Alpha-glucosidase inhibitory compounds from Vietnamese lichen : and aspects.

Using a bio-guided isolation on the Vietnamese lichen based on alpha-glucosidase inhibition, eleven compounds were isolated and structurally elucidated, namely, protocetraric acid (1), 8'-methylstictic acid (2), stictic acid (3), 4,6-diformyl-8-hydroxy-3-methoxy-1,9-dimethyl-11-oxo-11-dibenzo[,][1,4]dioxepine-7-carboxylic acid (4), vicanicin (5), norstictic acid (6), diffractaic acid (7), barbatic acid (8), atranol (9), 5-chlorohaematommic acid (10), and eumitrin A1 (11). Their chemical structures were identified by extensive 1D and 2D NMR analysis and high-resolution mass spectroscopy and compared with those reported in literature. Protocetraric acid (1) and norstictic acid (6) were selected for further modification to derive new compounds, namely, 1a-1e and 6a.

Chemical constituents with their alpha-glucosidase inhibitory activity from the whole plant of Ceratophyllum demersum.

From Ceratophyllum demersum growing in Vietnam, twelve compounds were isolated and structurally elucidated, including six previously undescribed compounds, demersones A-D (1-4), acetylvelutins A and B (8 and 9), together with six known compounds, (+)-cyclocolorenone (5), 1-hydroxycyclocolorenone (6), 10-hydroxycyclocolorenone (7), retusin (10), betulinic acid (11), and lupeol (12). The chemical structures and stereochemistry of 1-12 were identified through analysis of spectroscopic data (1D and 2D NMR and HRESIMS), ECD data, and DFT calculation. Notably, this is the first time that humulene-type (1 and 2), guaiane-type (3), and aromadendrane-type (4-7) sesquiterpenoids have been reported in this genus.

A new diphenyl ether from the cultured lichen mycobiont of cf. .

Lichen is well-known for its various purposes. However, understanding the chemical composition and antimicrobial characteristics of cf. remains insufficient.

Two New Benzoquinone Derivatives from Vietnamese Knema globularia Stems.

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.

Diphenyl ethers from the cultured lichen mycobiont of Zahlbr.

Purpose: Cultured lichen mycobionts are valuable sources of new natural compounds. Mycobiont of growing in Vietnam was isolated, cultivated and chemically investigated. The crude extract of this cultured mycobiont showed potent alpha-glucosidase inhibition with an IC value of 50 μg/mL.

Enhancement of Visible Light Antibacterial Activities of Cellulose Fibers from Lotus Petiole Decorated ZnO Nanoparticles.

Cellulose/ZnO (CZ) nanocomposites are promising antimicrobial materials known for their antibiotic-free nature, biocompatibility, and environmental friendliness. In this study, cellulose fibers extracted from lotus petioles were utilized as a substrate and decorated with various shapes of ZnO nanoparticles (NPs), including small bean, hexagonal ingot-like, long cylindrical, and hexagonal cylinder-shaped NPs. Increasing zinc salt molar concentration resulted in highly crystalline ZnO NPs forming and enhanced interactions between ZnO NPs and -OH groups of cellulose.

Antimicrobial sesquiterpenes from the cultured mycobiont against methicillin-resistant isolated from Vietnamese street foods.

Traditionally, lichen has been used for many purposes, but there remains a lack of understanding regarding the chemical composition and antimicrobial characteristics of , a lichen native to Vietnam. In this study, four sesquiterpenes, diorygmones B-E (1-4), one phenolic compound, 3,5-dihydroxy-4-methoxybenzoic acid (5), and one sterol, β-sitosterol (6), were isolated and structurally elucidated from the cultured mycobiont of the lichen . Additionally, two compounds, stictic acid (7) and norstictic acid (8), were also isolated from the lichen Compounds 2-4 were new compounds.

Bio-guided isolation of alpha-glucosidase inhibitory compounds from Vietnamese liverwort : and studies.

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).

Bio-guided isolation of alpha-glucosidase inhibitory compounds from Vietnamese fruits: and studies.

is an edible tree widely distributed in the southern region of Vietnam. Little is known about the alpha-glucosidase inhibition of the Vietnamese . The aim of the current study was to explore the anti-diabetic potential of fruits.

A New 3-Benzylphthalide from the Moss Erythrodontium julaceum.

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.

New Halogenated Flavonoids from Adenosma bracteosum and Vitex negundo and Their α-Glucosidase Inhibition.

Adenosma bracteosum and Vitex negundo are natural sources of methoxylated flavonoids. Little is known about the α-glucosidase inhibition of multi-methoxylated flavonoid derivatives. Eighteen natural flavonoids were isolated from A.

Examining financial distress of the Vietnamese listed firms using accounting-based models.

Financial distress is generally considered the most severe consequence for firms with poor financial performance. The emergence of the Covid-19 pandemic has adversely impacted the global business system and exacerbated the number of financially distressed firms in many countries. Only firms with strong financial fundamentals can survive extreme events such as the Covid-19 pandemic and the ongoing Russia-Ukraine conflict.

A New Carvotacetone Derivative from the Aerial Part of Sphaeranthus africanus.

Sphaeranthus africanus L. is native in Vietnam. Little is known about α-glucosidase inhibition of Sphaeranthus africanus and its isolated compounds.

Risk assessment of 3-MCPD esters and glycidyl esters from the formulas for infants and young children up to 36 months of age.

Esters of 2-monochloropropane-1,2-diol (2-MCPD), 3- monochloropropane-1,2-diol (3-MCPD), and glycidol are present in infant formulas, follow-on foods and similar compositions. They arise mainly from the vegetable oil content and may cause harmful effects in consumers. The contents of these substances in formulas were determined indirectly by converting the esters to the free form, followed by derivatization and analysis by gas chromatography-tandem mass spectrometry (GC-MS/MS).

Parmoferone A, a new depsidone from the lichen .

A new depsidone, parmoferone A (), together with three known compounds, parmosidone K (), albifolione (), and 4-chloroorcinol () were isolated from the lichen (Taylor) Hale (Parmeliaceae). The structures of isolated compounds were identified from its spectroscopic data and by comparison with the literature. Compounds were evaluated for alpha-glucosidase inhibition.

Sphaeranthone A, a new carvotacetone from the leaves of .

A new carvotacetone sphaeranthone A and four known compounds 3-angeloyloxy-5-[2″,3″-epoxy-2″-methylbutanoyloxy]-7-hydroxycarvotacetone (), 3-angeloyloxy-5-[3″-chloro-2″-hydroxy-2″-methylbutanoyloxy]-7-hydroxycarvotacetone (), chrysosplenol D (), and 3--methylquercetin () were isolated from leaves of growing in Vietnam. Their chemical structures were elucidated by extensive 1D and 2D NMR analysis and high-resolution mass spectroscopy as well as comparisons in literature. Compounds were evaluated for the alpha-glucosidase inhibition.

α-Glucosidase inhibitory activities of flavonoid derivatives isolated from : and studies.

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.

Two New α-Glucosidase Inhibitory Depsidones from the Lichen Parmotrema cristiferum (Taylor) Hale.

A bioactivity-guided investigation of the lichen Parmotrema cristiferum (Taylor) Hale (Parmeliaceae) led to the isolation of two new depsidones, cristifones A and B (1 and 2). The structures of the isolated compounds were identified by spectroscopic methods and comparison with the literature data. Compound 1 showed the initial combined structures of depsidone and depside cores.

Diorygmones A-B, two new guaiane-sesquiterpenes from the cultured lichen mycobiont of .

is a native crustose-lichen in Vietnam. A mycobiont of this lichen was isolated, then cultivated. The present study described the isolation and structural elucidation of two new guaiane-type sesquiterpenes, namely diorygmones A-B.

Enhancement of antibacterial activities of green synthesized-CuO/ZnO nanocomposites using Boehmeria nivea leaf extract.

This study investigated CuO and ZnO nanoparticles and CuO/ZnO nanocomposites in a friendly environment with a low-cost and renewable biosynthesis method. This approach involved using Boehmeria nivea leaf extract to facilitate the growth and formation of nanocomposites with performance-enhancing phytochemicals released during the co-precipitation process. All nanoparticles/nanocomposites explored the microstructure, morphology, and point defects using FTIR, XRD, SEM, and PL characterization techniques.

α-Glucosidase inhibitory derivatives of protocetraric acid.

Lichen-derived depsidones have been a successful source for alpha-glucosidase inhibitory agents with numerous advantages. In this article, derivatives of protocetraric acids were designed and synthesised. Diels-Alder reaction, esterification, and Friedel-Crafts alkylation of protocetraric acid with different reagents under Lewis acid were performed.

α-Glucosidase Inhibitory Cycloartanes from the Vietnamese Combretum quadrangulare.

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.

Tecomastane, a new megastigmane from the flowers of .

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 () and eleven known compounds, (3,5,6,7)-5,6-epoxy-3-hydroxy-7-megastigmane-9-one (), bosciallin (), chakyunglupulin B (), (2,6)-2,6-dimethyloctane-1,8-diol (), cleroindicin F (), rengyoxide (), 3,4-dihydroxybenzoic acid (), methyl 3,4-dihydrobenzoate (), 3,5-dihydroxybenzoic acid (), luteolin (), and indole-3-carboxylic acid ().

Two new phenolic compounds from collected in Vietnam.

is a tropical plant that is widely used in Asian folk medicine. Little is known about the alpha-glucosidase inhibition and antimicrobial properties of compounds from this plant. In the present study, the phytochemical study of the aerial parts of collected in Vietnam was conducted using multiple chromatographic methods.