Abstract.Propolis contains a variety of chemical compounds, including polyphenols, flavonoids, phenolic aldehydes, amino acids and vitamins, and presents numerous biological and pharmacological properties. The aim of the present study was to evaluate the effect of propolis on blood examination data in patients with type 2 diabetes. In the double-blind, 8-week randomized controlled study, 80 patients with type 2 diabetes were enrolled. Patients were randomly assigned to receive Brazilian green propolis (226.8 mg/day for 8 weeks) (n=41) or the placebo (n=39). The primary endpoint was to detect changes in blood examination data associated with metabolic disorders in patients suffering from diabetes mellitus, including the homeostasis model assessment of insulin resistance (HOMA-IR), uric acid and estimated glomerular filtration rate (eGFR) from baseline to the end of this study. The value of HOMA-IR was not significantly changed by the 8-week administration of propolis or placebo from the baseline data. Values of blood uric acid and eGFR in patients taking the placebo became worse at 8 weeks compared to the baseline, whereas this did not occur in patients consuming Brazilian green propolis. However, HOMA-IR was not improved by propolis intake. A randomized, controlled 8-week trial suggests that Brazilian green propolis (226.8 mg/day) prevents patients with type 2 diabetes from developing worse blood uric acid and eGFR.

Disorder of blood pressure control causes serious diseases in the cardiovascular system. This review focuses on the anti-hypertensive action of quercetin, a flavonoid, which is one of the polyphenols characterized as the compounds containing large multiples of phenol structural units, by varying the values of various blood pressure regulatory factors, such as vascular compliance, peripheral vascular resistance, and total blood volume via anti-inflammatory and anti-oxidant actions. In addition to the anti-inflammatory and anti-oxidant actions of quercetin, we especially describe a novel mechanism of quercetin’s action on the cytosolic Cl− concentration ([Cl−]c) and novel roles of the cytosolic Cl− i.e., (1) quercetin elevates [Cl−]c by activating Na+-K+-2Cl− cotransporter 1 (NKCC1) in renal epithelial cells contributing to Na+ reabsorption via the epithelial Na+ channel (ENaC); (2) the quercetin-induced elevation of [Cl−]c in renal epithelial cells diminishes expression of ENaC leading to a decrease in renal Na+ reabsorption; and (3) this reduction of ENaC-mediated Na+ reabsorption in renal epithelial cells drops volume-dependent elevated blood pressure. In this review, we introduce novel, unique mechanisms of quercetin’s anti-hypertensive action via activation of NKCC1 in detail.

This study demonstrated that PDE1 (phosphodiesterase 1) existing in the ciliary beat frequency (CBF)-regulating metabolon regulates CBF in procaterol-stimulated lung airway ciliary cells of mouse. Procaterol (an β-agonist) increased the ciliary bend angle (CBA) and CBF via cAMP accumulation in the ciliary cells of mice: interestingly, the time course of CBF increase was slower than that of CBA increase. However, IBMX (3-isobutyl-1-methylxanthine, an inhibitor of PDE) increased CBA and CBF in an identical time course. Lowering an intracellular Ca concentration ([Ca]) caused by switching to an EGTA-containing Ca-free solution from normal one elevated the procaterol-induced increasing rate of CBF. These observations suggest that Ca-dependent PDE1 controls cAMP-stimulated CBF increase. Either application of 8MmIBMX (8-methoxymethyl-IBMX, a selective PDE1 inhibitor), BAPTA-AM (an intracellular Ca chelator), or calmidazolium (an inhibitior of calmodulin) alone increased CBA and CBF in the lung airway ciliary cells and increased cAMP contents in the isolated lung cells, and like IBMX, each application of the compound made the time courses of CBA and CBF increase stimulated by procaterol identical. The immunoelectron microscopic examinations revealed that PDE1A exists in the space between the nine doublet tubules ring and plasma membrane in the lung airway cilium, where the outer dynein arm (a molecular motor regulating CBF) functions. In conclusion, PDE1A is a key factor slowing the time course of the procaterol-induced increase in CBF via degradation of cAMP in the CBF-regulating metabolon of the mouse lung airway cilia.