Racemosin C,a novel minor bisindole alkaloid with protein tyrosine phosphatase-1B inhibitory activity from the green alga Caulerpa racemosa

A novel minor bisindole alkaloid, racemosin C (1), characterized by a naturally unprecedented 8-hydroxy-2,4,6-cyclooctatrienone ring fused with two indole systems, was isolated from the green alga Caulerpa racemosa, together with one known related metabolite, caulersin (2). The structure of 1 was elucidated on the basis of extensive spectroscopic analysis, and by comparison with the data of related known compounds. A plausible biosynthetic pathway of 1 was proposed. Compounds 1 and 2 exhibited significant PTP1B inhibitory activity with IC₅₀ values of 5.86 ± 0.57 and 7.14 ± 1.00 μM, respectively, compared with the positive control oleanolic acid (IC₅₀ = 3.03 ± 0.20 μM). On the basis of the data obtained, the Caulerpa bisindole alkaloids may be considered as a new class of PTP1B inhibitors.     

A new bioactive steroidal ketone from the South China Sea sponge Xestospongia testudinaria

A new steroidal ketone (1), with an ergosta-22,25-diene side chain, was obtained from the South China Sea marine sponge Xestospongia testudinaria. The structure of 1 was determined on the basis of detailed spectroscopic analysis and by comparison with literature. Compound 1 exhibited significant inhibitory activity against protein tyrosine phosphatase 1B (PTP1B), a key target for the treatment of type II diabetes and obesity, with an IC₅₀ value of 4.27 ± 0.55 μM, which is comparable with the positive control oleanolic acid (IC₅₀ = 2.63 ± 0.22 μM).     

Six new C-21 steroidal glycosides from Dregea sinensis Hemsl

Six new C-21 steroidal glycosides (1–6) were separated from the root of Dregea sinensis Hemsl. and their structures were elucidated using extensive nuclear magnetic resonance, mass spectrometry, and infrared spectral analyses. Isolated compounds were evaluated for antitumor activity, which showed that compound 3 had moderate activity in Jurkat cells (IC₅₀ 19.54 ± 0.91 μM), and compounds 1–4 had significant effects against IL-2R and TNFR2 (IC₅₀ 1.518 ± 0.06 μM to 5.9 ± 0.07 μM).     

Selective cytotoxic eremophilane-type sesquiterpenes from Penicillium citreonigrum

Abstract

One new eremophilane-type sesquiterpene (1, citreopenin) was isolated from Penicillium citreonigrum (HQ738282), and the structure was elucidated by a combination of spectroscopic data interpretation and single-crystal X-ray diffraction analysis using Cu Kα radiation (CCDC 1030588). Compound 1 showed weak activity against KB-VIN (IC₅₀ = 11.0 ± 0.156 μM), while the known compound 3 exhibited selective cytotoxicity against MDA-MB-231 triple-negative breast cancer (TNBC) (IC₅₀ = 5.42 ± 0.167 μM).     

Brominated polyunsaturated lipids with protein tyrosine phosphatase-1B inhibitory activity from Chinese marine sponge Xestospongia testudinaria

A new brominated polyunsaturated lipid, methyl (E,E)-14,14-dibromo-4,6,13-tetradecatrienoate (1), along with three known related analogues (2–4), were isolated from the Et₂O-soluble portion of the acetone extract of Chinese marine sponge Xestospongia testudinaria treated with diazomethane. The structure of the new compound was elucidated by detailed spectroscopic analysis and by comparison with literature data. Compound 3 exhibited significant inhibitory activity against protein tyrosine phosphatase 1B (PTP1B), a key target for the treatment of type II diabetes and obesity, with an IC₅₀ value of 5.30 ± 0.61 μM, when compared to the positive control oleanolic acid (IC₅₀ = 2.39 ± 0.26 μM).     

Two new sesquiterpenoid glycosides from the leaves of Lycium barbarum

Two new sesquiterpenoid glycosides, lyciumionosides A–B (1–2), together with four known compounds (3–6), were isolated from the leaves of Lycium barbarum. Their structures were mainly established on the basis of MS, 1D and 2D NMR spectroscopic techniques. The antiproliferative activities of compounds 1–5 were evaluated. Compound 1 showed highest inhibitory activity against A549 cells with IC₅₀ value of 32.6 ± 2.6 μM, compound 3 showed highest inhibitory activity against PC-3 cells with IC₅₀ value of 36.0 ± 2.9 μM, and compound 5 exhibited highest inhibitory activity against HeLa cells with IC₅₀ value of 32.3 ± 4.2 μM.     

Anti-inflammatory and antimicrobial coumarins from the stems of Eurya chinensis

Two new coumarins, named (±)-euryacoumarin A (1) and 6-demethylobtusinin (2), and one new natural coumarin, named euryacoumarin B (3), along with two known compounds, scopoletin (4) and obtusinol (5), were isolated from the stems of Eurya chinensis. Their structures were elucidated by means of extensive spectroscopic methods and comparison with data reported in the literatures. Compound 1 exhibited significant inhibition of LPS-induced nitric oxide (NO) production in RAW264.7 cells with IC₅₀ value of 35.64 ± 1.73 μM, and showed marginal antibacterial activities against Bacillus subtilis and B. cereus with MIC values of 50.59 ± 2.12 and 35.42 ± 0.96 μM, respectively.     

Clemochinenosides C and D,two new macrocyclic glucosides from Clematis chinensis

Abstract

The EtOH extract of the roots and rhizomes of Clematis chinensis afforded two new macrocyclic glucosides clemochinenosides C (1) and D (2). Their structures were elucidated on the basis of spectroscopic means and hydrolysis products. These compounds were evaluated for inhibitory activity against lipopolysaccharides-induced TNF-α production in RAW 246.7 macrophages. Compounds 1 and 2 showed moderate inhibitory activity with IC₅₀ values of 12.9 ± 2.3 and 18.4 ± 2.7 μM, respectively. In addition, a proliferation study was used to evaluate the anti-angiogenic effects of these compounds in vitro (VEGF-induced human umbilical vein endothelial cell proliferation). Compounds 1 and 2 displayed weak inhibitory effects with inhibition rates of 26.3 ± 1.8 and 19.2 ± 2.6% at 50 μM, respectively.     

Two new triterpenes from Euphorbia alatavica

A phytochemical investigation on Euphorbia alatavica Boiss resulted in the isolation of nine compounds, including two new ones, alatavolide and alatavoic acid (1–2). Chemical structures of these compounds were established on the basis of 1D, 2D NMR, and HR-MS techniques, and by comparison with data reported in the literature. Compounds 1, 2, 4, 6, 8, and 9 were screened for cytotoxicity using the MTT assay. Among these compounds, the new compound 2 showed moderate cytotoxicity against Hela, MCF-7 and A549 cell lines (IC₅₀ values of 16.4 ± 3.2, 14.5 ± 2.8, 22.3 ± 3.1 μM, respectively), while the known compound 8 exhibited the most potent cytotoxicity with the IC₅₀ values of 6.5 ± 3.1, 1.9 ± 0.9, 8.6 ± 3.5 μM, respectively.     

(±) Cochlearoids N–P: three pairs of phenolic meroterpenoids from the fungus Ganoderma cochlear and their bioactivities

Three pairs of meroterpenoids (±) cochlearoids N–P (1–3) were isolated from the fruiting bodies of Ganoderma cochlear. Their structures including absolute configurations were assigned by spectroscopic techniques. All the isolated compounds were tested for their inhibitory activities toward BRD4, human cancer cells, and micro-organisms. The results show that the enantiomers of (±)-1 are BRD4 inhibitors, (?)-1 and (+)-3 are cytotoxic against human cancer cells (K562) with IC₅₀ values of 7.68 and 6.68 μM, respectively. Besides compounds (±)-2 and (±)-3 exhibit potent inhibitory activity against Staphylococcus aureus with IC₅₀ values in the range of 5.43–17.99 μM.     

Steroid constituents from the soft coral Sinularia microspiculata

A methanol extract of the soft coral Sinularia microspiculata revealed five sterols, including two new compounds. Using combined chromatographic and spectroscopic experiments, the new compounds were found to be 7-oxogorgosterol (1) and 16α-hydroxysarcosterol (2). Their structures were determined on the basis of spectroscopic data (¹H and ¹³C NMR, HSQC, HMBC, ¹H-¹H COSY, NOESY, and FT-ICR-MS) and by comparing obtained results to the values indicated in previous studies. Among the isolated compounds, 3 showed weak cytotoxic effects against HL-60 (IC_50? = 89.02 ± 9.93?μM) cell line, whereas 5 was weakly active against HL-60 (IC_50? = 82.80 ± 13.65?μM) and SK-Mel2 (IC_50? = 72.32 ± 1.30?μM) cell lines.     

Prenylated isoflavones from Cudrania tricuspidata inhibit NO production in RAW 264.7 macrophages and suppress HL-60 cells proliferation

Inhibitory effects of NO production in RAW 264.7 macrophages guided the isolation of nine prenylated isoflavones, including a new cudraisoflavone L (1) and eight known metabolites furowanin B (2), erysubin A (3), wighteone (4), lupalbigenin (5), laburnetin (6), isolupalbigenin (7), 6,8-diprenylorobol (8), millewanin H (9) from the leaves of Cudrania tricuspidata. At the concentration of 10 μM, compounds 1, 2, and 4 significantly inhibited NO production with the inhibitory values of 72.5 ± 2.4, 66.9 ± 1.8, and 55.4 ± 2.7%, respectively. In addition, all of isolated compounds 1–9 showed promising cytotoxic effects toward HL-60 cells (IC₅₀ 4.3 ± 0.7 to 18.0 ± 1.7 μM).     

New polyacetylenes glycoside from Eclipta prostrate with DGAT inhibitory activity

One new polyacetylene glycoside eprostrata Ⅰ (1), together with seven known compounds (2–8), were isolated from Eclipta prostrata. Their structures were elucidated on the basis of spectroscopic and physico-chemical analyses. All the isolates were evaluated inhibitory activity on DGAT in an in vitro assay. Compounds 1–8 were found to exhibit inhibitory activity of DGAT1 with IC₅₀ values ranging from 74.4 ± 1.3 to 101.1 ± 1.1 μM.     

Kinetics studies on the lignan class of natural compounds that inhibits α-chymotrypsin

The mechanism of inhibition of the α-chymotrypsin enzyme by two lignans of the fused bistetrahydrofuran series, epiexcelsin (1) and 5′-demethoxyepiexcelsin (2), which were isolated from the Commiphora mukul Engl., was investigated. Lineweaver–Burk and Dixon plots and their secondary replots showed that these compounds were noncompetitive inhibitors of the enzyme. K _i values for 1 and 2 were found to be 22.29 ± 0.015 and 336.30 ± 0.053 μM, respectively.     

Constituents from Polygonatum sibiricum and their inhibitions on the formation of advanced glycosylation end products

A new saponin, isonarthogenin 3-O-β-d-glucopyranosyl-(1→4)-β-d-galactopyranoside (1), together with twelve known compounds, were isolated from the rhizomes of Polygonatum sibiricum. The structures of these compounds were elucidated by analysis of their 1D/2D NMR and MS data. Among them, phenol compounds 4–7 and 9–10 showed significant inhibitions against the formation of advanced glycosylation end products, with IC₅₀ values of 0.091 ± 0.0021, 0.10 ± 0.041, 0.014 ± 0.0027, 0.11 ± 0.011, 0.13 ± 0.045, and 0.055 ± 0.019 μM, respectively. The results will promote exploiting potential medicinal use of these compounds in the prevention of diabetic complications and supporting Polygonatum sibiricum as a functional food for healthy and medicinal diet.     

Constituents from Apium graveolens and their anti-inflammatory effects

A phthalide glycoside, (3R, 4R)-4-O-β-D-glucopyranosyl-senkyunolide (1), and a megastigmane glycoside, (6S, 7R)-3-oxo-megastigma-4, 8-dien-7-O-β-D-glucoside (2), along with two known aglycones (3–4), were isolated from the 70% EtOH extract of fresh whole grass of Apium graveolens L. Their structures were elucidated by extensive spectroscopic analysis. All of these compounds were tested for their inhibitory effects on nitric oxide (NO) production in the RAW 264.7 macrophages. Among them, compounds 3 and 4 showed potent inhibitory activity against LPS-induced nitric oxide production in RAW 264.7 macrophages, with IC₅₀ values of 24.0 ± 2.1 μM and 28.6 ± 2.4 μM, respectively.     

New cyclopeptide alkaloid and lignan glycoside from Justicia procumbens

This study reported a new cyclopeptide alkaloid, justicianene A (1), and a new lignan glycoside, procumbenoside H (2), isolated from Justicia procumbens. The structures of the new compounds were elucidated by means of spectroscopic analysis, including extensive 2D NMR studies and mass spectrometry. Cyclopeptide alkaloids were first observed from the genus Justicia. Compound 2 was cytotoxic against human LoVo colon carcinoma cells with an IC₅₀ value of 17.908 ± 1.949 μM.     

Synthesis and antifungal evaluation of PCA amide analogues

To improve the physical and chemical properties of phenazine-1-carboxylic acid (PCA) and find higher antifungal compounds, a series of PCA amide analogues were designed and synthesized and their structures were confirmed by ¹H NMR, HRMS, and X-ray. Most compounds showed some antifungal activities in vitro. Particularly, compound 3d exhibited inhibition effect against Pyriculariaoryzac Cavgra with EC₅₀ value of 28.7 μM and compound 3q exhibited effect against Rhizoctonia solani with EC₅₀ value of 24.5 μM, more potently active than that of the positive control PCA with its EC₅₀ values of 37.3 μM (Pyriculariaoryzac Cavgra) and 33.2 μM (Rhizoctonia solani), respectively.     

Cytotoxic triterpene saponins from Clematis mandshurica

Two new triterpene saponins, mandshunosides A and B (1 and 2), were isolated from the roots and rhizomes of Clematis mandshurica. Their structures were elucidated on the basis of spectroscopic evidence and hydrolysis products. Compounds 1 and 2 showed inhibitory activities against two colorectal human cancer cells HCT 116 (IC₅₀ 2.1 μM for 1 and 2.5 μM for 2) and HT-29 (IC₅₀ 3.7 μM for 1 and 3.3 μM for 2).