Publications

Publications serve as the concrete art form for the scientist. It is his modus operandi. Authorship is akin to success and achievement. It cannot and should not deteriorate into a bargaining tool or commodity. Dardik
Tankeu, S., Vermaak, I., Viljoen, A.M., Sandasi, M., Kamatou, G.P.P. 2013. Essential oil variation of Tagetes minuta in South Africa – a chemometric approach. Biochemical Systematics and Ecology 51: 320-327.

Tagetes minuta L., generally known as wild marigold and locally as "Kakiebos”, has been used traditionally for medicinal purposes in many countries around the world. South Africa is currently the major producer of Tagetes essential oil which is used in perfumery, cosmetics and aromatherapy. The organoleptic and therapeutic properties of an essential oil are dependent upon the chemical profile of the oil. Tagetes essential oil from India, Egypt and the United Kingdom has been reported to be highly variable. In this study, possible chemotypic variation of South African Tagetes oil was explored. Eighty-three individual plants were collected from twenty-one different localities in South Africa. Essential oils were obtained by hydrodistillation using a Clevenger-type apparatus and the oil yield obtained ranged between 0.38–1.52%. The essential oils were analysed by gas chromatography coupled to mass spectroscopy with flame ionisation detector (GC–MS‒FID) and the major compounds accounting for > 85% of the total composition were identified as: (Z)-β-ocimene (27.9–56.0%), (E)-ocimenone (7.4–37.2%), (Z)-tagetone (1.4–24.9%), dihydrotagetone (n.d.–23.4%), (Z)-ocimenone (4.5–13.9%), limonene (n.d.–6.5%) and (E)-tagetone (n.d.–3.2%). Untargeted analysis of GC–MS data using MarkerLynx® and hierarchical clustering analysis (HCA) revealed two major chemotypes. Further analysis of the two chemotypes using orthogonal projections to latent structures-discriminant analysis (OPLS-DA) identified (E)-tagetone, dihydrotagetone and (Z)-tagetone as characteristic marker constituents for chemotype 1, while chemotype 2 was characterised by (Z)-β-ocimene, (E)-ocimenone and (Z)-ocimenone.




Tagetes minuta leaf - TUT, Pretoria, Gauteng, South Africa [2009 © alvaroviljoen.com]