Chemical Investigation Of Ceriops Tagal And Two Mangrove-Associated Endophytic Fungi

Mangroves are restricted to the intertidal zones of tropics and subtropics, which found a marine wetland ecosystem specially located between the continent and ocean. Due to the sediments, and subjected to the flushing tide and tropical air, the living environment of mangrove ecosystem turns to be harsh with high temperature, high salinity, high acidity and poor dissolving oxygen. Correspondingly, organisms inhabited in this ecosystem have adapted special physiological mechanisms and metabolic pathways, and are able to produce bioactive substances with novel chemical structures and functions. Therefore, exploring natural products with novel bioactivities from mangrove plants and associated endophytes has profound significance.In this dissertation, chemical constituent s from a mangrove plant and t wo mangrove-associated endophytic fungi were investigated. The target compounds were fast tracked by comprehensively using multiple techniques of TLC, HPLC-DAD, and LC-MS, and isolated by combinatorially applying column chromatographies including silica gel, ODS, Sephadex LH-20, and HPLC. Consequently, twelve compounds(C-1~C-12) were isolated from Ceriops tagal, consisting of eight dolabranes, a pimarane, and three lupanes, with tagalsin V(C-1) and tagalsin W(C-2) new dolabranes. Seven metabolites(X-1~X-7) were obtained from Thai mangrove endophytic fungu Pestalotiopsis sp. xy18, comprising three ɑ-pyrones, two isocoumarin derivatives, one ergosta, and thymidine, with(5-hydroxymethyl-4-methoxy-6-methyl-2-oxo-2H-pyran-3-yl)methyl acetate(X-1) and 3,5-bis(hydroxymethyl)-4-methoxy-6-methyl-2H-pyran-2-one(X-2) two new ɑ-pyrones, 6,8-dihydroxy-3-(hydroxymethyl)-7-methyl-1H-isochromen-1-one(X-3) a new isocoumarin. Ten substances(I-1~I-10) were gained from Malaysian mangrove endophytic fungu Phomopsis sp. I41, consisting of two new 14-member macrolides,(2E,6E,8E)-4,5-dihydroxy-13-methyloxacyclotetradeca-2,6,8-trien-1-one(I-1) and(2E,5Z,7E)-4,9-dihydroxy-13-methyloxacyclotetradeca-2,5,7-trien-1-one(I-2), one new phenol derivative, ethyl-1’-[1’’-(3-acetoxyhexanoyl)-5,7-dihydroxyphenyl]acetate(I-3), one new cyclohezanone derivative, 2,3,6-trihydroxy-2,5-dimethylcyclohex-5-enone(I-4), one sesesquiterpene, two cytochalasins, two glycerides, and L-tyrosine. All the compounds were structurally determined on basis of ORD, UV, MS, and NMR analyses.