A new tropane alkaloid and other constituents of Erythroxylum rimosum (Erythroxylaceae)

A new tropane alkaloid, named the 7β-acetoxy-3β,6β-dibenzoyloxytropane (1), was isolated from a methanol extract of Erythroxylum rimosum O.E. Schulz leaves. Other known compounds were detected, including quercetin, kaempferol-3-O-α-l-arabinofuranoside, (+)-catechin, epicatechin, quercetin-3-O-α-arabinofuranoside, quercetin-3-O-α-arabinopyranoside, quercetin-3-O-β-arabinopyranoside, quercetin-3-β-glucopyranoside, kaempferol, quercetin-3-O-β-galactopyranoside, β-sitosterol, α-amyrin, β-amyrin, and the ester derivatives of these two amyrins. Compound 1 exhibited weak inhibition of acetylcholinesterase. Structural identification was performed using IR, ESIHRMS and one- and two-dimensional NMR data analyses and confirmed by comparison with literature data.     

Three new benzophenone glycosides with MAO-A inhibitory activity from Hypericum thasium Griseb.

Purification of n-BuOH fraction from 80% ethanol extract of Hypericum thasium Griseb. resulted in the isolation of three new compounds 3′,4,5′-trihydroxy-6-methoxy-2-O-α-l-arabinosylbenzophenone (1), 3′,4,5′,6-tetrahydroxy-2-O-α-l-arabinosylbenzophenone (2), and 3′,4-dihydroxy-5′-methoxy-2-O-α-l-arabinosyl-6-O-β-d-xylosylbenzophenone (3) along with a known flavonoid glycoside quercetin-3-O-α-l-arabinofuranoside (4). The structures of the new compounds were elucidated by 1D and 2D NMR analysis as well as HRESIMS. The isolated compounds (1–4), as well as quercetin, and kaempferol previously isolated from EtOAc fraction were screened against MAO-A inhibitory activity. When tested against the MAO-A quercetin and kaempferol displayed IC₅₀ values of 19.6, and 17.5 μM, respectively. The IC₅₀ values for MAO-A inhibition by compounds (1–4) were 310.3, 111.2, 726.0, and 534.1 μM, respectively. Standard inhibitor (clorgyline) exhibited MAO-A inhibition with an IC₅₀ value of 0.5 μM.     

Phytochemical analysis of the labdanum-poor Cistus creticus subsp. eriocephalus (Viv.) Greuter et Burdet growing in central Italy

Phenolic constituents and essential oil from the aerial parts of Cistus creticus subsp. eriocephalus (Viv.) Greuter et Burdet growing in central Italy were analysed by HPLC-MSⁿ and GC–MS, respectively. Furthermore, six constituents were isolated by semipreparative HPLC from the methanol extract and their structures were determined on the basis of 1D and 2D NMR measurements as well as MS spectra. Isolated compounds were one new natural product, i.e. the shikimic acid ester 3,5-diihydroxy-4-(O-β-d-glucopyranosyl)-cyclohex-1-en-1-(O-β-d-glucopyranosyl)-ester (27), and six flavonoid glycosides, namely quercetin-3-O-β-D glucopyranoside (16), quercetin-3-O-rhamnoside (17), tricetin-4′-O-β-D glucopyranoside (24), tricetin-4′-O-β-D rutinoside (21), 3′-methoxy-quercetin-3-O-(3-β-Dglucopyranosyl-2-rhamnopyranosil-4-glucopyranosyl-2-rhamnopyranosil)-glucoside (25) and 3′,4′dimethoxyquercetin-3-O-rhamnopyranoside (26). GC–MS analysis of the essential oil highlighted the occurrence of aliphatic compounds, mainly fatty acids, whereas labdane-type compounds were very scant. Our results showed that C. creticus subsp. eriocephalus has a different chemical profile with respect to the other subspecies due to the lack of labdane derivatives. On the other hand, this subspecies contains several phenolic constituents like ellagitannins, gallotannins and flavonoids, some of which can be of chemotaxonomic value.     

α-Glucosidase inhibitory constituents from Chrozophora plicata

Five new secondary metabolites have been isolated from Chrozophora plicata including an acacetin derivative (1), three pyrrole alkaloids plicatanins A–C (2–4, resp.) and the bilactone plicatanone (5). Together with these compounds, the known compounds, β-sitosterol (6), methyl p-coumarate (7), 4-hydroxyphenylacetic acid (8), succinic acid (9), speranberculatine A (10), β-sitosterol-3-O-β-d-glucopyranoside (11) and apigenin-5-O-β-d-glucopyranoside (12) have also been isolated. The structures of isolates 1–12 were established by 1D (¹H, ¹³C) and 2D NMR (HMQC, HMBC, COSY) spectroscopy and mass spectrometry (EIMS, HREIMS, FABMS, HRFABMS). The structure of plicatanin A (3) was further confirmed through single crystal X-ray technique. Compounds 1–12 were evaluated for their inhibitory activity against the enzyme yeast α-glucosidase. The compound 4 was found to be most potent with IC₅₀ value 27.8 μM.     

Two new flavonol glycosides from the leaves of Cleome viscosa L.

From the leaves of Cleome viscosa L., two new flavonol glycosides, named visconoside A (1) and visconoside B (2), together with six known flavonol glycosides, vincetoxicoside A (3), vincetoxicoside B (4), kaempferitrin (5), kaempferide 3-O-β-d-glucopyranoside 7-O-α-l-rhamnopyranoside (6), kaempferol 3-O-β-d-glucopyranoside 7-O-α-l-rhamnopyranoside (7), and isorhamnetin 3-O-β-d-glucopyranoside (8) were isolated by various chromatography methods. Its chemical structure was elucidated by IR, UV, HR-ESI-MS, NMR 1D and 2D experiments and compared with literatures.     

Alkenylresorcinols and cytotoxic activity of the constituents isolated from Labisia pumila

Phytochemical investigation on the leaves of Labisia pumila (Myrsinaceae), an important medicinal herb in Malaysia, has led to the isolation of 1-O-methyl-6-acetoxy-5-(pentadec-10Z-enyl)resorcinol (1), labisiaquinone A (2) and labisiaquinone B (3). Along with these, 16 known compounds including 1-O-methyl-6-acetoxy-5-pentadecylresorcinol (4), 5-(pentadec-10Z-enyl)resorcinol (5), 5-(pentadecyl)resorcinol (6), (−)-loliolide (7), stigmasterol (8), 4-hydroxyphenylethylamine (9), 3,4,5-trihydroxybenzoic acid (10), 3,4-dihydroxybenzoic acid (11), (+)-catechin (12), (−)-epicatechin (13), kaempferol-3-O-α-rhamnopyranosyl-7-O-β-glycopyranoside (14), kaempferol-4′-O-β-glycopyranoside (15), quercetin-3-O-α-rhamnopyranoside (16), kaempferol-3-O-α-rhamnopyranoside (17), (9Z,12Z)-octadeca-9,12-dienoic acid (18) and stigmasterol-3-O-β-glycopyranoside (19) were also isolated. The structures of these compounds were established on the basis of 1D and 2D NMR spectroscopy techniques (¹H, ¹³C, COSY, HSQC, NOESY and HMBC experiments), mass spectrometry and chemical derivatization. Among the constituents tested 1 and 4 exhibited strongest cytotoxic activity against the PC3, HCT116 and MCF-7 cell lines (IC₅₀ values ⩽10 μM), and they showed selectivity towards the first two-cell lines relative to the last one.     

A new phenylpropanoid and an alkylglycoside from Piper retrofractum leaves with their antioxidant and α-glucosidase inhibitory activity

Two new compounds, piperoside (1) and isoheptanol 2(S)-O-β-d-xylopyranosyl (1→6)-O-β-d-glucopyranoside (11), along with 10 known compounds 3,4-dihydroxyallylbenzene (2), 1,2-di-O-β-d-glucopyranosyl-4-allylbenzene (3), tachioside (4), benzyl-O-β-d-glucopyranoside (5), icariside F₂ (6), dihydrovomifoliol-3′-O-β-d-glucopyranoside (7), isopropyl O-β-d-glucopyranoside (8), isopropyl primeveroside (9), n-butyl O-β-d-glucopyranoside (10), isoheptanol 2(S)-O-β-d-apiofuranosyl-(1→6)-O-β-d-glucopyranoside (12), were isolated from the leaves of Piper retrofractum. Their structures were determined from 1D-NMR, 2D-NMR, and HR-ESI-MS spectral, a modified Mosher’s method, and comparisons with previous reports. All of the isolated compounds showed modest α-glucosidase inhibitory (4.60 ± 1.74% to 11.97 ± 3.30%) and antioxidant activities under the tested conditions.     

Vavilosides A1/A2–B1/B2, new furostane glycosides from the bulbs of Allium vavilovii with cytotoxic activity

A phytochemical analysis of the bulbs of Allium vavilovii M. Pop. & Vved. was attained for the first time extensively, affording to the isolation of four new furostanol saponins, named vavilosides A1/A2–B1/B2 (1a/b–2a/2b), as two couple of isomers in equilibrium, together with ascalonicoside A1/A2 (3a/3b) and 22-O-methyl ascalonicoside A1/A2 (4a/4b), previously isolated from shallot, Allium ascalonicum. High concentrations of kaempferol, kaempferide, and kaempferol 4^I-glucoside were also isolated. The chemical structures of the new compounds, established through a combination of extensive nuclear magnetic resonance, mass spectrometry and chemical analyses, were identified as (25R)-furost-5(6)-en-1β,3β,22α,26-tetraol 1-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-galactopyranosyl 26-O-α-l-rhamnopyranoside (vaviloside A1), (25R)-furost-5(6)-en-1β,3β,22β,26-tetraol 1-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-galactopyranosyl 26-O-α-l-rhamnopyranoside (vaviloside A2), (25R)-furost-5(6)-en-1β,3β,22α,26-tetraol 1-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-xylopyranosyl 26-O-α-l-rhamnopyranoside (vaviloside B1), (25R)-furost-5(6)-en-1β,3β,22β,26-tetraol 1-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-xylopyranosyl 26-O-α-l-rhamnopyranoside (vaviloside B2). The isolated saponins showed cytotoxic activity on J-774, murine monocyte/macrophage, and WEHI-164, murine fibrosarcoma, cell lines with the following rank: vaviloside B1/B2 > ascalonicoside A1/A2 > vaviloside A1/A2.     

Sesquiterpenoids and flavonoids from Pteris multifida Poir.

Phytochemical research of Pteris multifida Poir. led to the isolation of fifteen compounds, including six flavonoids (1–6) and nine sesquiterpenoids (7–15). Their structures were characterized by NMR, MS, ORD and CD data. Compounds kaempferol 3-O-α-L-rhamnoside-7-O-β-D-glucoside (1), myricetin 3-O-β-D-glucoside (2), kaempferol 3-O-β-D-glucoside (4), luteolin-7-O-β-D-rutinoside (5), quercetin-3-O-α-L-rhamnopyranoside (6), (2S,3S)-12-hydroxypterosin Q (7), (2S,3S)-pterosin Q (8), 2-hydroxypterosin C (9) and (2S)-12-hydroxypterosin A (10) were first isolated from P. multifida, and compounds 1–2 and 10 were first isolated from the family Pteridaceae. Furthermore, the chemotaxonomic significance of the isolates was discussed.     

Acylated flavonol tetraglycosides from Delphinium gracile

An ethanol extract of the aerial parts of Delphinium gracile DC. yielded five flavonol glycosides quercetin-3-O-{[β-d-xylopyranosyl (1 → 3)-4-O-(E-p-caffeoyl)-α-l-rhamnopyranosyl (1 → 6)][β-d-glucopyranosyl (1 → 2)]}-β-d-glucopyranoside (1), quercetin-3-O-{[β-d-xylopyranosyl (1 → 3)-4-O-(E-p-coumaroyl)-α-l-rhamnopyranosyl (1 → 6)][β-d-glucopyranosyl (1 → 2)]}-β-d-glucopyranoside (2), quercetin-3-O-{[β-d-xylopyranosyl (1 → 3)-4-O-(Z-p-coumaroyl)-α-l-rhamnopyranosyl (1 → 6)][β-d-glucopyranosyl (1 → 2)]}-β-d-glucopyranoside (3), kaempferol-3-O-{[β-d-glucopyranosyl (1 → 3)-4-O-(E-p-coumaroyl)-α-l-rhamnopyranosyl (1 → 6)][β-d-glucopyranoside-7-O-(4-O-acetyl)-α-l-rhamnopyranoside (4) kaempferol-3-O-{[β-d-glucopyranosyl (1 → 3)-4-O-(E-p-coumaroyl)-α-l-rhamnopyranosyl (1 → 6)][β-d-glucopyranoside-7-O-(4-O-acetyl)-α-l-rhamnopyranoside (5) in addition to 4-(β-d-glucopyranosyloxy)-6-methyl-2H-pyran-2-one (6) and rutin. Structures were elucidated by spectroscopic methods.     

Triterpenoid profile and bioactivity study of Oenothera maritima

Four new triterpenoids, 2α,3α,20β,23-tetrahydroxy-ursa-12,19(29)-dien-28-oic acid (1), 2α,3α,20β,23-tetrahydroxy-ursa-12,19(29)-dien-28,20β-lactone (2), 2α,3α-dihydroxy-ursa-12,19-dien-28-oic acid 28-O-β-d-glucopyranoside (3) and 2α,3α,23-trihydroxy-ursa-12,19(29)-dien-28-oic acid (4) together with six known compounds (5–10), were isolated from the aerial parts of Oenothera maritima Nutt. Their structures were elucidated on the basis of spectroscopic data and chemical methods. Compounds 1, 3–10 were evaluated for their in vitro thrombin inhibitory activity and their selectivity against factor Xa and trypsin.     

Phytochemical and chemotaxonomic study of Pulsatilla cernua (Thunb.) Bercht. ex J. Presl

Twenty-two compounds were isolated from the 70% EtOH–H₂O extract of Pulsatilla cernua (Thunb.) Bercht. ex J. Presl roots, and their structures were determined based on ¹H NMR, ¹³C NMR and MS spectroscopic data, including (+)-pinoresinol (1), matairesinol (2), 4-ethoxycinnamic acid (3), p-hydroxy ethyl cinnamate (4), 3-(4′-methoxyphenyl)-2(E)-propenoic acid (5), methyl 4-hydroxycinnamate (6), radicol (7), cryptomeridiol (8), fraxinellone (9), diolmycin B2 (10), hederagonic acid (11), hederagenin (12), oleanolic acid (13), 3-O-α-L-arabinopyranosyl-oleanolic acid (14), hederagenin 3-O-α-L-arabinopyranoside (15), 3-O-[α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl] oleanolic acid (16), hederasaponin B (17), kizutasaponin K₁₂ (18), patrinia saponin H3 (19), hederacholichiside F (20), cernuoside A (21) and cernuoside B (22). Eight compounds (3–10) were isolated and identified from the genus Pulsatilla for the first time.     

Chemical constituents from the leaves of Cinnamomum parthenoxylon (Jack) Meisn. (Lauraceae)

Phytochemical investigation of the ethanolic extract from the leaves of Cinnamomum parthenoxylon (Jack) Meisn. led to the isolation of (3R, 4R, 3′R, 4′R)-6,6′-dimethoxy-3, 4, 3′, 4′-tetrahydro-2H, 2′H-[3, 3′]bichromenyl-4, 4′-diol (1), 4-hydroxybenzaldehyde (2), 1,2,4-trihydroxybenzene (3), kaempferol-3-O-α-l-rhamnoside (4), herbacetin (5), quercetin-3-O-α-l-rhamnoside (6), daucosterol (7), and β-sitosterol (8). The structures were established by extensive analysis of their MS and NMR spectroscopic data and comparison with literature data. In the present research, all of the isolated compounds 1–8 are reported for the first time in the species C. parthenoxylon. Compounds 1–6 were firstly isolated from genus Cinnamomum. Compounds 1, 3, 5 and 6 have not been reported from any species in Lauraceae family. The chemotaxonomic significance of the isolated compounds is discussed.     

New flavonoids from the fruits of Cornus mas,Cornaceae

One new β-hydroxychalcone, 4-acetoxy-5,2′,4′,6′,β-pentahydroxy-3-methoxychalcone (1), one new flavanone, 7,3′-dihydroxy-5,4′-dimethoxyflavanone (2) and seven known compounds, 2R, 3R-trans-aromadendrin (3), naringenin-7-O-methylether (4), myricetin (5), quercetin-3-O-rutinoside (6), ursolic acid (7), gallic acid (8) and d-glucose (9) were isolated from the methanolic fruit extract of Cornus mas L. (=Cornus mascula L.), Cornaceae. The structures of the new compounds were elucidated on the basis of extensive spectroscopic methods, including 2D NMR experiments and of known compounds by comparison of physical and spectral data with literature.     

α-Glucosidase inhibitory effects of polyphenols from Geranium asphodeloides: Inhibition kinetics and mechanistic insights through in vitro and in silico studies

Some Geranium species have been used to treat diabetes. To evaluate the scientific basis of this ethnopharmacological use, we aimed to isolate potent α-glucosidase inhibitory metabolites of Geranium asphodeloides Burm. through in vitro bioactivity-guided fractionation. All the tested extracts showed high α-glucosidase inhibitory effect compared to acarbose. Among the tested extracts, the ethyl acetate subextract showed the highest activity with an IC₅₀ value of 0.85 ± 0.01 µM. A hydrolysable tannin, 1,2,4-tri-O-galloyl-β-d-glucopyranose (1), and five flavonoid glycosides, kaempferol-3-O-α-rhamnopyranoside (2), kaempferol-3-O-α-arabinofuranoside (3), quercetin-3-O-β-glucopyranoside (4), quercetin-3-O-α-rhamnopyranoside (5), and quercetin-3-O-α-rhamnofuranoside (6), were isolated from the ethyl acetate subextract. Their structures were identified by 1D- and 2D-NMR experiments. 1 exhibited the highest α-glucosidase inhibitory effect, approximately 61 times more potent than positive control, acarbose, with an IC₅₀ value of 0.95 ± 0.07 µM. Also, 2 was more potent than acarbose. An enzyme kinetics analysis revealed that compounds 2, 3 and 4 were competitive, whereas 1 and 6 uncompetitive inhibitors. Molecular docking studies were performed to get insights into inhibition mechanisms of the isolated compounds in the light of the enzyme kinetic studies using various binding sites of the enzyme model.     

Microbial metabolism of cannflavin A and B isolated from Cannabis sativa

Microbial metabolism of cannflavin A (1) and B (2), two biologically active flavonoids isolated from Cannabis sativa L., produced five metabolites (3–7). Incubation of 1 and 2 with Mucor ramannianus (ATCC 9628) and Beauveria bassiana (ATCC 13144), respectively, yielded 6″S,7″-dihydroxycannflavin A (3), 6″S,7″-dihydroxycannflavin A 7-sulfate (4) and 6″S,7″-dihydroxycannflavin A 4′-O-α-l-rhamnopyranoside (5), and cannflavin B 7-O-β-d-4?-O-methylglucopyranoside (6) and cannflavin B 7-sulfate (7), respectively. All compounds were evaluated for antimicrobial and antiprotozoal activity.     

Chevalierinoside B and C: Two new isoflavonoid glycosides from the stem bark of Antidesma laciniatum Muell. Arg (syn. Antidesma chevalieri Beille)

Chevalierinosides B (1) and C (2), two new isoflavonoid glycosides, characterized as biochanin A 7-O-[β-d-apiofuranosyl-(1→2)-β-d-glucopyranoside] and genistein 7-O-[β-d-apiofuranosyl-(1→2)-β-d-glucopyranoside], together with the known isoflavonoids, chevalierinoside A (3) and genistein 7-O-β-d-glucopyranoside (4), kaempferol 3-O-β-d-glucopyranoside (5) and triterpenes, friedelin (6), betulinic acid (7), 30-oxobetulinic acid (8), 30-hydroxybetulinic acid (9), were isolated from the stem bark of Antidesma laciniatum Muell. Arg. (syn. Antidesma chevalieri Beille). Their structures were established by direct interpretation of their spectral data, mainly HR-TOFESIMS, 1D-NMR (¹H, ¹³C and DEPT) and 2D-NMR (COSY, NOESY, TOCSY, HSQC and HMBC), and by comparison with the literature.     

Two new glycosides and one new neolignan from the roots of Cynanchum stauntonii

Three new compounds including one C₂₁-steroidal glycoside, one methylglycoside, and one neolignan, named as Deoxyamplexicogenin A-3-O-yl-4-O-(4-O-α-l-cymaropyranosoyl-β-d-digitoxopyranosoyl)-β-d-canaropyranoside (1), Methyl-O-α-l-cymaropyranosoyl-(1 → 4)-β-D-digitoxopyranoside (2), and (+)-(7S, 8R, 7′E)-5-hydroxy-3, 5′-dimethoxy-4′, 7-epoxy-8, 3′-neolign-7′-ene-9, 9′-diol 9′-ethyl ether (3), respectively, were isolated from the roots of Cynanchum stauntonii. The structure elucidations were achieved by in-depth spectroscopic examination, mainly including the experiments and analyses of multiple 1D- and 2D-NMR and HRESIMS and CD analysis and qualitative chemical tests. Cytotoxicity activities of compounds 1–3 were evaluated against five tumor cell lines (HCT-8, Bel-7402, BGC-823, A549, and A2780) in cell based assays where they were found to be inactive.     

Acetolysis of Leuconostoc mesenteroides NRRL B-1299 Dextran. Isolation and characterization of tetrasacharrides containing secondary linkages from the borate-insoluble fraction

Fractionation of the deacetylated acetolyzate of the borate-insoluble fraction of the dextran elaborated by Leuconostoc mesenteroides NRRL B-1299 gave five tetrasaccharide fractions, isolated after chromatography on charcoal—Celite, paper chromatography, and paper electrophoresis. Examination of partial acid hydrolyzates of the tetrasaccharide fractions and their corresponding alditols, the relation between the logarithm of their partition functions (α') and molecular size, and methylation studies, showed them to be (a) 2³-α-d-glucosyl-nigerotriose (1), (b) a mixture of 6-α-nigerotriosyl-d-glucose (2) and 6¹-α-d-glucosyl-nigerotriose (3) and/or 6²-α-d-glucosyl-nigerotriose (4), (c) a mixture of 2¹-α-nigerosyl-isomaltose (5) and 3²-α-isomaltosyl-kojibiose (6) and/or 6²-α-nigerosyl-kojibiose (7), (d) 2-α-nigerotriosyl-d-glucose (8) and (e) nigerotetraose (9).     

Four new lanostane-type triterpenoids from Inonotus obliquus

Four new lanostane-type triterpenoids, inonotsuoxodiol B (1), inonotsuoxodiol C (2), epoxyinonotsudiol (3), and methoxyinonotsutriol (4), were isolated from the sclerotia of Inonotus obliquus. Their structures were determined to be 3β,22R-dihydroxylanosta-9(11),24-dien-7-one (1), 3β,22R-dihydroxylanosta-7,24-dien-11-one (2), 9α,11α-epoxy-lanosta-7,24-diene-3β,22R-diol (3), and 7β-methoxylanosta-8,24-diene-3β,11α,22R-triol (4) on the basis of NMR spectroscopy, including 1D and 2D (¹H–¹H-COSY, NOESY, HMQC, HMBC) NMR spectra, and EIMS.