Research On The Secondary Metobolites From Laurencia Nidifica, Symphyocladia Latiuscula And Its Symbiotic Trichoderma Harzianum EN-85

In the present dissertation, the secondary metobolites from the marine red algal Laurencia nidifica and Symphyocladia latiuscula as well as the algal-derived symbiotic Trichoderma harzianum EN-85 were investigated. Repeated column chromatography on silica gel, Rp-18, ploymide, and Sephadex LH-20, prep-TLC, and semi-preparative HPLC were used to separate the compounds. Elucidation of the structures was performed by IR, UV, EI-MS, ESI-MS, HR-ESI-MS, 1D NMR and 2D NMR. A total of 55 compounds were separated and identified, with 9 of them were found as new compounds.The marine red algal Laurencia nidifica was discovered for the first time in South China Sea. A total of 21 compounds were separated and identified from this species, including four new structures (one charmigrane sesquiterpene LS8, two bisabolene sesquiterpenes LS9 and LS10, and one C15-acetogein LS17). Compounds LS1, LS3, LS6, LS7, LS8, LS12, LS13, and LS17 were tested for the antimicrobial activity. Among them, compounds LS6 and LS7 exhibited weak inhibition against Alternaria brassicae (berk.) Sace and against Escherichia coli, Staphylococcus aureus, A. brassicae and Physalospora piricola Nose, respectively, while LS8 and LS12 exhibited weak inhibition against S. aureus and against S. aureus and P. piricola, respectively.Another marine red algal Symphyocladia latiuscula was collected at the coast of Weihai in Shandong province. A total of 13 compounds were isolated and identified from the species including one new compound (SL1). Compounds SL2-SL9 were evaluated the activity against the protein tyrosine phosphatase 1B (PTP1B). Bromophenols SL6, SL7, and SL8 displayed potent activity with IC50 values 3.9, 4.3, and 3.5μmol/L, respectively, which might be used as a potential source for developing anti-diabetes drug.The fungus Trichoderma harzianum EN-85 was isolated from the marine red algal Symphyocladia latiuscula and was identified by molecular biology methods. A total of 21 compounds were isolated and indentified from this fungal stain including 4 new compounds (two sesquiterpenes FS2 and FS4, one diterpene FS14, and one other compound FS15). The antimicrobial activity was evaluated. The inhibition on the A. brassicae and P. piricola were observed. Compounds FS1, FS3, FS4, FS8-FS10, and FS12-FS15 were tested the antimicrobial activity, and FS3 and FS4 exhibited weak inhibition against P. piricola and Fusarium oxysporium.In conclusion, phytochemical examination of the marine red algal L. nidifica, S. latiuscula and from the symbiotic fungus T. harzianum EN-85 led to the identification of 9 new compounds, which enriched the marine natural products library. Some compounds with PTP1B inhibitory activity and with anti-microbial activity were discovered.