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 0.08 mg 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 (1.01 mg g⁻¹ dry wt) and it also had the highest HupB content of all plants surveyed (0.34 mg 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.

Keywords::

• Acetylcholine esterase
• Alzheimer’s disease
• huperzine A
• huperzine B
• lycopod

Acknowledgments

A.R.F. acknowledges the support of Michelle Waycott. We thank Harry and Rita Kupke, Owen and Coral Rawlins, Bruce Gray and Holly Field for access to Huperzia plants.

Declaration of interest

This research was supported by funds from the Holsworth Wildlife Research Fund (Victorian Community Foundation, ANZ Charitable Trusts). The authors report no conflicts of interest.