Zhengxi Hu

Kadcoccinones A–F, New Biogenetically Related Lanostane-Type Triterpenoids with Diverse Skeletons from Kadsura coccinea

Six new lanostane-related triterpenoids, kadcoccinones A-F (1-6), were isolated from Kadsura coccinea. Compound 3 possesses a novel 6/6/9-fused carbocyclic core containing a rare oxabicyclo[4.3.1]decane system. Compounds 4 and 5 are isomers representing the first example of the 18(13 → 12)-abeo-26-norlanostane triterpenoid. The absolute configurations of 1 and 4-6 were defined by X-ray diffraction and experimental ECD spectra, and that of 3 was elucidated by quantum chemical calculations. The plausible biogenetic pathway of 1-6 is postulated.

Phomopsterones A and B, Two Functionalized Ergostane-Type Steroids from the Endophytic Fungus Phomopsis sp. TJ507A

Two new functionalized ergostane-type steroids, phomopsterones A (1) and B (2), were isolated from the plant-derived Phomopsis sp. TJ507A. Their structures were determined on the basis of spectroscopic data, a modified Moshers method, X-ray crystallographic analysis, and quantum chemical calculations. Compound 1 is an unprecedented ergosteroid featuring a rearranged bicyclo[3.3.1]nonane motif resulting from B-ring scission and a subsequent 180° rotation of the ring A during biosynthesis. Compound 2 exhibited anti-inflammatory activity.

Five New Secondary Metabolites Produced by a Marine-Associated Fungus, Daldinia eschscholzii

Five new compounds, including a benzopyran ribonic glycoside, daldiniside A (1), two isocoumarin ribonic glycosides, daldinisides B (2) and C (3), and two alkaloids, 1-(3-indolyl)-2R,3-dihydroxypropan-1-one (4) and 3-ethyl-2,5-pyrazinedipropanoic acid (5), along with five known compounds (6–10), were isolated from the EtOAc extract of the marine-associated fungus, Daldinia eschscholzii. Their structures were elucidated by extensive physicochemical and spectroscopic properties, besides comparison with literature data. The absolute configurations of compounds 1–3 were corroborated by chemical transformation, GC analysis and X-ray crystallographic analysis. Meanwhile, the absolute configuration of compound 4 and the planar structure of compound 6 were also determined based on the X-ray diffraction analysis. The cytotoxicity of compounds 1–10, antifungal and anti-HIV activities of compounds 1–5 and the in vitro assay for glucose consumption of compounds 1–3 were done in the anti-diabetic model, whereas none showed obvious activity.

Enantiomeric Lignans and Neolignans from Phyllanthus glaucus: Enantioseparation and Their Absolute Configurations.

Eight pairs of enantiomeric neolignans, norlignans, and sesquineolignans (1a/1b–8a/8b), together with five known neolignans (9a/9b and 10–12), have been isolated from 70% acetone extract of the whole plants of Phyllanthus glaucus Wall. (Euphorbiaceae). The racemic or partial racemic mixtures were successfully separated by chiral HPLC using different types of chiral columns with various mobile phases. Their structures were elucidated on the basis of extensive spectroscopic data. The absolute configurations of 2a/2b were determined by computational analysis of their electronic circular dichroism (ECD) spectrum, and the absolute configurations of other isolates were ascertained by comparing their experimental ECD spectra and optical rotation values with those of structure-relevant compounds reported in literatures. Compounds 4a/4b featured unique sesquineolignan skeletons with a novel 7-4′-epoxy-8′-8′′/7′-2′′ scaffold, consisting of an aryltetrahydronaphthalene and a dihydrobenzofuran moiety. The planar structures of compounds 2, 3, 7, and 8 were documented previously; however, their absolute configurations were established for the first time in this study. The antioxidant activities of 1a/1b–8a/8b were evaluated using DPPH free radical scavenging assay, and the results demonstrated that compounds 1b and 3b showed potent DPPH radical scavenging activities with IC50 values of 5.987 ± 1.212 and 9.641 ± 0.865 μg/mL, respectively.

Structural Characterization of Kadcoccinin A: A Sesquiterpenoid with a Tricyclo[4.4.0.03,10]decane Scaffold from Kadsura coccinea

Kadcoccinin A (1), a cage-like sesquiterpenoid possessing a tricyclo[4.4.0.0(3,10)]decane scaffold, and the biosynthetically related kadcoccinin B (2) were isolated from the stems of Kadsura coccinea. Their structures and absolute configurations were determined from extensive spectroscopic analysis and quantum chemical calculations. Additionally, their cytotoxic and antifungal effects were initially evaluated, and a plausible biosynthetic pathway was proposed.

Secondary metabolites from Colletotrichum capsici , an endophytic fungus derived from Siegesbeckia pubescens Makino

Abstract A rare new tremulane sesquiterpenoid analogue, 11,12-epoxy-5,6-seco-1,6(13)-tremuladien-5,12-olide (1), together with five known altenuene derivatives (2–6) was isolated from the cultures of Colletotrichum capsici, which was isolated as an endophytic fungus from fresh leaves of Siegesbeckia pubescens Makino (Compositae). Their structures were elucidated by means of spectroscopic methods and comparison with literature data. All compounds isolated were reported for the first time from the fungus C. capsici.

Kadcoccinic Acids A-J, Triterpene Acids from Kadsura coccinea

Eleven triterpene acids including 10 new compounds (kadcoccinic acids A-J, 1-10) were isolated from the stems of Kadsura coccinea. Except for 10, these compounds feature a rearranged lanostane skeleton with a 6/6/5/6 tetracyclic ring system, and compounds 1 and 2 are the first examples of 2,3-seco-6/6/5/6-fused tetracyclic triterpenoids. Their structures were established primarily by spectroscopic and spectrometric methods. Additionally, the absolute configuration of 3 was determined by single-crystal X-ray diffraction. Several of the compounds isolated were tested for their anti-HIV-1 and cytotoxic activities.

A New Breviane Spiroditerpenoid from the Marine-Derived Fungus Penicillium sp. TJ403-1

Marine-derived fungi are a promising and untapped reservoir for discovering structurally interesting and pharmacologically active natural products. In our efforts to identify novel bioactive compounds from marine-derived fungi, four breviane spiroditerpenoids, including a new compound, brevione O (1), and three known compounds breviones I (2), J (3), and H (4), together with a known diketopiperazine alkaloid brevicompanine G (5), were isolated and identified from an ethyl acetate extract of the fermented rice substrate of the coral-derived fungus Penicillium sp. TJ403-1. The absolute structure of 1 was elucidated by HRESIMS, one- and two-dimensional NMR spectroscopic data, and a comparison of its electronic circular dichroism (ECD) spectrum with the literature. Moreover, we confirmed the absolute configuration of 5 by single-crystal X-ray crystallography. All the isolated compounds were evaluated for isocitrate dehydrogenase 1 (IDH1) inhibitory activity and cytotoxicity, and compound 2 showed significant inhibitory activities against HL-60, A-549, and HEP3B tumor cell lines with IC50 values of 4.92 ± 0.65, 8.60 ± 1.36, and 5.50 ± 0.67 µM, respectively.

Asperspiropene A, a novel fungal metabolite as an inhibitor of cancer-associated mutant isocitrate dehydrogenase 1

In silico screening of an in-house natural product database and confirmatory bioassays led to the identification of asperspiropene A (1) as an inhibitor of cancer-associated mutant IDH1. Compound 1, a meroterpenoid with a highly functionalized 1,8-dioxaspiro[4.5]decane motif, showed potent ability to inhibit mutant IDH1 with inhibition constant (Ki) values as low as 0.27 μM. The half effective concentration (EC50) of 1 for reducing the cellular concentration of D2HG in HT1080 cells was 8.5 μM. Molecularly, treatment with 1 led to reduced levels of the H3 K9me3 signal in the HT1080 cells. To the best of our knowledge, 1 is the first fungal metabolite reported to exhibit inhibitory activity against mutant IDH1.

Anti-inflammatory butenolide derivatives from the coral-derived fungus Aspergillus terreus and structure revisions of aspernolides D and G, butyrolactone VI and 4′,8′′-diacetoxy butyrolactone VI

Chemical investigation of the coral-derived fungus Aspergillus terreus led to the discovery of ten butenolide derivatives (1–10), including four new ones (1–4). The new structures were characterized on the basis of comprehensive spectroscopic analysis, including 1D and 2D NMR and HRESIMS data. Compounds 1 and 2 were a pair of rare C-8′′ epimers with vicinal diol motifs. The absolute configurations of 1–4 were determined via [Mo2(AcO)4] induced circular dichroism (ICD) spectra and comparison of their experimental ECD spectra. Importantly, the structures of reported aspernolides D and G, butyrolactone VI and 4′,8′′-diacetoxy butyrolactone VI have been correspondingly revised via a combined strategy of experimental validations, 13C NMR predictions by ACD/Labs software, and 13C NMR calculations. Herein we provide valuable referenced 13C NMR data (C-7′′, C-8′′, and C-9′′) for the structure elucidations of butenolide derivatives with 1-(2-hydroxyphenyl)-3-methylbutane-2,3-diol, 2-(2,3-dihydrobenzofuran-2-yl)propan-2-ol, or 2,2-dimethylchroman-3-ol motifs. Additionally, all the isolates (1–10) were assessed for anti-inflammatory activity by measuring the amount of NO production in lipopolysaccharide (LPS)-induced RAW 264.7 mouse macrophages, and compound 10 showed an even stronger inhibitory effect than the postive control indomethacin, presenting it as a promising lead compound for the development of new anti-inflammatory agents.