A new thiophene and two new monoterpenoids from Xanthium sibiricum

Three new compounds (1–3), together with six known compounds (4–9), were isolated from the fruits of Xanthium sibiricum. The structures and the absolute configurations of sibiricumthionol (1), (+)-(5Z)-6-methyl-2-ethenyl-5-hepten-1,2,7-triol [(+)-2], ( ? )-(5Z)-6-methyl-2-ethenyl-5-hepten-1,2,7-triol [( ? )-2], (2E,4E,1′S, 2′R, 4′S, 6′R)-dihydrophaseic acid (3), (+)-xanthienopyran [(+)-4] and ( ? )-xanthienopyran [( ? )-4] were established by extensive spectroscopic analyses, X-ray crystallographic analysis, ECCD analysis and ECD calculations. Caffeic acid (7) and caffeic acid ethyl ester (8) weekly inhibited α-glucosidase enzymatic activity by 44.5% and 40.2%, respectively, at 40 μM. Protocatechuic acid (9) selectively exhibited cytotoxicity against HepG2 cell lines, with an IC₅₀ value of 2.92 μM.     

Two new flavonol glycosides from the leaves of Cleome chelidonii L.f.

From the leaves of Cleome chelidonii L.f., two new flavonol glycosides, named cleomesides A (1) and B (2), and four known compounds, quercetin 3-O-β-glucopyranosyl(1 → 2)-α-rhamnoside-7-O-α-rhamnoside (3), ethyl α-galactopyranoside (4), adenine (5) and glycerol monostearate (6), were isolated. The structures of all isolated compounds (1–6) were determined by NMR spectroscopy and mass spectrometry. The data of known compounds (3–6) were further compared with the reported data for these compounds.     

New acylated flavonoid glycosides from flowers of Aerva javanica

Chromatographic purification of ethyl acetate soluble fraction of the methanolic extract of the flowers of Aerva javanica yielded three new acylated flavone glycosides: kaempferol-3-O-β-d-[4?-E-p-coumaroyl-α-l-rhamnosyl(1 → 6)]-galactoside (1), kaempferol-3-O-β-d-[4?-E-p-coumaroyl-α-l-rhamnosyl(1 → 6)]-(3″-E-p-coumaroyl)galactoside (2), and kaempferol-3-O-β-d-[4?-E-p-coumaroyl-α-l-rhamnosyl(1 → 6)]-(4″-E-p-coumaroyl)galactoside (3), along with p-coumaric acid (4), caffeic acid (5), gallic acid (6), eicosanyl-trans-p-coumarate (7), hexadecyl ferulate (8), and hexacosyl ferulate (9). The compounds 1–9 were characterized using 1D (¹H, ¹³C) and 2D NMR (HMQC, HMBC, and COSY) spectroscopy and mass spectrometry (EI-MS, HR-EI-MS, FAB-MS, and HR-FAB-MS) and in comparison with the reported data in the literature. Compound 1 showed weak inhibitory activity against enzymes, such as acetylcholinesterase, butyrylcholinesterase, and lipoxygenase with IC₅₀ values 205.1, 304.1, and 212.3 μM, respectively, whereas compounds 2 and 3 were only weakly active against the enzyme acetylcholinesterase.     

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.     

New triterpenes from Salacia hainanensis Chun et How with α-glucosidase inhibitory activity

Fractionation of the methanol extract from the roots of Salacia hainanensis Chun et How showing the potent inhibitory activity on α-glucosidase afforded two new lupane derivatives, 3α,28-dihydroxy-lup-20(29)-en-2-one (1) and 3α-hydroxy-lup-20(29)-en-2-one (2), a new friedelane derivative, D:A-friedo-oleanane-7α,30-dihydroxy-3-one (3), and a novel natural product, 2,3-seco-lup-20(29)-en-2,3-dioic acid (4), along with four known compounds (5–8). Their structures were established on the basis of spectral analysis, especially on the data afforded by 2D NMR and high-resolution mass spectra experiments. All of them showed a much stronger inhibiting activity on α-glucosidase than the positive control (acarbose, IC₅₀ = 5.83 μM). Constituents with α-glucosidase inhibitory activity from this plant are reported for the first time.     

Cytotoxic triterpenoid saponins from Vaccaria segetalis

By the guidance of bioassay, one new cytotoxic triterpenoid saponin, 3-O-[β-d-galactopyranosyl-(1 → 2)-β-d-glucuronopyranosyl] quillaic acid 28-O-β-d-glucopyranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-[β-d-fucopyranosyl-(1 → 4)]-β-d-fucopyranoside (1), and five known cytotoxic triterpenoid saponins, vaccaroside E (2), vaccaroside G (3), vaccaroside B (4), segetoside H (5) and segetoside I (6), were isolated from Vaccaria segetalis. Their structures were established on the basis of ESI-MS, IR, extensive NMR (¹H NMR, ¹³C NMR, TOCSY, ¹H–¹H COSY, DEPT, HMQC, HMBC and ROESY) analyses, chemical degradation, and by comparing with previously reported data. Compounds 1–6 showed moderate cytotoxic activities against LNcap, P-388 and A-549 cell lines with IC₅₀ values in the range 0.1–12.9 μM.     

Aromatic acid derivatives from the lateral roots of Aconitum carmichaelii

Seven new aromatic acid derivatives (1–7), together with five known analogs, were isolated from the lateral roots of Aconitum carmichaelii. Structures of the new compounds were determined by spectroscopic and chemical methods as 4-methyl ( ? )-(R)-hydroxyeucomate (1), 4-butyl ( ? )-(R)-hydroxyeucomate (2), 4-butyl-1-methyl (+)-(R)-2-O-(4′-hydroxy-3′-methoxybenzoyl)malate (3), 1-butyl-4-methyl (+)-(R)-2-O-(4′-hydroxy-3′-methoxybenzoyl)malate (4), dimethyl (+)-(R)-2-O-(4′-hydroxy-3′-methoxybenzoyl)malate (5), dimethyl (+)-(R)-2-O-(4′-hydroxybenzoyl)malate (6), and methyl ( ± )-3-(4′-hydroxy-3′-methoxyphenyl)-3-sulfopropionate (7), respectively. Compounds 1 and 2 are 2-benzylmalates (eucomate derivatives), 3–6 belong to 2-O-benzoylmalates, and 7 is a rare phenylpropionate containing a sulfonic acid group. The absolute configurations of eucomate derivatives were confirmed by X-ray crystallographic analysis of 4-methyl eucomate (11).     

Acylphloroglucinol derivatives from Decaspermum gracilentum and their antiradical and cytotoxic activities

Two new acylphloroglucinol derivatives, 1-(hexanoyl)phloroglucinol-α-d-arabinopyranoside (1) and 1-(hexanoyl)phloroglucinol-β-d-glucopyranoside (2), along with two known ones, 1-(acetyl)phloroglucinol-β-d-glucopyranoside (3) and ethyl 2,4,6-trihydroxybenzoate (4), were isolated from the EtOAc soluble fraction of EtOH extract of Decaspermum gracilentum. The structures of the new compounds were determined by extensive spectroscopic analyses including HRESIMS, 1D and 2D NMR data. Interestingly, all of the compounds showed ABTS^·+ radical scavenging activity with the IC₅₀ values less than 10 μM. Furthermore, compounds 3 and 4 displayed moderate cytotoxicity on human non-small-cell lung carcinoma cell line A549 (IC₅₀ = 50.9 μΜ) and human renal carcinoma cell line 786-O (IC₅₀ = 38.6 μΜ), respectively.     

Three new diphenyl ether derivatives from the fermentation products of an endophytic fungus Phomopsis fukushii

Three new diphenyl ethers (1-3), together with four known isopentylated diphenyl ethers derivatives (4-7), were isolated from the fermentation products of an endophytic fungus Phomopsis fukushii. Their structures were elucidated by spectroscopic methods, including extensive 1D and 2D NMR techniques. Compounds 1-3 were evaluated for their anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) activity. The results revealed that compounds 1 and 2 showed strong inhibitions with inhibition zone diameters (IZD) of 20.2 ± 2.5 mm and 17.9 ± 2.2 mm, respectively. Compound 3 also showed good inhibition with IZD 15.2 ± 1.8 mm. The IZD data of compound 1 is close to that of positive control with IZD 21.9 ± 2.1 mm.     

Isolation and characterization of cytotoxic compounds from Euphorbia cornigera Boiss.

Methanolic extract of Euphorbia cornigera shoots was separated using HPLC, affording compounds 1–4. Their structures and relative stereochemistry were established after obtaining their spectroscopic (IR, ¹H, ¹³C NMR COSY-45°, HOHAHA, HSQC, HMBC, NOESY, and mass measurement) data. On the basis of these data, the compounds were characterized as 3-O-(2,3-dimethylbutanoyl)-13-O-dodecanoyl-20-O-tetradecanoylingenol (1), 3-O-decanoyl-20-O-hexanoylingenol (2), 3-O-(2,3-dimethylbutanoyl)-13-O-dodecanoyl-20-O-hexadecanoylingenol (3), and 13-O-dodecanoyl-20-O-hexanoylingenol (4); among these compounds, two (1 and 2) were new metabolites while the rest (3 and 4) were known. The MTT cytotoxicity assay was carried out using amrubicin hydrochloride as a positive control. Compound 1 displayed IC₅₀ as 5.0 and 2.9 μM against RAW and HT-29 cell lines, respectively, which is 5- and 1.5-folds stronger than the control with IC₅₀ values of 25 and 4.36 μM, respectively.     

Biologically active <Emphasis Type="Italic">C</Emphasis>-alkylated flavonoids from <Emphasis Type="Italic">Dodonaea viscosa</Emphasis>

A new C-alkylated flavonoid (5,7-dihydroxy-3′-(4″-acetoxy-3″-methylbutyl)-3,6,4′-trimethoxyflavone (1), along with two known C-alkylated flavonoids (5,7-dihydroxy-3′-(3-hydroxymethylbutyl)-3,6,4′-trimethoxyflavone (2), 5,7,4′-trihydroxy-3′-(3-hyroxymethylbutyl)-3,6-dimethoxyflavone (3) and two new source C-alkylated flavonoids (5,7-dihydroxy-3′-(2-hydroxy-3-methyl-3-butenyl)-3,6,4′-trimethoxyflavone (4), 5,7,4′-trihydroxy-3,6-dimethoxy-3′-isoprenyl-flavone (5) were isolated from the aerial parts of Dodonaea viscosa. The structures of all compounds were established on the basis of 1D and 2D NMR spectroscopy and mass spectrometry. The isolated compounds were evaluated for their inhibitory effect on urease and α-chymotrypsin enzyme. All the compounds (1–5) exhibited mild inhibition against urease but remained recessive in case of α-chymotrypsin.     

A new steroidal saponin from Dioscorea panthaica

A new steroidal saponin and three known saponins were isolated from the rhizomes of Dioscorea panthaica. Their structures were elucidated as 3-O-[α-l-rhamnopyranosyl-(1 → 2)-β-d-glucopyranosyl]-26-O-β-d-glucopyranosyl-20,22-seco-25(R)-furosta-5-ene-20,22-dione-3β,26-diol (1), pregnadienolone-3-O-β-chacotriside (2), pseudoprotodioscin (3), and dioscoreside D (4) mainly by NMR techniques and chemical methods. The inhibitory activities of the saponins against α-glucosidase were investigated, and compound 2 was found to exhibit potent activity with IC₅₀ values of 0.04 ± 0.01 mM.     

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.     

Alkaloids from Clematis manshurica Rupr.

Three new alkaloids together with two known compounds have been isolated from the roots of Clematis manshurica. On the basis of their spectroscopic and chemical evidence, the new compounds were elucidated as methyl 7-ethoxy-3-indolecarbonate (2), methyl 7-O-α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranosyl 3-indolecarbonate (3) and α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranosyl 3-indolecarbonate (4).     

Two new lignan glycosides from the seeds of Cuscuta chinensis

Two new lignan glycosides, 2′-hydroxyl asarinin 2′-O-β-D-glucopyranoside (cuscutoside C, 1) and 2′-hydroxyl asarinin 2′-O-β-D-apiofuranosyl-(1 → 2)-[β-D-glucopyranosyl-(1 → 6)]-β-D-glucopyranoside (cuscutoside D, 2), were isolated from the seeds of Cuscuta chinensis Lam., along with six known compounds, 2′-hydroxyl asarinin 2′-O-β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranoside (3), 2′-hydroxyl asarinin 2′-O-β-D-apiofuranosyl-(1 → 2)-β-D-glucopyranoside (cuscutoside A, 4), kaempferol 3,7-di-O-β-D-glucopyranoside (5), 5-caffeoyl quinic acid (6), 4-caffeoyl quinic acid (7), and cinnamic acid (8). Their structures were elucidated on the basis of spectroscopic analyses including HR-ESI-MS, ESI-MS/MS, ¹H and ¹³C NMR, HSQC, HMBC, and TOCSY.     

New steroidal glycosides from the rhizome of Anemarrhena asphodeloides

Two new steroidal saponins, timosaponin X (1) and timosaponin Y (2), and one new pregnane glycoside, timopregnane B (3), were isolated from the rhizomes of Anemarrhena asphodeloides, as well as three known compounds 25S-timosaponin BII (4), protodesgalactotigonin (5), and timosaponin BII-a (6) isolated from this plant for the first time. By the detailed analysis of 1D, 2D NMR, MS spectra, and chemical evidences, the structures of new compounds were elucidated as 26-O-β-d-glucopyranosyl-(25S)-5β-22-methoxy-furost-3β,26-diol 3-O-β-d-glucopyranosyl-(1 → 2)-α-l-arabinopyranoside (1), 5β-pseudo-spirost-3β,15α,23α-triol 3-O-β-d-glucopyranosyl-(1 → 2)-β-d-galactopyranoside (2), (5β,17α)-Δ¹⁶⁽¹⁷⁾-20-one-pregn-2β,3β-diol 3-O-β-d-glucopyranosyl-(1 → 2)-β-d-galactopyranoside (3).     

Terpenoids from the tuber of Cremastra appendiculata

Two new terpenoids including a cadinane sesquiterpene (1), and an ent-kaurane diterpene diglycoside (2), together with a known triterpene containing 32 carbons (3), have been isolated from the ethanolic extract of Cremastra appendiculata. Their structures were established by the spectroscopic methods including the IR, MS, 1D-, and 2D-NMR experiments as ( ? )-cadin-4,10(15)-dien-11-oic acid (1), ( ? )-ent-12β-hydroxykaur-16-en-19-oic acid, 19-O-β-d-xylopyranosyl-(1 → 6)-O-β-d-glucopyranoside (2), and (+)-24,24-dimethyl-25,32-cyclo-5α-lanosta-9(11)-en-3β-ol (3). Compounds 1–3 were evaluated against several human cancer cell lines. Compound 3 showed in vitro-selective cytotoxicity against human breast cancer cell lines (MCF-7) with an IC₅₀ of 3.18 μM, but 1 and 2 were inactive (IC₅₀>10 μg/ml).     

Unsymmetrical 1,3-disubstituted urea derivatives as α-chymotrypsin inhibitors

The objective of this study was to synthesize potent and/or novel inhibitors for α-chymotrypsin activity. Eighteen derivatives of N-methylphenyl-N′-(alkyl/aryl) urea (1–18) were synthesized, and their inhibitory effects on α-chymotrypsin enzyme were evaluated. Two compounds exhibited potent inhibitory activities. The most potent, N-(2-methylphenyl)-2-oxo-1-pyrrolidinecarboxamide (15) having a methyl group at ortho position was the most active inhibitor with an IC₅₀ value of 8.10 ± 0.14 μM, which was comparable to standard chymostatin (IC₅₀ = 8.24 ± 0.11 μM). A slightly less potent, N-(2-acetylphenyl)-N′-(3-methylphenyl) urea (10), exhibited an IC₅₀ of 13.6 ± 0.23 μM. Compounds 3, 4, 7, 11, and 13 exhibited moderate activities. The results demonstrated that α-chymotrypsin inhibition is related to the position of the methyl group and the presence of substituent at the nitrogen of the urea bridge. The inhibitory trend suggests that α-chymotrypsin inhibitory activity declines with ortho > meta > para substitution order. In conclusion, our data suggest that the compound 15 may serve as a lead compound for further designing of other potent or novel α-chymotrypsin inhibitors.     

Chemical constituents from the leaves of Boehmeria rugulosa with antidiabetic and antimicrobial activities

Three new flavonoid glycosides, named chalcone-6′-hydroxy-2′,3,4-trimethoxy-4′-O-β-d-glucopyranoside (1), isoflavone-3′,4′,5,6-tetrahydroxy-7-O-{β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranoside} (2), and isoflavone-3′,4′,5,6-tetrahydroxy-7-O-{β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranoside} (3), were isolated from the leaves of Boehmeria rugulosa, together with five known compounds, β-sitosterol, quercetin, 3,4-dimethoxy-ω-(2′-piperidyl)-acetophenone (4), boehmeriasin A (5), and quercetin-7-O-β-d-glucopyranoside. The structures of the isolated compounds were determined by means of chemical and spectral data including 2D NMR experiments. The ethanolic extract of leaves showed significant hypoglycemic activity on alloxan-induced diabetic mice. Glibenclamide, an oral hypoglycemic agent (5 mg/kg, p.o.), was used as a positive control. The ethanolic extract of the plant as well as the isolated compounds 1–3 (25 μg/ml) showed potent antimicrobial activity against two bacterial species (Staphylococcus aureus and Streptococcus mutans) and three fungus pathogens (Microsporum gypseum, Microsporum canis, and Trichophyton rubrum). The activities of the isolated compounds 1–3 have been compared with positive controls, novobiocin, and erythromycin (15 μg/ml).     

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.