P. M. García-López

Effects of Hibiscus sabdariffa extract powder and preventive treatment (diet) on the lipid profiles of patients with metabolic syndrome (MeSy).

Insulin resistance, obesity, hypertension, and dyslipidemia are strongly associated with metabolic syndrome (MeSy), which is considered to be a reversible clinical stage before its evolution to coronary heart disease and diabetes. Currently, the antihypertensive and hypolipidemic properties of aqueous Hibiscus sabdariffa extracts (HSE) have been demonstrated in clinical trials and in vivo experiments. The aim of the present study was to evaluate the effects of a Hibiscus sabdariffa extract powder (HSEP) and a recognized preventive treatment (diet) on the lipid profiles of individuals with and without MeSy according to the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) criteria. The protocol was a follow-up study carried out in a factorial, randomized design (T1=preventive treatment comprises Diet, T2=HSEP, T3=HSEP+preventive treatment (Diet) X MeSy, non-MeSy individuals). A total daily dose of 100 mg HSEP was orally administered in capsules for one month. The preventive treatment (diet) was selected according to NCEP-ATP III recommendations and adjusted individually. Total cholesterol, LDL-c, HDL-c, VLDL-c, triglycerides, glucose, urea, creatinine, AST, and ALT levels in the blood were determined in all individuals pre- and post-treatment. The MeSy patients treated with HSEP had significantly reduced glucose and total cholesterol levels, increased HDL-c levels, and an improved TAG/HDL-c ratio, a marker of insulin resistance (t-test p<0.05). Additionally, a triglyceride-lowering effect was observed in MeSy patients treated with HSEP plus diet, and in individuals without MeSy treated with HSEP. Significant differences in total cholesterol, HDL-c, and the TAG/HDL-c ratio were found when the means of absolute differences among treatments were compared (ANOVA p<0.02). Therefore, in addition to the well documented hypotensive effects of Hibiscus sabdariffa, we suggest the use of HSEP in individuals with dyslipidemia associated with MeSy.

Casimiroa edulis seed extracts show anticonvulsive properties in rats

A single dose of 5, 10 and 100 mg/kg of Casimiroa edulis aqueous extract (AQ); 10, 100 and 1000 mg/kg of C. edulis ethanolic extract (E-OH); in addition, 10, 30 and 12 mg/kg of propyleneglycol (Pg), phenytoin (Phen) and phenobarbital (Phb) was orally given to adult male Wistar rat groups. Thereafter, all groups were assayed for protection against maximal electroshock (MES) and pentylenetetrazole (METsc) seizure inducing tests at hourly intervals throughout 8 h. For MES, a maximal protection of 70% at the 2nd and 4th h with 10 mg/kg AQ and 100 mg/kg E-OH doses, occurred. That of Phen, Phb and Pg was 80, 90 and 10% at the 8th, 6th and 2nd h, respectively. The averaged values of the MES unprotected rats under 10 and 100 mg/kg of AQ and E-OH extracts, showed that a shortened reflex duration as well as a delayed latency and uprising times occurred. On the other hand, just an enlarged latency and no protection against METsc device in AQ and EOH was observed. Phen and Phb maximal protection was 80 and 100% at the 4th and 6th hour against METsc. Thus, AQ is tenfold more potent anticonvulsive extract than E-OH against MES.

Establishment of a cut‐point value of serum TNF‐α levels in the metabolic syndrome

Cardiovascular diseases and type 2 diabetes are the major causes of mortality in Mexico. Metabolic syndrome (MS) is a cluster of factors that increase the risk to develop such diseases. Previous studies have shown that MS is associated with high tumor necrosis factor (TNF‐α) levels. In fact, TNF‐α has been proposed to be a useful marker for clinical diagnosis of inflammation at an early stage. Therefore, we analyzed TNF‐α concentrations in Mexican individuals with or without MS and related these levels to the associated MS components. Clinical, anthropometric, and biochemical data were analyzed in 41 healthy and 39 MS individuals. Individuals were similarly grouped by age and gender.The serum TNF‐α levels measured bya highly sensitive enzyme‐linked immunosorbent assay (ELISA) kit were increased significantly in MS subjects compared with healthy individuals (P<0.001). The assay showed 78.1% sensitivity and 61.5% specificity with a cut‐point level of 1.36 pg/mL. TNF‐α levels higher than the cut‐point value were correlated with insulin resistance indices. These findings support the hypothesis that serum TNF‐α concentration could be a useful marker for early MS diagnosis. Nevertheless, we suggest the establishment of specific cut‐point values in each studied population to evaluate potential clinical applications. J. Clin. Lab. Anal. 23:51–56, 2009.

Lupanine Improves Glucose Homeostasis by Influencing KATP Channels and Insulin Gene Expression

The glucose-lowering effects of lupin seeds involve the combined action of several components. The present study investigates the influence of one of the main quinolizidine alkaloids, lupanine, on pancreatic beta cells and in an animal model of type-2 diabetes mellitus. In vitro studies were performed with insulin-secreting INS-1E cells or islets of C57BL/6 mice. In the in vivo experiments, hyperglycemia was induced in rats by injecting streptozotocin (65 mg/kg body weight). In the presence of 15 mmol/L glucose, insulin secretion was significantly elevated by 0.5 mmol/L lupanine, whereas the alkaloid did not stimulate insulin release with lower glucose concentrations. In islets treated with l-arginine, the potentiating effect of lupanine already occurred at 8 mmol/L glucose. Lupanine increased the expression of the Ins-1 gene. The potentiating effect on secretion was correlated to membrane depolarization and an increase in the frequency of Ca2+ action potentials. Determination of the current through ATP-dependent K+ channels (KATP channels) revealed that lupanine directly inhibited the channel. The effect was dose-dependent but, even with a high lupanine concentration of 1 mmol/L or after a prolonged exposure time (12 h), the KATP channel block was incomplete. Oral administration of lupanine did not induce hypoglycemia. By contrast, lupanine improved glycemic control in response to an oral glucose tolerance test in streptozotocin-diabetic rats. In summary, lupanine acts as a positive modulator of insulin release obviously without a risk for hypoglycemic episodes.