Xiu-Li Yin

Absolute Configurations of Unique Harziane Diterpenes from Trichoderma Species

Harzianone (2), a new harziane diterpene, was isolated from an alga-endophytic isolate of Trichoderma longibrachiatum. The structure and absolute configuration of 2 were unambiguously identified by NMR and mass spectrometric methods as well as quantum chemical calculations. The absolute configuration of harziandione (1) was supported by calculation of optical rotation, and the structure of isoharziandione was revised to 1 on the basis of (13)C NMR data comparison and calculation.

Three new xanthone derivatives from an algicolous isolate of Aspergillus wentii

Three new xanthone derivatives, yicathin A (1), yicathin B (2), and yicathin C (3), and three known anthraquinone derivatives, alatinone (4), 1,5‐dihydroxy‐3‐methoxy‐7‐methylanthraquinone (5), and 5‐hydroxy‐1,3‐dimethoxy‐7‐methylanthraquinone (6), were isolated from the cultures of Aspergillus wentii pt‐1, an endophytic fungus isolated from the marine red alga Gymnogongrus flabelliformis. Their structures were unambiguously elucidated by NMR and mass spectroscopic methods as well as quantum chemical calculations. Compound 2 was active against Escherichia coli, and 3 could inhibit E. coli, Staphylococcus aureus, and Colletotrichum lagenarium. Copyright

Steroids and an oxylipin from an algicolous isolate of Aspergillus flavus

A new oxylipin, (8E,12Z)‐10,11‐dihydroxyoctadeca‐8,12‐dienoic acid (1), a new steroid, 3β,4α‐dihydroxy‐26‐methoxyergosta‐7,24(28)‐dien‐6‐one (2), and four known steroids, episterol (3), (22E,24R)‐ergosta‐7,22‐dien‐3β,5α,6α‐triol (4), (22E,24R)‐ergosta‐5,22‐dien‐3β‐ol (5), and (22E,24R)‐ergosta‐4,6,8(14),22‐tetraen‐3‐one (6), were isolated from the cultures of Aspergillus flavus, an endophytic fungus isolated from the marine red alga Corallina officinalis. Their structures and relative stereochemistry were elucidated by 1D, 2D NMR and mass spectroscopic techniques. 1 and 2 exhibited low activity to inhibit acetylcholinesterase and no activity against plant pathogenic fungi Colletotrichum lagenarium and Fusarium oxysporum. Copyright

Sesquiterpenes from the marine red alga Laurencia composita

Four new chamigrane derivatives, laurecomin A (1), laurecomin B (2), laurecomin C (3), and laurecomin D (4), one new naturally occurring sesquiterpene, 2,10-dibromo-3-chloro-7-chamigren-9-ol acetate (5), and three known halogenated structures, deoxyprepacifenol (6), 1-bromoselin-4(14),11-diene (7), and 9-bromoselin-4(14),11-diene (8), were isolated from the marine red alga Laurencia composita collected from Pingtan Island, China. The structures of these compounds were unambiguously established by 1D, 2D NMR and mass spectroscopic techniques. The bioassay results showed that 2 was active against both brine shrimp and fungus Colletotrichum lagenarium.

Sesteralterin and Tricycloalterfurenes A-D: Terpenes with Rarely Occurring Frameworks from the Marine-Alga-Epiphytic Fungus Alternaria alternata k21-1

A new sesterterpene, sesteralterin (1), four new meroterpenes, tricycloalterfurenes A-D (2-5), and a known meroterpene, TCA-F (6), were obtained from the culture extract of an Alternaria alternata strain (k21-1) isolated from the surface of the marine red alga Lomentaria hakodatensis. The structures and relative/absolute configurations of these compounds were identified by spectroscopic analyses, mainly including 1D/2D NMR, ECD, and mass spectra and quantum chemical calculations. Compound 1 represents the first nitidasane sesterterpene naturally produced by fungi, and 2-5 feature a tetrahydrofuran unit rarely occurring in tricycloalternarenes. Compounds 1-6 were assayed for inhibition of the growth of four marine plankton and one marine alga-pathogenic bacterium.

Tricholumin A, a Highly Transformed Ergosterol Derivative from the Alga-Endophytic Fungus Trichoderma asperellum

Tricholumin A (1) with an unprecedented carbon skeleton was isolated from the fungus Trichoderma asperellum cf44-2, an endophyte from the marine brown alga Sargassum sp. Its structure and relative configuration were identified by extensive 1D/2D NMR and mass spectrometric data, and the absolute configuration was assigned by X-ray diffraction and ECD calculations. Compound 1 represents a highly transformed ergosterol derivative, and it exhibited inhibition of some pathogenic microbes and marine phytoplankton species.

Two new isomeric tricycloalternarenes from the marine alga-epiphytic fungus Alternaria alternata k23-3

Tricycloalternarenes (TCAs) and their possible precursors, bicycloalternarenes, represent a large class of fungal‐derived meroterpenes, which are regarded as the products through hybrid mevalonate and shikimate pathways. Totally, more than 70 members have been isolated and identified so far, with TCAs accounting for over 70%. Most of the TCAs feature a ring system that is constructed by the fusion of a cyclohex‐2‐enonyl group and a cyclopentenyl/cyclopentyl group via a methylene group and an oxygen atom, and they have been obtained from some species of the genera Alternaria, Aspergillus, Guignardia, Pycnoporus, Septoria, and Ulocladium. In our ongoing investigation towards the chemical diversity and biological activity of secondary metabolites from marine algicolous fungi, a marine red alga‐epiphytic strain (k23‐3) of Alternaria alternata was examined. As a result, two new 15‐hydroxytricycloalternarenes (1 and 2) along with a known one, TCA 11a (3), were isolated and identified (Figure 1). Details of the isolation, structure elucidation, and bioactivity of these compounds are described in this paper.

Trichorenins A–C, Algicidal Tetracyclic Metabolites from the Marine-Alga-Epiphytic Fungus Trichoderma virens Y13-3

Three novel polyketide-like metabolites, trichorenins A-C (1-3), with a unique tetracyclic carbon skeleton were obtained from the culture of Trichoderma virens Y13-3, an epiphyte of the marine red alga Gracilaria vermiculophylla. Their structures and relative configurations were established by analysis of 1D/2D NMR and MS data, and their absolute configurations were unequivocally assigned by X-ray diffraction and ECD spectra aided by quantum chemical calculations. Compounds 1-3 exhibited potent inhibition against two marine phytoplankton species, Chattonella marina and Karlodinium veneficum.

Halogenated and Nonhalogenated Metabolites from the Marine-Alga-Endophytic Fungus Trichoderma asperellum cf44-2

One new bisabolane sesquiterpene, bisabolan-1,10,11-triol (1), one new norbisabolane sesquiterpene, 12-nor-11-acetoxybisabolen-3,6,7-triol (2), two new naturally occurring monoterpenes, (7S)- and (7R)-1-hydroxy-3-p-menthen-9-oic acids (3 and 4), one new naturally occurring trichodenone, dechlorotrichodenone C (5), one new chlorine-containing trichodenone, 3-hydroxytrichodenone C (6), one new diketopiperazine, methylcordysinin A (7), and one new naturally occurring oxazole derivative, 4-oxazolepropanoic acid (8), were isolated from the culture of a marine brown alga-endophytic strain (cf44-2) of Trichoderma asperellum. Their structures and relative configurations were determined by extensive 1D/2D NMR and mass spectrometric data, and the absolute configurations of 3–6 were assigned by analysis of the ECD spectra aided by quantum chemical computations. Compounds 1, 2, 5, and 6 showed growth inhibition of some marine phytoplankton species and pathogenic bacteria.

Diterpenes and Sesquiterpenes from the Marine Algicolous Fungus Trichoderma harzianum X-5

Six new terpenes, including one harziane diterpene, 3 R-hydroxy-9 R,10 R-dihydroharzianone (1), one proharziane diterpene, 11 R-methoxy-5,9,13-proharzitrien-3-ol (2), three cyclonerane sesquiterpenes, 11-methoxy-9-cycloneren-3,7-diol (3), 10-cycloneren-3,5,7-triol (4), and methyl 3,7-dihydroxy-15-cycloneranate (5), and one acorane sesquiterpene, 8-acoren-3,11-diol (6), were isolated from the culture of Trichoderma harzianum X-5, an endophytic fungus obtained from the marine brown alga Laminaria japonica. Their structures and relative configurations were established by analysis of 1D/2D NMR, HREIMS, and IR data, and the absolute configurations were assigned on the basis of ECD curves or biogenetic considerations. These terpenes possess four different carbon skeletons, and compound 2, with a rarely occurring bicyclic framework, represents a possible precursor of tetracyclic harzianes. Compounds 1-6 exhibited growth inhibition of some marine phytoplankton species.