Identification of peptides in blood following oral administration of ß-conglycinin to Wistar rats.

In this study, ß-conglycinin (100 mg/kg) was orally administered to Wistar rats in order to identify peptides that may be derived from the protein in the blood. Plasma samples taken from the tail vein up to 8 h after administration were analyzed by matrix-assisted laser desorption/ionization (MALDI) and liquid chromatography-time-of-flight (LC-TOF) mass spectrometry (MS). In total, 126 signals were detected by MALDI-MS. Among the signals, nine oligopeptides (SEL, KGPL, SILGA, DSEL, GDANI, SYFV, CLQSC, GEQPRPF, and LVINEGDA) were successfully identified as ß-conglycinin-derived peptides by LC-TOF/MS at a plasma concentration of 0.75-756 pmol/mL. The results demonstrated that ß-conglycinin could be the dietary source protein for the oligopeptides produced prior to entering the circulating bloodstream of rats.

Soybean glycinin impaired immune function and caused inflammation associated with PKC-ζ/NF-κb and mTORC1 signaling in the intestine of juvenile grass carp (Ctenopharyngodon idella).

Glycinin is a major protein and antinutritional factor of soybean. However, how dietary glycinin affect intestinal immune function of fish were largely unknown. In this study, we used juvenile grass carp as a model to investigate the impacts of glycinin on intestinal immune function of fish and involved mechanisms. We set three treatments including control, glycinin and glycinin + glutamine in this trial. For immune components, results revealed that compared with control group, glycinin group had lower acid phosphatase activities in the foregut, midgut and hindgut, lower C3 and C4 content, and lower mRNA abundances of IgM, IgZ, hepcidin, LEAP-2A, LEAP-2B and ß-defensin-1 in the midgut and hindgut rather than foregut of grass carp. For pro-inflammatory cytokines and relevant signaling, glycinin elevated mRNA abundances of IL-1ß, IL-8, IL-12p35, IL-12p40 and IL-17D in the midgut and IL-1ß, IFN-γ2, IL-6, IL-8, IL-12p35, IL-12p40 and IL-17D in the hindgut, and increased protein abundances of PKC-ζ and nuclear NF-κB p65 in the midgut and hindgut in comparison to control. For anti-inflammatory cytokines and relevant signaling, glycinin reduced mRNA abundances of TGF-ß1, TGF-ß2, IL-4/13B (rather than IL-4/13A), IL-10 and IL-11 in the midgut and hindgut, and reduced p-mTOR (Ser 2448), p-S6K1 (Thr 389) and p-4EBP1 (Thr 37/46) protein abundances in the midgut and hindgut rather than foregut. Co-administration of glutamine with glycinin could partially enhance intestinal function and reduce intestinal inflammation compared with glycinin treatment. Concluded, glycinin decreased intestinal immune components and caused intestinal inflammation associated with PKC-ζ/NF-κB and mTORC1 signaling.

Protein-based nanoparticles for drug delivery purposes.

Proteins represent a group of biopolymers with interesting properties to be employed as raw materials in the preparation of nanoparticles for drug delivery purposes. Due to the inherent properties of proteins (i.e., biodegradability, amphiphilic properties, etc.) the resulting nanoparticles can be considered as versatility platforms for a variety of applications. Moreover, some proteins possess a GRAS (Generally Recognized as Safe) status or are considered as excipients by different Regulatory Agencies. As result of this, the resulting nanoparticles and potential translation to clinic would be facilitated, compared to other materials (i.e., polymers). This review is focused on the main proteins employed in the preparation of nanoparticles as well as the procedures permitting their transformation into nanoparticles able of accommodating a high variety of bioactive compounds and drugs. Moreover, the review also provides examples of application of nanoparticles prepared from albumins, globulins, prolamins or macromolecules derived from proteins.

The dynamic process of dietary soybean ß-conglycinin in digestion, absorption, and metabolism among different intestinal segments in grass carp (Ctenopharyngodon idella).

The present study aimed to investigate the dynamic process of soybean ß-conglycinin in digestion, absorption, and metabolism in the intestine of grass carp (Ctenopharyngodon idella). Fish fed with 80 g ß-conglycinin/kg diet for 7 weeks, the intestinal digestive enzyme was extracted to hydrolyze ß-conglycinin in vitro, the free amino acid and its metabolism product contents in intestinal segments were analyzed. The present study first found that ß-conglycinin cannot be thoroughly digested by fish intestine digestive enzyme and produces new products (about 60- and 55-kDa polypeptides). The indigestible ß-conglycinin further caused the free amino acid imbalance, especially caused free essential amino acid deficiency in the proximal intestine but excess in the distal intestine. Moreover, these results might be partly associated with the effect of ß-conglycinin in amino acid transporters and tight junction-regulated paracellular pathway. Finally, dietary ß-conglycinin increased the content of amino acid catabolism by-product ammonia while decreased the amino acid anabolism product carnosine content in the proximal intestine and distal intestine. Thus, the current study first and systemically explored the dynamic process of ß-conglycinin in digestion, absorption, and metabolism, which further supported our previous study that dietary ß-conglycinin suppressed fish growth and caused intestine injure.

Dietary supplementation of soybean glycinin can alter the growth, carcass traits, blood biochemical indices, and meat quality of broilers.

The current research aimed to estimate the effect of dietary supplementation with glycinin isolated from soybeans on the growth performance, carcass traits, and selected blood metabolites of broiler chicks. A total of 200 1-wk-old broiler chicks were administered diets without glycinin (control treatment) or diets supplemented with 3 concentrations of soy glycinin (0.5, 1.0, or 1.5 g/kg of feed) for 6 wk. At the end of the feeding period, body weight was significantly higher in broiler chicks with glycinin supplementation (P < 0.05 or 0.01). The best values for body weight and body weight gain were recorded in the groups fed diets supplemented with 0.5 and 1.0 g glycinin/kg feed. Feed conversion was significantly (P < 0.05) improved in broilers in the glycinin-supplemented groups during the 1 to 6 and 3 to 6 wk growth periods. The highest value of breast yield was observed in broiler chicks supplemented with glycinin at a concentration of 1.0 g/kg of feed. Water-holding capacity increased with increasing concentrations of glycinin in the feed, up to 1.0%. Serum creatinine and urea concentrations decreased gradually (P < 0.01) as the concentration of glycinin in the feed increased. Broiler chicks receiving increasing concentrations of glycinin exhibited significantly (P < 0.01) lower levels of serum triglycerides, total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol. All meat samples from broiler chicks supplemented with glycinin had significantly higher catalase activities. These data suggest that feeding broiler chicks diets supplemented with soy glycinin (0.5 to 1.5 g/kg of feed) can improve feed conversion, enhance body weight gain, and lower abdominal fat.

Dietary ß-Conglycinin Modulates Insulin Sensitivity, Body Fat Mass, and Lipid Metabolism in Obese Otsuka Long-Evans Tokushima Fatty (OLETF) Rats.

The physiological effects of dietary ß-conglycinin (ß-CON), one of the major components of soy protein (SOY), were examined in an obese animal model. Prior studies show that ß-CON intake decreases plasma triglycerides and visceral adipose tissue weight, and increases plasma adiponectin in rodents. Since plasma adiponectin is known to affect both lipid and glucose metabolism, feeding a diet containing ß-CON could modulate insulin sensitivity. Therefore, we examined the effects of dietary ß-CON on insulin sensitivity and blood glucose levels, as well as lipid metabolism in obese Otsuka Long-Evans Tokushima Fatty (OLETF) rats (pre-symptomatic stage of type 2 diabetes mellitus). Male OLETF rats (6 weeks old) were fed diets containing 20% protein such as casein (CAS), CAS replaced with soy protein (SOY), or ß-CON at a proportion of 50% for 13 weeks. Fasting blood glucose levels were measured every 3 weeks, and an insulin tolerance test (ITT; 0.75 IU/kg body weight) was conducted at week 12. During the feeding period, fasting blood glucose was comparable among the groups. Insulin sensitivity measured by the ITT revealed that the SOY and ß-CON diets decreased blood glucose levels at 30 min after intraperitoneal insulin injection (vs. CAS diet). In addition, the ß-CON diet increased plasma adiponectin concentrations, hepatic gene expression of insulin receptor substrate (IRS) 2, and muscle gene expression of adiponectin receptor 1 (AdipoR1) and IRS1, and with a decrease in plasma insulin concentration. Finally, the ß-CON diet decreased the mesenteric adipose tissue weight and liver triglyceride concentration compared to the CAS diet. These results suggest that the metabolic effects of dietary ß-CON are mediated by increasing plasma adiponectin to increase insulin sensitivity and influence the hepatic lipid metabolism in obese OLETF rats.

Effects of glycinin and ß-conglycinin on growth performance and intestinal health in juvenile Chinese mitten crabs (Eriocheir sinensis).

This study investigates the effects of two soybean antigens (glycinin and ß-conglycinin) as an antinutritional substance in the diet on the growth, digestive ability, intestinal health and microbiota of juvenile Chinese mitten crabs (Eriocheir sinensis). The isonitrogenous and isolipidic diets contained two soybean antigens at two levels each (70 and 140 g/kg ß-conglycinin, 80 and 160 g/kg glycinin) and a control diet without ß-conglycinin or glycinin supplementation, and were used respectively to feed juvenile E. sinensis for seven weeks. Dietary inclusion of either glycinin or ß-conglycinin significantly reduced crab survival and weight gain. The crabs fed diets containing soybean antigens had higher malondialdehyde concentrations and lower catalase activities in the intestine than those in the control. The activities of trypsin and amylase in the intestine were suppressed by dietary ß-conglycinin and glycinin. Dietary glycinin or ß-conglycinin impaired the immunity and morphological structure of intestine, especially the peritrophic membrane. The mRNA expression of constitutive and inducible immune responsive genes (lipopolysaccharide-induced TNF-α factor and interleukin-2 enhancer-binding factor 2) increased while the mRNA expression of the main genes related to the structural integrity peritrophic membrane (peritrophin-like gene and peritrophic 2) significantly decreased in the groups with soybean antigen addition. Soybean antigen could also change the intestinal microbial community. The abundance of pathogenic bacteria (Ochrobactrum, Burkholderia and Pseudomonas) increased significantly in both soybean antigen groups. Although pathogenic bacteria Vibrio were up-regulated in the glycinin group, the abundance of Dysgonomonas that degraded lignocellulose and ameliorated the gut environment decreased in the glycinin group. This study indicates that existence of soybean antigens (glycinin or ß-conglycinin) could induce gut inflammation, reshape the community of gut microbiota, and cause digestive dysfunction, ultimately leading to impaired growth in crabs.

Hepatic Fat Content Is Associated with Fasting-Induced Fibroblast Growth Factor 21 Secretion in Mice Fed Soy Proteins.

Previous studies suggest that circulating fibroblast growth factor 21 (FGF21) levels are elevated in patients with fatty liver, while fasting-induced secretion of FGF21 is lower in obese patients. It has been reported that soy protein prevents hepatic fat accumulation and induces FGF21 secretion. The present study was designed to evaluate the response of circulating FGF21 levels to feeding and fasting in mice fed soy protein-rich diets. For this, C57BL/6J mice were distributed into control, high-fat high-sucrose (HFHS)-casein protein, HFHS-soy protein, and HFHS-ß-conglycinin diet groups. Plasma samples were collected after 10 and 11 wk either in dark periods with feeding conditions or light periods under fasting conditions using a crossover design. After a 12-wk period of feeding, HFHS-induced hepatic fat accumulation was significantly reduced in the groups fed HFHS-soy protein and HFHS-ß-conglycinin as compared to that in the HFHS-casein-fed group (p<0.05). Plasma FGF21 concentration was significantly higher in the dark/feeding periods in the HFHS-casein group (p<0.05), while in the HFHS-ß-conglycinin group it was higher in the light/fasting periods (p<0.05). The amount of mesenteric fat was significantly lower in the HFHS-ß-conglycinin group than in the HFHS-casein and HFHS-soy protein groups (p<0.01). The fasting-induced FGF21 secretion was significantly and negatively correlated with hepatic fat content (p<0.05). The present study revealed that hepatic fat accumulation was associated with lower fasting-induced FGF21 secretion, which was regulated better by dietary intake of soy protein. These results support the preventive effects of soy protein on central obesity.

Soya protein ß-conglycinin ameliorates fatty liver and obesity in diet-induced obese mice through the down-regulation of PPARγ.

Diets high in fat can result in obesity and non-alcoholic fatty liver disease (NAFLD). The improvement of obesity and NAFLD is an important issue. ß-Conglycinin, one of the soya proteins, is known to prevent hyperlipidaemia, obesity and NAFLD. Therefore, we aimed to investigate the effects of ß-conglycinin on the improvement of obesity and NAFLD in high-fat (HF) diet-induced obese (DIO) mice and clarify the mechanism underlying these effects in liver and white adipose tissue (WAT). DIO male ddY mice were divided into six groups: HF, medium-fat (MF) and low-fat (LF) groups fed casein, and HF, MF and LF groups in all of which the casein was replaced by ß-conglycinin. A period of 5 weeks later, the ß-conglycinin-supplemented group resulted in lower body weight, relative weight of subcutaneous WAT, and hepatic TAG content (P=0·001). Furthermore, ß-conglycinin suppressed the hepatic expression of Pparγ2 in the HF dietary group, sterol regulatory element-binding protein-1c and the target genes. The expressions of inflammation-related genes were significantly low in the epididymal and subcutaneous WAT from the mice fed ß-conglycinin compared with those fed casein in the HF dietary group. Moreover, the expressions of Pparγ1 and Pparγ2 mRNA were suppressed in subcutaneous WAT in the HF dietary group but not in epididymal WAT. The concentrations of insulin and leptin were low in the serum of the mice fed ß-conglycinin. In conclusion, ß-conglycinin effectively improved obesity and NAFLD in DIO mice, and it appears to be a promising dietary protein for the amelioration of NAFLD and obesity.

Identification of the 7S and 11S globulins as percutaneously sensitizing soybean allergens as demonstrated through epidermal application of crude soybean extract.

Cutaneous exposure to food allergens can predispose individuals to food allergies. Soybean, a major allergenic food, is an ingredient in various cosmetic products. However, the types of soybean proteins that are percutaneously sensitizing in humans or animal models remain unknown. In this study, BALB/c mice were dorsally shaved and epicutaneously exposed to a crude soybean extract including sodium dodecyl sulfate or distilled water alone. Specific IgEs secreted in response to 7S globulin (Gly m 5), 11S globulin (Gly m 6), Gly m 3, and Gly m 4 were measured using enzyme-linked immunosorbent assays or immunoblots. Exposure to soybean extract elicited the secretion of soybean-specific IgEs. Of the soybean proteins, 7S and 11S globulins acted as percutaneous sensitizers in 6/9 mice (67%). Additionally, IgE bound specifically and preferentially to the 7S globulin ß subunit. In conclusion, this is the first report to identify percutaneously sensitizing soybean allergens in a mouse model.

Dietary ß-conglycinin prevents acute ethanol-induced fatty liver in mice.

Alcoholic fatty liver is the earliest stage of alcohol-induced liver disease leading to liver cirrhosis. ß-Conglycinin, one of the soy proteins, is known to prevent non-alcoholic fatty liver, hyperlipidemia and obesity. Therefore, we examined whether ß-conglycinin feeding has an effect on the prevention of acute ethanol-induced fatty liver in mice. Male C57BL/6J mice were fed with 20 energy% ß-conglycinin or casein for 4 weeks prior to ethanol administration and were then given ethanol or glucose, as a control, by gavage. Ethanol significantly increased liver triglyceride (TG) in mice fed casein due to the activation of peroxisome proliferator-activated receptor (PPAR) γ2, a nuclear transcription factor known for regulating lipid metabolism and de novo lipogenesis. The liver TG of ethanol-administered ß-conglycinin-fed mice was significantly lower than that in those fed casein, although ethanol increased the amount of liver TG in mice fed ß-conglycinin. The increased levels of PPARγ2 protein and its target gene CD36 in response to an ethanol were not observed in mice fed ß-conglycinin. Moreover, ß-conglycinin decreased the basal expression of de novo lipogenesis-related genes such as stearoyl-CoA desaturase-1, and therefore, the expressions of these genes were lower in the ethanol-administered ß-conglycinin-fed mice than in the casein-fed mice. In conclusion, ß-conglycinin supplementation appears to prevent the development of fatty liver in mice caused by ethanol consumption via the suppression of alcohol-induced activation of PPARγ2 and the downregulation of the basal expression of de novo lipogenesis.

Rational identification of a novel soy-derived anxiolytic-like undecapeptide acting via gut-brain axis after oral administration.

Here we found that the chymotryptic digest of soy ß-conglycinin, a major storage protein, exhibited anxiolytic-like effects in mice. We then searched for anxiolytic-like peptides in the digest. Based on a comprehensive peptide analysis of the chymotryptic digest by high performance liquid chromatograph connected to an LTQ Orbitrap mass spectrometer and the structure-activity relationship of known peptides, we explored anxiolytic-like peptides present in the digest. FLSSTEAQQSY, which corresponds to 323-333 of the ß-conglycinin α subunit [ßCGα(323-333)] emerged as a candidate. Oral administration of synthetic ßCGα(323-333) exhibited anxiolytic-like effects in the elevated plus-maze and open-field test in male mice. Orally administered ßCGα(323-333) exhibited anxiolytic-like effects in sham-operated control mice but not in vagotomized mice. In addition, oral administration of ßCGα(323-333) increased the expression of c-Fos, a marker of neuronal activity, in the nucleus of the solitary tract, which receives inputs from the vagus nerve. These results suggest that the anxiolytic-like effects were mediated by the vagus nerve. The anxiolytic-like effects of ßCGα(323-333) were also blocked by antagonists of the serotonin 5-HT1A, dopamine D1 and GABAA receptors. However ßCGα(323-333) had no affinity for these receptors, suggesting it stimulates the release of endogenous neurotransmitters to activate the receptors. Taken together, a soy-derived undecapeptide, ßCGα(323-333), may exhibit anxiolytic-like effects after oral administration via the vagus nerve and 5-HT1A, D1 and GABAA systems.

Addition of an Enzymatic Hydrolysate of Bovine Globulins to Bread and Determination of Hypotensive Effects in Spontaneously Hypertensive Rats.

The aim of this study was to develop bread containing a papain hydrolysate of bovine α- and ß-globulins (GPH) with in vitro and in vivo antihypertensive activities. The physical characteristics of the formulated bread were assessed over a six day period and results suggested that the overall quality and acceptance of bread was not affected by the inclusion of GPH at a concentration of 4% (w/w). Bright field light microscopy and confocal scanning laser microscopy images were used to visualize the main ingredients of the bread. In addition, the antihypertensive activity of the bread was assessed in spontaneously hypertensive rats (SHRs) over a 24 h period where a maximum significant decrease in systolic blood pressure of 36.2 ± 1.9 mmHg was observed 8 h after oral administration. Results demonstrate that the antihypertensive activity of GPH was resistant to the baking process and shows potential for use as a functional antihypertensive ingredient.

Soybean ß-Conglycinin Prevents Age-Related Hearing Impairment.

Obesity-related complications are associated with the development of age-related hearing impairment. ß-Conglycinin (ß-CG), one of the main storage proteins in soy, offers multiple health benefits, including anti-obesity and anti-atherosclerotic effects. Here, to elucidate the potential therapeutic application of ß-CG, we investigated the effect of ß-CG on age-related hearing impairment. Male wild-type mice (age 6 months) were randomly divided into ß-CG-fed and control groups. Six months later, the body weight was significantly lower in ß-CG-fed mice than in the controls. Consumption of ß-CG rescued the hearing impairment observed in control mice. Cochlear blood flow also increased in ß-CG-fed mice, as did the expression of eNOS in the stria vascularis (SV), which protects vasculature. ß-CG consumption also ameliorated oxidative status as assessed by 4-HNE staining. In the SV, lipofuscin granules of marginal cells and vacuolar degeneration of microvascular pericytes were decreased in ß-CG-fed mice, as shown by transmission electron microscopy. ß-CG consumption prevented loss of spiral ganglion cells and reduced the frequencies of lipofuscin granules, nuclear invaginations, and myelin vacuolation. Our observations indicate that ß-CG ameliorates age-related hearing impairment by preserving cochlear blood flow and suppressing oxidative stress.

Soybean ß-conglycinin improves carbohydrate and lipid metabolism in Wistar rats.

The effects of dietary soybean ß-conglycinin on lipid metabolism and energy consumption were studied in Wistar adult rats. Rats were fed, a diet containing casein (control group) or ß-conglycinin (ß-conglycinin group), for 4 weeks. Carbohydrate consumption was higher and fat consumption was lower in the ß-conglycinin group than in the control group, whereas the total energy consumption was the same between the two groups. Serum adiponectin was higher in the ß-conglycinin group than in the control group. Serum triacylglycerol levels in the ß-conglycinin group were significantly lower than those in the control group. The secretion rate of triacylglycerols from the liver after the administration of tyloxapol, an inhibitor of lipolysis, was significantly lower in the ß-conglycinin group than in the control group. These results suggest the possibility that ß-conglycinin exerts hypolipidemic effects through an acceleration in carbohydrate consumption associated with an increase in adiponectin in rats.

Prevention of osteoporosis by oral administration of phytate-removed and deamidated soybean ß-conglycinin.

Phytate-removed and deamidated soybean ß-conglycinin (PrDS) prepared by ion-exchange resins was supplemented to be 4% in the diet administered to ovariectomized rats to investigate its preventive effect on osteoporosis. The apparent calcium absorption rate decreased following ovariectomy and was not replenished by oral administration of phytate-removed soybean ß-conglycinin (PrS) or casein. On the other hand, administration of PrDS restored the calcium absorption rate to the same level as the sham group. Markers of bone resorption, such as serum parathyroid hormone (PTH) and urinary deoxypyridinoline (DPD), increased, and the bone mineral density and breaking stress decreased following ovariectomy. However, PrDS supplementation suppressed the changes caused by the decrease in calcium absorption from the small intestine. Therefore, PrDS supplementation shows promise for the prevention of postmenopausal osteoporosis.

Development of a novel transgenic rice with hypocholesterolemic activity via high-level accumulation of the α' subunit of soybean ß-conglycinin.

Soybean 7S globulin, known as ß-conglycinin, has been shown to regulate human plasma cholesterol and triglyceride levels. Furthermore, the α' subunit of ß-conglycinin has specifically been shown to possess low-density lipoprotein (LDL)-cholesterol-lowering activity. Therefore, accumulation of the α' subunit of ß-conglycinin in rice seeds could lead to the production of new functional rice that could promote human health. Herein, we used the low-glutelin rice mutant 'Koshihikari' (var. a123) and suppressed its glutelins and prolamins, the major seed storage proteins of rice, by RNA interference. The accumulation levels of the α' subunit in the lines with suppressed glutelin and prolamin levels were >20 mg in 1 g of rice seeds, which is considerably higher than those in previous studies. Oral administration of the transgenic rice containing the α' subunit exhibited a hypocholesterolemic activity in rats; the serum total cholesterol and LDL cholesterol levels were significantly reduced when compared to those of the control rice (var. a123). The cholesterol-lowering action by transgenic rice accumulating the α' subunit induces a significant increase in fecal bile acid excretion and a tendency to increase in fecal cholesterol excretion. This is the first report that transgenic rice exhibits a hypocholesterolemic activity in rats in vivo by using the ß-conglycinin α' subunit.

Role of soybean ß-conglycinin subunits as potential dietary allergens in piglets.

ß-Conglycinin, a major seed-storage protein in soybeans, is one of the primary antigenic proteins responsible for soybean-meal hypersensitivity in weaned piglets. The protein is a heterotrimer composed of subunits α, α' and ß. It is currently unknown which of the ß-conglycinin subunits are allergenic for piglets. The aim of this study was to identify potential allergenic subunits of ß-conglycinin for soybean sensitive piglets and to characterise these subunits by immunoglobulin (Ig) G and E immunoblotting, ELISA, 'skin prick' and whole blood histamine-release testing. The IgG and IgE binding capabilities of the purified α, α' and ß subunits of ß-conglycinin were determined by immunoblot analysis and ELISA with sera from ß-conglycinin sensitised piglets. Skin prick testing and whole blood histamine release testing were also performed to detect the activated effector cell response to specific allergens. Specific IgG and E antibodies were identified that recognised all three subunits of ß-conglycinin in the sera of ß-conglycinin sensitised piglets. All three subunits of ß-conglycinin elicited positive skin test and specific histamine release responses from the whole blood of ß-conglycinin sensitised piglets. These results suggest that all three ß-conglycinin subunits are potential allergens for piglets.

Anti-hyperglycaemic globulins from selected Cucurbitaceae seeds used as antidiabetic medicinal plants in Africa.

BACKGROUND: The recent epidemic of diabetes mellitus (DM) in Africa, coupled with rampant poverty, is an indication of the urgent need to develop new efficacious, cheaper and more available drugs to face this growing public health challenge. A number of plants products among which the protein-rich Cucurbitaceae seeds are commonly used in traditional medicine with increasing acclaimed efficacy against DM. The aim of this study was to analyse and evaluate the hypoglycaemic activity of storage proteins of five species of Cucurbitaceae, which include Telfairia occidentalis, Citrullus lanatus, Lagenaria siceraria, Cucumeropsis mannii and Cucurbita moschata. METHODS: The different families of storage proteins were extracted following differential solubility, and their contents were estimated using the Bradford method. The analysis of these proteins was done by electrophoresis in non-denaturing and denaturing conditions. The evaluation of hypoglycaemic properties of various globulins extracted was performed on male Wistar rats by the oral glucose tolerance test. RESULTS: The results showed that among the proteins extracted, globulins constitute the most abundant class of storage proteins in all five species selected. Citrullus lanatus and Cucurbita moschata presented the highest levels of globulin (275.34 and 295.11 mg/g dry matter, respectively). The results of electrophoresis showed that all species possess acidic and neutrals albumins and globulins, with molecular weight of protein subunits ranging from 6.36-44.11 kDa for albumins, 6.5-173.86 kDa for globulins and 6.5-49.66 kDa for glutelins. The 6.36 kDa of albumin subunit protein and the 6.5 kDa of globulin subunit protein were present in all the species. The oral glucose tolerance test showed that the globulins of the seeds of all species except Cucumeropsis mannii caused significant drop in blood sugar (88 - 137.80%, compared to the controls, p<0.05). CONCLUSIONS: These findings showed that the selected Cucurbitaceae seeds contained globulins with significant anti-hyperglycaemic activity. It is therefore highly encouraged to pursue investigations towards development of peptide-drugs and/or phytomedicines from these bioactive proteins which could be used as affordable alternative therapy against DM.

Soy ß-conglycinin (7S globulin) reduces plasma and liver cholesterol in rats fed hypercholesterolemic diet.

The aim of this study was to examine the comparative hypocholesterolemic effect of soybean 7S fraction in rats fed a high-cholesterol diet. Soybean 7S globulin (ß-conglycinin) was administered orally once a day to rats, and the effects were measured after 28 days. Wistar rats were divided into four groups: standard diet (STD) (casein alone), hypercholesterolemic (HC) diet (STD plus 1 g/100 g cholesterol and 0.5 g/100 g cholic acid), HC+7S(1) diet (HC diet plus 200 mg of 7S/kg of body weight/day), and HC+7S(2) diet (HC diet plus 300 mg of 7S/kg of body weight/day). Food intake, weight gain, animals' growth, and feeding efficiency ratio were similar among the STD and three HC groups, indicating that these parameters were not affected by treatments. Animals that had received different doses of soybean 7S globulin had lower total cholesterol (TC), triglycerides (TG), and low-density lipoprotein (LDL)/high-density lipoprotein (HDL) ratio in serum and lower levels of hepatic TC and TG than those fed only the HC diet. The atherogenic indexes of HC+7S(1) and HC+7S(2) groups were 40% and 55% lower than that of the HC group, respectively. The results showed that the oral daily administration of ß-conglycinin in the diet to HC rats, at between 1.85% and 2.75% of total ingested protein, promotes the reduction of TC, LDL-cholesterol, and TG and an increase in HDL-cholesterol in the plasma, besides a small but significant reduction in cholesterol and TG levels in the liver of the animals as well as a reduced atherogenic index.