Seasonal Chemical Variation and Antidiabetic Activity of Major Compounds in Artemisia afra Infusions

Abstract

Artemisia afra Jacq. ex Willd., Asteraceae, is a very popular herbal medicine in Southern Africa and is mainly used in the form of a tea infusion for the treatment of a wide variety of ailments, including diabetes. In this study, the phytochemical variation of four individual A. afra plants, collected monthly for a 1-year period, was determined. Eleven phytochemical com- pounds present in the infusions were identified and was used to illustrate the seasonal chemical variability. These compounds were also tested for their in vitro antidiabetic activity using the α-glucosidase inhibition bioassay. The results indicated that considerable phytochemical variation existed over a 1-year period within each plant but also between the four plants tested. The main bioactive compounds, namely, 1,5-dicaffeoylquinic acid and 3,5-dicaffeoylquinic acid, showed better α-glucosidase inhibition activity than the positive control, acarbose. Furthermore, these compounds appeared to show an interchangeable transition trend with its monomer, chlorogenic acid, and caffeic acid with the former seemingly increasing during summer and the latter two during the winter months. This study highlights the importance of quality control and standardisation of popular herbal remedies such as A. afra.