Isolation and quantification of the toxic methylazoxymethanol glycoside macrozamin in selected South African cycad species

Cycads are a group of slow-growing, perennial, dioecious plants which in geological times thrived during the Mesozoic era. The present worldwide complement of around 300 species is distributed through both tropical and subtropical regions of the globe, and has pronounced centres in Australia, Mexico and South Africa. These popular plants are known for their ornamental, economic, dietary and medicinal value. However, increased demand collectively from this sector, as well as decimation of large tracts of cycad populations in the wild through habitat destruction and unscrupulous collection, has precipitated a fragile conservation status for the family, with majority of its species listed as threatened by statutory bodies such as CITES and IUCN. Despite their popularity, cycads have for several centuries been known to be toxic. The plants have been shown to have carcinogenic, mutagenic, teratogenic and neurotoxic properties, and its major constituent principles macrozamin and cycasin have exhibited similar effects in model studies. Cycads are used widely in traditional medicine (TM) in South Africa and the majority of endemic species are commonly traded on local TM markets. The present study deals with the isolation of macrozamin from seed kernels of Encephalartos transvenosus and quantification of this toxic methylazoxymethanol (MAM) glycoside via HPLC in selected indigenous species.

► The glycoside macrozamin is described from Encephalartos transvenosus (Zamiaceae).
► Structure elucidation was aided by use of high field 2D NMR and mass spectroscopy.
► HPLC showed the compound to be ubiquitous in several indigenous cycad species.
► Fresh weight levels detected ranged from 0.026 to 0.23%.