Substitution at the C-3 Position of Catechins Has an Influence on the Binding Affinities against Serum Albumin.

It is known that catechins interact with the tryptophan (Trp) residue at the drug-binding site of serum albumin. In this study, we used catechin derivatives to investigate which position of the catechin structure strongly influences the binding affinity against bovine serum albumin (BSA) and human serum albumin (HSA). A docking simulation showed that (-)-epigallocatechin gallate (EGCg) interacted with both Trp residues of BSA (one at drug-binding site I and the other on the molecular surface), mainly by π-π stacking. Fluorescence analysis showed that EGCg and substituted EGCg caused a red shift of the peak wavelength of Trp similarly to warfarin (a drug-binding site I-specific compound), while 3-O-acyl-catechins caused a blue shift. To evaluate the binding affinities, the quenching constants were determined by the Stern-Volmer equation. A gallate ester at the C-3 position increased the quenching constants of the catechins. Against BSA, acyl substitution increased the quenching constant proportionally to the carbon chain lengths of the acyl group, whereas methyl substitution decreased the quenching constant. Against HSA, neither acyl nor methyl substitution affected the quenching constant. In conclusion, substitution at the C-3 position of catechins has an important influence on the binding affinity against serum albumin.

Successful Treatment of Protein-Losing Enteropathy After Superior Mesenteric Artery Occlusion without Surgery.

BACKGROUND Protein-losing enteropathy as a complication of superior mesenteric artery occlusion is extremely rare and severe, and sometimes requires intestinal resection. However, the ideal treatment strategy has not yet been determined. CASE REPORT A 77-year-old man with underlying hypertension and diabetes was admitted to the Emergency Department with acute abdominal pain after eating. Contrast-enhanced computed tomography revealed complete occlusion of the superior mesenteric artery with thrombosis, and superior mesenteric artery occlusion was diagnosed. It was successfully treated with interventional therapy, followed by continuous intra-arterial prostaglandin E1 infusion and continuous intravenous heparin infusion. However, the patient developed hypoproteinemia and diarrhea about 10 days after the interventional therapy. Colonoscopy and X-ray studies did not reveal any abnormal findings; however, technetium-99m-labeled human serum albumin scintigraphy indicated protein-losing enteropathy. With total parenteral nutrition and protein-rich oral nutrition, with protein intake at twice the amount in a standard diet, serum albumin improved from 15 g/L to 32 g/L after treatment. Additionally, we administered diuretics to avoiding edema related to the hypoproteinemia. The patient recovered from the hypoproteinemia and diarrhea without complications. CONCLUSIONS Protein-losing enteropathy is an extremely rare but critical complication of superior mesenteric artery occlusion. Treating the underlying pathology is the mainstay of protein-losing enteropathy and dietary modifications also play a critical role. Our patient was successfully treated with strict nutritional therapy, combined oral protein-rich nutrition and total parenteral nutrition, which avoided surgery.

Predictive factors of perforated appendicitis: Impact of the C-reactive protein level.

BACKGROUND: Perforated appendicitis without an associated abscess necessitates emergency surgery. However, it is difficult to predict the presence of perforation before surgery, and the predictive factors are still unclarified. Our purposes were to characterize a patient population with perforated appendicitis without an associated abscess to identify the preoperative predictive factors of appendiceal perforation. METHODS: We retrospectively identified 150 patients who underwent appendectomy for acute appendicitis at our institution from June 2018 to November 2020. Logistic regression analysis was performed to analyze the concurrent effects of various factors on the prevalence of perforated appendicitis. RESULTS: Forty (29%) of 150 patients had appendiceal perforation detected intraoperatively. Of these 40 patients, only 19 had appendiceal perforation detected on preoperative computed tomography. Multivariable analysis found that a higher C-reactive protein level, higher total bilirubin level, and the presence of an appendiceal fecalith were independent predictive factors for appendicitis with perforation. CONCLUSION: Our analysis suggests that the presence of an appendiceal fecalith, a total bilirubin level of more than 21.38 µmol/L, and a C-reactive protein level of more than 3.0 × 104 µg/L are predictive factors of perforated appendicitis.

Epigallocatechin gallate induces GLUT4 translocation in skeletal muscle through both PI3K- and AMPK-dependent pathways.

Our previous report demonstrated that epigallocatechin gallate (EGCg) promotes translocation of glucose transporter 4 (GLUT4) in skeletal muscle. In this study, we investigated the molecular mechanism of GLUT4 translocation by EGCg at the physiological concentration range. In L6 cells, EGCg induced phosphorylation of phosphatidylinositide 3'-kinase (PI3K) and downstream protein kinase C (PKC) λ/ξ without affecting the phosphorylation of insulin receptor and Akt. EGCg-induced GLUT4 translocation was suppressed by RNA interference-mediated knockdown of PI3K and treatment with PKC inhibitor Go6983. Moreover, EGCg increased Rac1 activity and actin remodelling as downstream events of PKCλ/ξ. These results indicate that EGCg induced GLUT4 translocation through a PI3K-dependent pathway, but its mode of action differed from that of insulin. EGCg also induced GLUT4 translocation through a 5'-adenosine monophosphate-activated protein kinase (AMPK)-dependent pathway. 67 kDa laminin receptor, which is a target molecule of EGCg, was not involved in EGCg-induced glucose uptake in L6 cells. The oral administration of EGCg suppressed postprandial hyperglycaemia accompanied by GLUT4 translocation through both PI3K- and AMPK-dependent pathways, and promoted glycogen accumulation in skeletal muscle of ICR mice. EGCg promotes GLUT4 translocation through both PI3K- and AMPK-dependent pathways and glycogen accumulation in skeletal muscle.

Propolis extract promotes translocation of glucose transporter 4 and glucose uptake through both PI3K- and AMPK-dependent pathways in skeletal muscle.

It is well known that propolis has the ability to prevent hyperglycemia. However, the underlying mechanism is not yet fully understood. We therefore investigated whether a Brazilian propolis ethanol extract affects glucose uptake and translocation of insulin-sensitive glucose transporter (GLUT) 4 in skeletal muscle cells. In L6 myotubes, the extract at 1 µg/mL significantly promoted GLUT4 translocation and glucose uptake activity. Regarding the mechanism of GLUT4 translocation, propolis extract induced both PI3K and AMPK phosphorylation in a dose-dependent manner in L6 myotubes. However, we could not define which pathway was preferentially associated with GLUT4 translocation, because both PI3K and AMPK inhibitors revealed off-target effects to each other. The main polyphenols found in the propolis extract, artepillin C, coumaric acid, and kaempferide, promoted GLUT4 translocation in L6 myotubes. Additionally, these compounds activated both PI3K- and AMPK-dependent dual-signaling pathways. However, only kaempferide increased glucose uptake activity under our experimental conditions. Single oral administrations of propolis extract, at 250 mg/kg body weight, lowered postprandial blood glucose levels in ICR mice. The extract promoted GLUT4 translocation in skeletal muscle of rats and mice, but did not inhibit α-glucosidase activity in the small intestine under our experimental conditions. It was confirmed that propolis extract promoted phosphorylation of both PI3K and AMPK in rat skeletal muscle. In conclusion, we show that Brazilian propolis has the potential to prevent hyperglycemia through the promotion of GLUT4 translocation in skeletal muscle and that kaempferide is one of the candidates for active compound in propolis.