Huperzine alkaloids from Australasian and southeast Asian Huperzia

Abstract

Context: The pharmaceutical alkaloid huperzine A (HupA), currently used in herbal supplements and medicines worldwide, is predominantly sourced from the Chinese lycopod Huperzia serrata (Thunb. ex Murray) Trev. (Lycopodiaceae), which on average contains only 0.08mg HupA g−1 dry weight, and is experiencing a rapid decline in China due to over-harvesting.

Objective: To find a high-yielding, natural source of HupA and/or the related huperzine B (HupB) that could potentially be used as the starting material in a commercial propagation program.

Materials and methods: We surveyed 17 Huperzia species (15 indigenous to Australia and southeast Asia) for their foliar HupA and HupB concentrations. We also studied intra-specific variation for the huperzines in four species that were available in sufficient numbers, and determined tissue-specific accumulation in larger specimens.

Results: HupA was detected in 11 Australasian and southeast Asian species, with eight also containing HupB, albeit at much lower concentrations. A H. elmeri (Herter) Holub plant from the Philippines had one of the highest HupA concentrations recorded (1.01mg g−1 dry wt) and it also had the highest HupB content of all plants surveyed (0.34mg g−1 dry wt). Intra-specific HupA and HupB concentrations were extremely variable, and at the intra-plant level, reproductive strobili were found to accumulate the highest HupA concentrations.

Discussion and conclusion: Select Huperzia species from Australia and southeast Asia have potential as the starting material for establishing commercial HupA plantations, but the high intra-specific variability observed suggests that detailed screening is needed to isolate high huperzine-yielding individuals.