Identification of semi-volatile specialized metabolites from Vitellaria paradoxa (shea) kernels using GC-MS

Abstract

Nuts from the African wild tree Vitellaria paradoxa (shea) represent a valuable source of plant-based butter used in cosmetics and foods, e.g. as a cocoa butter equivalent. Beyond glyceridic lipids, kernels contain triterpene esters, phytosterols, and tocopherols with bioactive properties such as antioxidative, anti-inflammatory, anticancer, and cholesterol-lowering effects. Here, GC-MS was used to profile triterpene alcohols, acetates, cinnamates, and related metabolites. Identification relied on comparisons with standards, retention time and spectral libraries, and literature. Through saponification, the presence of ten triterpene alcohols was confirmed, while 18 triterpene esters, spinasterol and 22,23-dihydrospinasterol were identified in unsaponified extracts. The triterpene esters are derived from the triterpene alcohols amyrin (α, β and δ), lupeol, butyrospermol, taraxasterol, Ψ-taraxasterol, lanosterol, parkeol, and 24-methylenecycloartanol. Abundant ones are α-amyrin- and lupeol cinnamate (together 15.4 mg/g), α-amyrin acetate (2.8 mg/g), butyrospermol cinnamate (2.8 mg/g) and acetate (1.6 mg/g), lupeol acetate (2.2 mg/g), β-amyrin cinnamate (1.6 mg/g) and acetate (0.7 mg/g), with triterpene esters comprising up to 3.6 % of the shea kernels. This study provides the first GC-MS-based absolute quantities of triterpene acetates and cinnamates in shea kernels. The method adds to knowledge about shea’s specialized metabolites, which may enhance understanding of their bioactive potential.