Neomacrophorin X, a [4.4.3]Propellane-Type Meroterpenoid from <i>Trichoderma</i> sp. 1212-03

Neomacrophorin X (<b>1</b>) was isolated from <i>Trichoderma</i> sp. 1212-03. Heteronuclear multiple bond correlation (HMBC) spectral analysis indicated a unique [4.4.3]­propellane framework, which was verified by the ¹H and ¹³C chemical shift calculations based on density functional theory (DFT) and subsequent comparison with experimental data obtained in CDCl₃. The DFT-based electronic circular dichroism (ECD) calculations were effective in not only determining the absolute configuration but also confirming the relative structure. The predominant conformation of <b>1</b> was found to be solvent-dependent, with different conformations presenting different NMR and ECD profiles. Introduction of <i>J</i>-based analysis with a <i>J</i>-resolved HMBC aided in this investigation. This conformational alternation was reproduced by considering the solvation with the SM5.4 model in the calculation, although it was not sufficiently quantitative. Although the calculations without solvent effects suggested a conformer that satisfies the spectral profiles in CDCl₃, postcalculations with the SM5.4 solvation protocol stabilized the second major conformer, which reproduces the NMR and ECD profiles in polar solvents. Neomacrophorin X (<b>1</b>) is assumed to be biosynthesized by a coupling between the reduced form of anthraquinone and a neomacrophorin derivative. This hypothesis was supported experimentally by the isolation of pachybasin and chrysophanol, as well as acyclic premacrophorin (<b>2</b>), from the same fungus. Some biological properties of <b>1</b> are described

Cyclohelminthol X, a Hexa-Substituted Spirocyclopropane from <i>Helminthosporium velutinum</i> yone96: Structural Elucidation, Electronic Circular Dichroism Analysis, and Biological Properties

<i>Helminthosporium velutinum</i> yone96 produces cyclohelminthol X (<b>1</b>), a unique hexa-substituted spirocyclopropane. Although its molecular formula and NMR spectral data resemble those of AD0157, being isolated from marine fungus <i>Paraconiothyrium</i> sp. HL-78-gCHSP3-B005, our detailed analyses disclosed a totally different structure. Chemical shift calculations and electronic circular dichroism spectral calculations were quite helpful to establish the structure, when those were performed based on density functional theory. The carbon framework of cyclohelminthols I–IV is found at the C1–C8 propenylcyclopentene substructure of <b>1</b>. Thus, <b>1</b> is assumed to be biosynthesized by cyclopropanation between an oxidized form of cyclohelminthol IV and a succinic anhydride derivative <b>4</b>. Cytotoxicity for two cancer cell lines and proteasome inhibition efficiency are measured

Albidosides H and I, two new triterpene saponins from the barks of <i>Acacia albida</i> Del. (Mimosaceae)

<p>Two new triterpene saponins, albidosides H (<b>1</b>) and I (<b>2</b>), along with the three known saponins were isolated from the barks of <i>Acacia albida</i>. Their structures were elucidated on the basis of extensive 1D- and 2D-NMR studies and mass spectrometry. Albidosides H (<b>1</b>) and I (<b>2</b>) were assayed for their cytotoxicity against HeLa and HL60 cells using MTT method.</p

Ca²⁺-Signal Transduction Inhibitors, Kujiol A and Kujigamberol B, Isolated from Kuji Amber Using a Mutant Yeast

A podocarpatriene and a labdatriene derivative, named kujiol A [13-methyl-8,11,13-podocarpatrien-19-ol (<b>1</b>)] and kujigamberol B [15,20-dinor-5,7,9-labdatrien-13-ol (<b>2</b>)], respectively, were isolated from Kuji amber through detection with the aid of their growth-restoring activity against a mutant yeast strain (<i>zds1</i>Δ <i>erg3</i>Δ <i>pdr1</i>Δ <i>pdr3</i>Δ), which is known to be hypersensitive with respect to Ca²⁺-signal transduction. The structures were elucidated by spectroscopic data analysis. Compounds <b>1</b> and <b>2</b> are rare organic compounds from Late Cretaceous amber, and the mutant yeast used seems useful for elucidating a variety of new compounds from Kuji amber specimens, produced before the K–Pg boundary

Secondary metabolites with antiproliferative effects from <i>Albizia glaberrima</i> var glabrescens Oliv. (Mimosoideae)

<p>A new 5-dehydroxyflavan, namely Albiziaflavan B or (+)-(2<i>R</i>, 3<i>S</i>, 4<i>R</i>)-3′,4′, 7-trihydroxy-4-methoxy-2,3-<i>trans</i>-flavan-3,4-<i>trans</i>-diol (<b>1)</b> was isolated from the root bark of <i>Albizia glaberrima</i>, together with six known compounds including three flavans: (+)-mollisacacidin (<b>2</b>), (+)-fustin <b>(3</b>) and butin (<b>4</b>); two steroids: chondrillasterol (<b>5)</b> and chondrillasterone (<b>6)</b>, and a triterpenoid: lupeol (<b>7</b>). The structure of <b>1</b> was established by detailed analysis of its spectroscopic data, especially 1D and 2D NMR spectra, HRESIMS and CD data. Compounds <b>1</b>–<b>6</b> were assayed for their antiproliferative effects on two human cancer cells, HeLa at 50 μM (<i>n</i> = 2) and HL60 at 20 μM (<i>n</i> = 2). Compound <b>3</b> and <b>4</b> were the most active on HL60 with IC₅₀ of 8.1 and 8.3 μM, respectively. Compound <b>6</b> was the most active with an IC₅₀ of 4.6 μM on HeLa.</p