Isolation and Characterization of Novel Huperzine-Producing Endophytic Fungi from Lycopodiaceae Species.

Huperzine A (HupA) is an important drug for treating Alzheimer's disease (AD) and is primarily extracted from the Huperzia serrata (Lycopodiaceae). Failures in the chemical synthesis of Hup and in vitro culture have put H. serrata in danger of extinction, and there is a need for an extensive investigation of Hup from alternative perspectives. The aim of this study is to identify endophytic fungi that produce high Hup or simultaneously produce many types of Hup and have high genetic stability derived from other Lycopodiaceae species as a source of materials for natural Hup production. In this work, Hup-producing endophytic fungi were isolated from three species: Lycopodium clavatum, Phlegmariurus squarrosus, and P. phlegmaria. Of these, L. clavatum and P. squarrosus were confirmed as novel sources of Hup-producing fungi. Based on morphological characteristics and nuclear ribosomal DNA ITS sequences, four endophytic fungi Colletotrichum siamense THG1-17, Epicoccum sorghinum THG01-18, Phoma sp. TKH3-2, and Phyllosticta sp. THG2-27 were firstly isolated from these Lycopodiaceae plants, which were capable of simultaneously producing both HupA and HupB, as evidenced by high-performance liquid chromatography analysis. The four strains showed stability in Hup yield over 50 generations of culture with an in vitro storage period of 3 months. These isolated fungi will provide a new source of materials for further research to develop drugs containing HupA as well as HupB for AD treatment in the future.

A novel huperzine A-producing endophytic fungus Fusarium sp. Rsp5.2 isolated from Huperzia serrate.

The isolation, identification and characterization of a novel huperzine A (HupA)-producing fungal strain Rsp5.2 isolated from Huperzia serrata (Thunb. ex Murray) Trev. in Vietnam. The fifty-eight endophytic fungi were recovered from roots of natural H. serrata in Lao Cai province of northern Vietnam and screened for HupA-producing by thin-layer chromatography (TLC). The only one of the 58 strains, Rsp5.2, could produce HupA. The amount of HupA produced by Rsp5.2 was quantified to be 19.45 µg g-1 dried mycelium by high-performance liquid chromatography (HPLC). Acetylcholine esterase (AchE) inhibition (IC50) of the crude HupA extract from Rsp5.2 fermentation broth was 2.849 ± 0.0026 µg mL-1. The fungus was identified as Fusarium sp. Rsp5.2 by morphological characteristics and Internal Transcribed Spacer (ITS) sequences. This is the first report of Fusarium sp. as a HupA-producing endophyte isolated from H. serrata.