Compositions and melanogenesis-inhibitory activities of the extracts of defatted shea (Vitellaria paradoxa) kernels from seven African countries

Abstract

Constituents of shea (Vitellaria paradoxa; Sapotaceae) kernels are commonly used as functional food and for skin care by indigenous peoples in Africa. Twenty-six MeOH extract samples of defatted shea kernels from seven sub-Saharan countries, i.e., Côte d'Ivoire, Ghana, Nigeria, Cameroon, Chad, Sudan, and Uganda, were investigated in this study. HPLC coupled to an evaporative light-scattering detector and LC-QTOF (time-of-flight)-MS revealed that the extracts contained sugars (25.6–80.2%) as the most predominant constituents, followed by oleanane-type triterpene glycosides (4.9–35.2%), accompanied by minor amounts of cucurbates (1.0–21.0%) and phenolic compounds (0.3–16.0%). Principal component analysis and hierarchical clustering analysis classified the twenty-six samples into three groups. Upon evaluation of the melanogenesis-inhibitory activities of all samples in B16 melanoma cells induced by α-melanocyte-stimulating hormone, it was found that samples S2, S3, and S21 were lower-risk melanogenesis inhibitors (39.4–42.5% melanin content, 78.6–91.6% cell viability) with a small activity-to-cytotoxicity ratio (0.18–0.94), and were superior to reference arbutin at a concentration of 100 μg/mL. These results suggest that the extracts of defatted shea kernels and their constituents can be regarded as skin-whitening agents.