Khalid Z. Alshali

Phenolics from Garcinia mangostana Inhibit Advanced Glycation Endproducts Formation: Effect on Amadori Products, Cross-Linked Structures and Protein Thiols

Accumulation of Advanced Glycation Endproducts (AGEs) in body tissues plays a major role in the development of diabetic complications. Here, the inhibitory effect of bioactive metabolites isolated from fruit hulls of Garcinia mangostana on AGE formation was investigated through bio-guided approach using aminoguanidine (AG) as a positive control. Including G. mangostana total methanol extract (GMT) in the reaction mixture of bovine serum albumin (BSA) and glucose or ribose inhibited the fluorescent and non-fluorescent AGEs formation in a dose dependent manner. The bioassay guided fractionation of GMT revealed isolation of four bioactive constituents from the bioactive fraction; which were identified as: garcimangosone D (1), aromadendrin-8-C-glucopyranoside (2), epicatechin (3), and 2,3′,4,5′,6-pentahydroxybenzophenone (4). All the tested compounds significantly inhibited fluorescent and non-fluorescent AGEs formation in a dose dependent manner whereas compound 3 (epicatechin) was found to be the most potent. In search for the level of action, addition of GMT, and compounds 2–4 inhibited fructosamine (Amadori product) and protein aggregation formation in both glucose and ribose. To explore the mechanism of action, it was found that addition of GMT and only compound (3) to reaction mixture increased protein thiol in both glucose and ribose while compounds 1, 2 and 4 only increased thiol in case of ribose. In conclusion, phenolic compounds 1–4 inhibited AGEs formation at the levels of Amadori product and protein aggregation formation through saving protein thiol.

Mangostanaxanthones III and IV: advanced glycation end-product inhibitors from the pericarp of Garcinia mangostana

Advanced glycation end-products (AGEs) are associated with a non-enzymatic reaction between the amino group of a protein and the carbonyl group of a sugar during hyperglycemia. The precipitation of AGEs in different tissues leads to many complications, such as endothelial dysfunction, cardiovascular complications, atherosclerosis, retinopathy, neuropathy, and Alzheimer’s disease. Garcinia mangostana L. (Clusiaceae) (GM) was selected owing to the ability of its polar and non-polar fractions to inhibit AGE formation. For the first time, the bioguided fractionation of its pericarp MeOH extract (GMT) gave rise to two new xanthones, namely, mangostanaxanthones III (1) and IV (3), in addition to six known compounds, β-mangostin (2), garcinone E (4), rubraxanthone (5), α-mangostin (6), garcinone C (7), and 9-hydroxycalabaxanthone (8), from the non-polar faction. Their structures were verified by various spectroscopic methods, including 1D and 2D NMR studies and high-resolution MS data. All of the isolated xanthones significantly inhibited both sugar (ribose) and dicarbonyl compound (methylglyoxal)-induced protein glycation in a dose-dependent manner. This is explained by the ability of the isolated xanthones to inhibit protein oxidation, as indicated by the decreases in dityrosine and N′-formylkynurenine formation.

Bioactive Hydantoin Alkaloids from the Red Sea Marine Sponge Hemimycale arabica

In the course of our continuing efforts to identify bioactive secondary metabolites from Red Sea marine invertebrates, we have investigated the sponge Hemimycale arabica. The antimicrobial fraction of an organic extract of the sponge afforded two new hydantoin alkaloids, hemimycalins A and B (2 and 3), together with the previously reported compound (Z)-5-(4-hydroxybenzylidene)imidazolidine-2,4-dione (1). The structures of the compounds were determined by extensive 1D and 2D NMR (COSY, HSQC and HMBC) studies and high-resolution mass spectral determinations. Hemimycalins A (2) and B (3) represent the first examples of the natural N-alkylated hydantoins from the sponge Hemimycale arabica. Compounds 1–3 displayed variable antimicrobial activities against E. coli, S. aureus, and C. albicans. In addition, compound 1 displayed moderate antiproliferative activity against the human cervical carcinoma (HeLa) cell line. These findings provide further insight into the chemical diversity as well as the biological activity of this class of compounds.

Iodine Deficiency Among Hypothyroid Patients Living in Jeddah

The objective was to determine the prevalence of iodine deficiency among hypothyroid patients and the effect of dietary goitrogens on indices of iodine and thyroid status. This is a case-control study of 106 subjects who were recruited from King Abdulaziz University Hospital, Jeddah. Blood and urine were collected for serum thyroid hormones, thyroid autoantibodies, thyroglobulin (Tg) and urinary iodine concentration (UIC). Dietary iodine and goitrogenic food intake were assessed by questionnaire. Using World Health Organization (WHO) cutoff values for UIC, both controls and cases were iodine deficient (85% and 83%, respectively). Furthermore, dietary iodine was deficient in 23% of controls and 36% of cases. In cases, there was a positive association between UIC levels and serum thyroid stimulating hormone (r = 0.405, p < 0.01) and a negative association with serum fT4 (r = −0.358, p < 0.01). Serum Tg antibody titers were also positively associated with dietary iodine (r = 0.328, p < 0.05). Patients with elevated serum autoantibodies had lower UIC and dietary iodine than those with normal serum autoantibodies. UIC was associated with dietary goitrogens including turnip (r = 0.280, p < 0.05) and pine (r = 0.289, p < 0.05) among cases. Iodine deficiency is common and the consumption of dietary goitrogens is high among euthyroid and hypothyroid subjects living in Jeddah.

The relationship of management modality in Saudi patients with type 2 diabetes to components of metabolic syndrome, γ glutamyl transferase and highly sensitive C-reactive protein

Background: The aim of this study was to investigate the relationship among management modality, glycemic control, components of metabolic syndrome (MS) and serum levels of γ glutamyl transferase (GGT) and C-reactive protein (CRP) in patients with type 2 diabetes (T2DM). Methods: Patients with T2DM, not suffering from diabetes complications, were recruited from outpatients clinics at two hospitals in Jeddah. Anthropometric measurements and blood pressure (BP) were taken. A treatment plan was recorded. Fasting blood samples were obtained to measure glucose, glycated hemoglobin (HbA1c), lipids profile, highly sensitive (hs)-CRP and GGT. Results: A total of 71 men and 82 women were recruited. Lower mean HbA1c was found in people receiving oral glucose-lowering drugs compared with those on insulin therapy (p < 0.001). Management modality had no effect on mean GGT or hs-CRP. Higher mean GGT was associated with poor glycemic control, dyslipidemia, hypertension, and abdominal obesity. GGT correlated significantly (p < 0.05) and directly with triglycerides in men (r = 0.401) and diastolic BP (r = 0.279 for men, r = 0.194, for women), but inversely with high-density lipoprotein cholesterol (HDL-C) (r = −0.298 for men, r = −0.171 for women). hs-CRP correlated with waist circumference (p < 0.05, r = 0.312, for men, r = 0.305, for women), with a higher mean being found in men with poor glycemic control (p = 0.015), in hypertensive women (p = 0.030), and in patients who were abdominally obese (p < 0.05). Conclusions: High levels of GGT and hs-CRP are associated with components of MS and poor glycemic control, hence increased cardiovascular risk. Due to their value as independent risk predictors of vascular injury, these measures should be included in routine monitoring of patients with T2DM.

Clinical safety of insulin detemir in patients with Type 2 diabetes in the Gulf countries: The multicenter, noninterventional, open-label LevSafe study.

Aim: To evaluate the safety profile of insulin detemir (IDet) in people with Type 2 diabetes mellitus (T2DM) in the Gulf countries in the 32-week, noninterventional LevSafe study. Methods: People with T2DM whose physicians had opted to start IDet therapy were included in the study. Safety parameters, including serious adverse drug reactions (SADRs) and hypoglycemia, and changes in body weight and glycemic control were evaluated at baseline, week 16 and week 32. Results: A total of 686 patients were exposed to IDet therapy with a mean (±standard deviation) age, body mass index, and diabetes duration of 51.3 ± 11.0 years, 31.3 ± 5.5 kg/m2, and 10.2 ± 6.1 years, respectively. The mean total daily dose of IDet was 32.0 ± 32.8 U at baseline and 44.7 ± 60.7 U at week 32. No SADRs were reported during the study. Total hypoglycemia decreased from 435 events at baseline to 204 events at week 32 (mean change analyzed by Wilcoxon signed rank test: −0.34; P = 0.0115), and no major hypoglycemia was reported at week 32. Over the 32-week treatment period, the mean body weight decreased from 85.7 ± 15.2 kg to 85.4 ± 14.5 kg (P = 0.0203), glycated hemoglobin A1c from 9.9 ± 1.67% to 7.7 ± 1.36% (P < 0.0001), and fasting plasma glucose from 11.9 ± 3.27 mmol/L to 7.4 ± 1.85 mmol/L (P < 0.0001). Conclusion: IDet therapy was well-tolerated and was associated with a decreased number of hypoglycemic events and improved glycemic control after 32 weeks in patients with T2DM in the Gulf countries.

Carboxylated osteocalcin and adiponectin correlate with glycated hemoglobin and 25(OH) vitamin D levels in Saudi females with type 2 diabetes mellitus following ingestion of vitamin D supplements.

1 Department of Clinical Biochemistry, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia. 2 Saudi Diabetes Study Research Group, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia. Biochemistry Department, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia. 4 Department of Internal Medicine, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia. 5 Department of Nutrition, Faculty of Home Economics, King Abdulaziz University, Jeddah, Saudi Arabia.

Urgineaglyceride A: a new monoacylglycerol from the Egyptian Drimia maritima bulbs

One new compound, (2S)-1-O-(Z)-tetracos-6-enoate glycerol (1) named urgineaglyceride A, along with six known compounds, 3,5,7,3′,5′-pentahydroxydihydroflavonol (2), stigmasterol (3), (25S)-5β-furostane-3β-22α-26-triol (4), scillaridin A (5), (2S)-(+)-2-hydroxynaringenin-4′-O-β-d-glucopyranoside (6) and quercetin-3′-O-β-d-glucopyranoside (7), were isolated from the EtOAc fraction of Drimia maritima (L.) Stearn bulbs. Their structures were secured based on their IR, UV, 1D and 2D NMR data, in addition to HR-MS data and comparison with the literature data. The isolated compounds were evaluated for their in vitro growth inhibitory activity against A549 non-small cell lung cancer (NSCLC), U373 glioblastoma (GBM) and PC-3 prostate cancer cell lines. Compounds 2 and 3 displayed variable activities against the tested cancer cell lines. Compound 2 was a selective inhibitor of the NSCLC cell line with an IC50 of 2.3 μM, whereas 3 was selective against GBM with IC50 of 0.5 μM and against PC-3 with 2.0 μM.

Volatile oil profile of some lamiaceous plants growing in Saudi Arabia and their biological activities

Abstract A comparative investigation of hydro-distilled essential oils from aerial parts of Mentha longifolia L. (ML), Mentha microphylla K.Koch (MM), Mentha australis R.Br. (MA), and Teucrium polium L. (TP) growing in Al Madinah Al Munawwarah, Saudi Arabia, was carried out. The total numbers of identified constituents were 22, 23, 14, and 20 in ML, MM, MA, and TP oils, representing 93.0, 99.3, 78.1, and 81.1% of the total oil composition, respectively. Pulegone (40.7%) and cineole (33.4%) were the major components in ML, whereas carvone (64.6%) was the major one in MM. Furthermore, β-linalool (22.9%) and α-terpineol (12%) were the major components in MA, whereas, (E)-3-caren-2-ol accounted for 12.1% in TP. The essential oils of TP and MA exhibited promising activities against Leishmania donovani promastigotes with IC50 values of 2.3 and 3.7 μg/mL, respectively. In contrast, MA essential oils exhibited antifungal activities towards Candida krusei and C. glabrata with IC50 values of 1 and 1.2 μg/mL, respectively.

A review of glycemic efficacy of liraglutide once daily in achieving glycated hemoglobin targets compared with exenatide twice daily, or sitagliptin once daily in the treatment of type 2 diabetes

Incretin-based therapies such as glucagon-like peptide-1 (GLP-1) receptor agonists (RA) and dipeptidyl peptidase-4 (DPP-4) inhibitors have gained prominence in recent years for the treatment of type 2 diabetes (T2D). Such therapies offer the potential to stimulate endogenous insulin activity in proportion to circulating glucose levels; thereby, lowering the risk of hypoglycemic episodes. The synthetic GLP-1 RA exenatide, the human GLP-1 RA liraglutide, and the DPP-4 inhibitor sitagliptin are the first agents in their respective classes to be approved for the treatment of T2D and their efficacy and safety has been studied extensively in clinical trials. This article reviewed the efficacy of liraglutide once daily in achieving clinical guidelines-recommended glycated hemoglobin A1c levels in patients with T2D compared with exenatide twice daily, or sitagliptin once daily, based on published literature, with an aim to elucidate the preferred choice of incretin-related therapy in treating uncontrolled T2D.