The ethnobotany and major essential oil compounds of anise root (Annesorhiza species, Apiaceae)

Abstract

A comprehensive review of indigenous knowledge about a traditional Cape, San and Khoi food item called anise root or anyswortel (genus Annesorhiza) is presented. The first accurate record was by Thunberg in 1772 at the Berg River near Vlermuisdrift (now Bridgetown) in the Western Cape and applied to A. grandiflora. Four species have recorded food uses as root vegetables (A. grandiflora, A. macrocarpa, A. nuda and an as yet undescribed species from Namaqualand) and two species (A. nuda and A. flagellifolia) as leaf vegetables. Essential oils of this genus were studied for the first time. Hydro-distilled oil from the fleshy roots, leaves and fruits of three species recorded as edible (A. grandiflora, A. macrocarpa and A. nuda) were chemically characterized using GC–MS and NMR spectroscopy. Noteworthy differences were found between plant parts as well as species. Estragole and a small amount of anethole occur in the roots of A. nuda (but not in any of the other two species). The major components of A. grandiflora fruits were dillapiole, nothoapiole and limonene, while elemicin was identified in the roots of the same species. Fruits of A. macrocarpa contained methyleugenol, the leaves ethyl-benzenes and α-terpineol, whereas the roots yielded nerolidol and an unidentified sesquiterpene. In contrast, leaves and roots of A. nuda were quite similar with the exception of the occurrence of estragole and anethole in roots only and not in the leaves. This partially explains the reported anise flavor of the edible roots of this species. The main compound of both roots and leaves of A. nuda was butan-2-yl (2Z)-3-(methylsulfanyl) prop-2-enoate, a new trans-β-methylthioacrylate derivative. This α, β-unsaturated methylsulfanyl ester, colloquially named (−)-nudaic ester, was characterized and assigned using 2D-NMR spectroscopy. The pronounced chemical differences between the examined species require further chemosystematic studies and the differences between roots, leaves and fruits may reflect the distinct vegetative (winter) and reproductive (summer) growth phases in these summer-deciduous plants.