Apple oil as a source of ursolic acid for the treatment of hyperpigmentary disorders with molecular and clinical evaluation.

Summary

A standardized, ursolic acid–rich apple oil (AAO) inhibited tyrosinase, reduced melanin, and downregulated TYRP-1/2 and MITF in vitro, then translated to a 28-day randomized, double-blind, placebo-controlled trial (n=42) with significant improvements in UV/brown spot scores, melanin index, ITA°, and L*. Findings support AAO as a multi-target topical option for hyperpigmentation.

Key Findings

• The AAO extract was standardized to 784.40 ± 7.58 μg/mL ursolic acid.
• In vitro, AAO inhibited tyrosinase, reduced melanin in A375 cells, and downregulated TYRP-1, TYRP-2, and MITF with modulation of oxidative stress markers.
• In a 28-day randomized, double-blind, placebo-controlled trial (n=42), 2.5% AAO reduced UV and brown spot scores (-6.4% and -4.1%), decreased melanin index (-10.2%), and increased ITA° (+12.4°) and L* (+3.1%) versus placebo (all p<0.001).

Clinical Implications

AAO 2.5% topical formulations may serve as an adjunct or alternative depigmenting therapy, offering measurable improvements in melanin and spot metrics over 28 days; longer-term and dose-ranging studies can guide routine use.

Limitations

• Short intervention period (28 days) limits assessment of durability
• Single tested concentration (2.5%) and modest sample size (n=42) constrain dose-response and generalizability

Future Directions

Conduct longer-term, dose-ranging trials across diverse phototypes and compare AAO to standard depigmenting agents (e.g., hydroquinone, azelaic acid) with safety monitoring.