Influence of antioxidant rich fresh vegetable juices on starch induced postprandial hyperglycemia in rats

Texture Characteristics of Sea Buckthorn (Hippophae rhamnoides) Jelly for the Elderly Based on the Gelling Agent

The aim of this study was to identify the nutritional components of sea buckthorn berries and to evaluate the hardness control of the elderly with mastication difficulties using various types and concentrations of gelling agents in the preparation of sea buckthorn jelly. As a result, sea buckthorn berry comprised various bioactive nutrients, including minerals, essential fatty acids, and antioxidative and antidiabetic substances. In addition, jelly added with 3.01% guar gum, 5.74% xanthan gum, and 11.38% locust bean gum had a smooth hardness that could be chewed with the elderly’s tongue. Guar gum at 3.23~6.40%, 6.02~9.90% xanthan gum, and 12.42~27.00% locust bean gum showed soft hardness that can be chewed with gum. These results show that the gelling agent is suitable for the development of food for the elderly that meets Korean Industrial Standards, considering the mastication difficulty and dysphagia in the elderly.

Inhibitory Effect of Ascorbic Acid on in vitro Enzymatic Digestion of Raw and Cooked Starches

Ascorbic acid, also known as vitamin C, was previously reported to inhibit the activity of pancreatic α-amylase, the primary digestive enzyme for starch. A major implication of such inhibition is a slowed rate of starch digestion into glucose, which thereby reduces postprandial hyperglycemia. The aim of this study was to explore the inhibitory effects of ascorbic acid at various concentrations on the in vitro digestion of high amylose maize starch (HAMS) and potato starch (PS) in both raw and cooked conditions. Resistant starch (RS) content, defined as the starch that remained after 4 h of simulated in vitro enzymatic digestion, was measured for the starch samples. Upon the addition of ascorbic acid, the RS contents increased in both raw and cooked starches. Cooking significantly reduced the RS contents as compared to raw starches, and less increase in RS was observed with the addition of ascorbic acid. The inhibitory effect of ascorbic acid on the digestion of raw starches showed a dose-dependent trend until it reached the maximum extent of inhibition. At the concentrations of 12.5 and 18.75 mg/mL, ascorbic acid exhibited the most potent inhibitory effect on the in vitro starch digestion in raw and cooked conditions, respectively. Overall, our results strongly indicate that ascorbic acid may function as a glycemic modulatory agent beyond other important functions, and its effects persist upon cooking with certain concentrations applied.

Effect of Administration of CHAGURO Made of Chayote (Sechium edule) and Tuna (Thunnus sp.) on Rats Induced with Streptozotocin-Nicotinamide and a High-Fat Diet

This study was conducted to develop Chaguro, a low-cost supplementary food made of chayote (Sechium edule (Jacq.) Swartz) and tuna fish (Thunnus sp.), for diabetes and dyslipidemia diet therapy. In order to find a formula with effective hypoglycaemic and antidyslipidemic properties, dried tuna and chayote were mixed at different ratios: F1 (75% tuna, 25% chayote), F2 (50% tuna, 50% chayote), and F3 (25% tuna, 75% chayote). Thirty male Sprague Dawley rats were assigned into healthy control group or groups induced with streptozotocin-nicotinamide and a high-fat diet. Chaguro was administered 2.7 g/ kgBW/ day using a gavage for 28 days. The administration of all Chaguro formulas improved blood markers compared to the negative control group (p < 0.001). Chaguro F2 lowered fasting blood glucose (97.07±1.18 vs 266.31±5.31), total cholesterol (113.59±2.22 vs 208.78±4.31), triglycerides (89.93±2.51 vs 142.35±2.83), LDL-c (33.87±1.87 vs 87.85±3.34) and increased HDL-c (69,08±1,85 vs 23,91±1,64) level the most compared to the negative control group (p < 0.001). Streptozotocin-induced weight loss was also prevented in all diabetic rats fed with Chaguro, with the bodyweight being similar to that of healthy controls at the end of the intervention (p < 0.001). This study found that Chaguro may be a potential food product to help lower blood glucose and improve lipid profile in diabetes and dyslipidemia.

Chemo-biological evaluation of antidiabetic activity of Mentha arvensis L. and its role in inhibition of advanced glycation end products

Background

There has been enormous curiosity in the development of alternative plant based medicines to control diabetes, oxidative stress and related disorders. One of the therapeutic approaches is to reduce postprandial release of glucose in the blood. Two key enzymes that are involved in reducing postprandial glucose are α-amylase and α-glucosidase. Mentha arvensis L. has been traditionally used by several tribes as a medicinal plant to treat various disorders.

Objective

The present study was undertaken to test M. arvenisis L. for inhibition of postprandial hyperglycemia.

Material and method

We performed various in vitro and in vivo tests to evaluate efficacy of M. arvenisis L. for antidiabetic activity (postprandial hyperglycemia).

Results

Methanolic extract of M. arvensis L. leaves showed DPPH free radical scavenging activity (more than 78% μg/μl) and high antiglycation potential (more than 90% inhibition of AGE formation). Methanolic extract also showed remarkable inhibitory effects on α-amylase (more than 50% μg/μl) and α-glucosidase (68% μg/μl) and significant inhibition of postprandial hyperglycemia in starch induced diabetic Wistar rats.

Conclusion

The non-insulin dependent antidiabetic or inhibition of postprandial hyperglycemic activity of methanolic extract of M. arvensis L. leaves was shown by using in vitro and in vivo approaches in the present study.

Bioactive compounds from mangrove derived rare actinobacterium Saccharomonospora oceani VJDS-3

A rare actinobacterium was isolated from Nizampatnam mangrove ecosystem of Andhra Pradesh, India, and was screened for its ability to produce bioactive compounds. The potential strain was identified as Saccharomonospora oceani VJDS-3 by polyphasic taxonomy. Purification of the biologically active compounds by column chromatography led to the isolation of three compounds, namely methoxy ethyl cinnamate (ethyl(E)-3-(4-methoxyphenyl)acrylate) (R1), 4-hydroxy methyl cinnamate (methyl(E)-3-(4-hydroxyphenyl)acrylate) (R2) and 4-methylbenzoic acid (R3). The structure of the compounds was elucidated on the basis of spectroscopic analysis including FTIR, EIMS, 1HNMR and 13CNMR spectroscopies. The antimicrobial activity of the bioactive compounds produced by the strain was tested against a panel of bacteria and fungi, and expressed in terms of minimum inhibitory concentration. Compound (R1) exhibited higher antimicrobial potential (50 µg/ml) against Staphylococcus aureus, Bacillus megaterium and Candida albicans compared to R2 and R3. Antioxidant activity of compounds was determined by DPPH and ABTS radical scavenging activities. The results revealed that compound R3 effectively scavenged DPPH (73.08 ± 1.29) and ABTS (99.74 ± 0.00) radicals at a concentration of 25 and 50 µg/ml, respectively. Antidiabetic and anti-obesity activities were evaluated by inhibitory potential of compounds against alpha-glucosidase, alpha-amylase and pancreatic lipase by spectrophotometric assays. Compound R1 showed effective inhibition against alpha-glucosidase (66.8 ± 1.2) at 20 µg/ml while moderate to weak activities were found against alpha-amylase and pancreatic lipase. To the best of our knowledge, this is the first report on the isolation of supra said compounds from the genus Saccharomonospora.

Composition, antioxidant activities and hepatoprotective effects of the water extract of Ziziphus jujuba cv. Jinsixiaozao

In this study, we aimed to evaluate the composition, antioxidant activities, and hepatoprotective effects of water extracts ofZiziphus jujubacv. Jinsixiaozao.

Polyphenol Rich Extract of Garcinia pedunculata Fruit Attenuates the Hyperlipidemia Induced by High Fat Diet

Fatty foods, the most common diet today are the crux of many metabolic disorders which need urgent attention. Garcinia pedunculata Roxb. (GP, Clusiaceae) is a plant found available in Northeast (NE) region of India, is considered to have versatile therapeutic properties. The people of this region has been using dried pulp of GP fruit for the treatment of different stomach related diseases traditionally. This study aimed at evaluating the potential therapeutic action of the polyphenol-rich methanolic extract of the fruit in experimental induced obese rats. In vitro antioxidant and antidiabetic activity of GP extracts, i.e., fruit extract (GF) and seed extract (GS) were determined by using various methods viz., 1,1-diphenyl-2 picrylhydrazyl (DPPH), 2,2′-Azinobis (3-ethyl benzthiazoline-6-sulphonic acid) (ABTS^•+), nitroblue tetrazolium (NBT) and α-glucosidase inhibition assay for detection of antihyperglycemic activity. In vivo antilipidemic and antiobesity activities were evaluated by administrating oral dose of GF for 60 days on a high-fat diet (HFD) induced hyperlipidemia in the rat. GF showed higher antioxidant activity than GS by DPPH radical scavenging (IC₅₀ = 4.01 μg/ml), ABTS^•+ (IC₅₀ = 0.82 μg/ml), NBT (IC₅₀ = 0.07 μg/ml) and also showed notable α-glucosidase inhibitory activity (IC₅₀ = 19.26 μg/ml). Furthermore, GF treated rat revealed a reduction in the body weight (~60%), serum total cholesterol (33%), triglycerides (32%), low-density lipoprotein (38%) and liver biomarker enzymes after 60 days HFD fed animals. Simultaneously, GF supplementation significantly protected the HFD induced changes in hematological parameters. Histological observations clearly differentiate the structural changes in liver of HFD and GF treated group. This novel dietary lipid adsorbing agent of GF exhibited prevention of hyperlipidemia induced by HFD in the rat.

Dosakaya Juice Assuages Development of Sucrose Induced Impaired Glucose Tolerance and Imbalance in Antioxidant Defense

Objective:

The objective was to explore the effect of Dosakaya (DK) (Cucumis melo var. chito) juice on sucrose induced dysglycemia and disturbances in antioxidant defense in rats.

Materials and Methods:

Rats were preconditioned with DK juice before administration of sucrose beverage continuously for 1-month. Blood glucose tolerance test and glutathione (GSH) homeostasis pathways in kidney were analyzed in different group of animals at the end of the study.

Results:

DK juice diffused (P < 0.001) hypertriglyceridemia inducing effect of sucrose and arrested sucrose induced weight gain. It improved glucose tolerance ability by significantly reducing (P < 0.05) first-hour glycemic excursion and decreasing 2 h glycemic load (P < 0.05) following oral glucose tolerance test in sucrose fed animals. Furthermore, disturbances in antioxidant defense mechanisms in terms of GSH homeostasis in kidney were restored due to juice feeding. DK juice administration checked reduction in GSH-S-transferase and glyoxalase-I activity, thus, significantly mitigated lipid peroxidation (P < 0.05), and formation of advanced glycation end-products (P < 0.001) in kidney and serum (P < 0.01). Quantitative analysis of juice found it a rich source of protein and polyphenols. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis revealed the presence of multiple protein bands in whole fruit juice. Therefore, SDS-PAGE protein fingerprint of DK juice may serve as a quality control tool for standardization of juice.

Conclusion:

The whole fruit juice of DK may become cost-effective, affordable health beverage in extenuating ill-health effects of sugar consumption. This is the first report identifying DK juice in preventing development dysglycemia, dyslipidemia, and oxidative stress induced due to chronic sucrose feeding in rats.

SUMMARY

Chronic sucrose consumption induced development of dysglycemia and also impaired antioxidant defense mechanism in rats. The oral administration of Dosakaya juice prior to sucrose feeding however, mitigated the development of dysglycemia and impairment in antioxidant defense in rats.

Free radical scavenging, α-glucosidase inhibitory and anti-inflammatory constituents from Indian sedges, Cyperus scariosus R.Br and Cyperus rotundus L

BACKGROUND

Cyperus scariosus R. Br and Cyperus rotundus L are widely used in ayurvedic preparation for the treatment of diabetes and other diseases. The early literature, so far, does not indicate the presence of any bioactive principle isolated from these plants.

OBJECTIVE

To identify free radical scavenging, anti-diabetic and anti- inflammatory principles from these two species.

MATERIALS AND METHODS

The bioassay guided fractionation and isolation of active constituents was done by chromatographic techniques. They also evaluated their anti-oxidant activity by DPPH and ABTS. The anti-diabetic activity was screened by α- glucosidase and α- amylase assays. Also, the further evaluation of in vitro anti-inflammatory activity using THP-1 monocytic cells and in vivo anti- inflammatory activity, was confirmed by carrageenan induced rat paw edema as model.

RESULTS

The activity guided isolation led to isolation of twelve compounds Which are: Stigmasterol^[1], β- sitosterol^[2], Lupeol^[3], Gallic acid^[4], Quercetin^[5], β- amyrin^[6], Oleanolic acid^[7], β- amyrin acetate^[8], 4- hydroxyl butyl cinnamate^[9], 4- hydroxyl cinnamic acid^[10], Caffeic acid,^[11] and Kaempferol^[12] respectively. Among the isolates, the compounds 4 and 5 displayed potent radical scavenging activity with an IC₅₀ values of 0.43 and 0.067 ΅g/ml. The compounds 4, 5 and 10 showed significant anti-diabetic activities. while lupeol^[3] showed potent IL-1 β activity inhibition in THP-1 monocytic cells and also displayed significant (p<0.0025) in vivo anti-inflammatory activity.

CONCLUSION

Inbrief, we isolated twelve compounds from both the species. Collectively, our results suggested that aromatic compounds showed good anti-oxidant and anti-diabetic activities.

SUMMARY

The study investigates the free radical scavenging, α-glucosidase inhibitory and anti-inflammatory effects of constituents isolated from Indian sedges viz. C. scariosus and C. rotundus. The results indicated that phenolic compounds displayed potent fee radical scavenging activty and alpha-glucosidase inhibition activity. While terpene constituent, Lupeol[3] showed good IL-1^β activity inhibition in THP-1 monocytic cells and also displayed significant (p<0.0025) in vivo anti inflammatory activity in carrageenan induced rat paw edema. However, further studies are required to know the exact molecular mechanism. Abbreviations used: DPPH: 2,2- Diphenyl-1-1-picryl hydrazyl, ABTS: 2,2-Azinobis-3-ethylbenzo thiazoline-6-sulfonic acid, THP-1: Human leukaemia monocytic cell line, IL-1β: Interleukin-1β, IC₅₀-Inhibitory concentration 50%.

Antioxidant and α-glucosidase inhibitory activities of 40 tropical juices from Malaysia and identification of phenolics from the bioactive fruit juices of Barringtonia racemosa and Phyllanthus acidus

The present study compared pH, total soluble solids, vitamin C, and total phenolic contents, antioxidant activities, and α-glucosidase inhibitory activities of 40 fresh juices. The juice of Baccaurea polyneura showed the highest yield (74.17 ± 1.44%) and total soluble solids (32.83 ± 0.27 °Brix). The highest and lowest pH values were respectively measured from the juices of Dimocarpus longan (6.87 ± 0.01) and Averrhoa bilimbi (1.67 ± 0.67). The juice of Psidium guajava gave the highest total phenolic (857.24 ± 12.65 μg GAE/g sample) and vitamin C contents (590.31 ± 7.44 μg AAE/g sample). The juice of Phyllanthus acidus with moderate contents of total phenolics and vitamin C was found to exhibit the greatest scavenging (613.71 ± 2.59 μg VCEAC/g sample), reducing (2784.89 ± 3.93 μg TEAC/g sample), and α-glucosidase inhibitory activities (95.37 ± 0.15%). The juice of Barringtonia racemosa was ranked second in the activities and total phenolic content. Gallic and ellagic acids, which were quantified as the major phenolics of the respective juices, are suggested to be the main contributors to the antioxidant activities. The α-glucosidase inhibitory activity of the juices could be derived from myricetin and quercetin (that were previously reported as potent α-glucosidase inhibitors) in the hydrolyzed juice extracts. The juice of Syzygium samarangense, which was found to be highest in metal chelating activity (82.28 ± 0.10%), also was found to have these phenolics.

Revisiting "Vegetables" to combat modern epidemic of imbalanced glucose homeostasis

Vegetables have been part of human food since prehistoric times and are considered nutritionally necessary and good for health. Vegetables are rich natural resource of biological antioxidants and possess capabilities of maintaining glucose homeostasis. When taken before starch-rich diet, juice also of vegetables such as ridge gourd, bottle gourd, ash gourd, chayote and juice of leaves of vegetables such as radish, Indian Dill, ajwain, tropical green amaranth, and bladder dock are reported to arrest significantly the rise in postprandial blood glucose level. Juice of vegetables such as ash gourd, squash gourd, and tropical green amaranth leaves are observed to tone-down sweet-beverages such as sucrose, fructose, and glucose-induced postprandial glycemic excursion. On the other hand, juice of egg-plant and juice of leaves of Ceylon spinach, Joyweed, and palak are reported to augment starch-induced postprandial glycemic excursion; and juice of leaves of Ceylon spinach, Joyweed, and radish supplement to the glucose-induced postprandial glycemia. Vegetables possess multifaceted antihyperglycemic activities such as inhibition of pancreatic α-amylase and intestinal α-glucosidase, inhibition of protein-tyrosine phosphatase 1β in liver and skeletal muscles, and insulin mimetic and secretagogue activities. Furthermore, they are also reported to influence polyol pathway in favor of reducing development of oxidative stress, and consequently the development of diabetic complications. In the wake of emergence of modern maladaptive diet-induced hyperglycemic epidemic therefore, vegetables may offer cost-effective dietary regimen to control diet-induced glycemic over load and future development of diabetes mellitus. However, for vegetables have been reported to do both, mitigate as well as supplement to the diet-induced postprandial glycemic load, care is required in selection of vegetables when considered as medicament.

Compared with the intake of commercial vegetable juice, the intake of fresh fruit and komatsuna (Brassica rapa L. var. perviridis) juice mixture reduces serum cholesterol in middle-aged men: a randomized controlled pilot study

Background

Vegetables and fruits are rich in vitamins, minerals and, dietary fiber and contribute to the prevention and improvement of obesity and metabolic syndrome. However, inadequate intake of vegetable and fruit is a concern in Japan.

We therefore produced a juice mixture of fresh fruit and komatsuna (Brassica rapa L. var. perviridis: B. rapa) with the aim to investigate the effects of this juice mixture on anthropometric data, blood parameters, and dietary intake differences.

Methods

This study was performed as a single blind and randomized controlled trial. Subjects were 16 men (mean age, 46.4 ± 7.1 years), and they were divided into two groups (control group and intervention group). The intervention group consumed the juice mixture of fresh fruit and B. rapa. The control group consumed commercial vegetable juice. Subjects consumed juice twice a day throughout the weekday, for 4 weeks. We prepared both juices with an equivalent energy balance.

Results

Weight and body mass index (BMI) of the control group after 4 weeks were significantly increased compared with baseline values. Serum total cholesterol (T-Chol) and low-density lipoprotein cholesterol (LDL-Chol) of the intervention group after 4 weeks were significantly reduced compared with baseline values. Furthermore, intake of total vegetables and fruits were significantly increased compared with baseline values in both groups.

Conclusions

Both vegetable juices contributed to improved intake of total vegetables and fruit. Compared with the intake of commercial vegetable juice, the intake of fresh fruit and B. rapa juice is highly effective in reducing serum cholesterol. Short-term intake of fresh fruit and B. rapa juice was shown to enhance cholesterol metabolism.

Effects of a beetroot juice with high neobetanin content on the early-phase insulin response in healthy volunteers

Produce rich in phytochemicals may alter postprandial glucose and insulin responses by interacting with the pathways that regulate glucose uptake and insulin secretion in humans. The aims of the present study were to assess the phytochemical constituents of red beetroot juice and to measure the postprandial glucose and insulin responses elicited by either 225 ml beetroot juice (BEET), a control beverage matched for macronutrient content (MCON) or a glucose beverage in healthy adults. Beetroot juice was a particularly rich source of betalain degradation compounds. The orange/yellow pigment neobetanin was measured in particularly high quantities (providing 1·3 g in the 225 ml). A total of sixteen healthy individuals were recruited, and consumed the test meals in a controlled single-blind cross-over design. Results revealed a significant lowering of the postprandial insulin response in the early phase (0-60 min) (P < 0·05) and a significantly lower glucose response in the 0-30 min phase (P < 0·05) in the BEET treatment compared with MCON. Betalains, polyphenols and dietary nitrate found in the beetroot juice may each contribute to the observed differences in the postprandial insulin concentration.

Vegetables' juice influences polyol pathway by multiple mechanisms in favour of reducing development of oxidative stress and resultant diabetic complications

OBJECTIVE

Hyperglycemia induced generation of free radicals and consequent development of oxidative stress by polyol pathway is one of the crucial mechanisms stirring up development of diabetic complications. We evaluated influence of ten vegetables' juice on polyol pathway along with their antioxidant and antioxidative stress potentials.

MATERIALS AND METHODS

Aldose reductase activity was determined utilising goat lens and human erythrocytes. In goat lens, utilization of nicotinamine adenine dinucleotide phosphate (NADPH) and aldose reductase inhibition was assayed. In human erythrocytes, sorbitol formation was measured as an index of aldose reductase activity under normoglycemic and hyperglycemic conditions. Ability of juices in inhibiting oxidative damage to deoxyribose sugar and calf thymus DNA and inhibitory activity against hydrogen peroxide induced hemolysis of erythrocytes was also analysed. Phytochemical contents like total polyphenol, total flavonoid and total protein were measured to find their influence on biological activities.

RESULTS

Vegetables' juice displayed varying degrees of inhibitory potentials in mitigating NADPH dependent catalytic activity of aldose reductase in goat lens, accumulation of sorbitol in human erythrocytes under different glucose concentrations; Fenton-reaction induced oxidative damage to deoxyribose sugar, and calf thymus DNA. Substantial variations in vegetables phytochemicals content were also noticed in this study.

CONCLUSIONS

Vegetables' juice possesses potent activities in influencing polyol pathway by various mechanisms in favour of reducing development of oxidative stress independent of their inherent antioxidative properties. Juice of ivy gourd followed by green cucumber and ridge gourd were among the most potent for they displayed strong activities on various parameters analysed in this study. These vegetables' juice may become part of mechanism-based complementary antioxidant therapy to prevent development of diabetic complications.

Mitigation of starch-induced postprandial glycemic spikes in rats by antioxidants-rich extract of Cicer arietinum Linn. seeds and sprouts

Introduction:

Consumption of highly processed calories dense diet leads abrupt increase in postprandial blood glucose level, which in turn induces immediate oxidative stress. Postprandial hyperglycemia (PPHG) and resultant oxidative stress is one of the earliest detectable abnormalities in diabetes prone individuals, independent risk factor for development of cardiovascular disorders (CVD), a major pathophysiological link between diabetes and CVD and an important contributing factor in atherogenesis even in non-diabetic individuals. Therefore, dietary supplements mitigating PPHG spikes along with potent antioxidant activities may help decrease development of PPHG and oxidative stress induced pathogenesis.

Objectives:

The study evaluated free radicals scavenging, antioxidant properties and intestinal α-glucosidase inhibitory activity in methanol extract of two varieties of Cicer arietinum Linn viz. Bengal gram and Kabuli chana and green gram (Vigna radiata Linn. Wilczek) raw grains and their sprouts and studied their influence on starch-induced postprandial glycemic excursion in rats.

Materials and Methods:

Healthy grains were procured from local markets. Free radicals scavenging antioxidant and glucose-induced hemoglobin (Hb)-glycation inhibition activities were analyzed using standard in vitro procedures. In vitro antihyperglycemic activity was evaluated by assessing rat intestinal α-glucosidase inhibitory activity. Influence on starch-induced postprandial glycemic excursion in rats was studied by pre-treatment of rats with extracts.

Results:

Compared with raw seeds increase in total polyphenol and flavonoids concentration in green gram sprouts and Kabuli chana sprouts (KCs) were observed. Total protein concentrations in sprouts did not differ from non-sprouted grains. 2,2’- Azinobis (3-ethyl benzthiazoline-6-sulphonic acid) cation scavenging activity was more than twice in Bengal gram sprouts of (BGs) and KCs than their raw seeds. 2,2-diphenyl-1-picrylhydrazyl, hydrogen peroxide scavenging, nitro blue tetrazolium reducing and glucose-induced Hb-glycation inhibitory activity did not differ from non-sprouted raw grains. Increase in rat intestinal α-glucosidase inhibitory activity was observed in BGs and KCs. BGs significantly mitigated 1^st 30 min starch-induced postprandial glycemic excursions and reduced 2 h postprandial glycemic load.

Conclusion:

Sprouting leads dynamic changes in free radicals scavenging potentials and antioxidant activities in grains. Consumption of seeds as well as BGs before the starch-rich meal can significantly mitigate 1^st 30 min postprandial glycemic excursion and reduce 2 h postprandial glycemic burden.

Increase in the free radical scavenging capability of bitter gourd by a heat-drying process

Bitter gourd (Momordica charantia Linn.) is widely regarded as one of the best remedy foods for diabetes. The positive effect of bitter gourd on diabetes has been attributed in part to the remarkable free radical scavenging activity of its boiled water extract from sun-dried fruits. It is well known that a heat process significantly influences the antioxidant activity of fresh fruits. However, the heat drying processes of bitter gourd have not been studied so far. Here, we show that the free radical scavenging capability of bitter gourd extract significantly increases after the heat drying process, while the content of flavonoids and phenols, which are generally regarded as the main antioxidant components in bitter gourd, remain unaffected. Furthermore, the content of free amino acids and the total reducing sugar were found to decrease with increasing browning index, indicating the progression of the Maillard reaction, products of which are known to possess significant antioxidant activity. Therefore, it suggests that Maillard reaction products may be the main contributors to the increase in antioxidant capability. Finally, the bitter gourd extract with the higher antioxidant activity, was shown to manifest a corresponding higher proliferation activity on NIT-1 beta-cells. These results suggest that controllable conditions in the heat-drying processing of fresh bitter gourd fruit is of significance for enhancing the total free radical scavenging capacity, beta-cell proliferation activity and possibly the anti-diabetic activity of this fruit.

Mitigation of starch and glucose-induced postprandial glycemic excursion in rats by antioxidant-rich green-leafy vegetables' juice

Objective:

Consumption of green-leafy vegetables is being advocated beneficial for type 2 diabetes mellitus individuals possibly because they are cost effective source of potent biological antioxidants. This research analyzed various phytochemicals, free radicals scavenging antioxidant potentials and starch digesting enzymes inhibitory activities in fresh juice of nine green-leafy vegetables. Furthermore, this study also investigated influence of these vegetables juice on starch and glucose induced postprandial glycemic load.

Materials and Methods:

Phytochemical constituents, in vitro free radicals scavenging antioxidant and enzymes inhibitory activities were evaluated applying various reported methods. Post-prandial glycemic excursion was induced in rats pretreated with vegetables juice by oral administration of starch and glucose.

Results:

All the leafy vegetables juice displayed potent free radicals scavenging activities. Juice of amaranthus, rumex, palak and raphanus displayed potential anti-oxidative property by reducing H₂O₂ induced hemolysis in rats red blood cells RBCs. Ajwain and rumex juice showed pancreatic α-amylase inhibitory activity. Alternanthera, ajwain, methi, amaranthus and sowa leaves juice displayed intestinal α-glucosidase inhibitory activity. Juice of raphanus, ajwain and sowa significantly mitigated starch-induced postprandial glycemic load. Amaranthus leaves juice potently mitigated glucose-induced postprandial glycemic load and also reduced hemoglobin glycation induced by glucose in vitro.

Conclusions:

This investigation finds that juice of leafy vegetables is potent source of biological antioxidants. In addition, juice of raphanus, ajwain and sowa leaves possess capacity to mitigate starch induced postprandial glycemic burden and amaranthus leaves’ juice can reduce glucose induced postprandial glycemic excursion.