Carica papaya Flower Extracts Possess Antioxidant and 5α-reductase Inhibitory Activities

Carica papaya has been widely used commercially for skin care due to its therapeutic benefits. The potential of its flower to promote hair growth has been traditionally recognized in other countries but not in the Philippines. In this study, we explored the effect of various extracts of C. papaya flower in the biological activities associated with hair loss, including 5α-reductase inhibition and antioxidation, as well as identified the putative compounds present in the most potent extract.

The flowers of C. papaya were macerated separately with ethanol, ethyl acetate, and hexane to obtain their corresponding crude extracts. These extracts were subjected to antioxidant tests via 2,2'-diphenyl-1-picrylhydrazyl (DPPH), and ferric-reducing antioxidant power (FRAP) assays. The total phenolic and flavonoid contents (TPC and TFC) of the crude extracts were determined, as well as the ability of the extracts to inhibit 5α-reductase. The compounds present in the most potent extract were determined using ultraperformance liquid chromatography quadrupole time of flight mass spectrometer (UPLC/MS-QToF).

Ethyl acetate extract displayed significantly higher DPPH activity (0.001755 ± 0.00092 ascorbic acid equivalent antioxidant capacity) and 5α-reductase inhibitory activity (115.18 ± 11.61 mg dutasteride/g) compared to ethanol (DPPH: p=0.0121; 5α-reductase: p=0.0016) and hexane (DPPH: p=0.0038; 5α-reductase: p<0.0001) extracts. Similarly, ethyl acetate extract gave the highest FRAP (0.4842 ± 0.0936 mg ascorbic acid/g) activity, TFC (0.0403 mg quercetin/g), and TPC (0.0463 mg gallic acid/g) among the extracts. Forty-nine compounds were annotated in the ethyl acetate extract, with seven (7) putatively identified as fatty acids (9-hydroxy-10,12-pentadecadienoic acid, 9,12,15-octadecatrienoic acid), hydroxyflavone (5-methylkaempferol), alkaloid (allomatrine), dipeptide derivative (aurantiamide acetate), bufotalinin, and 6β-acetoxy-5-epilimonin based on the Traditional Chinese Medicine Library.

These results suggest that local C. papaya flowers can be a source of hair growth-promoting agents via their antioxidant and 5α-reductase inhibitory potential.