Effects of the aqueous extracts of Rhodamnia cinerea on metabolic indices and sorbitol-related complications in Type 2 diabetic rats

There is growing interest in the use of plant bioresources for managing Type 2 diabetes. In this study, Rhodamnia cinerea, which is used traditionally to manage diseases in Malaysia, was explored for its antidiabetic effects. Type 2 diabetic rats were managed for 4 weeks using aqueous extract of R. cinerea or quercetin. Weights and fasting glucose were measured weekly, while serum lipid profiles, insulin, antioxidant status, urea, creatinine and liver enzymes were assayed at the end. Sorbitol contents, antioxidant capacities and aldose reductase activities of the kidney, lens and sciatic nerve were also assessed. The results showed that the aqueous extract of R. Cinerea mainly contained Myricitrin and it reduced glycemia (p>0.05), lipid profiles (p<0.05), F2-isoprostanes (p<0.05) and overall metabolic condition of type 2 diabetic rats. R. cinerea also attenuated sorbitol contents of the nerve (p<0.05) and kidney (p<0.05), partly through regulating the activity of aldose reductase (p<0.05 for nerve) and sorbitol dehydrogenase (p<0.05 for kidney) in comparison with diabetic untreated group. Quercetin is a known aldose reductase inhibitor and can improve several metabolic indices related to Type 2 diabetes. In this study, the results of R. cinerea were comparable to or better than those of quercetin, suggesting that R. cinerea extract can be a good candidate for managing Type 2 diabetes and its complications related to sorbitol accumulation

Ethyl acetate extract of germinated brown rice attenuates hydrogen peroxide-induced oxidative stress in human SH-SY5Y neuroblastoma cells: role of anti-apoptotic, pro-survival and antioxidant genes

Background There are reports of improved metabolic outcomes due to consumption of germinated brown rice (GBR). Many of the functional effects of GBR can be linked to its high amounts of antioxidants. Interestingly, dietary components with high antioxidants have shown promise in the prevention of neurodegenerative diseases like Alzheimer’s disease (AD). This effect of dietary components is mostly based on their ability to prevent apoptosis, which is believed to link oxidative damage to pathological changes in AD. In view of the rich antioxidant content of GBR, we studied its potential to modulate processes leading up to AD. Methods The total phenolic content and antioxidant capacity of the ethyl acetate extract of GBR were compared to that of brown rice (BR), and the cytotoxicity of both extracts were determined on human SH-SY5Y neuronal cells using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) Assay. Based on its higher antioxidant potentials, the effect of the GBR extract on morphological changes due to hydrogen peroxide (H2O2)-induced oxidative damage in human SH-SY5Y neuronal cells was examined using inverted light microscope and fluorescence microscope by means of acridine orange-propidium iodide (AO/PI) staining. Also, evaluation of the transcriptional regulation of antioxidant and apoptotic genes was carried out using Multiplex Gene Expression System. Results The ethyl acetate extract of GBR had higher total phenolic content and antioxidant capacity compared to BR. The cytotoxicity results showed that GBR extract did not cause any damage to the human SH-SY5Y neuronal cells at concentrations of up to 20 ppm, and the morphological analyses showed that the GBR extract (up to 10 ppm) prevented H2O2-induced apoptotic changes in the cells. Furthermore, multiplex gene expression analyses showed that the protection of the cells by the GBR extract was linked to its ability to induce transcriptional changes in antioxidant (SOD 1, SOD 2 and catalase) and apoptotic (AKT, NF-Kβ, ERK1/2, JNK, p53 and p38 MAPK) genes that tended towards survival. Conclusions Taken together, the results of our study showed that the ethyl acetate extract of GBR, with high antioxidant potentials, could prevent H2O2-induced oxidative damage in SH-SY5Y cells. The potential of GBR and its neuroprotective mechanism in ameliorating oxidative stress-related cytotoxicity is therefore worth exploring further

Effects of germinated brown rice and its bioactive compounds on the expression of the peroxisome proliferator-activated receptor gamma gene

Dysregulated metabolism is implicated in obesity and other disease conditions like type 2 diabetes mellitus and cardiovascular diseases, which are linked to abnormalities of peroxisome proliferator-activated receptor gamma (PPARγ). PPARγ has been the focus of much research aimed at managing these diseases. Also, germinated brown rice (GBR) is known to possess antidiabetic, antiobesity and hypocholesterolemic effects. We hypothesized that GBR bioactive compounds may mediate some of the improvements in metabolic indices through PPARγ modulation. Cultured HEP-G2 cells were treated with 50 ppm and 100 ppm of extracts from GBR (GABA, ASG and oryzanol) after determination of cell viabilities using MTT assays. Results showed that all extracts upregulated the expression of the PPARγ. However, combination of all three extracts showed downregulation of the gene, suggesting that, in combination, the effects of these bioactives differ from their individual effects likely mediated through competitive inhibition of the gene. Upregulation of the gene may have therapeutic potential in diabetes mellitus and cardiovascular diseases, while its downregulation likely contributes to GBR’s antiobesity effects. These potentials are worth studying further

Effects of germinated brown rice on the expression of alzheimer’s disease biomarkers in high fat/cholesterol diet-induced neurodegenerative changes

Excessive amyloid-β (Aβ) accumulation has been strongly implicated in Alzheimer’s disease (AD). Various experiments utilized diet-induced animal models of atherosclerosis/hypercholesterolemia and diabetes to investigate the convergent mechanisms between metabolic disorders and sporadic AD. While saturated fats and high cholesterol levels are associated with an increased risk of AD, consumption of certain dietary components may exert a protective role. Herewith, the effects of germinated brown rice (GBR) extract in a high fat/cholesterol diet (HFCD)-induced sporadic model of AD were investigated for 24 weeks in adult Sprague-Dawley rats. Rats were divided into 7 groups (n=70): Normal control, HFCD, HFCD with Donepezil (1.5 mg/kg BW), HFCD with Simvastatin (10 mg/kg BW), HFCD with Probucol (25 mg/kg BW), HFCD with GBR-100 (100 mg/kg BW), and HFCD with GBR-200 (200 mg/kg BW). Biochemical assays, mRNA levels of inflammatory-related genes and markers of neurodegeneration in the hippocampus and frontal cortex were analyzed. GBR regulated inflammatory genes such as CRP, PPAR-γ and TNF-α, and the expressions were significantly different from HFCD group. HFCD-fed rats also exhibited increased Aβ levels and altered expressions of proteins involved in Aβ generation, degradation and clearance. In terms of these biomarkers, GBR groups exhibited significant differences when compared to HFCD group, and the effects were comparable with the normal and some of the drug control groups. Taken together, the results suggested that GBR had the potential to attenuate HFCD diet-induced neurodegenerative changes, likely due to reduced brain inflammation in addition to modulation of Aβ processing and metabolism pathway

Nanoemulsified gamma-oryzanol rich fraction blend regulates hepatic cholesterol metabolism and cardiovascular disease risk in hypercholesterolaemic rats

We have reported that a bioactive-rich fraction, called EORY, from a combination of supercritical fluid-extracted rice bran oil and palm oil has abundant gamma-oryzanol, tocopherols and tocotrienol. Moreover, EORY has balanced composition of polyunsaturated:saturated fatty acids, with the potential for hypocholesterolaemic and antioxidant effects. However, the bioactive compounds in EORY are lipophilic and therefore pose bioavailability problems. This study evaluated the cardioprotective effects of orally-administered EORY emulsion and its nanoemulsion (NEORY) on diet-induced hypercholesterolaemic rats. NEORY reduced body weight gain, heart weight, lipid parameters and oxidised LDL, and improved HDL better than EORY and simvastatin. NEORY also significantly increased hepatic mRNA expression of HMGCoA reductase, apolipoprotein A1 and LDLR, and lowered apolipoprotein B and LPL. The effects of NEORY on lipid parameters, lipid peroxidation markers and hepatic cholesterol metabolism suggested that it could regulate the risk of cardiovascular disease, possibly due to increased absorption of gamma-oryzanol, tocopherols and tocotrienol

Antioxidative effects of germinated brown rice-derived extracts on H2O2-induced oxidative stress in HepG2 cells

The antioxidant properties of germinated brown rice (GBR) are likely mediated by multiple bioactives. To test this hypothesis, HepG2 cells pretreated with GBR extracts, rich in acylated steryl glycoside (ASG), gamma amino butyric acid GABA), phenolics or oryzanol, were incubated with hydrogen peroxide (H2O2) and their hydroxyl radical (OH•) scavenging capacities and thiobarbituric acid-reactive substances (TBARS) generation were evaluated. Results showed that GBR-extracts increased OH• scavenging activities in both cell-free medium and posttreatment culture media, suggesting that the extracts were both direct- and indirect-acting against OH•. The levels of TBARS in the culture medium after treatment were also reduced by all the extracts. In addition, H2O2 produced transcriptional changes in p53, JNK, p38 MAPK, AKT, BAX, and CDK4 that were inclined towards apoptosis, while GBR-extracts showed some transcriptional changes (upregulation of BAX and p53) that suggested an inclination for apoptosis although other changes (upregulation of antioxidant genes, AKT, JNK, and p38 MAPK) suggested that GBR-extracts favored survival of the HepG2 cells. Our findings show that GBR bioactive-rich extracts reduce oxidative stress through improvement in antioxidant capacity, partly mediated through transcriptional regulation of antioxidant and prosurvival genes

Polyphenol-rich ethyl acetate fraction isolated from Molineria latifolia ameliorates insulin resistance in experimental diabetic rats via IRS1/AKT activation

This study aimed to evaluate the effect of ethyl acetate fraction (EAF) isolated from Molineria latifolia rhizome as dietary interventions for type 2 diabetes mellitus (T2DM) and its underlying molecular mechanisms in vivo. Experimental rats were induced by high fat diet feeding coupled with combined exposure to streptozotocin and nicotinamide. Treatment with EAF improved glucose tolerance and lipid profiles, but the insulin secretion was unaltered. Gene expression analyses on insulin/adipocytokine signalling-related genes demonstrated tissue-specific transcriptional responses. In skeletal muscle and liver tissues, Socs1, Tnf and Mapk8 showed consistent transcript regulation. Furthermore, hepatic translational analyses revealed sensitization on proximal insulin signalling, with reduced expression of IRS1 serine phosphorylation, increased IRS1 tyrosine phosphorylation and increased phospho-AKT (Ser473). The present findings suggested that EAF exerted its effect by modulating insulin signalling, potentially via IRS1/AKT activation. The pharmacological attributes of EAF may implicate its potential therapeutic applications for diabetes management

Polyphenol-rich ethyl acetate fraction of Molineria latifolia rhizome restores oxidant-antioxidant balance by possible engagement of KEAP1-NRF2 and PKC/NF-κB signalling pathways

The present study examined the potential of ethyl acetate fraction (EAF) isolated from Molineria latifolia rhizome to modulate the oxidant-antioxidant balance in high fat diet and nicotinamide/streptozotocin-induced diabetic rats. Administration with EAF ameliorated systemic antioxidant status- and oxidative stress-related parameters without affecting the renal and liver functions in the diabetic rats. Further analyses on adipose, muscle and liver tissues demonstrated differing ability to scavenge free radicals and protection against lipid peroxidation. Transcriptional changes proposed concerted modulation of both KEAP1-NRF2 and PKC/NF-κB signallings in tissue-specific manner. Qualitative profiling of compounds present in EAF was analysed by non-targeted HPLC-QTOF mass spectrometry. A total of 23 unique mass signals were detected in EAF. Putative identification revealed a mixture of naturally occurring polyphenols ranging from cinnamic acid-, benzoic acid- and flavonoid-derived groups. Overall, the study demonstrated potential application of EAF to reinstate diabetes-induced oxidant-antioxidant imbalance by potentially modulating the NRF2–NF-κB signalling axis

Characterization of rice bran wax policosanol and its nanoemulsion formulation

Policosanol, a mixture of long-chain alcohols found in animal and plant waxes, has several biological effects; however, it has a bioavailability of less than 10%. Therefore, there is a need to improve its bioavailability, and one of the ways of doing this is by nanoemulsion formulation. Different droplet size distributions are usually achieved when emulsions are formed, which solely depends on the preparation method used. Mostly, emulsions are intended for better delivery with maintenance of the characteristics and properties of the leading components. In this study, policosanol was extracted from rice bran wax, its composition was determined by gas chromatography mass spectrophotometry, nanoemulsion was made, and the physical stability characteristics were determined. The results showed that policosanol nanoemulsion has a nanosize particle distribution below 100 nm (92.56–94.52 nm), with optimum charge distribution (-55.8 to -45.12 mV), pH (6.79–6.92) and refractive index (1.50); these were monitored and found to be stable for 8 weeks. The stability of policosanol nanoemulsion confers the potential to withstand long storage times

Estrogen receptor modulatory effects of germinated brown rice bioactives in the uterus of rats through the regulation of estrogen-induced genes

PURPOSE: The expression of genes regulated by estrogen in the uterus was studied in ovariectomized (OVX) rats treated with germinated brown rice (GBR) bioactives, and compared to Remifemin or estrogen at different doses to identify the regulation of these genes in the uterus and their molecular mechanisms. METHODS: Rats were treated orally with GBR bioactives (phenolics), acylated steryl glucosides (ASG), γ-amino butyric acid (GABA), and γ-oryzanol (ORZ) at 100 and 200 mg/kg, Remifemin (REM) at 10 mg/kg and 20 mg/kg, or estrogen (EST) at 0.2 mg/kg. Ribonucleic acid (RNA) was extracted from the uterus, and messenger (m)RNA expression of selected genes encoding estrogen receptor-beta (ER-β), calcium-binding protein (CaBP9k), complement protein (C3), heat shock protein 70 kDa (HSP70), and interleukin (IL)-4 receptor were quantified. Similarly, serum steroid hormone concentration was monitored at 2, 4, and 8 weeks after treatments. ER-β antibody binding to the uterus sections was also studied using immunohistochemistry. RESULTS: The group treated with EST (0.2 mg/kg) upregulated ER-β, C3, and IL-4 receptor genes compared to other groups (P0.05) in the progesterone levels in the OVX untreated group compared to the sham and other treated groups. There was a significant increase at 8 weeks in the level of FSH (P0.05) in serum luteinizing hormone (LH) between the OVX untreated group and other groups. The sham and GBR phenolics treated group showed ER-β reactivity at the glandular epithelium, while the group treated with EST showed immunoreactivity at the glandular, luminal, and stromal epithelium. CONCLUSION: GBR phenolics moderately regulate the expression of ER-β, HSP70, and IL-4 receptor genes, and gave a positive immunoreaction to ER-β antigen in the uterus. ASG regulates the expression of CaBP9k and IL-4 receptor genes, and ORZ regulates the expression of the CaBP9k gene, while GABA at 100 mg/kg regulates the expression of the HSP70 gene. GBR and its bioactives might have an effect on estrogen-regulated genes in the uterus of rats