Phenolic constituents from the branches of Viburnum chinshanense as potential α-amylase and α-glucosidase inhibitory agents.

This paper reports the isolation of two undescribed phenolic glycosides (1 and 2), together with seven known compounds (3-9) from the branches of Viburnum chinshanense. The structures of undescribed compounds were elucidated by comprehensive spectroscopic methods (1D NMR, 2D NMR, and HRESIMS). The sugar units of compounds 1 and 2 were identified by acid hydrolysis and HPLC analysis of the chiral derivatives of the monosaccharides. Furthermore, the α­amylase and α-glucosidase inhibitory activities of all isolates were evaluated and compounds 1, 5, and 8 displayed potential α­amylase and α-glucosidase inhibitory activities. The molecular docking analyses of compounds 1 and 8 with the potent inhibition towards the target enzymes were also performed.

Lignan and phenolic glycosides from Viburnum betulifolium fruits and their α­amylase and α-glucosidase inhibitory activities.

The phytochemical investigation on the methanol extract of Viburnum betulifolium fruits resulted in the isolation and identification of two new lignan constituents (1 and 2) and seven known phenolic glycosides (3-9). The structures of new isolates, including their absolute configurations were elucidated by extensive spectroscopic analyses (1H and 13C NMR, HSQC, HMBC, HRESIMS, and ECD) and chemical methods. In the in vitro enzyme assays, compounds 1, 2, 6, and 8 showed potential α­amylase and α-glucosidase inhibitory activities. Among them, compound 1 exhibited stronger inhibitory effects towards α-amylase and α-glucosidase with the IC50 values of 12.68 and 15.17 µM, respectively, than those of the positive control acarbose (IC50, 29.19 and 18.15 µM, respectively). In addition, the molecular docking analyses of compound 1 with strongest inhibition against the target enzymes were also performed.

LC-MS guided isolation of phenolic glycosides from Viburnum luzonicum Rolfe leaves and their α­amylase and α-glucosidase inhibitory activities.

Viburnum luzonicum Rolfe is widely used in China as folk medicine. The bioactivity evaluation indicated that the n-BuOH fraction of V. luzonicum leaves (VLLB) could significantly inhibit α­amylase and α-glucosidase. In order to clarify its active constituents, the phytochemical analysis on VLLB was first performed using HPLC-QTOF-MS/MS, and three new phenolic compounds, viburosides A-C (1-3), along with seven known analogues (4-10) were isolated through preparative HPLC. The undescribed compounds were determined by extensive spectroscopic analyses (1H and 13C NMR, HSQC, HMBC, HRESIMS, and ORD) and enzymatic hydrolysis. In the in vitro enzyme assays, compounds 1-8 showed potent α­amylase and α-glucosidase inhibitory activities. The enzymatic kinetics and molecular docking of the strongest inhibitors 2 and 3 against the corresponding target enzyme were also performed.

Two new phenolic allopyranosides and their analogues from the stems of Viburnum luzonicum Rolfe guided by LC-MS.

Two new phenolic allopyranosides, named viburluzosides A and B (1, 2), together with eight known phenolic glycosides (3 - 10) were discovered from the stems of Viburnum luzonicum Rolfe under the guidance of LC-MS analyses coupled with bioactivity evaluation. They were purified through various chromatography methods and identified by extensive spectroscopic analyses (1H and 13C NMR, HSQC, HMBC, and HRESIMS) and chemical methods. The in vitro evaluation on α-glucosidase and aldose reductase (AR) inhibitory activities of isolated compounds were conducted. Compounds 1 - 4 and 6 - 9 exhibited α-glucosidase inhibitory activities with IC50 values of 5.35 - 21.34 µM and AR inhibitory activities with IC50 values of 6.21 - 40.06 µM. Moreover, the inhibitory kinetics analyses of compounds 1 and 2 were also performed.

Recent Advance on Chemistry and Bioactivities of Secondary Metabolites from Viburnum Plants: An Update.

Viburnum species are a group of small trees or shrubs that are of great ornamental and medicinal values. Some of them have been used for a long time both as conventional and ethnic medicine. Viburnum fruits, eaten in fresh and processed forms, have been revealed to contain various health-promoting nutrients. With the increasing research on Viburnum plants, they are considered to be an abundant resource of bioactive natural products possessing diverse pharmacological properties and unique chemical structures, that is powerfully proved by the existence of structurally novel vibsane-type diterpenoids which only occur in Viburnum species, newly discovered lignan constituents with unusual side chains and other noteworthy natural components. This review describes 185 new and 228 known secondary metabolites from Viburnum genus between 2008 and 2020, including their chemical structures, sources and bioactivities, and highlights the corresponding structure-activity relationships.

Lignan Constituents from the Fruits of Viburnum macrocephalum f. keteleeri and Their α-Amylase, α-Glucosidase, and Protein Tyrosine Phosphatase 1B Inhibitory Activities.

Eight previously undescribed lignan glycosides, viburmacrosides A-H (1-8), and seven known analogues (9-15) were isolated from Viburnum macrocephalum f. keteleeri fruits through bioactivity-guided fractionation. Their structures and absolute configurations were elucidated by extensive spectroscopic analyses and chemical evidence. Using the well-recognized carbohydrate-hydrolyzing enzymes α-amylase and α-glucosidase, as well as the promising protein tyrosine phosphatase 1B (PTP1B), as inhibitory targets, all isolated compounds were tested for their antidiabetic potential in vitro. Compound 4 displayed potent inhibitory activities with IC50 values of 9.9 ± 0.6 and 8.9 ± 0.5 µM against α-glucosidase and PTP1B, respectively. The enzymatic kinetics results suggested that compound 4 competitively inhibited α-glucosidase while it suppressed α-amylase and PTP1B in the mixed-type manner. These findings supported that V. macrocephalum f. keteleeri fruits may be a new functional food resource with antidiabetic potential.

Phenolic glycoside constituents from Brassica rapa flowers and their α-glucosidase inhibitory activity.

Two new phenolic glycoside compounds (1, 2) and ten known analogues (3-12) have been isolated from the ethanolic extract of Brassica rapa flowers and identified as 2-O-ß-d-glucopyranosyl-(1S)-(4-methoxyphenyl)ethylene glycol (1), 2-(4-O-ß-d-allopyranosyl)phenyl-ethanol (2), 2-O-ß-d-glucopyranosyl-(1S)-phenylethylene glycol (3), 2-O-ß-d-glucopyranosyl-(1R)-phenylethylene glycol (4), (Z)-p-coumaryl-O-ß-d-glucopyranoside (5), phenyl-O-ß-d-glucopyranoside (6), 2-phenylethyl-O-ß-d-glucopyranoside (7), salidroside (8), 2-(2-hydroxyphenyl)ethanol-O-ß-d-glucopyranoside (9), 4-methoxybenzyl-O-ß-d-glucopyranoside (10), 2,4,6-trimethoxyphenyl-1-O-ß-d-glucopyranoside (11) and sachaliside 1 (12). The structures of 1 and 2, including absolute configurations, were determined by spectroscopic data (1H NMR, 13C NMR, HSQC, HMBC and ORD) and chemical methods. In addition, most of them exhibited inhibitory activity with IC50 values ranging from 14.43 to 50.20 µM in comparison to the positive control acarbose (IC50 = 15.76 µM) in intestinal α-glucosidase inhibitory activity tests.

Insecticidal and α-glucosidase inhibitory activities of chemical constituents from Viburnum fordiae Hance.

The ethanolic extract of the stems of Viburnum fordiae Hance showed insecticidal and α-glucosidase inhibitory activities and then was fractionated by bioactivity-guided fractionation to obtain a rare C13-norisoprenoid (1), together with a new phenolic glycoside (2), and seven known compounds, alangionoside C (3), pisumionoside (4), koaburaside (5), 3,5-dimethoxy-benzyl alcohol 4-O-ß-d-glucopyranoside (6), 3,4,5-trimethoxybenzyl-ß-d-glucopyranoside (7), arbutin (8), and salidroside (9). The previously undescribed compounds were elucidated as (3R,9R)-3-hydroxy-7,8-didehydro-ß-ionyl 9-O-α-d-arabinopyranosyl-(1→6)-ß-d-glucopyranoside (1) and 2-(4-O-ß-d-glucopyranosyl)syringylpropane-1,3-diol (2) by spectroscopic data (1H and 13C NMR, HSQC, HMBC, 1H-1H COSY, HSQC-TOCSY, HRESIMS, IR and ORD) and chemical methods. Compound 1 showed potent insecticidal effect against Mythimna separata with LD50 value of 140 µg g-1. Compounds 2, 5, 6, 8 and 9 showed varying α-glucosidase inhibitory activity with IC50 values ranging from 148.2 to 230.9 µM.

Chemical constituents and biological activities of Viburnum macrocephalum f. keteleeri.

Three new compounds (1-3) and seven known compounds (4-10) have been isolated from the ethanolic extract of Viburnum macrocephalum f. keteleeri using bioactivity-guided fractionation and identified as methyl (2-α-L-rhamnopyranosyloxy)acetate (1), methyl (2R-3-α-L-rhamnopyranosyloxy)glycerate (2), methyl (3R-4-α-L-rhamnopyranosyloxy-3-hydroxy)butanoate (3), bridelionoside B (4), (6S,7E,9R)-roseoside (5), linarionoside A (6), 3,7,11-trimethyl-1,6-dodecadien-3,10,11-triol (7), (+)-8-hydroxylinalool (8), ß-sitosterol (9) and daucosterol (10). The structures of 1-3, including absolute configurations, were determined by spectroscopic data (1H and 13C NMR, HSQC, HMBC and ORD) and chemical methods. In addition, compounds 1-8 were assayed for their insecticidal and antimicrobial activities. Compounds 7 and 8 exhibited moderately insecticidal effects against Mythimna separata with LD50 values of 180 and 230 µg g-1, respectively. Compounds 2, 3, 7 and 8 showed varying antimicrobial activities with IC50 values ranging from 125 to 529 µM.

Two new compounds from Helichrysum arenarium (L.).

Two new compounds were isolated from the whole plant of Helichrysum arenarium (L.) Moench. By means of spectroscopic data (IR, UV, 1D and 2D NMR, HR-MS, ESI-MS, and NOESY) and chemical evidence, the structures were established as 6,7-dimethoxy-4-hydroxy-1-naphthoic acid (1) and (Z)-5-hydroxy-7-methoxy-4-[3-methyl-4-(O-beta-D-xylopyranosyl)but-2-enyl]isobenzofuran-1(3H)-one (2).

New flavonoid glycosides and cyanogenic glycosides from Dracocephalum peregrinum.

Separation of ethyl acetate fractionation of Dracocephalum peregrinum afforded three new flavonoid glucosides (1-3), and a new cyanogenic glucoside (4). Their structures were elucidated based on HR-electron spray ionization (ESI)-MS, EI-MS, UV, IR, 1D-, and 2D-NMR data. 1-4 were tested in vitro for their antiinflammatory activity against the RAW 264.7, 293 cells. Among the compounds tested, 1-4 shown good antiinflammatory activity at 100 mug/ml by the measurement of nitric oxide (NO) in lipopolysaccharide (LPS) activated macrophages. But only 2 and 3 shown weak antiinflammatory activity at 100 mug/ml during the nuclear factor (NF)-kappaB activation assay.

A new ferulic acid ester and other constituents from Dracocephalum peregrinum.

A new ferulic acid ester, 1'-methyl-2'-hydroxyethyl ferulate (1), together with methylcaffeate (2), 4-hydroxy cinnamic acid (3), ferulic acid (4), caffeic acid (5), diosmetin (6), luteolin (7), 5,3',4'-trihydroxy-3,7-dimethoxyflavone (8), eriodictyol (9), kaempferol (10), quercetin (11), acacetin-7-O-glcopyranoside (12), 4-(beta-glucopyranosyloxy) benzoic acid (13), luteolin-7-O-(6''-feruloyl) glucopyranoside (14), luteolin-7-O-glucopyranoside (15), kaempferide-3-O-rhamnopyranoside (16), quercitrin (17), kaempferol-3-O-glucopyranoside (18), prunasin (19), quercetin-7-O-glucopyranoside (20), quercetin-3-O-glucopyranoside (21), plantaginin (22), linarin (23), luteolin-7-O-rutinoside (24), and chlorogenic acid (25) were isolated from the aerial parts of Dacocephalum peregrinum. The structure of 1 was elucidated on the basis of spectroscopic and HR-ESI-MS analyses. In addition, compound 1 exhibited mild inhibitory effect on NO production in LPS-stimulated RAW264.7 cells.

Pregnane glycosides and steroid saponins from Smilax bockii Warb. and their NGF-potentiating activity.

The chemical constituents of the roots of Smilax bockii Warb. were investigated and two pregnane glycosides and three steroid saponins were isolated. Their structures were established as 3beta-hydroxypregna-5,16-dien-20-one-3-O-alpha-L-rhamnopyranosyl(1 --> 4)-alpha-L-rhamnopyranosyl(1 --> 4)-[alpha-L-rhamnopyranosyl(1 --> 2)]-beta-D-glucopyranoside (1), 3beta-hydroxypregna-5,16-dien-20-one-3-O-alpha-L-rhamnopyranosyl(1 --> 2)-[alpha-L-rhamnopyranosyl(1 --> 4)]-beta-D-glucopyranoside (2), dioscin (3), methyl protodioscin (4), 26-O-beta-D-glucopyranosyl-22alpha-methoxyl-(25R)-furost-5-en-3beta, 26-diol 3-O-alpha-L-rhamnopyranosyl(1 --> 4)-alpha-L-rhamnopyranosyl(1 --> 4)-[alpha-L-rhamnopyranosyl(1 --> 2)]-beta-D-glucopyranoside (5) on the basis of spectral analysis and chemical methods. Compound 1 is a new natural product and compounds 2, 5 were first isolated from the genus Smilax. Compound 5 showed enhancing activity of nerve growth factor (NGF)-induced neurite outgrowth in PC 12D cells.

Flavonoids from Galium verum L.

Two new flavonoids, compounds 1 and 2, together with seven known flavonoids, were isolated from Galium verum L. Their structures were elucidated as diosmetin 7-O-alpha-l-rhamnopyranosyl-(1-2)-[beta-d-xylopyranosyl-(1-6)]-beta-d-glucopyranoside (1) and 3,5,7,3',4',3'',5'',7'',3''',4'''-decahydroxyl-[8-CH(2)-8'']-biflavone (2) by chemical methods and spectroscopic analyses. Compounds 3 and 4 were isolated from the genus Galium for the first time.

Two new anthraquinones from Hedyotis diffusa W.

Two new anthraquinones, 2,6-dihydroxy-3-methyl-4-methoxyanthraquinone (1) and 2-hydroxy-7-hydroxymethyl-3-methoxyanthraquinone (2), were isolated from Hedyotis diffusa W. Their structures were elucidated by means of spectroscopic evidence.

A new cerebroside from fruits of Ailanthus altissima Swingle.

A new cerebroside and three known cycloartan triterpenes were isolated from fruits of Ailanthus altissima Swingle. Their structures were identified as 1-O-beta-D-glucopyranosyl-(2S, 3R, 4E, 9E)-2-(2'R-hydroxyhexadecenoy)-4, 9-octadecadiene-1, 3-diol (1), 9, 19-cyclolanost-23 (Z)-ene-3beta, 25-diol (2), cycloart-25-ene-3beta, 24R-diol (3), and cycloart-25-ene-3beta, 24S-diol (4) by means of chemical and spectroscopic analysis. Compounds 2, 3, and 4 were isolated from genus Ailanthus for the first time. The analgesic activity of 1 was also evaluated.

A new anthraquinone from Galium verum L.

A new anthraquinone (4) and three known anthraquinones (1-3) were isolated from Galium verum L. Their structures were identified as 1,3-dihydroxy-2-methylanthraquinone (1), physcion (2), 2-hydroxy-1,3-dimethoxyanthraquinone (3), 2,5-dihydroxy-1,3-dimethoxyanthraquinone (4) by means of chemical and spectroscopic analysis. Compound 2 was isolated from the genus Galium for the first time. In addition, compound 4 was assayed for antimicrobial activity in vitro.

Antimicrobial constituents from fruits of Ailanthus altissima SWINGLE.

A new naturally occurring sterol, compound 5, and six known stigmasterols were isolated from fruits of Ailanthus altissima Swingle by repeated column chromatography and RP-HPLC. Their structures were identified as, 5alpha-stigmastane-3,6-dione (1), 3beta-hydroxystigmast-5-en-7-one (2), stigmast-5-ene-3beta, 7alpha-diol (3), 6alpha-hydroxystigmast-4-en-3-one (4), 5alpha-stigmastane-3beta, 6beta-diol (5), stigmast-4-ene-3beta, 6alpha-diol (6), stigmast-5-ene-3beta, 7alpha, 20xi-triol (7) by spectral analysis and comparison with the published data. These compounds have not been reported from genus Ailanthus, whereas compound 7 was identified by NMR for the first time. In addition, the 95% ethanol extract and compounds from the fruits of Ailanthus altissima SWINGLE were assayed for in vitro antimicrobial activity. The extract was potent active against the assayed bacteria while compounds 3 and 7 exhibited moderate activity.