New bisbibenzyl and phenanthrene derivatives from Dendrobium scabrilingue and their α-glucosidase inhibitory activity

Abstract

Phytochemical investigation of the whole plant of Dendrobium scabrilingue resulted in the isolation of two new compounds namely dendroscabrols A (1) and B (2), along with eight known compounds (3–10). The structures of these compounds were determined by NMR and HR-ESI-MS experiments. All of the isolates were evaluated for their α-glucosidase inhibitory effect. Dendroscabrol B (2) and RF-3192C (10) showed the most potent α-glucosidase inhibitory activity. Dendroscabrol A (1), gigantol (5), coelonin (7) and lusianthridin (9) also exhibited strong activity as compared with the positive control acarbose.     

New 2-arylbenzofurans from the root bark of Artocarpus gomezianus and their α-glucosidase inhibitory activity

Two new 2-arylbenzofurans, namely 13-O-methyllakoochin B (1) and artogomezianin (2), were isolated from the root bark of Artocarpus gomezianus, along with six known compounds (3–8). The structures of new compounds were determined by spectroscopic and chemical methods. All of the isolates were evaluated for their α-glucosidase inhibitory activity. Artogomezianin (2) and lakoochin A (3) exhibited strong α-glucosidase inhibitory activity with IC₅₀ values of 18.25 and 26.19 µM, respectively, as compared with the positive control acarbose.     

A new flavone glucoside together with known ellagitannins and flavones with anti-diabetic and anti-obesity activities from the flowers of pomegranate (Punica granatum)

A new flavone glucoside tricetin 4′-O-β-glucopyranoside (1) and four known ellagitannins and flavones tricetin (2), luteolin (3), ellagic acid (4), and granatin B (5) were isolated from the flowers of Punica granatum L. (Lythraceae). Their structures were established by 1D and 2D NMR as well as mass spectrometry analyses. Among all tested compounds, tricetin (2) exhibited the strongest α-glucosidase inhibitory activity that was comparable to the anti-diabetic drug acarbose. Comparative structure-function analysis of tri-, tetra-, and pentahydroxy flavones [apigenin, luteolin (3), and tricetin (2), respectively] suggested that a greater number of hydroxyl groups on the flavone molecule enhanced its suppression of α-glucosidase, α-amylase, and lipase activities.     

Phenolic compounds isolated from Morus nigra and their α-glucosidase inhibitory activities

Abstract

A novel benzofuranone unprecedentedly with a prenyl group at C-3, nigranol A (1), a new flavonol, nigranol B (2), and three known compounds, sanggenon M (3), nigrasin C (4), and nigrasin A (5) were isolated from the twigs of Morus nigra Linn. Their structures were elucidated on the basis of the analysis of multiple spectroscopic data. All of the compounds, along with eight previously isolated ones (6–13) were investigated for their α-glucosidase inhibitory activities. The result showed that compounds 1–13 except 4 exhibited prominent inhibitory activities against α-glucosidase. Among them, compounds 2 and 7 were the best α-glucosidase inhibitory candidates with IC₅₀ values at 1.63 and 1.43?μM, respectively. Furthermore, the structure-activity relationships of the sanggenon-type flavanones were summarized.     

A new aldehyde compound from the fruit of Pandanus tectorius Parkinson ex Du Roi

From the fruit of Pandanus tectorius Parkinson ex Du Roi, one new (1) and six known aldehyde compounds (2–7) were isolated by various chromatography methods. Based on their spectroscopic data, these compounds were identified as (Z)-4-hydroxy-3-(4-hydroxy-3-methylbut-2-en-1-yl) benzaldehyde (1), p-hydroxybenzaldehyde (2), syringaldehyde (3), (E)-ferulaldehyde (4), (E)-sinapinaldehyde (5), vanillin (6) and 5-hydroxymethylfurfual (7). The α-glucosidase inhibitory activity of all compounds was measured. The isolated compounds (1–6) showed better α-glucosidase inhibitory activity (IC₅₀ values ranging from 36.5 to 192.4 μM) than the standard drug acarbose (IC₅₀ = 214.5 μM).     

Two novel compounds from the root bark of Morus alba L.

Chemical investigation of the root bark of Morus alba led to the isolation of a new flavone, dioxycudraflavone A (1) and a new 2-arylbenzofuran, 5-hydroxyethyl moracin M (2), together with seven known compounds namely sanggenon V (3), morusin (4), morusignin L (5), licoflavone C (6), moracin C (7), alfafuran (8) and mulberrofuran G (9). The structure elucidation of these compounds was based on analyses of spectroscopic data including 1D, 2D NMR and HR-ESI-MS. All compounds were evaluated for the α-glucosidase inhibitory and cytotoxic activities. Compounds 2–4, 8 and 9 exhibited strong α-glucosidase inhibitory activities with IC₅₀ less than 10 μM, while only 4 and 9 showed moderate cytotoxic effects against lung cancer cells.     

Heptyl vicianoside and methyl caramboside from sour star fruit

Two new alkyl glycosides, heptyl vicianoside (1) and methyl 2-O-β-d-fucopyranosyl-α-l-arabinofuranoside (methyl caramboside, 4), were isolated from the sour fruit of Averrhoa carambola L. (Oxalidaceae), along with octyl vicianoside (2), cis-3-hexenyl rutinoside (3), and methyl α-d-fructofuranoside (5). Their structures were determined by spectroscopic and chemical methods. Compounds 2, 3, and 5 were obtained from the genus Averrhoa for the first time. All the compounds were evaluated for in vitro α-glucosidase, pancreatic lipase, and acetylcholinesterase inhibitory activities, but none of them were potent.     

Alpha-glucosidase inhibitory activity of ethanol extract,fractions and purified compounds from the wood of Albizia myriophylla

Albizia myriophylla Benth. is a medicinal herb which is used as a traditional remedy for various ailments including diabetes in Thailand. In our continued investigation of the biological activity of A. myriophylla, the ethanol extract, fractions and the isolated compounds from the wood of this plant were evaluated for in vitro α-glucosidase inhibition using spectrophotometric method. The plant ethanol extract and its different fractions possessed α-glucosidase inhibitory activity in a concentration-dependent manner. Dichloromethane fraction of the wood ethanol extract exhibited the highest percent inhibition against α-glucosidase (69.30%) among all fractions. Subsequent α-glucosidase inhibition assay proved that indenoic acid (1), 8-methoxy-7, 3′,4′-trihydroxyflavone (2) and 3,4,7,3′-tetrahydroxyflavan (3) were partially rational for antidiabetic effect of this plant species. Among these compounds, 3 (IC₅₀ 98.59 μg/mL) exhibited potent inhibition of α-glucosidase, compared with a positive control acarbose (IC₅₀ 125 μg/mL). The inhibitory effect towards α-glucosidase of compounds 1–3 was reported herein for the first time.     

New onoceranoid xyloside from Lansium parasiticum

A novel onoceranoid triterpene xyloside named methyl lansioside C (1) together with two known glycosides (2 and 3) were isolated from polar fraction of the fruit peels of Lansium parasiticum. The structure and absolute configuration of the new compound were established using extensive spectroscopic techniques as well as Mosher’s method. The antioxidant activity and α-glucosidase inhibitory effect of the isolated compounds were evaluated. Compounds 1 and 3 displayed moderate radical scavenging activity with SC₅₀ values of 14.5 and 13.7?mM, respectively. However, all isolated compounds exhibited no inhibition against α-glucosidase.     

含肉桂酰胺类化合物的合成及α-糖苷酶抑制活性

合成了4个未见报道的含肉桂酰胺类化合物9a～9b, 初步评价了它们的α-糖苷酶抑制活性. 这些化合物均具有α-糖苷酶抑制活性, 是一类结构新颖的α-糖苷酶抑制活性化合物, 其中, 化合物9b和9c的活性高于阳性对照药物阿卡波糖.     

A new phenanthrene and a new 9,10-dihydrophenanthren from Bulbophyllum retusiusculum

A new phenanthrene, bobulretin A (1), and a new 9,10-dihydrophenanthrene, bobulretin B (2) along with four known bibenzyls (3–6) were isolated from the whole plants of Bulbophyllum retusiusculum. Their structures were elucidated by means of extensive spectroscopic analysis. Bobulretin B (2), isolated as enantiomer mixture with unequal proportions, was verified by analysis on a chiral OD-H HPLC column. Compounds 1, 3 and 4 were evaluated for their α-glucosidase inhibitory activity. Neither of them showed obvious activity.     

A new triterpenoid glucoside from Leucas zeylanica

Abstract

A new triterpenoid glucoside, leuctriterpencoside (1), along with two known compounds (2–3) were isolated from Leucas zeylanica. The structure of the new compound was elucidated using comprehensive spectroscopic methods. Compound 1 showed significant inhibitory activity against α-glucosidase (IC₅₀ value of 0.85?±?0.12?μM).     

New C20-gibberellin diterpene from the leaves of Schefflera sessiliflora De P. V.

From the leaves of Schefflera sessiliflora De P. V., one new C₂₀-gibberellin diterpene 2β,12β-dihydroxygibberellin (12β-hydroxy-GA₁₁₀ or 2β-hydroxy-GA₁₁₂) (1), together with three known compounds, trans-tiliroside (2), kaempferol 3-O-β-d-glucuronopyranoside (3), 5-p-trans-coumaroylquinic acid (4), was isolated for the first time from the genus Schefflera by various chromatography methods. Their structures were elucidated by IR, UV, HR-ESI-MS, NMR 1D and 2D experiments and comparison with previous reported data. The α-glucosidase inhibitory activity of all compounds was measured. The isolates (2, 3) showed better α-glucosidase inhibitory activity (IC₅₀ = 134.60, 147.10 μM, respectively) than the standard drug acarbose (IC₅₀ = 214.50 μM).     

A new megastigmane sulphoglycoside and polyphenolic constituents from pericarps of Garcinia mangostana

A megastigmane sulphoglycoside together with three phenolic compounds were isolated from the water-soluble fraction of the pericarps of Garcinia mangostana. The structure of the new compound was determined as 4-O-sulpho-β-d-glucopyranosyl abscisate (1) by spectroscopic data. Proanthocyanidin A2 (2) showed potent α-glucosidase inhibitory and DPPH scavenging activities with IC₅₀ values of 3.46 and 11.6 μM, respectively.     

Cumin scented leaf essential oil of Cinnamomum chemungianum: compositions and their in vitro antioxidant, α-amylase, α-glucosidase and lipase inhibitory activities

As part of our work on prospecting of Cinnamomum of the Western Ghats, chemical compositions, antioxidant, α-amylase, α-glucosidase and lipase inhibitory activities of leaf essential oil (EO) of Cinnamomum chemungianum were evaluated. Chemical characterisation of the cumin scented leaf EO from five locations in the southern Western Ghats revealed that they were highly varied. EO from Kannikatti (CC²) exhibited good α-amylase inhibitory activity with IC₅₀ value of 5.97 μg/mL, whereas the EOs from Chemungi (CC¹) and Athirumala (CC⁵) showed better α-glucosidase inhibition with IC₅₀ of 56.65 and 62.12 μg/mL, respectively. The EOs from Chemungi, Kannikatti and Athirumala were found to inhibit lipase with IC₅₀ of 919.75, 923.17 and 838.46 μg/mL, respectively. The EO of C. chemungianum may be used in food products as it has cumin scent and mild inhibitory activities.     

Potent α-glucosidase inhibitory activity of compounds isolated from the leaf extracts of Uvaria hamiltonii

Abstract

The phytochemical investigation of the leaf extracts of Uvaria hamiltonii (Annonaceae) led to the isolation and identification of ten compounds including a new seco-cyclohexene (1) together with nine known compounds (2–10). Their structures were elucidated by intensive analysis by spectroscopic methods and comparisons of their spectroscopic data with those of compounds reported in the literature. Compounds 2, 8, and 9 showed potent α-glucosidase inhibitory activity with the IC₅₀ values ranging from 2.6–7.1?µM.     

A new dihydrofurocoumarin from the fruits of Pandanus tectorius Parkinson ex Du Roi

From the fruit of Pandanus tectorius Parkinson ex Du Roi, one new dihydrofurocoumarin, named pandanusin A (1) and 15 known compounds, including one furanocoumarin (2), two coumarins (3, 4), four lignans (5–8), one neolignan (9), two flavonoids (10, 11), three phenolics (12–14), one monoglyceride (15) and one monosaccharide (16) were isolated by various chromatography methods. Among them, compounds (3–5) were obtained from the Pandanus genus for the first time and compounds (9–14, 16) were reported from this species for the first time. Their structures were elucidated by HR–ESI–MS, NMR 1D and 2D experiments and comparison with previous reported data. The α-glucosidase inhibitory activity of all compounds was measured. The isolated compounds (1–12, 14) showed better α-glucosidase inhibitory activity (IC₅₀ = 42.2, 36.5, 84.7, 73.2, 40.8, 26.7, 76.5, 33.8, 68.1, 14.4, 22.1, 81.5, 43.8 μM, respectively) than the standard drug acarbose (IC₅₀ = 214.5 μM).     

Betulinic acid derivatives: a new class of α-glucosidase inhibitors and LPS-stimulated nitric oxide production inhibition on mouse macrophage RAW 264.7 cells

Chemical manipulation studies were conducted on betulinic acid (1), twenty-one new rationally designed analogues of 1 with modifications at C-28 were synthesized for their evaluation of inhibitory effects on α-glucosidase and LPS-stimulated nitric oxide production in mouse macrophage RAW 264.7 cells. Compound 2 (IC₅₀ = 5.4 μM) exhibited an almost 1.4-fold increase in α-glucosidase inhibitory activity on yeast α-glucosidase while analogues 5 (IC₅₀ 16.4 μM) and 11 (IC₅₀ 16.6 μM) exhibited a 2-fold enhanced inhibitory activity on NO-production than betulinic acid.     

Antioxidant and alpha-glucosidase inhibitory activities of isoflavonoids from the rhizomes of Ficus tikoua Bur

A new unique isoflavone derivatives with a cyclic-monoterpene-substituent, ficusin C (1), together with five known compounds (2–6), were isolated from the rhizomes of Ficus tikoua. Their structures were elucidated on the basis of spectroscopic data interpretation, mass spectrometric analysis and comparison with literature data of related compounds. Antioxidant and α-glucosidase inhibitory activities of these compounds were evaluated by 1,1-diphenyl-2-picryhydrazyl (DPPH) radical-scavenging assay and α-glucosidase inhibitory experiment, respectively.     

New α-glucosidase inhibiting anthracenone from the barks of Harungana madagascariensis Lam

Two new 10-hydroxy-9(10H)-anthracenone, madagascenone A (1) and B (2), were isolated from the barks of Harungana madagascariensis Lam. The structures of the compounds were determined using 1D- and 2D-NMR and mass spectroscopic techniques. Both of the compounds showed an in vitro α-glucosidase inhibition with IC₅₀ = 69.9 ± 4.21 and 122.3 ± 1.13 μM, respectively, more potent than the standard acarbose (IC₅₀ = 840 ± 1.23 μM).