From the moss Erythrodontium julaceum Paris growing in Vietnam, julacelide (1), a new 3‐benzylphthalide, along with methyl orsellinate (2), ethyl orsellinate (3), 4‐O‐methylhaematommic acid (4), and ...zeorin (5), were isolated and structurally elucidated. Their chemical structures were elucidated through extensive 1D and 2D NMR analysis and high‐resolution mass spectroscopy as well as through comparisons to the existing literature. Compound 4‐O‐methylhaematommic acid was a new natural product. The absolute configuration of julacelide was defined using time‐dependent density functional theory (TDDFT) calculations. Julacelide was evaluated for α‐glucosidase inhibition.
A new natural Diels‐Alder adduct (3) was isolated from the leaves and stem bark of Artocarpus integer, along with seventeen known compounds (1, 2, and 4–18). Structural elucidation was conducted ...using NMR and HR‐ESI‐MS data, and comparisons were made with previous studies. Deoxyartonin I (3) exhibited the most potent α‐glucosidase inhibition (IC50 7.80±0.1 μM), outperforming the acarbose positive control. This was mixed‐mode inhibition, as indicated by the intersect in the second quadrant of each respective plot. An in silico molecular docking model and the pharmacokinetic features of 3 suggest that it is a potential inhibitor of enzyme α‐glucosidase, and is therefore a lead candidate as a drug against diabetes mellitus.
In continuation of our search for bioactive compounds from the
(
) plant, we describe herein eight flavonoid-type compounds including mearsetin (1), mearnsitrin (2), kampferol (3), afzelin (4), ...quercetin (5), quercitrin (6), myricitin (7), and naringenin (8) with the aim of investigating their antidiabetic properties. Compounds 3 and 5 were selected for aromatic bromination to provide two new products 3a and 5a, respectively. All compounds showed promising α-glucosidase inhibition, with IC
values ranging from 9.2 to 266 μM apart from compound (2). Remarkably, compound 5a, 8-bromoquercetin, showed the highest inhibition activity, and it was thirty-seven times better than the standard drug acarbose. Pose 261/compound 5a interacted well with enzyme 3TOP
docking, and the complex of pose 261 and target enzyme proved its stability in MD. Compound 5a, pose 261 was predicted to be safe and seemed to have good absorption, distribution, metabolism, and excretion properties as assessed
the ADMET model
. Our findings revealed the α-glucosidase inhibitory potential of the flavonoids isolated from the leaves of
with a predictive pharmacokinetics profile, which may be helpful in their development as potential drugs.
Tecoma stans is a tropical plant that is widely used in folk medicine. Little is known about the chemical constituents of flowers of this plant. From flowers of the native plant in Vietnam, 12 ...compounds were isolated and elucidated, including one new compound tecomastane (1) and eleven known compounds, (3S,5R,6S,7E)-5,6-epoxy-3-hydroxy-7-megastigmane-9-one (2), bosciallin (3), chakyunglupulin B (4), (2S,6R)-2,6-dimethyloctane-1,8-diol (5), cleroindicin F (6), rengyoxide (7), 3,4-dihydroxybenzoic acid (8), methyl 3,4-dihydrobenzoate (9), 3,5-dihydroxybenzoic acid (10), luteolin (11), and indole-3-carboxylic acid (12). Compound 5 was a new natural product. The chemical structures of isolated compounds were identified by interpretation of their spectroscopic data (1D, 2D NMR, and HRESIMS) and by comparison with the literature. Compounds 1-7 and 10-12 were evaluated for alpha-glucosidase inhibition and antimicrobial activity against antibiotic-resistant, pathogenic bacteria Enterococcus faecium, Staphylococcus aureus, and Acinetobacter baumannii.
Bio-guided isolation was applied to Vietnamese
L. to find alpha-glucosidase inhibition. Fifteen compounds were isolated and structurally determined, including two new compounds, marchatoside (7) and ...marchanol (8), along with thirteen known compounds: marchantin A (1), isoriccardin C (2), riccardin C (3), marchantin K (4), lunularin (5), 3
-(3,4-dimethoxybenzyl)-5,7-dimethoxyphthalide (6), vitexilactone (9), 12-oleanene-3-one (10), 3,11-dioxoursolic acid (11), ursolic acid (12), artemetin (13), kaempferol (14), and quercetin (15). The structures of these compounds were determined through extensive spectroscopic analyses (1D and 2D NMR, HRESIMS, and ECD) and by comparisons to the existing literature. There are five types of carbon skeleton, including bibenzyl (1-5), 3-benzylphthalide (6 and 7), diterpenoid (8 and 9), triterpenoid (10-12), and flavonoid (13-15). Compounds 6-12 were reported for the first time within the genus
. Compounds 1-12 were evaluated for their alpha-glucosidase inhibition. Among them, 1-5 and 10-12 displayed potent inhibition, with IC
values ranging from 28.9 to 130.6 μM, compared to the positive control acarbose 330.9 μM. A kinetic study and molecular docking were also performed to understand the mechanism.
Sphaeranthus africanus L. is native in Vietnam. Little is known about α‐glucosidase inhibition of Sphaeranthus africanus and its isolated compounds. A bioactive‐guided isolation was applied to the ...Vietnamese Sphaeranthus africanus to find α‐glucosidase inhibitory components. Eight compounds were detected and structurally elucidated. They are 3‐angeloyloxy‐5‐2′′,3′′‐epoxy‐2′′‐methylbutanoyloxy‐7‐hydroxycarvotacetone, 3‐angeloyloxy‐5‐3′′‐chloro‐2′′‐hydroxy‐2′′‐methylbutanoyloxy‐7‐hydroxycarvotacetone, 3‐angeloyloxy‐5‐2′′R,3′′R‐dihydroxy‐2′′‐methyl‐butanoyloxy‐7‐hydroxycarvotacetone, 3‐angeloyloxy‐5‐2′′S,3′′R‐dihydroxy‐2′′‐methylbutanoyloxy‐7‐hydroxycarvotacetone, 3‐angeloyloxy‐5‐2′′S,3′′S‐dihydroxy‐2′′‐methylbutanoyloxy‐7‐hydroxycarvotacetone, 5‐angeloyloxy‐7‐hydroxy‐3‐tigloyloxycarvotacetone, 3‐O‐methylquercetin, and chrysosplenol D. Their chemical structures were elucidated by extensive 1D and 2D NMR analysis and high‐resolution mass spectroscopy as well as comparisons in literature. 3‐Angeloyloxy‐5‐2′′S,3′′S‐dihydroxy‐2′′‐methylbutanoyloxy‐7‐hydroxycarvotacetone is a new compound. Isolated compounds were evaluated for the α‐glucosidase inhibition. Isolated compounds showed moderate activity with IC50 values ranging from 128.9–274.3 μM while others are weak. A molecular docking study was conducted, indicating that isolated compounds are potent α‐glucosidase inhibitory compounds.
The chemical investigation of the stems of Knema globularia led to the isolation of two new benzoquinones derivatives, embenones A and B (1 and 2), along with three known compounds (3–5). The ...structures of the isolated compounds were determined using spectroscopic techniques, including HRESIMS, 1D and 2D NMR, in conjunction with comparison to existing literature data. Compounds 1 and 2 represent new carbon skeletons in nature. Furthermore, all isolated compounds were evaluated for their α‐glucosidase inhibitory activity, with compounds 1–3 exhibiting superior potency relative to the positive control (acarbose, IC50 331 μM). Their IC50 values ranged from 1.40 to 96.1 μM.
Leaves of Combretum quadrangulare Kurz showed potent α‐glucosidase inhibition. Two new cycloartane‐type triterpenes, combretic acids D and E were isolated from the bioactive fraction. The chemical ...structures were determined using NMR and MS methods. Combretic acid D represents for the first cycloartane having a dihydrofuran ring in the side chain. Combretic acids D and E showed significant α‐glucosidase inhibition, with IC50 values of 13.9 and 30.7 μM, respectively. Combretic acid D was determined to be a non‐competitive type in the kinetic study. The docking study in combination with dynamic simulations of this compound provided the molecular understanding of α‐glucosidase inhibition.
Chemical investigation of the lichen Parmotrema tinctorum (Nyl.) Hale led to the isolation of two new phenolic compounds, 2-ethylhexyl orsellinate (1) and tinctorinone (2). The structures were ...determined by analysis of their MS and NMR data as well as by comparison with literature data. The 2-ethylhexyl ester group of 2-ethylhexyl orsellinate is uncommon among lichen metabolites. Tinctorinone revealed strong inhibition towards α-glucosidase.
Two new cycloartanes, combretic acid C (1) and combretanone I (3), were isolated from the leaves of Combretum quadrangulare Kurz, together with the previously-reported combretic acids A-B (2 and 5) ...and combretanone A (4). An extensive set of spectroscopic methods were used to elucidate the structures of these compounds. Cytotoxicity against the K562 cancer cell line was evaluated. Compound 1 showed strong activity, with an IC
50
value of 9.7 µM. The other compounds showed moderate activity. Alpha-glucosidase inhibition was also evaluated. The isolated compounds showed moderate inhibition, with IC
50
values in the range 102.2-194.7 µM.
