RESUMO
Accumulated evidence has focused on the use of natural polyphenolic compounds as nutraceuticals since they showed a wide range of bioactivities and exhibited protection against variety of age-related disorders. Polyphenols have variable potencies to interact, and hence alter the activities of various transporter proteins, many of them classified as anion transporting polypeptide-binding cassette transporters like multidrug resistance protein and p-glycoprotein. Some of the efflux transporters are, generally, linked with anticancer and antiviral drug resistance; in this context, polyphenols may be beneficial in modulating drug resistance by increasing the efficacy of anticancer and antiviral drugs. In addition, these effects were implicated to explain the influence of dietary polyphenols on drug efficacy as result of food-drug interactions. However, limited data are available about the influence of these components on uptake transporters. Therefore, the objective of this article is to review the potential efficacies of polyphenols in modulating the functional integrity of uptake transporter proteins, including those terminated the effect of neurotransmitters, and their possible influence in neuropharmacology.
RESUMO
BACKGROUND: Many of flavonoid rich natural products found to have a significant influence on postprandial hyperglycemia, a major risk factor for diabetic complications. Enhancement of insulinotropic gut hormones by inhibition of dipeptidyl peptidase-IV (DPP-IV) are among the newest strategies for treatments of Type 2 diabetes which thought to be the underlying action through which flavonoid can reduce postprandial hyperglycemia. AIM: This study aim was designed to investigate the potential role of standardized grape seed proanthocyanidin in controlling postprandial hyperglycemia by enhancing the regulatory incretin effect of gut hormones in response to oral and intraperitoneal (I.P) glucose load in healthy rats. MATERIALS AND METHODS: Five groups of animals each of six rats were used in this study, which was conducted in March 2013. Groups (II and V) treated with single oral dose of proanthocyanidin (50 mg/kg), Group III received single oral dose of sitagliptin (40 mg/kg) and Groups (I and IV) treated with vehicle serve as control groups. All treatments were given 30 min before oral or I.P glucose load. Blood glucose was estimated over 2 h duration at (0, 30, 60, 90, and 120) min from glucose load. RESULT: Both proanthocyanidin and sitagliptin significantly improve hyperglycemia induced by oral glucose load relative to control. While non-significant changes were achieved by proanthocyanidin after I.P glucose challenge compared to untreated control group. CONCLUSION: The result of this study indicated that proanthocyanidin may possess an enhancement of incretin effect of gut peptides, which could be responsible for some of its action on glucose homeostasis. This finding may provide an opportunity for further pharmacological studies using more specific models to clarify the possible action of proanthocyanidin as a natural DPP-IV inhibitor.
