Study on secondary metabolites and α – glucosidase inhibitory activity of endophytic fungus Phomopsis prunorum in Camellia sinensis
Phomopsis fungi are a common type of plant pathogen that can cause serious diseases in various crops; Meanwhile, some species within this genus are also important endophytic fungi, widely present in most plants in nature. Phomopsis fungi, as endophytic fungi in plants, can produce a diverse range of active secondary metabolites, including α – pyranone, terpenes, alkaloids, and cell relaxants. These compounds not only exhibit pharmacological activities such as antifungal, anti-tumor, neuroprotective, and α – glucosidase inhibition, but also can be used as cell growth regulators. They have broad application prospects in the fields of medicine and agriculture.
Hypericum ascyron L. is a plant of the Primulaceae family, belonging to the genus Hypericum. It is used as a medicinal herb and has the effects of stopping bleeding, relieving pain, antibacterial and anti-inflammatory properties. There have been reports on the chemical composition of Camellia sinensis, mainly including flavonoids, terpenes, and polycyclic polyisoprene substituted triphenylphenols. However, there are few reports on the secondary metabolites of endophytic fungi in Camellia sinensis. Our research group obtained an endophytic fungus Phomopsis prunorum (F4-3) from the leaves of Camellia sinensis plants in the Shennongjia area in the early stage. After small-scale fermentation and cultivation, it was found that the rice fermentation products had a rich variety of structural types. Previous research on this fungus P New myrrh sesquiterpenes and isocoumarins have been discovered in prunorum (F4-3), demonstrating good activity against agricultural pathogenic bacteria. This study further investigates the fungus P Research was conducted on the rice fermentation products of prunorum (F4-3), and the biological activity of the isolated secondary metabolites was evaluated in order to discover compounds with novel structural types and significant pharmacological activities.

In this study, silica gel column chromatography, gel column chromatography and semi preparative HPLC were used to separate P Six secondary metabolites were isolated from prunorum (F4-3), including two new α – pyranone compounds and two known dibenzo α – pyranone compounds, one isocoumarin compound, and one alkaloid compound. The side chain structures of α – pyranone compounds 1 and 2 both contain adjacent dihydroxy fragments, and compounds 4-6 were isolated for the first time from this genus of fungi. Pharmacological activity evaluation showed that only compound 3 had moderate alpha glucosidase inhibitory activity, while compounds 1-6 showed no significant antibacterial activity. According to literature reports, compound 3 also exhibits certain cytotoxic activity and DPPH radical scavenging activity (IC50 of 46.5 μ M), and has weak antibacterial activity against various plant pathogens. This study did not isolate compounds with chemical composition structures similar to those of Camellia sinensis. This may be due to the fact that many gene clusters related to secondary metabolite synthesis pathways are silenced under normal laboratory culture conditions. In the future, attempts will be made to induce the expression of silenced genes in bacterial strains by changing the type of culture medium or adding chemical epigenetic modifiers to the culture medium, in order to increase the diversity of secondary metabolite structures and improve the probability of discovering novel and active compounds.