treat several diseases like malaria, dengue, inflammation, and skin infections. In this study, preliminary phytochemical screening for C. papaya flowers was carried out using different methods as TLC screening and UV-spectroscopy along with evaluation of antioxidant and antibacterial activities. Methods were also developed for TLC and UV-visible spectroscopic analysis of the extracts. Results Results of phytochemical screening revealed that the methanol extract contains alkaloids, flavonoids, saponins, and tannins as major components. Saponins and tannins were present in chloroform and n -hexane extracts; however, steroids and flavonoids were additionally found in n -hexane extract. Flavonoids, saponins, and tannins were present in aqueous extract of papaya flower. TLC and UV-visible spectroscopy also confirmed the presence of phenolics and flavonoids in different plant extracts. The total phenolic content (0.76 ± 0.04 mg GAE/g dry weight) and total flavonoid content (1.53 ± 0.10 mg QE/g dry weight) were the highest in the n -hexane extract of the flower. Antioxidant activity using DPPH free radical scavenging assay was the highest in n -hexane extract (64.07%). Antibacterial screening was carried out using well diffusion method against two pathogens Gram-negative bacteria Escherichia coli and Gram-positive bacteria Bacillus subtilis . The antibacterial assays of the extracts displayed the highest activity in methanolic extract against both E. coli ( 4.00 ± 0.08) and B. subtilis (01.00 ± 0.05). Conclusion This is the first report for the presence of alkaloids and saponins in C. papaya flowers. Also, it is the first report for determination of total phenolics and total flavonoids in C. papaya flowers. Methanolic extract displayed considerable antibacterial activity against E. coli and B. subtilis . The antioxidant and antibacterial properties of phytochemical extracts make them attractive alternative complementary medicines. More chemical investigation for chemical constituents is important for further drug development programs. Graphical abstract