Isolation and Structural Characterization of Specific Bacterial ß-Glucuronidase Inhibitors from Noni (Morinda citrifolia) Fruits.

An extract of noni (Morinda citrifolia) fruits has shown potent inhibitory activity on gut bacterial ß-glucuronidase, which could help reduce irinotecan-induced diarrhea. In this study, four bacterial ß-glucuronidase inhibitors were obtained following bioactive assay-guided isolation, including two sesquineolignans, (7S,8S,7'R,8'R)-isoamericanol B (1) and americanol B (2), and two dineolignans, moricitrins A (3) and B (4). Compounds 2-4 are new, and the absolute configuration of compound 1 was determined for the first time. Their chemical structures were elucidated through HRESIMS and NMR spectra, and their absolute configurations were established via the comparison of the experimental and calculated electronic circular dichroism spectra. These compounds showed potent inhibition against gut bacterial ß-glucuronidase with IC50 values in the range 0.62-6.91 µM. The inhibition presented specificity for ß-glucuronidase, as all the compounds showed no or weak effects on digestive enzymes such as α-amylase, α-glucosidase, and lipase, suggesting that their gastrointestinal side effects could be minimized. These specific inhibitors as naturally occurring dietary compounds may be developed as promising candidates to alleviate irinotecan-induced diarrhea.

The Flavonoid Kaempferol Ameliorates Streptozotocin-Induced Diabetes by Suppressing Hepatic Glucose Production.

In diabetes mellitus, the excessive rate of glucose production from the liver is considered a primary contributor for the development of hyperglycemia, in particular, fasting hyperglycemia. In this study, we investigated whether kaempferol, a flavonol present in several medicinal herbs and foods, can be used to ameliorate diabetes in an animal model of insulin deficiency and further explored the mechanism underlying the anti-diabetic effect of this flavonol. We demonstrate that oral administration of kaempferol (50 mg/kg/day) to streptozotocin-induced diabetic mice significantly improved hyperglycemia and reduced the incidence of overt diabetes from 100% to 77.8%. This outcome was accompanied by a reduction in hepatic glucose production and an increase in glucose oxidation in the muscle of the diabetic mice, whereas body weight, calorie intake, body composition, and plasma insulin and glucagon levels were not altered. Consistently, treatment with kaempferol restored hexokinase activity in the liver and skeletal muscle of diabetic mice while suppressed hepatic pyruvate carboxylase activity and gluconeogenesis. These results suggest that kaempferol may exert antidiabetic action via promoting glucose metabolism in skeletal muscle and inhibiting gluconeogenesis in the liver.

UHPLC/MS Identifying Potent α-glucosidase Inhibitors of Grape Pomace via Enzyme Immobilized Method.

α-Glucosidases have been a major target in controlling and managing postprandial blood glucose and therefore diabetes treatment. This study aims to further identify and purify active compounds from the most active ethyl acetate fraction collected previously in Tinta Cão grape pomace extract (TCEE) using a newly developed and highly effective immobilization method, including obtaining compounds previously shown to inhibit the enzyme. Purification used crosslinked chitosan beads with α-glucosidases bound to polymer, which acted as immobilized enzyme vehicle to collect inhibitors. Compounds absorbed into the beads were eluded using methanol, where collected fraction was subjected to UHPLC-MS analysis to identify active compounds. Results presented 5 major compounds: viniferifuran (amurensin H), p-coumaroyl-6-O-D-glucopyranoside, p-coumaroyl-6-O-hexoside, (epi)catechin-hexoside, 10-carboxyl-pyranopeonidin 3-O-(6''-O-p-coumaroyl)-glucoside. These findings indicated the particular molecules can be utilized as potent α-glucosidases inhibitors, and may be further tested for postprandial glucose control. PRACTICAL APPLICATION: A potential approach enriched and identified α-glucosidase inhibitors of grape pomace. Set-up of UHPLC/MS detection and identification of active compounds provide qualify assessment in developing grape pomace extract into potent dietary supplement and new drug for diabetes.

Antibacterial Activity of 2-(3',5'-Dibromo-2'-methoxyphenoxy)-3,5- dibromophenol Isolated from Phyllospongia papyracea.

A principal active antimicrobial compound, 2-(3',5'-dibromo-2'-methoxyphenoxy)-3,5-dibromophenol, was isolated from the methanol extract of Phyllospongiapapyracea via bioassay-guided fractionation and isolation. The crude extract and the purified compound were assayed to determine the minimal - inhibitory concentration and minimal bactericidal concentration (MBC) using the broth. microdilution method. The purified compound was found to be highly active against Bacillus subtilis and Staphylococcus aureus at MIC=1 µg/mL, Campylobacter jejuni at MIC=2 gg/mL, Pseudomonas aeruginosa at MIC=4 µg/mL; and Streptococcus pneumoniae and Listeria monocytogenes at MIC = 8 µg/mL. The activity of this compound was found to be comparable with antibiotics commonly used to control these species of bacteria. The results establish 2-(3',5'-dibromo-2'-methoxyphenoxy)-3,5-dibromopheno as a potential lead molecule for the development of antibacterial agents.

A potent antimicrobial compound isolated from Clathria cervicornis.

The sponge of Clathria cervicornis is commonly used in traditional medicine. This study aims to identify the active compound in C. cervicornis and to evaluate its antimicrobial activity. The purified active compound was determined to be crambescidin 800 and was found to be highly active against Acinetobacter baumannii (minimal inhibitory concentration, MIC=2 µg/ml), Klebsiella pneumoniae (MIC=1 µg/ml) and Pseudomonas aeruginosa (MIC=1 µg/ml). A potent antimicrobial compound, crambescidin 800, was isolated in Clathria cervicornis. It is extremely active against three common pathogenic bacteria.

Antibacterial and cytotoxic activity of isoprenylated coumarin mammea A/AA isolated from Mammea africana.

ETHNOPHARMACOLOGICAL RELEVANCE: The stem bark of Mammea africana is widely distributed in tropical Africa and commonly used in traditional medicine. This study aims to identify the active compound in Mammea africana and to evaluate its antimicrobial and antiproliferative activity. MATERIALS AND METHODS: Methanol extract from the bark of the Mammea africana was separated by liquid-liquid extraction, followed by open column chromatography. A principal antimicrobial compound was purified by high performance liquid chromatography (HPLC) and its structure was elucidated by nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS). The antibacterial activity of the purified compound was determined using the broth microdilution method against 7 common pathogenic bacteria. The compound was also evaluated for cytotoxicity by cell proliferation assay (MTS) using the mouse embryonic fibroblast cell line NIH 3T3 and the non-small cell lung cancer cell line A549. RESULTS: The purified active compound was determined to be mammea A/AA and was found to be highly active against Campylobacter jejuni (MIC=0.5 µg/ml), Streptococcus pneumoniae (MIC=0.25 µg/ml), and Clostridium difficile (MIC=0.25 µg/ml). The compound exhibited significant antiproliferative activities against both NIH 3T3 and A549 cell lines. CONCLUSION: Mammea A/AA isolated from Mammea africana exerts specific inhibitory activity against Campylobacter jejuni, Streptococcus pneumoniae, and Campylobacter difficile. Mammea A/AA was also found to exhibit significant cytotoxicity against both cancer and normal cell lines.

Selective growth inhibition of human breast cancer cells by graviola fruit extract in vitro and in vivo involving downregulation of EGFR expression.

The epidermal growth factor receptor (EGFR) is an oncogene frequently overexpressed in breast cancer (BC), and its overexpression has been associated with poor prognosis and drug resistance. EGFR is therefore a rational target for BC therapy development. This study demonstrated that a graviola fruit extract (GFE) significantly downregulated EGFR gene expression and inhibited the growth of BC cells and xenografts. GFE selectively inhibited the growth of EGFR-overexpressing human BC (MDA-MB-468) cells (IC(50) = 4.8 µg/ml) but had no effect on nontumorigenic human breast epithelial cells (MCF-10A). GFE significantly downregulated EGFR mRNA expression, arrested cell cycle in the G0/G1 phase, and induced apoptosis in MDA-MB-468 cells. In the mouse xenograft model, a 5-wk dietary treatment of GFE (200 mg/kg diet) significantly reduced the protein expression of EGFR, p-EGFR, and p-ERK in MDA-MB-468 tumors by 56%, 54%, and 32.5%, respectively. Overall, dietary GFE inhibited tumor growth, as measured by wet weight, by 32% (P < 0.01). These data showed that dietary GFE induced significant growth inhibition of MDA-MB-468 cells in vitro and in vivo through a mechanism involving the EGFR/ERK signaling pathway, suggesting that GFE may have a protective effect for women against EGFR-overexpressing BC.

ORAChromatography and total phenolics content of peanut root extracts.

A large number of compounds have been reported in peanut plants. Many of these compounds are phytoalexins, which are produced by plants experiencing environmental stress and often exhibit antioxidant activity. It is difficult to determine which of the many compounds has the greatest impact on total antioxidant capacity in a mixture. The objectives of this research were to examine the oxygen-radical absorbing capacity (ORAC) value and total phenolic contents of peanut root extracts and peanut root extract fractions collected via HPLC. Peanut roots were extracted from four different cultivars (Brantley, NC-12, Phillips, and Wilson) with 70% aqueous ethanol with ultrasonic assistance. Each cultivar was sampled in duplicate. The extracts were fractionated into 18 3-min fractions by HPLC using a C-18 column. Fractions and crude extracts were freeze dried. ORAC values and total phenolic content were then determined for all fractions and crude extracts. Fractions had a significant effect on the µM TE/mg gallic acid equivalents (GAE). ORAC values ranged from -46.89 µM TE to 185 µM TE in HPLC fractions. ORAChromatography can be used to focus on antioxidants in complex samples.

Dietary supplementation of grape skin extract improves glycemia and inflammation in diet-induced obese mice fed a Western high fat diet.

Dietary antioxidants may provide a cost-effective strategy to promote health in obesity by targeting oxidative stress and inflammation. We recently found that the antioxidant-rich grape skin extract (GSE) also exerts a novel anti-hyperglycemic activity. This study investigated whether 3-month GSE supplementation can improve oxidative stress, inflammation, and hyperglycemia associated with a Western diet-induced obesity. Young diet-induced obese (DIO) mice were randomly divided to three treatment groups (n = 12): a standard diet (S group), a Western high fat diet (W group), and the Western diet plus GSE (2.4 g GSE/kg diet, WGSE group). By week 12, DIO mice in the WGSE group gained significantly more weight (24.6 g) than the W (20.2 g) and S groups (11.2 g); the high fat diet groups gained 80% more weight than the standard diet group. Eight of 12 mice in the W group, compared to only 1 of 12 mice in the WGSE group, had fasting blood glucose levels above 140 mg/dL. Mice in the WGSE group also had 21% lower fasting blood glucose and 17.1% lower C-reactive protein levels than mice in the W group (P < 0.05). However, the GSE supplementation did not affect oxidative stress in diet-induced obesity as determined by plasma oxygen radical absorbance capacity, glutathione peroxidase, and liver lipid peroxidation. Collectively, the results indicated a beneficial role of GSE supplementation for improving glycemic control and inflammation in diet-induced obesity.

Effects of grape pomace antioxidant extract on oxidative stress and inflammation in diet induced obese mice.

Norton grape is one of the most important wine grapes in Southern and Midwestern states and generates massive pomace byproducts. The objective of this study is to characterize the antioxidant compounds and activity in Norton grape pomace extract (GPE) and further assess the potential health promoting properties of Norton GPE using an animal disease model. The total phenolic content and anthocyanins in Norton GPE were 475.4 mg of gallic acid equiv/g and 156.9 mg of cyanidin 3-glucoside equiv/g, respectively. Catechin and epicatechin in GPE were 28.6 and 24.5 mg/g, respectively. Other major antioxidants in GPE included quercetin (1.6 mg/g), trans-resveratrol (60 µg/g), gallic acid (867.2 µg/g), coutaric acid (511.8 µg/g), p-hydroxybenzoic acid (408.3 µg/g), and protocatechuic acid (371.5 µg/g). The antioxidant activity of GPE was evaluated by oxygen radical absorbance capacity (ORAC) and was 4133 µmol of Trolox equiv/g. Male diet-induced obese (DIO) mice were randomly divided to three treatment groups (n = 12): a normal diet (ND group), a high fat diet (HF group), and the high fat diet supplemented with GPE (HFGPE group). After 12-week treatment, mice in the high fat diet groups gained 29% more weight than the ND group. The GPE supplementation (estimated 250 mg/kg bw/d) lowered plasma C-reactive protein levels by 15.5% in the high fat diet fed mice (P < 0.05), suggesting a potential anti-inflammatory effect by dietary GPE. However, dietary GPE did not improve oxidative stress in DIO mice as determined by plasma ORAC, glutathione peroxidase, and liver lipid peroxidation. The results showed that GPE contained significant antioxidants and dietary GPE exerted an anti-inflammatory effect in diet induced obesity.

Comparison of different strategies for soybean antioxidant extraction.

Three extraction strategies including Soxhlet extraction, conventional solid-liquid extraction, and ultrasonic-assisted extraction (UAE) were compared for their efficiency to extract phenolic antioxidants from Virginia-grown soybean seeds. Five extraction solvents were evaluated in UAE and the conventional extraction. The soybean extracts were compared for their total phenolic contents (TPC), oxygen radical absorbance capacity (ORAC), and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH(*)) scavenging activities. The results showed that UAE improved the extraction of soybean phenolic compounds by >54% compared to the conventional and Soxhlet extractions. Among the tested solvents, 50% acetone was the most efficient for extracting soybean phenolic compounds. There was no significant correlation between the TPC and antioxidant activities of the soybean extracts. The extracts prepared by 70% ethanol had the highest ORAC values. Overall, UAE with 50% acetone or 70% ethanol is recommended for extracting soybean antioxidants on the basis of the TPC and ORAC results.

Antioxidant properties of Fusarium head blight-resistant and -susceptible soft red winter wheat grains grown in Virginia.

Fusarium head blight (FHB) has emerged as a major threat to wheat crops around the world, and it has been hypothesized that wheat antioxidants may play a role against Fusarium infections. The current study aimed to determine antioxidant properties of FHB-resistant wheat grains as compared to susceptible wheat. The wheat samples were collected from a single growing location (Warsaw, VA) and the same growing season. The results showed that both FHB-resistant and -susceptible wheat grains exerted strong radical scavenging activities against DPPH* radical [0.91-1.53 micromol of Trolox equivalents (TE)/g], peroxyl radical (15.5-24.5 micromol of TE/g), and hydroxyl radical (15.7-35.8 micromol of TE/g). Their total phenolic contents ranged from 888 to 1117 microg of gallic acid equivalents (GAE)/g. Five phenolic acids including ferulic, syringic, vanillic, caffeic, and p-coumaric acids were determined in soluble and insoluble fractions of wheat grains, altogether with a range of 219-389 microg/g. On average, the FHB-resistant wheat group showed significantly higher average values in DPPH* and hydroxyl radicals scavenging activities (30 and 41% higher, respectively) than the FHB-susceptible wheat group.

Fatty acid composition and antioxidant properties of cold-pressed marionberry, boysenberry, red raspberry, and blueberry seed oils.

Cold-pressed marionberry, boysenberry, red raspberry, and blueberry seed oils were evaluated for their fatty acid composition, carotenoid content, tocopherol profile, total phenolic content (TPC), oxidative stability index (OSI), peroxide value, and antioxidant properties. All tested seed oils contained significant levels of alpha-linolenic acid ranging from 19.6 to 32.4 g per 100 g of oil, along with a low ratio of n-6/n-3 fatty acids (1.64-3.99). The total carotenoid content ranged from 12.5 to 30.0 micromoles per kg oil. Zeaxanthin was the major carotenoid compound in all tested berry seed oils, along with beta-carotene, lutein, and cryptoxanthin. Total tocopherol was 260.6-2276.9 mumoles per kg oil, including alpha-, gamma-, and delta-tocopherols. OSI values were 20.07, 20.30, and 44.76 h for the marionberry, red raspberry, and boysenberry seed oils, respectively. The highest TPC of 2.0 mg gallic acid equivalents per gram of oil was observed in the red raspberry seed oil, while the strongest oxygen radical absorbance capacity was in boysenberry seed oil extract (77.9 micromol trolox equivalents per g oil). All tested berry seed oils directly reacted with and quenched DPPH radicals in a dose- and time-dependent manner. These data suggest that the cold-pressed berry seed oils may serve as potential dietary sources of tocopherols, carotenoids, and natural antioxidants.

Antioxidant properties of bran extracts from Trego wheat grown at different locations.

The effects of growing conditions during the grain-filling period, including high temperature stress, total solar radiation, and average daily solar radiation, on the antioxidant properties of Trego wheat were evaluated. Bran extracts were prepared from Trego wheat, grown at four nonirrigated and one irrigated location in Colorado, and compared for their radical scavenging activities against ABTS*+ and DPPH*, Fe(2+) chelating capacities, and total phenolic contents. Significant differences in radical scavenging activities, chelating capacities, and total phenolic contents were detected among Trego bran samples grown at different locations, suggesting that growing conditions may influence the antioxidant properties of wheat. The bran sample obtained from Fort Collins had the strongest scavenging activity against either ABTS*+ or DPPH* radicals and the greatest chelating activity, whereas the highest total phenolic content was detected in bran samples from Walsh, indicating that each antioxidant activity may respond to the environmental changes differently. Positive correlations were detected between the DPPH* scavenging activity and either total solar radiation (r = 0.97, p = 0.03) or average daily solar radiation (r = 0.97, p = 0.03). In addition, HPLC analysis detected the presence of ferulic, syringic, vanillic, p-hydroxybenzoic, and coumaric acids in wheat bran. Additional research is needed to further investigate the effects of environmental conditions and the interactions between genotype and environmental factors on the antioxidant properties of wheat to promote the production of wheat with improved antioxidant properties by optimizing the growing conditions for a selected genotype.