Yongji Lai

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.

Cytotoxic ent-Kaurane Diterpenoids from Salvia cavaleriei

Fifteen new ent-kaurane diterpenoids, compounds 1-15, and two known analogues, 4-epi-henryine A (16) and leukamenin E (17), were isolated from the whole plants of Salvia cavaleriei. The structures of the new compounds were established by spectroscopic methods, and their absolute configurations were determined by electronic circular dichroism and single-crystal X-ray diffraction analyses with Cu Kα radiation. Compounds 1-15 were evaluated for their cytotoxicity against five human cancer cell lines, HL-60, SMMC-7721, A-549, MCF-7, and SW480, as well as the noncancerous Beas-2B cell line. Compounds 1-10, 12, 14, and 15 showed broad-spectrum cytotoxicity, with compounds 1, 3, 6-10, 12, and 15 exhibiting more potent cytotoxicity than the positive control, cis-platin, with IC50 values ranging from 0.65 to 6.4 μM.

Neolignans with a Rare 2-Oxaspiro[4.5]deca-6,9-dien-8-one Motif from the Stem Bark of Cinnamomum subavenium

Two pairs of racemic spirodienone neolignans with a rare 2-oxaspiro[4.5]deca-6,9-dien-8-one motif, named (±)-subaveniumins A (1) and B (2), were isolated from the bark of Cinnamomum subavenium. The chiral separation of the (+)-1, (-)-1, (+)-2, and (-)-2 enantiomers was accomplished via high-performance liquid chromatography on a chiral column. Their structures were elucidated using single-crystal X-ray diffraction and spectroscopic analyses (UV, IR, HRESIMS, and 1D and 2D NMR). The absolute configurations of the enantiomers were determined by comparing the experimental and calculated electronic circular dichroic spectra. The (+)-1, (-)-1, (+)-2, and (-)-2 enantiomers exhibited moderate inhibitory effects against NO production in RAW264.7 mouse macrophages induced by lipopolysaccharide, with IC50 values of 17.9, 5.6, 15.1, and 4.3 μM, respectively.

Scapiformolactones A-I: germacrane sesquiterpenoids with an unusual Δ3-15,6-lactone moiety from Salvia scapiformis.

Nine germacrane sesquiterpenoids with an unusual Δ(3)-15,6-lactone moiety, scapiformolactones A-I (1-9), and one known seco-germacrane sesquiterpenoid, 3,7,11-trimethyldodeca-l,6,9-triene-3,11-diol (10), were isolated from whole plants of Salvia scapiformis Hance. Their structures were elucidated by spectroscopic methods including HR-ESIMS, IR, UV, NMR, and CD, as well as by quantum mechanical calculations and chemical transformations. Structures of compounds 1-3 were also confirmed by single-crystal X-ray diffraction analysis. Six germacrane 6,15-diol derivatives (11-16) were obtained by chemical transformation. Compounds 1-9 and 11-16 were evaluated for their in vitro immunomodulatory effects on T and B cells, as well as their in vitro cytotoxicity against five human cancer cell lines, HL-60, SMMC-7721, A-549, MCF-7, and SW480.

Efficient Synthesis of Kinsenoside and Goodyeroside A by a Chemo-Enzymatic Approach

Kinsenoside (1) and goodyeroside A (2), two naturally occurring stereoisomers with diverse biological activities, have been synthesized efficiently by a chemo-enzymatic approach with a total yield of 12.7%. The aglycones, (R)- and (S)-3-hydroxy-γ-butyrolactone, were prepared from d- and l-malic acid by a four-step chemical approach with a yield of 75%, respectively. These butyrolactones were then successfully glycosidated using β-d-glucosidase as a catalyst in a homogeneous organic-water system. Under the optimized enzymatic conditions, the yields of kinsenoside and goodyeroside A in the enzymatic steps both reached 16.8%.

A new lignan glucoside from the whole plants of Salvia scapiformis.

Phytochemical investigation of the whole plants of Salvia scapiformis Hance afforded eight compounds, including one new lignan, (+)-8α-hydroxypinoresinol-8-O-[6′′-O-(4′′′-hydroxybenzoyl)]-β-d-glucopyranoside (1), four known lignans, (+)-8α-hydroxy-pinoresinol-8-O-β-d-glucopyranoside (2), (+)-8α-hydroxypinoresinol (3), (+)-pinoresinol (4), and (+)-medioresinol (5), and three known triterpenoids, ursolic acid (6), 4-epi-niga-ichigoside F1 (7), and niga-ichigoside F1 (8). Their structures were determined on the basis of extensive spectroscopic analyses and comparison with spectroscopic data in the literature. The absolute configuration of the new compound 1 was determined by chemical transformation and GC analysis.

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.

A New Phenolic Glycoside from the Barks of Cinnamomum cassia

A new phenolic glycoside (1), named methyl 2-phenylpropanoate-2-O-β-d-apiofuranosyl-(1→6)-O-β-d–glucopyranoside, was isolated from the barks of Cinnamomum cassia, along with three known phenolic glycosides and four known lignan glycosides. The structure of 1 was elucidated by extensive interpretation of spectroscopic data and chemical method. Selected compounds were evaluated for their immunosuppressive activities against murine lymphocytes. Compounds 1, 2, 6 and 8 exhibited differential inhibition against ConA-induced T cells proliferation.

Brasilane sesquiterpenoids and dihydrobenzofuran derivatives from Aspergillus terreus [CFCC 81836]

Brasilanones A-F and asperterreusines A-C, undescribed brasilane sesquiterpenoids and dihydrobenzofuran derivatives, were isolated from the marine-derived fungus Aspergillus terreus [CFCC 81836]. Their structures with absolute configurations were elucidated on the basis of spectroscopic data, X-ray crystallographic analyses, and electronic circular dichroism (ECD) calculations. Brasilanones A-F are unusual brasilane sesquiterpenoids with an α,β-unsaturated ketone unit, interestingly, brasilanones B-D are stereo isomers. All of the isolates were evaluated for their inhibitory activities against NO production and cytotoxic activities against five human cancer cell lines (HL-60, SW-480, A-549, MCF-7, and SMMC-7721). Brasilanones A and E showed moderate inhibitory effect with NO inhibition rates of 47.7% (p < 0.001) and 37.3% (p < 0.001) at the concentration of 40 μM. Asperterreusines A showed cytotoxicity against HL-60 and SW-480 cell lines with IC50 values of 15.3 and 25.7 μM, respectively.

BACE1 Inhibitory Meroterpenoids from Aspergillus terreus

Sixteen 3,5-dimethylorsellinic acid-based (DMOA-based) meroterpenoids, including 10 new compounds, asperterpenes D-M (1-10), were obtained from Aspergillus terreus. The structures and absolute configurations of the new compounds were confirmed by extensive spectroscopy, single-crystal X-ray diffraction analysis, and experimental electronic circular dichroism (ECD) measurements. Compounds 2, 3, and 7 are the first 3,5-dimethylorsellinic acid-based meroterpenoids possessing a unique cis-fused A/B ring system. These new compounds were evaluated for their inhibitory activity against β-site amyloid precursor protein-cleaving enzyme 1 (BACE1). Compounds 2, 3, and 7, the first 3,5-dimethylorsellinic acid-based meroterpenoids possessing cis-fused A/B rings, exhibited significant inhibitory activities against BACE1 with IC50 values of 3.3, 5.9, and 31.7 μM, respectively.