Bioprospecting the Curculigoside-Cinnamic Acid-Rich Fraction from Molineria latifolia Rhizome as a Potential Antioxidant Therapeutic Agent.

Increasing evidence from both experimental and clinical studies depicts the involvement of oxidative stress in the pathogenesis of various diseases. Specifically, disruption of homeostatic redox balance in accumulated body fat mass leads to obesity-associated metabolic syndrome. Strategies for the restoration of redox balance, potentially by exploring potent plant bioactives, have thus become the focus of therapeutic intervention. The present study aimed to bioprospect the potential use of the curculigoside-cinnamic acid-rich fraction from Molineria latifolia rhizome as an antioxidant therapeutic agent. The ethyl acetate fraction (EAF) isolated from M. latifolia rhizome methanolic extract (RME) contained the highest amount of phenolic compounds, particularly curculigoside and cinnamic acid. EAF demonstrated glycation inhibitory activities in both glucose- and fructose-mediated glycation models. In addition, in vitro chemical-based and cellular-based antioxidant assays showed that EAF exhibited high antioxidant activities and a protective effect against oxidative damage in 3T3-L1 preadipocytes. Although the efficacies of individual phenolics differed depending on the structure and concentration, a correlational study revealed strong correlations between total phenolic contents and antioxidant capacities. The results concluded that enriched phenolic contents in EAF (curculigoside-cinnamic acid-rich fraction) contributed to the overall better reactivity. Our data suggest that this bioactive-rich fraction warrants therapeutic potential against oxidative stress-related disorders.

Effects of phenolic-rich extracts of Clinacanthus nutans on high fat and high cholesterol diet-induced insulin resistance.

BACKGROUND: Clinacanthus nutans is used traditionally in many parts of Asia to improve well-being, but there are limited studies on its efficacy. We explored the potential use of C. nutans for prevention of high fat and high cholesterol diet-(HFHC-) induced insulin resistance in rats. METHODS: The leaf of C. nutans was extracted using water (AL extract) and methanol (AML extract), and the extracts were fed to rats alongside the HFHC diet for 7 weeks, and compared with simvastatin. Oral glucose tolerance test, and serum insulin, retinol binding protein 4 (RBP4), adiponectin and leptin were measured. Homeostatic model assessment of insulin resistance (HOMA-IR) was computed, while transcriptional regulation of hepatic insulin signaling genes was also assessed. RESULTS: Glycemic response was higher in the HFHC group compared with the AL and AML groups, which also had lower serum RBP4, fasting glucose, insulin and HOMA-IR. Serum adiponectin levels were higher, while leptin levels were lower in the AML and AL groups compared to the HFHC group. There was upregulation of the Insulin receptor substrate, phosphotidyl inositol-3-phosphate, adiponectin receptor and leptin recetor genes, in comparison with the HFHC group. CONCLUSIONS: Overall, the results showed that the HFHC diet worsened metabolic indices and induced insulin resistance partly through transcriptional regulation of the insulin signaling genes. C.nutans, on the other hand, attenuated the metabolic effects and transcriptional changes induced by the HFHC diet. The results suggested that C.nutans may be a good source of functional ingredient for the prevention of insulin resistance.

Phenolic Rich Extract from Clinacanthus nutans Attenuates Hyperlipidemia-Associated Oxidative Stress in Rats.

Clinacanthus nutans is used as traditional medicine in Asia but there are limited scientific studies to support its use. In this study, the stem and leaf of C. nutans were extracted using solvents of differing polarities, and their antioxidant capacities were determined using multiple antioxidant assays. The water and aqueous methanolic leaf extracts were further fractionated and their antioxidant capacities and phenolic compositions were tested. Furthermore, the efficacies of the water and aqueous methanolic leaf extracts were tested against hyperlipidemia-induced oxidative stress in rats. Serum and hepatic antioxidant and oxidative stress markers were tested after feeding the rats with high fat diet together with the extracts or simvastatin for 7 weeks. The results indicated that both leaf extracts attenuated oxidative stress through increasing serum antioxidant enzymes activity and upregulating the expression of hepatic antioxidant genes. Multiple phenolic compounds were detected in the extracts and fractions of C. nutans, although protocatechuic acid was one of the most abundant and may have contributed significantly towards the bioactivities of the extracts. However, synergistic effects of different phenolics may have contributed to the overall bioactivities. C. nutans can be a good source of functional ingredients for the management of oxidative stress-related diseases.

Are bioactive-rich fractions functionally richer?

Plant bioresources are relied upon as natural, inexpensive, and sustainable remedies for the management of several chronic diseases worldwide. Plants have historically been consumed for medicinal purposes based on traditional belief, but this trend is currently changing. The growing interest in the medicinal properties of plant bioresources stems from concerns of side effects and other adverse effects caused by synthetic drugs. This interest has yielded a better understanding of the roles of plant bioactive compounds in health promotion and disease prevention, including the underlying mechanisms involved in such functional effects. The desire to maximize the potential of phytochemicals has led to the development of "rich fractions," in which extracts contain bioactive compounds in addition to elevated levels of the primary compound. Although a rich fraction effectively increases the bioactivity of the extract, the standardization and quality assurance process can be challenging. However, the supercritical fluid extraction (SFE) system is a promising green technology in this regard. Future clinical and pharmacological studies are needed to fully elucidate the implications of these preparations in the management of human diseases, thereby fostering a move toward evidence-based medicine.

Edible Bird's Nest Prevents High Fat Diet-Induced Insulin Resistance in Rats.

Edible bird's nest (EBN) is used traditionally in many parts of Asia to improve wellbeing, but there are limited studies on its efficacy. We explored the potential use of EBN for prevention of high fat diet- (HFD-) induced insulin resistance in rats. HFD was given to rats with or without simvastatin or EBN for 12 weeks. During the intervention period, weight measurements were recorded weekly. Blood samples were collected at the end of the intervention and oral glucose tolerance test conducted, after which the rats were sacrificed and their liver and adipose tissues collected for further studies. Serum adiponectin, leptin, F2-isoprostane, insulin, and lipid profile were estimated, and homeostatic model assessment of insulin resistance computed. Effects of the different interventions on transcriptional regulation of insulin signaling genes were also evaluated. The results showed that HFD worsened metabolic indices and induced insulin resistance partly through transcriptional regulation of the insulin signaling genes. Additionally, simvastatin was able to prevent hypercholesterolemia but promoted insulin resistance similar to HFD. EBN, on the other hand, prevented the worsening of metabolic indices and transcriptional changes in insulin signaling genes due to HFD. The results suggest that EBN may be used as functional food to prevent insulin resistance.

Effects of edible bird's nest on hippocampal and cortical neurodegeneration in ovariectomized rats.

The aim of this research is to investigate whether edible bird's nest (EBN) attenuates cortical and hippocampal neurodegeneration in ovariectomized rats. Ovariectomized rats were randomly divided into seven experimental groups (n = 6): the ovariectomy (OVX) group had their ovaries surgically removed; the sham group underwent surgical procedure similar to OVX group, but ovaries were left intact; estrogen group had OVX and received estrogen therapy (0.2 mg kg(-1) per day); EBN treatment groups received 6%, 3%, and 1.5% EBN, respectively. Control group was not ovariectomized. After 12 weeks of intervention, biochemical assays were performed for markers of neurodegeneration, and messenger ribonucleic acid (mRNA) levels of oxidative stress-related genes in the hippocampus and frontal cortex of the brain were analysed. Caspase 3 (cysteine-aspartic proteases 3) protein levels in the hippocampus and frontal cortex were also determined using western blotting. The results show that EBNs significantly decreased estrogen deficiency-associated serum elevation of advanced glycation end-products (AGEs), and they changed redox status as evidenced by oxidative damage (malondialdehyde content) and enzymatic antioxidant defense (superoxide dismutase and catalase) markers. Furthermore, genes associated with neurodegeneration and apoptosis were downregulated in the hippocampus and frontal cortex by EBN supplementation. Taken together, the results suggest that EBN has potential for neuroprotection against estrogen deficiency-associated senescence, at least in part via modification of the redox system and attenuation of AGEs.

Increased risk of insulin resistance in rat offsprings exposed prenatally to white rice.

White rice (WR) is a major staple food for people in developing countries and it may be responsible for the growing incidence of type 2 diabetes. Nonpregnant Female Sprague Dawley rats fed with WR or brown rice (BR) for 8 weeks were mated with age-matched male rats maintained on normal pellet over the same period. Offsprings were fed normal pellet after weaning until 8 weeks postdelivery. Rats fed with WR and their offsprings showed worsened oral glucose tolerance test, lower serum adiponectin levels, and higher weights, homeostatic model assessment of insulin resistance, serum retinol binding protein-4 levels, and leptin levels, compared with the normal and BR groups, suggesting an increased risk of insulin resistance. Furthermore, transcriptional levels of genes involved in insulin signaling showed different expression patterns in the liver, muscle, and adipose tissues of mothers and offsprings in both WR and BR groups. The results propose that the cycle of WR-induced insulin resistance in offsprings due to prenatal exposure, followed by their consumption of WR later in life may contribute to diabetes incidents. These findings are worth studying further.