Sterols and sterolins in Hypoxis hemerocallidea (African potato)

Commercially available health supplements and herbal remedies containing sterols and sterolins, either from African potato (Hypoxis hemerocallidea) alone, or whether enriched with sterols and sterolins, are claimed to be efficacious in the treatment of a variety of ailments. Sterols and sterolins in African potato are purported to be the relevant constituents that are required for the therapeutic claims of such products. A patent describing the extraction of sterolins from African potato plant material has claimed that approximately 9 mg sterolins can be isolated from 100 g of an enriched aqueous African potato extract. Our analysis of African potato plant material and its sterol and sterolin content, when similarly prepared, shows that the measureable content of sterols and sterolins in African potato is far less than the amounts of these compounds that have been claimed to be necessary for therapeutic benefit. We conclude that therapeutic claims relating to sterol and sterolin content in African potato are unsubstantiated, in view of the extremely low content of such compounds that we have isolated from our plant material, and in products containing African potato, or extracts thereof.