Hoodia gordonii (Masson) Sweet ex Decne, and other Hoodia spp.

Scytanthus gordonii (Masson) Hook; Stapelia gordonii Masson

Apocynaceae (previously in Asclepiadaceae)

Bushman’s hat; hoodia ‘cactus’; Kalahari ‘cactus’; xhoba

Stem

H. gordonii extract has been extensively characterised; chemical profiles of other Hoodia species are less well known. Main constituents of H. gordonii are steroidal (pregnane) glycosides (>70% w/w), based on hoodigogenin A and calogenin, including the hoodigosides, the hoodistanalosides and the gordonosides. The isolated appetite-suppressant component, a minor constituent, was identified as a triglycoside of 12β-tigloyloxy-14β-hydroxypregn-5-en-20-one (known as ‘P57’). Several other closely related glycosides have been characterised, all of them containing 6-deoxy- and 2,6-dideoxy sugars. H. gordonii extracts also contain fatty acids (e.g. myristic acid, palmitic acid, stearic acid, oleic acid, and linoleic acids); sterols (e.g. cholesterol, β-sitosterol, stigmasterol); α-tocopherol; and alcohols (van Heerden 2008; Russell and Swindells 2012; Shukla et al. 2009).

The main focus of research into hoodia has been on the patented extract enriched with the pregnane glycoside P57, which has been the subject of controversial intellectual property rights and benefit sharing issues. Development of hoodia extracts by Unilever for use in functional food products was abandoned in 2008 due to safety and efficacy concerns (Vermaak et al. 2011). Few clinical studies on hoodia extracts have been published. A number of unpublished clinical studies (using crude extracts and concentrated active ingredients of Hoodia) undertaken by the pharmaceutical/functional foods industry are available from the South African Council for Scientific and Industrial Research. While evidence of appetite-suppressant effects was observed in some (but not all) of these trials, adverse effects, including hyperbilirubinaemia, and tolerability issues were reported in some individuals administered the concentrated active ingredient extracts (CSIR 2011).

In a published randomised controlled-trial in 49 healthy overweight women, administration of purified hoodia extract (1110 mg twice per day for 15 days) did not result in any significant reduction in energy intakes or body weights relative to placebo. However, the hoodia preparation resulted in a significant (p < 0.05) increase in adverse effects, including increase in blood pressure, pulse, heart rate, bilirubin and alkaline phosphatase, and was less tolerated than placebo (Blom et al. 2011).