Saccharomyces Cerevisiae Α-glucosidase Research Articles

Design, synthesis, and evaluation of novel substituted imidazo[1,2-c]quinazoline derivatives as potential α-glucosidase inhibitors with bioactivity and molecular docking insights.

α-Glucosidase inhibitors are important in the treatment of type 2 diabetes by regulating blood glucose levels and reducing carbohydrate absorption. The present study focuses on identifying new inhibitors bearing imidazo[1,2-c]quinazoline backbone through multi-step synthesis. The inhibitory potencies of the novel derivatives were tested against Saccharomyces cerevisiae α-glucosidase, revealing IC50 values ranging from 50.0 ± 0.12 µM to 268.25 ± 0.09 µM. Among them, 2-(4-(((2,3-diphenylimidazo[1,2-c]quinazolin-5-yl)thio)methyl)-1H-1,2,3-triazol-1-yl)-N-(2-methoxyphenyl)acetamide (19e) and 2-(4-((benzo[4,5]imidazo[1,2-c]quinazolin-6-ylthio)methyl)-1H-1,2,3-triazol-1-yl)-N-(2-methoxyphenyl)acetamide (27e) emerged as the most potent inhibitors and were further investigated in various assessments. Finally, molecular docking studies were performed to reveal the crucial binding interactions and to confirm the results obtained from structure-activity relationship (SAR) analysis.

Hydrocotyle umbellata L.; a natural source of bioactives to mitigate diabetes mellitus and its complications

Metabolomics study of Hydrocotyle umbellata L. revealed the richness of its aerial parts in phenolics primarily; quercetin and its glycoside derivatives, which are well-reported to exert antidiabetic activity owing to their powerful antioxidant capacity. Hence, the antioxidant and antidiabetic potentials of the quercetin standardized ethanolic extract of H. umbellata aerial parts were investigated. The antioxidant activity was examined by using in-vitro 2,2-diphenyl-1-picrylhydrazyl free radical scavenging assay, while the antidiabetic activity was examined by using in-vitro α-glucosidase inhibitory assay and further confirmed by in-vivo experiments using streptozotocin-induced diabetes in rat model. Interestingly, the standardized ethanolic extract showed significant in-vitro antioxidant activity, and effectively inhibited Saccharomyces cerevisiae α-glucosidase enzyme activity. Moreover, it significantly reduced fasting blood glucose, triglycerides, and cholesterol levels. Thus, H. umbellata is a potential natural candidate to attenuate diabetes mellitus and its altered lipid profile complications, which could be attributed to its quercetin and quercetin glycosides content.

Imidazo[1,2-c]quinazolines as a novel and potent scaffold of α-glucosidase inhibitors: design, synthesis, biological evaluations, and in silico studies

α-Glucosidase inhibition is an approved treatment for type 2 diabetes mellitus (T2DM). In an attempt to develop novel anti-α-glucosidase agents, two series of substituted imidazo[1,2-c]quinazolines, namely 6a–c and 11a–o, were synthesized using a simple, straightforward synthetic routes. These compounds were thoroughly characterized by IR, 1H and 13C NMR spectroscopy, as well as mass spectrometry and elemental analysis. Subsequently, the inhibitory activities of these compounds were evaluated against Saccharomyces cerevisiae α-glucosidase. In present study, acarbose was utilized as a positive control. These imidazoquinazolines exhibited excellent to great inhibitory potencies with IC50 values ranging from 12.44 ± 0.38 μM to 308.33 ± 0.06 μM, which were several times more potent than standard drug with IC50 value of 750.0 ± 1.5 μM. Representatively, compound 11j showed remarkable anti-α-glucosidase potency with IC50 = 12.44 ± 0.38 μM, which was 60.3 times more potent than positive control acarbose. To explore the potential inhibition mechanism, further evaluations including kinetic analysis, circular dichroism, fluorescence spectroscopy, and thermodynamic profile were carried out for the most potent compound 11j. Moreover, molecular docking studies and in silico ADME prediction for all imidazoquinazolines 6a–c and 11a–o were performed to reveal their important binding interactions, as well as their physicochemical and drug-likeness properties, respectively.

Synthesis, α-Glucosidase Inhibitory Activity and Molecular Docking Study of Chalcone Derivatives Bearing a 1H-1,2,3-Triazole Unit.

Diabetes mellitus (DM) is a metabolic condition that is a major health concern around the world. The current study investigates the synthesis of a series of chalcone and 1H-1,2,3-triazole hybrid compounds and their in vitro inhibitory potential against α-glucosidase. The antidiabetic analysis revealed that compounds 4a and 4b are highly active agents with IC50 of 3.90 and 4.77 µM, respectively. These results are close to quercetin (IC50 = 4.24 µM) as the reference standard. Molecular docking study strongly supports the active interaction of the 4a and 4b to the enzyme through cation-π interaction and hydrogen bonding between the ligands and the active site of Saccharomyces cerevisiae α-glucosidase enzyme. This study broadened the potential of designing chalcone-triazole hybrid compounds as antidiabetic drug candidates in the pharmaceutical sector.

Antioxidant and antidiabetic activities of vanadium-binding protein and trifuhalol A.

The antioxidant and antidiabetic activities of vanadium-binding protein (VBP) and trifuhalol A, alone or combined, were investigated. Both VBP and trifuhalol A showed potent radical scavenging activity (RSA) on 2,2'-azinobis (3-ethylbenzothiazoline)-6-sulfonic acid (ABTS), hydrogen peroxide, and ferric-reducing antioxidant power. Their combination at a concentration of 100μg/ml VBP and 40μg/ml trifuhalol A exhibited more than 99% RSA against ABTS. Additionally, VBP and trifuhalol A, alone or combined, displayed potential antidiabetic activities against Saccharomyces cerevisiae α-glucosidase. The highest inhibition of 70.26% against S. cerevisiae α-glucosidase was observed in the case of the combination of 250μg/ml VBP and 1.75μg/ml trifuhalol A. Kinetics study revealed that VBP and trifuhalol A were noncompetitive inhibition type against S. cerevisiae α-glucosidase, while VBP and trifuhalol A combined treatment was a mixed inhibition type against S. cerevisiae α-glucosidase. These results indicated that VBP and trifuhalol A, alone or combined, had high free radical scavenging activity and inhibitory activity against S. cerevisiae a-glucosidase, suggesting that VBP and trifuhalol A could be used as candidates for the development of natural antidiabetic drugs or functional food. PRACTICAL APPLICATIONS: The present study showed that VBP and trifuhalol A, alone or combined, had potential antioxidant and antidiabetic activities, suggesting that VBP and trifuhalol A could be developed to a novel nutraceutical or natural antidiabetic drugs in the management of obesity or diabetes. This finding will be beneficial for all peoples who are directly or indirectly associated with obesity or diabetes.

Antidiabetic and cytotoxic polyhydroxylated oleanane and ursane type triterpenoids from Salvia grossheimii

Two polyhydroxylated oleanane and seven ursane triterpenoids were isolated from aerial parts of Salvia grossheimii. The chemical structures of the undescribed triterpenoids (1–6) were characterized using 1 and 2 D NMR and ESI-MS spectral data as; 2α, 3β, 11α –trihydroxy-olean-12- ene (1), 2α, 3β, 11α-trihydroxy-olean-18-ene (2), 2α- acetoxy-urs-12-ene-3β, 11α, 20β-triol (3), 3-keto-urs-12-ene-1β, 11α, 20β -triol (4), 2α, 3β-diacetoxy-urs-12-ene-1β, 11α, 20β -triol (5), and 3β-acetoxy-urs-12-ene-1β, 11α, 20β –triol (6). All compounds were evaluated for the in vitro α-glucosidase inhibitory and cytotoxic activities against MCF-7 human cancer cell line. Compounds 1, 2, 4, and 6 showed in vitro α-glucosidase inhibitory activity with IC50 = 43.6–198.4 µM, which were more potent than the antidiabetic medicine, acarbose. The remaining compounds; 3, and 7–9 showed potent cytotoxic activity (IC50 = 6.2–31.9 µM) against the cancerous cell line, while the potent α-glucosidase inhibitors were inactive. Molecular docking analysis and kinetic studies were applied to investigate the structure activity relationships and mechanisms of the human and Saccharomyces cerevisiae α-glucosidase inhibitory of the purified compounds. Comparing the high cytotoxicity and α-glucosidase inhibitory of the oleanane and ursane type triterpenoids suggest them as potential lead compounds for further research in anticancer and antidiabetic research.

Rac- and meso-Cyclohexanoids: Their α-, β-glycosidases, antibacterial, antifungal activities, and molecular docking studies.

An efficient and versatile synthesis method has been postulated for hydroxymethylated rac- and meso-cyclohexanoid derivatives. The synthesis of these stereoisomers was achieved easily with traditional methods using hexahydroisobenzofuran 6, prepared from commercially available cis-hydrophthalic anhydride. The study, involving diastereoselective epoxidation and cis-hydroxylation, was conducted to obtain epoxy-, cis-, and trans-diol-furans 7, 8, and 9. After sulfamic acid-catalyzed ring-opening reaction of the epoxide and furan rings, rac- and meso-tetraacetates 14, 15, and 16 were afforded. Hydrolysis of acetate groups with ammonia in absolute methanol yielded the desired tetrols rac-17, meso-18, and meso-19. All structures, after purification by chromatographic methods and elucidation by spectral techniques, were screened against α- and β-glucosidases. Compounds 7, 8, 10, 17, 18, and 19 were also evaluated for their antibacterial and antifungal activity against some selected synthesized compounds with varying degrees of inhibitory effects on the growth of different pathogenic microorganisms by the well-diffusion method. In addition, Saccharomyces cerevisiae α-glucosidase molecular modeling studies were performed for all rac- and meso-compounds 7, 8, 10, 17, 18, and 19.

Study on the interaction of triaryl-dihydro-1,2,4-oxadiazoles with α-glucosidase.

One of the therapeutic approaches in the management of Type 2 diabetes is delaying the absorption of glucose through α-glucosidase enzymes inhibition, which can reduce the incidence of postprandial hyperglycemia. The existence of chronic postprandial hyperglycemia impaired the endogenous antioxidant defense due to inducing oxidative stress induced pancreatic β-cell destruction through uncontrolled free radicals generation such as ROS, which in turn, leads to various macrovascular and microvascular complications. This study aimed to synthesize 2-aryl-4,6-diarylpyrimidine derivatives, screen their α-glucosidase inhibitory activity, perform kinetic and molecular docking studies. A series of 3,4,5-triphenyl-4,5-dihydro-1,2,4-oxadiazole derivatives were synthesized and their α-glucosidase inhibitory activity was screened in vitro. Compounds 6a-k were synthesized via a two-step reaction with a yield between 65 and 88%. The structural elucidation of the synthesized derivatives was performed by different spectroscopic techniques. α-Glucosidase inhibitory activity of the oxadiazole derivatives 6a-k was evaluated against Saccharomyces cerevisiae α-glucosidase. Most of the synthesized compounds demonstrated α-glucosidase inhibitory action. Particularly compounds 6c, 6d and 6k were the most active compounds with IC50 values 215 ± 3, 256 ± 3, and 295 ± 4μM respectively. A kinetic study performed for compound 6c revealed that the compound is a competitive inhibitor of Saccharomyces cerevisiae α-glucosidase with Ki of 122μM. The docking study also revealed that the two compounds, 6c and 6k, have important binding interactions with the enzyme active site. The overall results of our study reveal that the synthesized compounds could be a potential candidate in the search for novel α-glucosidase inhibitors to manage the postprandial hyperglycemia incidence. Graphical abstract.

Spectroscopy and molecular docking analysis reveal structural specificity of flavonoids in the inhibition of α-glucosidase activity

The inhibition of α-glucosidase activity is a prospective approach to prevent postprandial hyperglycemia. As two flavonoids extracted from citrus fruits, eriocitrin and eriodictyol have similar structures and show multiple pharmacological activities. In order to investigate the effects of flavonoids structure on enzyme inhibition, spectroscopy and molecular docking analysis were used. Saccharomyces cerevisiae α-glucosidase (GH13) was used for studying the inhibitory mechanism by multi-spectroscopic analysis. Results indicated that they could quench the intrinsic fluorescence of α-glucosidase, the binding constants at 298 K were (7.02 ± 0.22) × 104 and (4.57 ± 0.16) × 104 L mol−1, respectively. The interaction between them with α-glucosidase were mainly driven by hydrophobic interaction, they induced conformational changes of α-glucosidase. The human α-glucosidase (C-terminal maltase-glucoamylase, GH31) was used in the molecular docking analysis to determine the interaction of eriocitrin and eriodictyol with the α-glucosidase. The results revealed that they could bind with α-glucosidase and might cause the decrease of α-glucosidase activity. The inhibitory effect of eriocitrin was stronger than that of eriodictyol, which might be due to the position and amount of hydroxyl groups. This work confirmed two novel α-glucosidase inhibitors and provided the structure-function relationship of flavonoids in inhibition of α-glucosidase activity.

New gorgonane sesquiterpenoid from Teucrium mascatense Boiss, as α-glucosidase inhibitor

One new sesquiterpene, 6-isopropyl-4,10-dimethyldecahydro-2,3,4-naphthalenetriol (1), together with five known phytochemicals including apigenin 7,4′ dimethyl ether (2), genkwanin (3), betulinic acid (4), β-sitosterol (5), and 1-docosanol (6) have been isolated for the first time from Teucrium mascatense. The structure of the new compound was deduced on the basis of spectroscopic techniques (ESI-MS, 1H and 13C NMR, HMQC and HMBC). Compound 1 showed significant inhibition against yeast α-glucosidase enzyme with IC50 value of 121.2 ± 1.9 μM as compared to standard drug acarbose (IC50 = 942.0 ± 0.60 μM). To evaluate the binding affinity and interaction of the experimentally tested compounds, at active site of enzyme, docking studies were carried out using MOE. For docking, homology model of Saccharomyces cerevisiae α-glucosidase enzyme was created. The docking results suggest that the compound forms strong interactions at the catalytic site of yeast α-glucosidase, particularly hydrogen bonded to the Asp68, Asp349, Arg439 and two water molecules.

α-Glucosidase Inhibitory Activities of Lutein and Zeaxanthin Purified from Green Alga Chlorella ellipsoidea

α-Glucosidase inhibitors are used therapeutically to treat type-2 diabetes mellitus. Through a bioassay-guided fractionation technique, three carotenoids, (all-E)-lutein, (all-E)-zeaxanthin and (9-Z)-zeaxanthin, were purified from the green alga Chlorella ellipsoidea, in which (all-E)-lutein and (9-Z)-zeaxanthin had potent α-glucosidase inhibitory activity. IC50 values of (all-E)-lutein and (9-Z)-zeaxanthin were 70 and 53.5 μmol L−1 against Saccharomyces cerevisiae α-glucosidase, respectively, with non-competitive inhibition. In addition, IC50 values of (9-Z)-zeaxanthin against Bacillus stearothermophilus and rat-intestinal α-glucosidase were 805.1 and 671.2 μmol L−1, respectively. The Ki values of (all-E)-lutein and (9-Z)-zeaxanthin against S. cerevisiae α-glucosidase were 78.1 and 16.5 μmol L−1, respectively. Therefore, C. ellipsoidea carotenoids might be utilized as a novel candidate to prevent type-2 diabetes mellitus related disorders in food and medical industry.

Biological interaction of newly synthesized astaxanthin-s-allyl cysteine biconjugate with Saccharomyces cerevisiae and mammalian α-glucosidase: In vitro kinetics and in silico docking analysis

In humans, alpha-glucosidase activity is present in sucrase-isomaltase (SI) and maltase-glucoamylase (MGAM). α-glucosidase is involved in the hydrolyses of disaccharide into monosaccharides and results in hyperglycemia. Subsequently chronic hyperglycemia induces oxidative stress and ultimately leads to the secondary complications of diabetes. Hence, identifying compounds with dual beneficial activity such as efficient antioxidant and α-glucosidase inhibition property has attracted the attention in recent years. Keeping these views, in the present study astaxanthin (AST; a natural antioxidant present in marine microalgae) was biconjugated with allyl sulfur amino acid such as s-allyl cysteine (SAC). The synthesized AST-SAC (with molecular weight of 883.28) was characterized using UV–visible spectrophotometer, ESI-MS, and NMR analysis. AST-SAC showed potent antioxidant property in vitro. AST-SAC inhibited Saccharomyces cerevisiae α-glucosidase (IC50 = 3.98 μM; Ki = 1 μM) and mammalian α-glucosidase [rat intestinal maltase (IC50 = 6.4 μM; Ki = 1.3 μM) and sucrase (IC50 = 1.6 μM; Ki = 0.18 μM)] enzyme activity in a dose-dependent manner. Kinetic analysis revealed that AST-SAC inhibited all the α-glucosidases in a competitive mode. In silico analysis determined the interaction of AST-SAC with the amino acids present in the active site of S. cerevisiae and human (MGAM and SI) α-glucosidases.

Anti-hyperglycemic activity of polyphenols isolated from barnyard millet (Echinochloa utilis L.) and their role inhibiting α-glucosidase

The extracts and chemical compounds isolated from barnyard millet (Echinochloa utilis) grains were investigated as part of a search for naturally derived anti-hyperglycemic medicinal plants. Among the five different solvent extracts, the ethyl acetate extract showed the lowest IC50 value against Saccharomyces cerevisiae α-glucosidase (70.2 μg/mL). Chromatography yielded eight phenolic compounds that may have been responsible for this effect. Among them, N-p-coumaroyl serotonin (1, CS), feruloyl serotonin (2, FS), and luteolin (5) potently inhibited α-glucosidase with IC50 values of 1.3–17.8 μM compared with those of deoxynojirimycin (DNJ, IC50 = 2.5 ± 0.1 μM) and acarbose (IC50 = 255.1 ± 15.6 μM). Additionally, for the first time, we found that CS and FS were significantly inhibited mammalian rat intestinal sucrase (IC50 of 3.0 and 8.2 μM) and reduced glucose content (73 and 52 % at 0.1 mg/wells) in Caco-2 (human intestinal epithelial) cells. Furthermore, oral glucose tolerance test revealed improved glucose tolerance following treatment with the barnyard millet grains extract by retarding the postprandial rise in blood glucose in vivo. These results suggest that barnyard millet grain can be used as a natural functional medicine to prevent and alleviate type-2 diabetes.

α-Glucosidase inhibitory activities of fatty acids purified from the internal organ of sea cucumber Stichopus japonicas.

α-Glucosidase inhibitory activities of the various solvent fractions (n-hexane, CHCl3 , EtOAc, BuOH, and water) of sea cucumber internal organ were investigated. 1,3-Dipalmitolein (1) and cis-9-octadecenoic acid (2) with potent α-glucosidase inhibitory activity were purified from the n-hexane fraction of sea cucumber internal organ. IC50 values of compounds 1 and 2 were 4.45 and 14.87 μM against Saccharomyces cerevisiae α-glucosidase. These compounds mildly inhibited rat-intestinal α-glucosidase. In addition, both compounds showed a mixed competitive inhibition against S. cerevisiae α-glucosidase and were very stable at pH 2 up to 60 min. The KI values of compounds 1 and 2 were 0.48 and 1.24 μM, respectively. Therefore, the internal organ of sea cucumber might be a potential new source of α-glucosidase inhibitors suitably used for prevention of obesity and diabetes mellitus.

α-Glucosidase Inhibitors from a Xylaria feejeensis Associated with Hintonia latiflora.

Two new compounds, pestalotin 4'-O-methyl-β-mannopyranoside (1) and 3S,4R-(+)-4-hydroxymellein (2), were isolated from an organic extract of a Xylaria feejeensis, which was isolated as an endophytic fungus from Hintonia latiflora. In addition, the known compounds 3S,4S-(+)-4-hydroxymellein (3), 3S-(+)-8-methoxymellein (4), and the quinone derivatives 2-hydroxy-5-methoxy-3-methylcyclohexa-2,5-diene-1,4-dione (5), 4S,5S,6S-4-hydroxy-3-methoxy-5-methyl-5,6-epoxycyclohex-2-en-1-one (6), and 4R,5R-dihydroxy-3-methoxy-5-methylcyclohexen-2-en-1-one (7) were obtained. The structures of 1 and 2 were elucidated using a set of spectroscopic and spectrometric techniques. The absolute configuration of the stereogenic centers of 1 and 2 was determined using ECD spectroscopy combined with time-dependent density functional theory calculations. In the case of 1, comparison of the experimental and theoretical (3)J6-7 coupling constants provided further evidence for the stereochemical assignments. Compounds 2 and 3 inhibited Saccharomyces cerevisiae α-glucosidase (αGHY), with IC50 values of 441 ± 23 and 549 ± 2.5 μM, respectively. Their activity was comparable to that of acarbose (IC50 = 545 ± 19 μM), used as positive control. Molecular docking predicted that both compounds bind to αGHY in a site different from the catalytic domain, which could imply an allosteric type of inhibition.

Antioxidant activity and inhibition of α-glucosidase by hydroxyl-functionalized 2-arylbenzo[b]furans

This study synthesized a series of hydroxyl-functionalized 2-arylbenzo[b]furans based on the structure of tournefolic acid A and evaluated them for antioxidant and α-glucosidase inhibitory activities. Compounds 5a, 5e, and 5n showed remarkable inhibition of α-glucosidase (IC50 values of 1.9–3.0 μM), and they appear to be even more potent than quercetin. A kinetic binding study indicated that compounds 5a and 5n used a mechanism of mixed-competition to inhibit α-glucosidase. This study also revealed that compounds 5a and 5n bind to either the α-glucosidase or α-glucosidase-4-NPGP complex. Using the crystal structure of the Saccharomyces cerevisiae α-glucosidase, the molecular docking study has predicted the binding of compounds 5a and 5n to the active site of α-glucosidase through both hydrophobic and hydrogen interactions. A DPPH radical scavenging assay further showed that most hydroxyl-functionalized 2-arylbenzo[b]furans possess antioxidant activity. The exception was compound 5p, which has only one hydroxyl group on the 2-phenyl ring of 2-arylbenzo[b]furan. Our results indicate that hydroxyl-functionalized 2-arylbenzo[b]furans possess both antidiabetic as well as antioxidant properties.

New pregnane glycosides from Gymnema sylvestre.

Four new pregnane glycosides 1–4 were isolated from the ethanol extract of the stem of Gymnema sylvestre and named gymsylvestrosides A–D. Hydrolysis of compound 1 under the catalysis of Aspergilus niger β-glucosidase afforded compound 5 (gymsylvestroside E). Their structures were determined by spectroscopic methods such as HRESIMS, 1D and 2D NMR, as well as HMQC-TOCSY experiment. Compounds 1–4 were screened for Saccharomyces cerevisiae α-glucosidase inhibitory activity.

The specificity of α-glucosidase from Saccharomyces cerevisiae differs depending on the type of reaction: hydrolysis versus transglucosylation

Our investigation of the catalytic properties of Saccharomyces cerevisiae α-glucosidase (AGL) using hydroxybenzyl alcohol (HBA) isomers as transglucosylation substrates and their glucosides in hydrolytic reactions demonstrated interesting findings pertaining to the aglycon specificity of this important enzyme. AGL specificity increased from the para(p)- to the ortho(o)-HBA isomer in transglucosylation, whereas such AGL aglycon specificity was not seen in hydrolysis, thus indicating that the second step of the reaction (i.e., binding of the glucosyl acceptor) is rate-determining. To study the influence of substitution pattern on AGL kinetics, we compared AGL specificity, inferred from kinetic constants, for HBA isomers and other aglycon substrates. The demonstrated inhibitory effects of HBA isomers and their corresponding glucosides on AGL-catalyzed hydrolysis of p-nitrophenyl α-glucoside (PNPG) suggest that HBA glucosides act as competitive, whereas HBA isomers are noncompetitive, inhibitors. As such, we postulate that aromatic moieties cannot bind to an active site unless an enzyme-glucosyl complex has already formed, but they can interact with other regions of the enzyme molecule resulting in inhibition.

Two Unsaturated Fatty Acids with Potent α‐Glucosidase Inhibitory Activity Purified from the Body Wall of Sea Cucumber (Stichopus japonicus)

One therapeutic approach for preventing diabetes mellitus and obesity is to retard the absorption of glucose via inhibition of α-glucosidase. Two unsaturated fatty acids with strong α-glucosidase inhibitory activity, 7(Z)-octadecenoic acid (1) and 7(Z),10(Z)-octadecadienoic acid (2), were purified from the body wall of Stichopus japonicus. IC(50) values of compounds 1 and 2 were 0.51 and 0.67 μg/mL against Saccharomyces cerevisiae α-glucosidase and 0.49 and 0.60 μg/mL against Bacillus stearothermophilus α-glucosidase, respectively. These compounds mildly inhibited rat-intestinal sucrase and maltase. In addition, both compounds showed a mixed type of inhibition against S. cerevisiae α-glucosidase and were very stable under thermal and acidic conditions up to 60 min. The K(I) and K(IS) values of compounds 1 and 2 were 0.44 and 0.22 μg/mL, and 0.39 and 0.13 μg/mL, respectively. One therapeutic approach for preventing diabetes mellitus is to retard the absorption of glucose via inhibition of α-glucosidase. In this study, 2 fatty acids with strong α-glucosidase-inhibitory activity, 7(Z)-octadecenoic acid and 7(Z),10(Z)-octadecadienoic acid, were purified and identified from sea cucumber. Therefore, sea cucumber fatty acids can potentially be developed as a novel natural nutraceutical for the management of type-2 diabetes.

Bioactivities of Kernel Extracts of 18 Strains of Maize (Zea mays)

Aqueous and ethanolic extracts of maize kernels from 18 varieties/strains were prepared for the evaluation of inhibitory activities toward α-glucosidase and scavenging activities toward nitric oxide (NO•) and superoxide (•O(2)(-)). All ethanolic extracts of maize strains tested inhibited yeast (Saccharomyces cerevisiae) α-glucosidase with the highest potency (49% to 54%) found for 2 purple and a yellow strains. However, inhibitory effects of maize extracts on rat intestinal α-glucosidase were as a whole about 10% as effective as with the yeast enzyme. Maize extracts were capable of scavenging NO• at the level of 0.25 mg/mL to extents ranging from 24% to 50% and 26% to 57%, respectively, for aqueous and ethanolic extracts. All tested aqueous extracts were also capable of scavenging •O(2)(-), with efficacies ranging from 8% to 38%, at the level of 1.5 mg/mL, whereas almost none of the ethanolic extracts scavenged •O(2)(-), except for one purple strain (approximately 10% effective). The effectiveness in the enzyme inhibition and antioxidant assays did not correlate with total phenolic and/or anthocyanin levels, nor with the nature of pigmentation among the maize strains evaluated. Practical Application: A diversity of pigmented maize strains was evaluated for biological activities related to mitigating oxidative stress and slowing down glucose absorption from the diet. Certain strains tended to be more abundant in these biological activities and have potential to be used in dietary regimes that are designed to promote human health.