Browsing by Author "Ding, Ling"

Penicillium herquei isolate GA4 was isolated from the infected Conchocelis of Porphyra yezoensis. A large-scale fermentation using yeast extract sucrose medium and repeated chromatography afforded a new symmetrical urea derivative, hualyzin (1). The structure was determined by detailed NMR spectroscopic investigations and MS fragmentation analysis.

Cladosporium sp. isolate N5 was isolated as a dominant fungus from the healthy conchocelis of Porphyra yezoensis. In the re-infection test, it did not cause any pathogenic symptoms in the alga. Twenty-one cultural conditions were chosen to test its antimicrobial activity in order to obtain the best condition for large-scale fermentation. Phenylacetic acid, p-hydroxyphenylethyl alcohol, and L-beta-phenyllactic acid were isolated from the crude extract as strong antimicrobial compounds and they are the first reported secondary metabolites for the genus Cladosporium. In addition, the Cladosporium sp. produced the reported Porphyra yezoensis growth regulators phenylacetic acid and p-hydroxyphenylacetic acid. No cytotoxicity was found in the brine shrimp lethality test, which indicated that the environmental-friendly Cladosporium sp. could be used as a potential biocontrol agent to protect the alga from pathogens.

Secondary magnetic remanences are used to study late-orogenic rotation and tilting on a E-W transect in southern Tibet at similar to 28.5 degrees N. Sampling was performed on both sides of the Ama Drime Massif (ADM). Remanent magnetization resides in pyrrhotite formed during metamorphism and is related to the last cooling event through 325 degrees C (Curie temperature of pyrrhotite). The existence of antipodal pTRMs demonstrates that the ChRM is of thermoremanent origin and was acquired during cooling of the Tethyan metasediments. Penetrative deformation was still going on in Ronghbuk area until ca 250 degrees C, whereas it was already completed in Dinggye area. Significant departures from the expected field direction during the age of remanence acquisition cannot be interpreted by consistent vertical axis rotation of blocks. Antagonist deviations on both sides of the ADM are explained as tiltings around an horizontal axis striking similar to N20 degrees. These tiltings are estimated to be younger than 13-12 Ma and they are related to the ADM exhumation initiated since 33 Ma. (C) 2012 Elsevier Ltd. All rights reserved.

Two new sesquiterpenes, 15-hydroxy-T-muurolol (3d) and 11,15-dihydroxy-T-muurolol (3e), along with the plant cadinenes T-muurolol (3f) and 3 alpha-hydroxy-T-muurolol (3g), were isolated from the marine-derived Streptomyces sp. M491. Their absolute configuration was established via NMR spectroscopy and X-ray crystallography of 3-oxo-T-muurolol (3a), which was reisolated from this strain. In addition, the absolute configuration of further sesquiterpenes previously reported from this strain was revised. These products were tested for their cytotoxicity against 37 human tumor cell lines using the MTT method. Only 3d was cytotoxic against a range of human tumor cell lines with a mean IC(50) of 6.7 mu g/mL.