Tandyukisin,a novel ketoaldehyde decalin derivative,produced by a marine sponge-derived Trichoderma harzianum

Tandyukisin (1), a novel decalin derivative with an enolic β-ketoaldehyde, has been isolated from a strain of Trichoderma harzianum OUPS-111D-4 originally derived from the marine sponge Halichondria okadai, and its structure has been elucidated on the basis of spectroscopic analyses using 1D and 2D NMR techniques. In addition, the absolute configuration for 1 was established by the application of CD spectrum to the tribenzoate derivative. This compounds exhibited moderate cytotoxicity against human cancer cell lines.     

Ukulactones A and B, new NADH-fumarate reductase inhibitors produced by Penicillium sp. FKI-3389

Screening for NADH-fumarate reductase inhibitors led to the isolation of the new polyketide compounds, ukulactones A and B (1 and 2, Fig. 1) from a culture broth of Penicillium sp. FKI-3389. The structure of ukulactone A was elucidated as a methylated derivative of prugosene A1, which was produced by Penicillium rugulosum and NOESY experiment revealed ukulactone B was a stereoisomer of ukulactone A. Ukulactone A showed potent inhibitory activity against NADH-fumarate reductase of the roundworm Ascaris suum in vitro.     

Tricalysiolides A-F, new rearranged ent-kaurane diterpenes from Tricalysia dubia

Six rearranged ent-kaurane diterpenes, tricalysiolides A-F, having the cafestol-type carbon framework were isolated from the wood of Tricalysia dubia (Rubiaceae). Their absolute structures were determined on the basis of the 2D NMR spectroscopy, X-ray crystallographic analysis, and chemical methods.     

Dilospiranes A and B: diterpenes featuring novel carbocyclic units from the brown alga Dilophus spiralis

Dilospiranes A and B (1 and 2), two diterpenes featuring unprecedented carbocycles, were isolated from the organic extract of the brown alga Dilophus spiralis, collected from the coast of Elafonissos Island, Greece. The structures and the relative configurations of the isolated natural products were determined on the basis of extensive analyses of their spectroscopic data.     

A trypanocidal diterpene with novel skeleton from Dracocephalum komarovi

A new diterpene, komarovispirone (1) with a spiro-octahydroindene skeleton, was isolated from Dracocephalum komarovi. The structure was elucidated by extensive analyses of spectral data. Komarovispirone (1) showed trypanocidal activity against epimastigote of Trypanosoma cruzi, the causative agent of American trypanosomiasis, with a minimum lethal concentration of 23 μM.     

New alkaloids and diterpenes from a deep ocean sediment derived fungus Penicillium sp.

Four new alkaloids, including two new meleagrin analogs, meleagrins B (2) and C (3), and two new diketopiperazines, roquefortines F (5) and G (6), together with six new diterpenes, conidiogenones B-G (7-12), were isolated from a deep ocean sediment derived fungus Penicillium sp. The structures and stereochemistry of the new compounds were elucidated by spectroscopic methods. The cytotoxicity of the new compounds against the HL-60, A-549, BEL-7402, and MOLT-4 cell lines was evaluated.     

New oxygenated diterpenes from an Australian nudibranch of the genus Chromodoris

Chemical analysis of a chromodorid nudibranch has provided two new diterpene metabolites 1 and 2 together with the known metabolites 3-6. In an NMR study, the dialdehyde metabolite 1 underwent facile conversion to cyclic hemiacetals 8-9 on exposure to methanol, a reaction that mimics chemical conversions that may occur during the isolation of some diterpenes from molluscs and sponges. Compounds 1, 2, 5 and 8 showed moderate cytotoxicity against P388 cells (IC₅₀=1.2-4.1 μg/mL).     

Synthesis and structure of diastereomers of pentenocin B produced by Trichoderma hamatum FO-6903

All diastereomers of pentenocin B, an inhibitor of interleukin-1β converting enzyme produced by Trichoderma hamatum FO-6903, were synthesized in chiral forms starting from l-threonine. Absolute configurations of natural pentenocin B were clarified to be 4S, 5R, and 6R.     

Biverlactones A-D, new circumventors of arbekacin resistance in MRSA, produced by Penicillium sp. FKI-4429

Biverlactones, new circumventors of arbekacin resistance in methicillin-resistant Staphylococcus aureus (MRSA) were isolated from a culture broth of Penicillium sp. FKI-4429. Their structures were elucidated by spectroscopic studies, including various NMR experiments. Biverlactones A-D had novel skeletons, consisting of a lactone ring conjugated with exo- or endo-olefin, a carboxylic group and a characteristic alkyl side chain in common.     

Nukiangendines A and B,two novel 13,14-seco-abietanes from Abies nukiangensis

From Abies nukiangensis, two novel 13,14-seco-abietane diterpenes, nukiangendines A (1) and B (2) were isolated. Their relative structures were determined by extensive NMR and HRMS spectroscopic analysis. The absolute configuration of 1 was established by ECD calculations. Compound 1 showed significant anti-hepatitis C virus (HCV) effects.     

Acremines H-N, novel prenylated polyketide metabolites produced by a strain of Acremonium byssoides

Five novel metabolites, acremines H-N, have been isolated from malt extract-peptone-glucose agar cultures of a strain of Acremonium byssoides. Their structures and stereochemistry were elucidated using a combination of ¹³C and ¹H homo and heteronuclear 2D NMR experiments. Acremines H-N inhibited the germination of sporangia of Plasmopara viticola.     

Taxodal, a novel irregular abietane-type diterpene from the cones of Taxodium distichum

One novel irregular abietane-type diterpene denominated taxodal 1 was isolated from the cones of Taxodium distichum. The structure was estimated on the basis of NMR spectral data and confirmed by X-ray crystallographic analysis.     

Salviatalin A and salvitrijudin A, two diterpenes with novel skeletons from roots of Salvia digitaloides and anti-inflammatory evaluation

Salviatalin A (1) and salvitrijudin A (2), two diterpenes with novel skeletons, were isolated from the roots of Salvia digitaloides. Their structures were determined using 1D, 2D NMR, and HRESI-MS spectroscopic analyses. Salviatalin A (1) from bioassay-guided fractionation showed a potent inhibitory effect on superoxide anion production in GMLP/CB-activated human neutrophils as well as other anti-inflammatory effects. A plausible biosynthetic pathway is also discussed.     

Biotransformation of two stemodane diterpenes by Mucor plumbeus

The microbiological transformation of 13α,17-dihydroxy-stemodane (2) by the fungus Mucor plumbeus afforded 13α,17,19-trihydroxy-stemodane (3), 3β,13α,17-trihydroxy-stemodane (5), 3-oxo-13α,17-dihydroxy-stemodane (7), 7α,13α,17,19-tetrahydroxy-stemodane (8), 3β,11α,13α,17-tetrahydroxy-stemodane (10), 3β,7α,13α,17-tetrahydroxy-stemodane (12), 3β,8β,13α,17-tetrahydroxy-stemodane (14), 2α,13α,17-trihydroxy-stemodane (16), 2α,13α,17,19-tetrahydroxy-stemodane (17), 2α,3β,13α,17-tetrahydroxy-stemodane (20) and 3β,11β,13α,17-tetrahydroxy-stemodane (22), whilst the incubation of 13α,14-dihydroxy-stemodane (25) gave 3β,13α,14-trihydroxy-stemodane (28), 2α,13α,14-trihydroxy-stemodane (29) and 13α,14,19-trihydroxy-stemodane (30). Preference for hydroxylations of ring A at C-2(α), C-3(β) and C-19 were observed in both incubations. An interesting rearrangement of 13α,14α-dihydroxy-stemodanes to 14-oxo derivatives with an unusual carbon framework has been observed under acetylation conditions. We have named this skeleton prestemodane, which, as a hydrocarbon ion, had been postulated as a biogenetic precursor of stemodane.     

Coelodiol and coeloic acid, ent-isocopalane diterpenes from the Indonesian sponge Coelocarteria cfr. singaporensis

Two novel ent-isocopalane diterpenes, coelodiol (1) and coeloic acid (2), the latter characterized by an unique oxidative degradation of ring A, have been isolated from the Indonesian sponge Coelocarteria cfr. singaporensis. The stereostructure of these metabolites has been established through interpretation of NMR data and application of the exciton chirality CD method. Coelodiol (1) and coeloic acids (2) were found to inhibit the growth of MKN-45 cell line (human gastric adenocarcinoma).     

Trypanocidal constituents of Dracocephalum komarovi

Trypanocidal constituents of Dracocephalum komarovi were investigated. Under guidance of the in vitro trypanocidal activity against epimastigotes of Trypanosoma cruzi, the causative agent of Chagas' disease, two new diterpenes, dracocequinones A (1) and B (2), and two known triterpene acids, ursonic acid and ursolic acid, were isolated as trypanocidal constituents, in addition to previously reported diterpenes, cyclocoulterone (4), komaroviquinone (5), dracocephalone A (6) and komarovispirone (7). Furthermore a new diterpene, komarovinone A (3), was isolated, together with four known terpenes. Among these compounds, komaroviquinone (5) showed the most potent activity with minimum lethal concentration of 0.4 μM. Structure elucidation of the new diterpenes 1-3 was described.     

Bisbakuchiols A and B, novel dimeric meroterpenoids from Psoralea corylifolia

Two novel dimeric meroterpenoids, bisbakuchiols A and B, along with (S)-bakuchiol were isolated from the seeds of Psoralea corylifolia L. (Fabaceae). Bisbakuchiols A and B contain an unprecedented dimeric meroterpenoid skeleton in which two meroterpenes are linked through a dioxane bridge. All compounds were evaluated for their potential to inhibit hypoxia-inducible factor-1 (HIF-1) activation induced by hypoxia in a HIF-1-mediated reporter gene assay in AGS human gastric cancer cells. (S)-Bakuchiol inhibited hypoxic activation of HIF-1 with an IC₅₀ value of 6.1 μM.     

A novel labdane diterpene from Acritopappus longifolius

A novel labdane diterpene was isolated from the plant Acritopappus longifolius. The structure of this compound was established by 1D- and 2D-nuclear magnetic resonance spectroscopic techniques and mass spectrometry data. N-Methyl-4-hydroxy-trans-proline, stigmasterol-3-O-β-d-glycoside, and the flavonoids quercetin, luteolin, kaempferol, and rutin were also isolated.     

Aminocadambines A and B, two novel indole alkaloids from Neolamarckia cadamba

Two novel monoterpenoid indole alkaloids, aminocadambines A (1) and B (2), characterized by tetrahydrofuran and 1,2,3,4-tetrahydropyridine rings, were isolated from the leaves of Neolamarckia cadamba. Their structures were elucidated on the basis of spectroscopic and computational methods. The absolute configuration of 1 was established by CD analysis. A plausible biosynthetic pathway for 1 and 2 is proposed.