Abstract
Background
Bletilla striata was the main medicine of many skin whitening classic formulas in traditional Chinese medicine (TCM) and was widely used in cosmetic industry recently. However, its active ingredient was still unclear and its fibrous roots were not used effectively. The aim of the present study was to discover and identify its potential anti-melanogenic active constituents by zebrafish model and molecular docking.
Methods
The antioxidant activities were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2’-azino-bis-(3-ethylbenthiazoline-6-sulphonic acid) (ABTS) radical scavenging activity and ferric reducing antioxidant power (FRAP) assay. The anti-melanogenic activity was assessed by tyrosinase inhibitory activity in vitro and melanin inhibitory in zebrafish. The chemical profiles were performed by ultra-high-performance liquid chromatography combined with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS). Meanwhile, the potential anti-melanogenic active constituents were temporary identified by molecular docking.
Results
The 95% ethanol extract of B. striata fibrous roots (EFB) possesses the strongest DPPH, ABTS, FRAP and tyrosinase inhibition activity, with IC50 5.94 mg/L, 11.69 mg/L, 6.92 mmol FeSO4/g, and 58.92 mg/L, respectively. In addition, EFB and 95% ethanol extract of B. striata tuber (ETB) can significantly reduce the melanin synthesis of zebrafish embryos in dose-dependent manner. 39 chemical compositions, including 24 stilbenoids were tentatively identified from EFB and ETB. Molecular docking indicated that there were 83 (including 60 stilbenoids) and 85 (including 70 stilbenoids) compounds exhibit stronger binding affinities toward tyrosinase and adenylate cyclase.
Conclusion
The present findings supported the rationale for the use of EFB and ETB as natural skin-whitening agents in pharmaceutical and cosmetic industries.
The anti-Staphylococcus aureus activity of the phenanthrene fraction from fibrous roots of Bletilla striata
