The Lycopodiaceae is an ancient and cosmopolitan family of fern allies that include an estimated 35 Huperzia species occurring throughout the South-East Asian and Australian region. Thirteen species naturally occur in Australia and are found mainly in the tropical rainforests of far north Queensland. Over the past decade, there has been renewed interest in Huperzia and their respective Huperzine alkaloid concentrations following the discovery of Huperzine A (HupA) and Huperzine B (HupB) alkaloids in H. serrata (Thunb. ex Murray) Trevis. Both alkaloids are of pharmaceutical interest since they are highly selective and potent reversible inhibitors of acetylcholine esterase. Huperzine alkaloid concentrations of Australasian Huperzia have not been well documented, and no prior studies have been undertaken to investigate the amenability of Australasian Huperzia to alternative propagation techniques such as axenic culture. / This research presents an extensive screen of 16 Australasian Huperzia species to investigate their Huperzine alkaloid concentrations. HupA (0.032 to 1.012 mg g-1 DW) was detected in ten out of the sixteen Huperzia species examined, while HupB (0.008 to 0.339 mg g-1 DW) was detected in eight. From this extensive study, H. elmeri (Herter) Holub was observed as the species with the greatest potential to yield high Huperzine-containing individuals. In addition, the screen established that Australasian Huperzia generally contain higher HupA levels than H. serrata, the main source of commercial HupA, which on average only contains 0.082 mg g-1 DW HupA. The fractionation and spectrometric analysis of alkaloids as part of the screen led to the discovery of three Huperzine alkaloids co-occurring within the same plant: HupA, HupB and Huperzine C, isolated from an individual of an Australian H. carinata (Desv. Ex Poir.) Trevis. / The potential of establishing axenic cultures of Australasian Huperzia was also investigated in this research. Actively growing axenic cultures of H. carinata, H. squarrosa (C.Forster) Trevisan, H. phlegmaria (L.) Rothm. and H. phlegmarioidies (Gaudich.) Rothm., together with callus and cell suspension cultures of H. carinata and H. phlegmaria, were successfully established. The results suggest that culturing in total darkness is essential to allow for optimal callus and cell suspension growth. In addition, this study also investigated the possibilities of germinating various Huperzia spores, by both symbiotic and asymbiotic means. Germination of H. squarrosa spores was achieved by both symbiotic and asymbiotic means, and was only observed in cultures which were kept in the dark, implying that there is a form of photo-inhibition mechanism preventing spores from germinating when they are exposed to light. Beneficial effects of various types of spore treatments prior to sowing, in terms of increased spore germination was also observed. / In conclusion, the results presented suggest that Australasian Huperzia are indeed a potentially valuable resource for Huperzine alkaloids. The investigations into the conditions required for the successful introduction and maintenance of Australasian Huperzia in axenic culture has also further extended our understanding of these plants, and their amenability towards axenic culture conditions as a means of alternative propagation.

No / The alkaloid cryptolepine (1) and eight synthetic analogues (2-8) were assessed for in vitro activities against Trypanosoma brucei. Four of the analogues were found to be highly potent with IC50 values of less than 3 nM and three of these were assessed against T. brucei brucei infection in rats. The most effective compound was 2,7-dibromocryptolepine (7); a single oral dose of 20 mg/Kg suppressed parasitaemia and increased the mean survival time to 13.6 days compared with 8.4 days for untreated controls. In addition, four huperzine derivatives (9-12) were shown to have in vitro antitrypanosomal activities with IC50 values from 303-377 nM.