The novel natural product xyloallenoide A, isolated from the marine mangrove endophytic fungus from the South China Sea, and its diastereoisomer xyloallenoide A1, which contain N-methyl-substituted amino acids, were synthesized. The absolute configurations of the amino acid units of xyloallenoide A were finally confirmed to be L-Lys, Me-D-Val, and Me-L-Ala. This report represents a practical and attractive alternative for the synthesis of N-methyl-substituted cyclotripeptides. In the preliminary bioassay, synthetic xyloallenoide A showed marginal activities against KB (IC₅₀=9.6 μM) and KBv200 cells (IC₅₀=10.3 μM), and xyloallenoide A1 was inactive against KB and KBv200 cells.

Two new meroterpenes, ‘acetoxydehydroaustin B’ (1) and ‘1,2-dihydro-acetoxydehydroaustin B’ (2) were isolated in the form of a mixed crystal from the mangrove endophytic fungus Aspergillus sp. 085241B. Their structures and absolute configurations were determined by extensive analysis of their spectra and X-ray diffraction data. In a preliminary bioassay, the mixed crystal did not exhibit activities against cancer cell lines of MDA-MB-435, SKBR3, HepG2, HEP3B, PC-3, and A549, as well as against α-glucosidase and tyrosinase.

Three unique metabolites, namely, phomopsis-H76 A (1), B (2), and C (3), were isolated from the mangrove endophytic fungus Phomopsis sp. (#zsu-H76). Structures were determined by spectroscopic methods, mainly 1D and 2D NMR spectroscopy. Compound 1–3 are all dimers. Compounds 2 and 3 possesses a pyrano[4,3-b]pyran-5(2H)-one ring system that is unprecedented in nature. Primary bioassays showed that 1 accelerated the growth of subintestinal vessel plexus (SIV) branch markedly, whereas 3 showed inhibition of SIV. Compounds 1–3 showed no activity in antibacterial and cytotoxic tests.

A mild and efficient protocol for the synthesis of the benzopyran ring has been described and a series of chromans compounds is reported, the yield is from 72% to 95%. The diadduct tended to angular product and showed good regioselectivity. This strategy was applied for the benzopyran derived natural products (±)-xyloketals and (±)-alboatrin. The crystal of compound 9 exhibited centro-symmetric space group, containing two isomers in one unit. The relative configurations were 1R,10R,15S and 34S,22R,30S, respectively.

A new lactone, 1,8-dihydroxy-10-methoxy-3-methyldibenzo[b,e]oxepine-6,11-dione (1), and two new xanthones, 1-hydroxy-8-(hydroxymethyl)-6-methoxy-3-methyl-9H-xanthen-9-one (2) and 1-hydroxy-8-(hydroxymethyl)-3-methoxy-6-methyl-9H-xanthen-9-one (3), were isolated from a mangrove endophytic fungus Phoma sp. SK3RW1M collected from the South China Sea. This is the first report on xanthone derivatives isolated as secondary metabolites from Phoma species. Their structures were elucidated by spectroscopic methods, mainly 1D- and 2D-NMR techniques, and the structure of compound 2 was confirmed by X-ray crystallography. Cytotoxicity assays showed that compounds 1–3 were inactive against KB and KBv200 cells.

A novel metabolite xylopyridine A (1), together with a known compound pyrocoll (2), was isolated from mangrove endophytic fungus Xylaria sp. (#2508) collected from the South China Sea coast. Their structures were established on the basis of spectroscopic analysis, especially 2D-NMR. Their affinities toward calf thymus (CT) DNA were studied by fluorescence quenching and spectrophotometric titration experiments. The results indicate that 1 showes strong DNA-binding affinity presumably via an intercalation mechanism, thus it is exploitable as strong DNA-binders.

A copper coordination compound ZZF51(A) named bis(5-butyl-2-pyridinecarboxylato-N1,O2)-copper, the first time found in the nature, was isolated from a marine endophytic fungus Fusarium sp. ZZF51 from the South China Sea coast. Its structure was elucidated using spectroscopic methods and single crystal X-ray diffraction analysis. The antimicrobial cytotoxicity experiments exhibited that ZZF51(A) had mutagenicity activities against four aerobic reference strains Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Salmonella enteritidis with respective MIC values of 12.5, 25, 12.5, and 50 µg/mL. The anti-cancer tests showed that the compound had strong inhibitory activities against three human cancer lines KB, KBv200, and HepG2 with IC₅₀ values of 3.54, 3.68 and 25.12 µg/mL respectively. In the course of investigating the source of ZZF51(A) in biomass, it was found that the output of ZZF51(A) was largely influenced by the amount of CuCl₂ in the liquid medium, and the fungus (No. ZZF51) had two notable characteristics:endurance of high concentration Cu(II) ions and biosorption of Cu(II) ions.

A chiral product, (+)-2-methoxy-2-methylchroman-7-ol, was obtained from β-cyclodextrin (β-CD)/1,3-dihydroxylbenzene (complex A) and methyl vinyl ketone/β-cyclodextrin (complex B). The reaction was carried out at room temperature in a solid state to give the desired product in 82.8% yield and 78.4% ee. Low optically active product (19.5% ee) was obtained from complex B and 1,3-dihydroxylbenzene (A), and non-optically active product was obtained from complex A and methyl vinyl ketone (B) under the same conditions. The structures of the inclusion compounds were elucidated by melting points, X-ray diffraction, solid-state ¹³C CP/MAS NMR (100 MHz, spin5000), and ROESY analyses. The ratios (1:1) of host-guest in the inclusion compounds were decided by ¹H NMR spectra (400 MHz). The mechanism of the solid-state conjugated cyclic addition reaction was also discussed.

In our ongoing investigation of the bioactive constituents from plants, two new lignans, magnolignan A-2-O-β-D-glucopyranoside and strebluslignanol were isolated from heartwood of Streblus asper, along with three known lignans, magnolignan A, magnolol, and magnaldehyde D. 1D and 2D NMR experiments, including COSY, HMQC, and HMBC, and other spectroscopic methods, including UV, IR, and MS were used for the determination of the structures and NMR assignments. Primary bioassays showed that magnolignan A-2-O-β-D-glucopyranoside and strebluslignanol have medium cytotoxic activity against HEp-2 and HepG2 cells, with IC₅₀ of 13.3 µM, 46.4 µM and 10.1 µM, 21.7 µM, respectively. Copyright © 2008 John Wiley & Sons, Ltd.

A new natural product, named phomopsin A, 1-(meta-hydroxyphenyl)-4-hydroxy-3-isoquinolone (1), together with two known compounds cytochalasin H (2) and glucosylceramide (3), was isolated from the mangrove endophytic fungus Phomopsis sp. (ZZF08) obtained from the South China Sea coast. The structures were elucidated by 1D and 2D NMR experiments including COSY, HMQC, and HMBC. According to NMR and single-crystal X-ray diffraction, it was found that some assignments about ¹H and ¹³C NMR data for cytochalasin H (2) were probably uncorrected in the previous reports. In our cytotoxicity assays, compound 1 showed moderate cytotoxicity toward KB cells with IC₅₀ at 28.0 µg ml⁻¹ and KBv200 cells with IC₅₀ at 16.8 µg ml⁻¹, and compound 2 exhibited strong cytotoxicity toward KB cells and KBv200 cells with IC₅₀ less than 1.25 µg ml⁻¹. Copyright © 2008 John Wiley & Sons, Ltd.

Two new diaryl ethers, named phomopside A (1) and B (2), together with known excelsione (3) were isolated from the mangrove endophytic fungus Phomopsis sp. (ZZF08) obtained from the South China Sea coast. The structure of 1 was elucidated by NMR spectroscopy and confirmed by X-ray crystallography. Compounds 2 and 3 were identified by NMR spectroscopy and comparing the spectroscopic data with literature values. In addition, the plausible biogenetic path of 1, 2 and 3 is discussed. Copyright © 2008 John Wiley & Sons, Ltd.