Withania somnifera shows a protective effect in monocrotaline-induced pulmonary hypertension

Abstract

Context: Withania somnifera (Linn.) Dunal (Solanaceae), a clinically used herbal drug in Ayurveda, shows potent antioxidant, anti-inflammatory, pro-apoptotic, and cardioprotective effects. However, the efficacy of W. somnifera in pulmonary hypertension (PH), a cardiopulmonary disorder, remains unexplored.

Objective: The present study investigates the effect of W. somnifera root powder on monocrotaline (MCT)-induced PH in rats.

Materials and methods: In preventive studies, W. somnifera root powder (50 and 100?mg/kg/d, p.o.) was administered from day 1 following single administration of MCT (60?mg/kg, s.c.) in Sprague–Dawley (SD) rats. After 35?d, right ventricular pressure (RVP) was measured in anesthetized rats. Various physical markers of right ventricular hypertrophy (RVH) were measured in isolated hearts. Markers of endothelial function, inflammation, and oxidative stress were estimated in lung homogenate. Vasoreactivity of pulmonary arteries was also studied. In therapeutic treatment, W. somnifera (50 and 100?mg/kg/d, p.o.) was administered from day 21 to 35 post-MCT administration.

Results: Preventive treatment with 50 and 100?mg/kg W. somnifera significantly reduced the RVP (32.18?±?1.273?mm?Hg and 29.98?±?1.119?mm?Hg, respectively, versus 42.96?±?1.789?mm?Hg of MCT) and all markers of RVH in MCT-challenged rats. There was an improvement in inflammation, oxidative stress and endothelial dysfunction, and attenuation of proliferative marker and apoptotic resistance in lungs. Therapeutic treatment with W. somnifera (100?mg/kg) also reduced RVP and RVH.

Discussion: This study demonstrated that W. somnifera significantly protected against MCT-induced PH due to its antioxidant, anti-inflammatory, pro-apoptotic, and cardioprotective properties.     

Crataegus Aronia protects and reverses vascular inflammation in a high fat diet rat model by an antioxidant mechanism and modulating serum levels of oxidized low-density lipoprotein

Context: Crataegus aronia (Willd.) Bosc (Rosaceae) (syn. Azarolus L) is traditionally used to treat cardiovascular disorders.

Objectives: To investigate C. aronia protection against a high-fat diet (HFD)-induced vascular inflammation in rats.

Materials and methods: Wistar Male rats (180–220?g) were divided (n?=?10/group) as control fed a standard diet (STD), STD + C. aronia (200?mg/kg, orally), HFD, HFD + C. aronia and HFD post-treated with C. aronia. Simvastatin (20?mg/kg) was co- or post-administered as a positive control drug. HFD was given for 8?weeks, and all other treatments were administered for 4?weeks.

Results: Most significantly, co-administration of C. aronia to HFD-fed rats reduced the thickness of aorta tunica media (90?±?5 vs. 160?±?11.3?µm) and adventitia (54.3?±?3.8 vs. 93.6?±?9.4?µm). It also lowered protein levels of TNF-α (0.51?±?0.15 and 0.15?±?0.16 vs. 0.1?±?0.09%) and IL-6 (0.52?±?0.19 vs. 1.0?±?0.2%) in their aorta or serum (5.9?±?0.91 vs. 12.98?±?1.3?ng/mL and 78.1?±?6.7 vs. 439?±?78?pg/mL, respectively). It also lowered all serum lipids and increased aorta levels of GSH levels (70.4?±?4.0 vs. 40.7?µM) and activity of SOD (5.7?±?0.7 vs. 2.9?±?0.6?U/mg) and decreased serum levels of ox-LDL-c (566.7?±?46 vs. 1817?±?147?ng/mL). Such effects were more profound than all other treatments.

Conclusions: C. aronia inhibits the HFD-induced vascular inflammation and its use in clinical trials is recommended.     

Co-administration of walnut (Juglans regia) prevents systemic hypertension induced by long-term use of dexamethasone: a promising strategy for steroid consumers

Context: The long-term consumption of glucocorticoids (GCs) may induce serious adverse effects such as hypertension. There is sufficient evidence related to the benefit of walnuts on the cardiovascular system.

Objective: This study assesses the effect of methanol extract of walnut [Juglans regia L. (Juglandaceae)] on dexamethasone-induced hypertension and the possible mechanisms in Wistar rats.

Material and methods: Animals were randomized into control, kernel extract (100 and 200?mg/kg/d, orally), dexamethasone (0.03?mg/kg/d, subcutaneously), dexamethasone?+?kernel (100 and 200?mg/kg/d, separately), and dexamethasone?+?captopril (25?mg/kg/d, orally) groups. Animals were treated with water, kernel extract or captopril by gavage 4 d before and during 11 d of saline or dexamethasone treatment. On the 16th day, blood pressure (BP) was recorded and blood samples were collected to measure nitric oxide (NO). Animal hearts were frozen for measurement of malondialdehyde (MDA) and glutathione peroxidase (GPX).

Results: Dexamethasone increased the diastolic BP and MDA/GPX ratio in comparison with control group (128?±?7 vs. 105?±?3?mmHg, p?p?p?p?Conclusion: Similar to captopril, walnut extract normalized dexamethasone-induced hypertension. A part of this beneficial effect apparently involves maintaining balance of the redox system and NO production.     

Mineral pitch stimulates humoral,cellular and innate immune responses in mice

Abstract

Context: Mineral pitch (MP), a traditional medicine, is proposed to boost immunity in conditions that suppress Th1 cytokines such as AIDS/HIV, tuberculosis, leishmaniasis and cancer.

Objective: This study investigates the immunoregulatory mechanisms of MP in innate, humoral and cell-mediated immunity.

Materials and methods: Mice given MP (100, 200, 300 or 400?mg/kg, orally) for 10 consecutive days were immunized intravenously with goat RBC or ovalbumin, and investigated for plaque-forming cells (PFC), hemagglutination titer, hypersensitivity response, lymphocyte proliferation and macrophage function.

Results: MP increased PFC (330.2 versus 182.2/10⁶ splenocytes) in mice immunized with goat RBC and elicited ovalbumin-specific IgG titer at 400?mg/kg. Increase in Th1 immunity was correlated with the increased level of IFN-γ (724 versus 470?pg/ml) and decreased IL-4 (96 versus 178?pg/ml). CD4⁺/CD3⁺ ratio and delayed-type hypersensitivity response also increased to, respectively, 20.62?±?0.59 (versus 16.47?±?0.72) and 1.59?±?0.12 (versus 0.87?±?0.10?mm) in MP-treated mice. MP increased lymphocyte proliferation (11.14?±?0.60 versus 5.81?±?0.40 SI) and macrophage phagocyte response (0.24?±?0.02 versus 0.15?±?0.009), expressed as absorbance at 570?nm, but decreased nitrite production (17.4?±?1.10 versus 24.3?±?1.30?µM/10⁶ cells). We also observed an increased bone marrow cellularity (24.5?±?1.10 versus 17.10?±?0.70 cells/femur) and WBC count (12?667?±?377 versus 9178?±?213 cells/mm³) following MP treatment. There was no sign of toxicity at 400?mg/kg, 1/12th of reported LD₅₀.

Conclusion: MP elicits a dose-dependent Th1 immune response.     

Nephroprotective activity of Macrothelypteris oligophlebia rhizomes ethanol extract

Context: Macrothelypteris oligophlebia (Bak.) Ching (Thelypteridaceae) is a Chinese herbal medicine used traditionally for the treatment of diseases such as edema, boils, burns, and roundworms. However, research about the nephroprotective potential of this plant is not available.

Objective: Present study was designed to evaluate the protective effect of ethanol extract of M. oligophlebia rhizomes (EMO) on gentamicin (GM)-induced nephrotoxicity.

Materials and methods: Rats were intraperitoneal (i.p.) injected with GM (100?mg/kg) to induce nephrotoxicity and simultaneously EMO (250 and 500?mg/kg) was orally given to GM-treated rats for 8 days. Blood urea nitrogen (BUN), serum creatinine (Cr), malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were evaluated in renal tissues. Histopathological analysis was used for evaluation of the renal damage.

Results: Administration with GM-induced renal dysfunction in rats. Pre-treatment with EMO (500?mg/kg) significantly decreased the levels of BUN, Cr, MDA and NO (decreased BUN from 12.71?±?1.28 to 7.19?±?0.23 mmol/l, Cr from 39.77?±?5.34 to 19.17?±?0.90 μmol/l, MDA from 5.60?±?0.37 to 2.63?±?0.24 nmol/ml, and NO from 868.17?±?22.67 to 589.51?±?8.83 μmol/ml), and also restored the activities of renal antioxidant enzymes (SOD, CAT, and GSH-Px) (restored SOD from 1.59?±?0.17 to 2.94?±?0.13?U/mg protein, CAT from 3.22?±?0.34 to 10.57?±?0.27?U/mg protein, and GSH-Px from 9.11?±?1.29 to 20.72?±?1.83?U/mg protein).

Discussion and conclusion: Our results suggest that the rhizomes of M. oligophlebia potentially have a protective role in renal tissue against oxidative stress in acute renal failure.     

The effects of Melissa officinalis (lemon balm) pretreatment on the resistance of the heart to myocardial injury

Context: The antihyperlipidemic, antiarrhythmic, neuroprotective and hepatoprotective effects of Melissa officinalis L. (Lamiaceae) have been reported. However, no study has examined its effects on the resistance of the heart to stressful conditions.

Objective: The objective of this study is to evaluate the effects of aqueous extract of M. officinalis aerial parts on Wistar rat heart with/without cardiac injury.

Materials and methods: Animals were grouped as control, isoproterenol (ISO), M. officinalis without (M50, M100, and M200) and with isoproterenol (M50?+?ISO, M100?+?ISO, and M200?+?ISO). The aqueous extract of M. officinalis was orally administered at dosages of 50, 100, and 200?mg/kg/d, respectively, for 7 consecutive days. On the 6th and 7th day, ISO, M50?+?ISO, M100?+?ISO, and M200?+?ISO groups received 85?mg/kg of isoproterenol for myocardial injury induction. On day 8, hemodynamic parameters were recorded and samplings were done.

Results: The extract (50, 100, and 200?mg/kg) significantly reduced the heart rate (264?±?5, 259?±?5 and 281?±?3 versus 377?±?13 in control group, p?<?0.01). Blood pressure was significantly decreased in M50?+?ISO (75?±?5) versus M50 (110?±?6) and M100?+?ISO (72?±?6) versus M100 (105?±?5?mmHg, p?<?0.01). The malondialdehyde levels of the injured hearts were lower in M50?+?ISO and M100?+?ISO groups than in the ISO group (p?<?0.05). Serum cardiac troponin I was higher in the M200?+?ISO group (5.1?±?1.7) than in the ISO group (2.7?±?0.7?ng/ml, p?<?0.05).

Conclusion: The lower dose of extract, by improving the balance of the redox system and by reducing the heart rate, may increase the heart resistance to injury. However, the higher doses of extract may intensify the injury of ischemic heart.     

Treated effect of silymarin on vascular function of aged rats: Dependant on nitric oxide pathway

Context: Aging leads to endothelial dysfunction and vascular stiffness which are the main causes of many cardiovascular diseases. Previous reports have shown that the cell protective effect of silymarin (SM) is dependent on its antioxidant properties.

Objectives: We investigated the effect of SM on vascular functions of aged rats and the involvement of nitric oxide or cyclooxygenase (COX) activity in this effect.

Materials and methods: Isolated rat aortas were obtained from 22-month old rats. Each ring was incubated with SM (50?mg/L), SM/l-nitro-arginine methyl ester (100?μM, l-NAME) or SM/indomethacin (10?μM, INDO) in tissue bath. Three- to four-month-old rats were used as young controls. Endothelium-intact rings were precontracted with α-receptor agonist phenylephrine (0.001–30?µM) or voltage-dependent high potassium (40?mM), endothelium dependent/independent relaxant responses were obtained using acetylcholine (0.001–30?µM) and sodium nitroprusside (0.0001–3?µM), respectively.

Results: Aging increased phenylephrine sensitivity (6.45?±?0.08; 6.88?±?0.09) and decreased KCl contraction (882?±?118.4; 499?±?80.4). SM treatment decreased the E_max of both agents (548?±?109; 223?±?48.9). Aging deteriorated acetylcholine relaxation (93.9?±?2.09; 72.0?±?2.56) and SM improved the response (86.3?±?1.90). l-NAME prevented the SM effect whereas INDO was ineffective.

Discussion and Conclusion: Immediate SM treatment partially restored endothelial dysfunction and vascular tone in aging. The possible mechanism might not be mediated by prostacyclin or the COX pathway in acute administration; the nitric oxide pathway and calcium antagonistic features of SM relate to its action on the vessel.     

Pharmacokinetics of the prodrug thiamphenicol glycinate and its active parent compound thiamphenicol in beagle dogs following intravenous administration

1. This study investigated the pharmacokinetics of thiamphenicol glycinate (TG) and thiamphenicol (TAP) in beagles (n?=?6) after intravenous administration of 50?mg/kg TG hydrochloride. Plasma concentrations of TG and TAP were measured by a HPLC-UV method.

2. Two-compartment model was selected to describe the pharmacokinetic characteristics of TG and TAP in vivo. Main parameters were as follows: AUC_0–∞ of TAP and TG were 16,328?±?1682 µg·min/mL and 3943?±?546 µg·min/mL, respectively. The total plasma clearance (CL) of TG and TAP were 12.7?±?2.0?mL/min/kg and 2.5?±?0.3?mL/min/kg, respectively. Mean residence time (MRT) of TG and TAP were 27.5?±?3.5 and 207.2?±?20.2?min, respectively. The transformative rate constant (k_1M) from TG to TAP was 0.0477?±?0.0028?min^?1. The elimination rate constant (k_M10) from TAP was 0.0238?±?0.0044?min^?1. Coefficients of variation (CV) between observed values and predicted ones were 5.9% and 18.2%, respectively. The volume of distribution of the central compartment for TG (V_C) and TAP (V_CM) were 0.264?±?0.022?L/kg and 0.127?±?0.023?L/kg, respectively.

3. Pharmacokinetic parameters suggested that TG was presumably cleaved quickly by tissue esterase to release TAP for effectiveness in beagles after administration.

     

The protective effect of selenium in cisplatin-related retinotoxicity

Purpose: The aim of this study is to evaluate the retinal toxicity of cisplatin and neuroprotective effect of selenium in cisplatin-related retinal toxicity.

Methods: Eighteen adult Wistar-Albino rats were divided into three groups. Group 1 (n?=?6) received intraperitoneal (i.p.) injection of 2.5?ml physiologic saline for three days, group 2 (n?=?6) received i.p. 16?mg/kg cisplatin for three days and group 3 (n?=?6) received i.p. 16?mg/kg cisplatin for three days and 1.5?mg/kg twice daily selenium via gavage five days prior to cisplatin injection and for three days concomitantly with cisplatin injections. The total retinal thickness, outer nuclear layer (ONL), inner nuclear layer (INL) and inner plexiform layer (IPL) thicknesses were measured in hematoxylin/eosin and apoptotic index (AI) of ganglion cell layer (GCL) and INL was evaluated in TdT-mediated dUTP-biotin nick end labeling (TUNEL)-stained retina sections.

Results: Selenium statistically succeeded to reduce total retinal thickness in cisplatin-toxicated retinas: from 210.17?±?23.40 to 173.55?±?20.43, ONL: 49.79?±?5.32 to 41.87?±?6.30, INL: 33.72?±?7.93 to 25.06?±?5.73 and IPL: 53.61?±?8.63 to 45.61?±?6.92?µm in hematoxylin/eosin-stained retina sections. The AI was also reduced in INL (30.10?±?12.02 to 19.48?±?12.99) and in GCL (37.59?±?17.70 to 33.15?±?13.78). However, statistical significance was present in only AI values of INL.

Conclusions: Selenium limited edema due to the toxicity and reduced the retinal thickness and showed neuroprotection in cisplatin-induced retinotoxicity.     

Hepatoprotective effects of cod liver oil against sodium nitrite toxicity in rats

Abstract

Context: Exposure to high levels of nitrites for a prolonged time have adverse health effects on several organs especially the liver due to oxidative properties. Meanwhile, cod liver oil has been reported to ameliorate organ dysfunction in animal models that involve oxidative stress.

Objective: Examine the impact of dietary cod liver oil on sodium nitrite-induced liver damage.

Materials and methods: Thirty-two adult male Sprague-Dawely rats were daily treated with sodium nitrite (80?mg/kg) in presence or absence of cod liver oil (5?ml/kg). Morphological changes were assessed in liver sections. Oxidative stress and antioxidant markers were measured in serum and liver homogenates. Liver samples were used for measurements of MCP-1, DNA fragmentation and mitochondrial function.

Results: The hepatoprotective effect of cod liver oil was proved by significant reduction of elevated liver enzymes and normal appearance of hepatocytes. Cod liver oil significantly reduced hepatic malondialdehyde, hydrogen peroxide and superoxide anion (224.3?±?18.9?nmol/g, 59.3?±?5.1 and 62.5?±?5.1?µmol/g, respectively) compared with sodium nitrite (332.5?±?25.5?nmol/g, 83.1?±?8.1 and 93.9?±?6.5?µmol/g, respectively). Cod liver oil restored hepatic cytochrome c oxidase activity after 38% reduction by sodium nitrite. Furthermore, cod liver oil significantly reduced hepatic MCP-1 (79.8?pg/mg) and DNA fragmentation (13.8%) compared with sodium nitrite (168.7?pg/mg and 41.3%, respectively).

Discussion and conclusion: Cod liver oil ameliorates sodium nitrite induced hepatic impairment through several mechanisms including attenuation of oxidative stress, blocking MCP-1, reactivation of mitochondrial function and reduction of DNA fragmentation.     

Reduced central corneal thickness in patients with isotretinoin treatment

Context: It is well known that oral isotretinoin treatment causes numerous ocular side-effects.

Objective: To investigate the effect of systemic isotretinoin treatment on central corneal thickness (CCT) values due to meibomian gland disease (MGD).

Participants: In this prospective study, 47 patients (27 men, 20 women) with nodulocystic acne vulgaris treated with oral isotretinoin (0.8?mg/kg daily) were included.

Methods: All patients were analyzed with the Pentacam Scheimpflug topography at baseline, on the 3rd and 6th month of treatment. Main outcome measures were MGD scores and CCT.

Results: The mean age of patients was 25.1?±?4.4 years. The mean MGD scores were significantly higher at 3rd month (1.3?±?0.9) and 6th month (1.5?±?1.0) of treatment compared with baseline (1.1?±?0.9) (p?p?p?=?0.038, r?=??0.221).

Conclusion: Isotretinoin treatment causes higher MGD scores. A statistically significant decrease in CCT due to MGD was detected at 6th month of treatment.     

Effects of rosmarinic acid on an experimental model of painful diabetic neuropathy in rats

Context: Diabetic neuropathic (DN) pain is one of the diabetes complications. Rosmarinic acid (RA), a natural phenol antioxidant, shows some biological activities, including anti-inflammatory, analgesic, and anti-diabetic effects.

Objectives: We investigated the efficacy of RA administration (10 and 30?mg/kg) on streptozotocin (STZ)-induced neuropathy in rats.

Material and methods: The animals received saline or RA (10 and 30?mg/kg, p.o.; once daily) for 8 weeks. DN was evaluated by the tail flick (TF) method, formalin test, and tactile allodynia. At the end, all rats were weighed and underwent plasma glucose measurement.

Results: There was an increase in licking time during both formalin test phases in diabetic animals (138.5?±?10.7 and 448.7?±?2.6?s) that was decreased by RA10?mg/kg (103.5?±?7.5 and 284.4?±?19?s) and RA 30?mg/kg (81.8?±?11 and 192.7?±?14?s). RA 30?mg/kg caused anti-nociception during the early phase in treated controls (52.1?±?6?s) than untreated controls (99.4?±?5.9?s). The TF latency in diabetics (2.9?±?0.1?s) was increased in RA10 and 30?mg/kg treated diabetics (5.3?±?0.4 and 6?±?0.86?s). The paw withdrawal threshold (PWT) of the diabetics (3.6?±?0.7?g) was increased after RA 10 and 30?mg/kg (13.8?±?0.3 and 14?±?0.4?g) treatment. RA did not induce a significant change in body weight and plasma glucose of rats.

Conclusion: RA showed efficacy in amelioration of some aspects of DN. Therefore, RA makes a good candidate for DN treatment in clinical studies.     

Effect of pramlintide as an adjunct to basal insulin on markers of cardiovascular risk in patients with type 2 diabetes

ABSTRACT

Objective: Intensification of insulin therapy in patients with type 2 diabetes, while improving glycemic control, often leads to an increase in body weight and other markers of cardiovascular risk. The effects of pramlintide as an adjunct to basal insulin titration (without mealtime insulin) on glycemia and cardiovascular risk markers were examined.

Research design and methods: This was a post hoc analysis of a 16-week, double-blind, placebo-controlled study in patients with type 2 diabetes (N?=?211) using insulin glargine (without mealtime insulin)?±?oral agents. Patients were randomized to treatment with placebo or pramlintide (60 or 120?µg with major meals), and insulin glargine was titrated to target a fasting plasma glucose concentration of ≥70 to <100?mg/dL.

Main outcome measures: Endpoints included the change from baseline to Week 16 in body weight, high sensitivity C-reactive protein (hsCRP), triglycerides, HDL, LDL, and blood pressure.

Results: Pramlintide-treated patients lost weight and placebo-treated patients gained weight during 16 weeks of treatment (?1.6?±?0.3?kg vs. +0.7?±?0.3?kg, p?<?0.001; mean?±?SE). hsCRP was reduced in pramlintide-treated versus placebo-treated patients (?0.8?±?0.2?mg/L vs. 0.1?±?0.2?mg/L, p?<?0.01; mean?±?SE). Patients with baseline hsCRP?>?3?mg/L (high cardiovascular risk) demonstrated greater hsCRP reductions with pramlintide versus placebo treatment at Week 16 (p?<?0.05). Patients with baseline triglycerides ≥150?mg/dL or ≥200?mg/dL (high cardiovascular risk) showed significant reductions from baseline in triglyceride concentrations with pramlintide (?43?±?14?mg/dL or ?59?±?19?mg/dL; p?<?0.05; mean?±?SE) but not with placebo (1?±?29?mg/dLor ?3?±?54?mg/dL; mean?±?SE). No significant differences between pramlintide and placebo were observed for changes in HDL, LDL, or blood pressure. Pramlintide treatment was generally well tolerated. The most frequent adverse event related to pramlintide was mild-to-moderate nausea (31% pramlintide vs. 10% placebo). Pramlintide added to basal insulin did not increase the incidence of hypoglycemia. A limitation of the study was its relatively short duration.

Conclusions: Pramlintide, as an adjunct to basal insulin, was associated with improvements in several cardiovascular risk markers, warranting long-term clinical studies to determine its potential effects on cardiovascular risk.     

Effects of exenatide versus sitagliptin on postprandial glucose,insulin and glucagon secretion,gastric emptying,and caloric intake: a randomized,cross-over study

ABSTRACT

Background: This study evaluated the effects of exenatide, a GLP-1 receptor agonist, and sitagliptin, a DPP-4 inhibitor, on 2-h postprandial glucose (PPG), insulin and glucagon secretion, gastric emptying, and caloric intake in T2D patients.

Methods: This double-blind, randomized cross-over, multi-center study was conducted in metformin-treated T2D patients: 54% female; BMI: 33?±?5?kg/m²; HbA_1c: 8.5?±?1.2%; 2-h PPG: 245?±?65?mg/dL. Patients received exenatide (5?µg BID for 1 week, then 10?µg BID for 1 week) or sitagliptin (100?mg QAM) for 2 weeks. After 2 weeks, patients crossed-over to the alternate therapy. Postprandial glycemic measures were assessed via standard meal test; caloric intake assessed by ad libitum dinner (subset of patients). Gastric emptying was assessed by acetaminophen absorption (Clinicaltrials.gov Registry Number: NCT00477581).

Results: After 2 weeks of therapy, 2-h PPG was lower with exenatide versus sitagliptin: 133?±?6?mg/dL versus 208?±?6?mg/dL, p?<?0.0001 (evaluable, N?=?61). Switching from exenatide to sitagliptin increased 2-h PPG by +73?±?11?mg/dL, while switching from sitagliptin to exenatide further reduced 2-h PPG by ?76?±?10?mg/dL. Postprandial glucose parameters (AUC, C_ave, C_max) were lower with exenatide than sitagliptin (p?<?0.0001). Reduction in fasting glucose was similar with exenatide and sitagliptin (?15?±?4?mg/dL vs. ?19?±?4?mg/dL, p?=?0.3234). Compared to sitagliptin, exenatide improved the insulinogenic index of insulin secretion (ratio exenatide to sitagliptin: 1.50?±?0.26, p?=?0.0239), reduced postprandial glucagon (AUC ratio exenatide to sitagliptin: 0.88?±?0.03, p?=?0.0011), reduced postprandial triglycerides (AUC ratio exenatide to sitagliptin: 0.90?±?0.04, p?=?0.0118), and slowed gastric emptying (acetaminophen AUC ratio exenatide to sitagliptin: 0.56?±?0.05, p?<?0.0001). Exenatide reduced total caloric intake compared to sitagliptin (?134?±?97?kcal vs. +130?±?97?kcal, p?=?0.0227, N?=?25). Common adverse events with both treatments were mild to moderate in intensity and gastrointestinal in nature.

Conclusions: Although this study was limited by a 2-week duration of exposure, these data demonstrate that, exenatide had: (i) a greater effect than sitagliptin to lower postprandial glucose and (ii) a more potent effect to increase insulin secretion and reduce postprandial glucagon secretion in T2D patients. In contrast to sitagliptin, exenatide slowed gastric emptying and reduced caloric intake. These key findings differentiate the therapeutic actions of the two incretin-based approaches, and may have meaningful clinical implications.     

Protective potential of Tamarindus indica against gentamicin-induced nephrotoxicity

Context: Gentamicin is an antibiotic that is effective against Gram-negative microorganisms. However, its clinical applications are often limited due to nephrotoxic effects.

Objective: This study investigated the protective effects of aqueous-ethanol extract of Tamarindus indica L. (Leguminosae) fruits against gentamicin-induced renal toxicity.

Materials and methods: A daily dose of 200?mg/kg of 70% aqueous-ethanol extract derived from T. indica was employed in male rabbits as a co-therapy with gentamicin (80?mg/kg) for a period of three weeks. Serum and urinary renal function parameters and histological assessments were carried out and compared with one way analysis of variance (Graphpad prism version 5.00, Graphpad Software, San Diego, CA).

Results: The results showed that gentamicin-treated animals had significantly elevated blood urea nitrogen (54.1?±?2.6?mg/dl), serum creatinine (4.0?±?0.1?mg/dl), serum uric acid (2.3?±?0.1?mg/dl) and urinary protein excretion (3.8?±?0.3?mg/dl) with a fall in body weight (10?±?1%), creatinine clearance (0.7?±?0.09?ml/min), serum potassium (3.4?±?0.1?mEq/l), serum calcium (7.6?±?0.2?mg/dl), urinary volume (126?±?9?ml/24?h) and urinary lactate dehydrogenase secretion (103.1?±?4.2?U/l). However, animals treated by co-therapy with gentamicin and T. indica had significantly improved renal structure and function.

Discussion and conclusion: Co-therapy of 200?mg/kg/d of T. indica for a period of three weeks successfully prevented functional and morphological derangements caused by gentamicin as assessed by different renal function parameters and histological examinations.     

Enantiospecific effects of chiral drugs on cytochrome P450 inhibition in vitro

1.?The aim of this work was to examine the differences in the inhibitory potency of individual enantiomers and racemic mixtures of selected chiral drugs on human liver microsomal cytochromes P450.

2.?The interaction of enantiomeric forms of six drugs (tamsulosin, tolterodine, citalopram, modafinil, zopiclone, ketoconazole) with nine cytochromes P450 (CYP3A4, CYP2E1, CYP2D6, CYP2C19, CYP2C9, CYP2C8, CYP2B6, CYP2A6, CYP1A2) was examined. HPLC methods were used to estimate the extent of the inhibition of specific activity in vitro.

3.?Tamsulosin (TAM) and tolterodine (TOL) inhibited CYP3A4 activity with an enantiospecific pattern. The inhibition of CYP3A4 activity differed for R-TAM (K_i 2.88?±?0.12?µM) and S-TAM (K_i 14.22?±?0.53?µM) as well as for S-TOL (K_i 1.71?±?0.03?µM) and R-TOL (K_i 4.78?±?0.17?µM). Also, the inhibition of CYP2C19 by ketoconazole (KET) cis-enantiomers exhibited enantioselective behavior: the (+)-KET (IC₅₀ 23.64?±?6.25?µM) was more potent than (?)-KET (IC₅₀ 66.12?±?12.6?µM). The inhibition of CYP2C19 by modafinil (MOD) enantiomers (R-MOD IC₅₀?=?51.79?±?8.58?µM, S-MOD IC₅₀?=?48.62?±?9.74?µM) and the inhibition of CYP2D6 by citalopram (CIT) enantiomers (R-CIT IC₅₀?=?68.17?±?5.70?µM, S-CIT IC₅₀?=?62.63?±?7.89?µM) was not enantiospecific.

4.?Although enantiospecific interactions were found (TAM, TOL, KET), they are probably not clinically relevant as the plasma levels are generally lower than the drug concentration needed for prominent inhibition (at least 50% of CYP activity).     

Pharmacokinetic study of methylnaltrexone after single and multiple subcutaneous administrations in healthy Chinese subjects

1. Pharmacokinetics of methylnaltrexone (MNTX) were evaluated after subcutaneous administrations (s.c.) in healthy Chinese subjects.

2. In a cross-over single dose study, 12 subjects were given 0.075, 0.15, and 0.3?mg/kg of MNTX bromide injection. In a multiple doses study, another 12 subjects subcutaneously received 0.15?mg/kg of MNTX bromide injection every 48?h, in total five administrations. The concentrations of MNTX in plasma were quantified by LC–MS/MS.

3. After single s.c. administrations of 0.075, 0.15, and 0.3?mg/kg of MNTX bromide, C_max values of MNTX were 93.5?±?28.6, 191?±?37, and 364?±?54?ng/mL, respectively, and AUC_0–∞ were 88.8?±?8.8, 181?±?16, and 357?±?34?ng?h/mL, respectively. The t_1/2 of MNTX was about 7.7?h. After multiple doses administration, the C_max, C_av, AUC_ss, and MRT_0–∞ values were 191?±?50, 3.79?±?0.40?ng/mL, 182?±?19?ng?h/mL, and 3.56?±?1.17?h, respectively.

4. Methylnaltrexone bromide displayed dose-proportional pharmacokinetics in the dose range of 0.075–0.3?mg/kg. After multiple doses administration, t_1/2 was slightly prolonged, with the cumulative factor of 1.02. This study provides a pharmacokinetic reference after a single dose and multiple doses of MNTX bromide in Chinese subjects.     

In vitro antioxidant and anti-cholinesterase activities of Rhizophora mucronata

Context: Rhizophora mucronata Lam. (Rhizophoraceae), commonly known as Asiatic mangrove, has been used traditionally among Asian countries as folk medicine.

Objective: This study investigates the cholinesterase inhibitory potential and antioxidant activities of R. mucronata.

Materials and method: Rhizophora mucronata leaves were successively extracted using solvents of varying polarity and a dosage of 100–500?µg/ml were used for each assay. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities were assessed according to the method of Ellman. In vitro antioxidant activity was assessed using free radical scavenging, reducing power, and metal-chelating activity (duration – 3 months). Total phenolic and flavonoid content were quantified spectrophotometrically. Compound characterization was done using column chromatography, NMR, FTIR, and LC-MS analysis.

Results: Methanolic leaf extract (500?µg/ml) exhibited the highest inhibitory activity against AChE (92.73?±?0.54%) and BuChE (98.98?±?0.17%), with an IC₅₀ value of 59.31?±?0.35 and 51.72?±?0.33?µg/ml, respectively. Among the different solvent extracts, methanolic extract exhibited the highest antioxidant activity with an IC₅₀ value of 47.39?±?0.43, 401.45?±?18.52, 80.23?±?0.70, and 316.47?±?3.56?µg/ml for DPPH, hydroxyl, nitric oxide radical, and hydrogen peroxide, respectively. Total polyphenolic and flavonoid contents in methanolic extract were observed to be 598.13?±?1.85?µg of gallic acid equivalent and 48.85?±?0.70?μg of rutin equivalent/mg of extract. Compound characterization illustrated (+)-catechin as the bioactive compound responsible for cholinesterase inhibitory and antioxidant activities.

Conclusion: The presence of rich source of flavonoids, in particular catechin, might be responsible for its cholinesterase inhibitory and antioxidant activities.     

Antioxidant activity and cytotoxicity of Cyrtosperma johnstonii extracts on drug sensitive and resistant leukemia and small cell lung carcinoma cells

Context: The number of patients with cancer is increasing. New therapeutic agents to overcome drug-resistant tumors are urgently needed. Cyrtosperma johnstonii N.E. Br. (Araceae) is used for treatment of cancer in Thai traditional medicine. This study aimed to evaluate antioxidant activity and cytotoxicity of C. johnstonii extracts on human cancer cells.

Materials and methods: Dried powder of C. johnstonii rhizomes was extracted with several solvents. The 0.1?mg/ml extract solution was tested for antioxidant activity by 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and ferric reducing antioxidant power (FRAP) assays. Color formation from 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide was used to determine cell viability. Standardization of the extract was performed by high-performance liquid chromatography (HPLC) with photodiode array detector at 254 and 360?nm. Cell cycle arrest was evaluated by flow cytometry after 5?min, 12?h and 24?h treated with 20 µg/ml of the acetone extract.

Results: The acetone extract exhibited the highest phenolic content and antioxidant activity (TEAC and EC values = 19.2?±?0.14 and 19.2?±?0.31?mM/mg, respectively). The IC₅₀ values for leukemia ranged from 11?±?1 to 29?±?3 µg/ml and from 5?±?2 to 6?±?0 µg/ml for small cell lung carcinoma cells. Cell cycle arrest occurred at the G2/M phase followed by apoptosis. HPLC analysis revealed that rutin is the major constituents of the extract.

Discussion and conclusion: The acetone extract of C. johnstoni is a promising source of natural antioxidants and anticancer. The extract inhibits cancer cells effectively with less effect on normal cells.     

Phytoextract of Indian mustard seeds acts by suppressing the generation of ROS against acetaminophen-induced hepatotoxicity in HepG2 cells

Abstract

Context: Indian mustard [Brassica juncea (L.) Czern. & Coss. (Brassicaceae)] is reported to possess diverse pharmacological properties. However, limited information is available concerning its hepatoprotective activity and mechanism of action.

Objective: To study the protective mechanism of mustard seed extract against acetaminophen (APAP) toxicity in a hepatocellular carcinoma (HepG2) cell line.

Materials and methods: Hepatotoxicity models were established using APAP (2.5–22.5?mM) based on the cytotoxicity profile. An antioxidant-rich fraction from mustard seeds was extracted and evaluated for its hepatoprotective potential. The mechanism of action was elucidated using various in vitro antioxidant assays, the detection of intracellular generation of reactive oxygen species (ROS), and cell cycle analysis. The phytoconstituents isolated via HPLC-DAD were also evaluated for hepatoprotective activity.

Results: Hydromethanolic seed extract exhibited hepatoprotective activity in post- and pre-treatment models of 20?mM APAP toxicity and restored the elevated levels of liver indices to normal values (p?<?0.05). Post-treatment suppressed the generation of ROS by 58.37% and pre-treatment effectively prevented the generation of ROS by 90.5%. The mechanism of ROS suppression was further supported by antioxidant activity (IC₅₀) data from DPPH (103.37?±?4.2?µg AAE/mg), FRAP (83.26?±?1.1?µg AAE/mg), ORAC (1115?µM GAE/ml), ABTS (83.05?µg GAE/ml), and superoxide (345.22?±?5.15?µg AAE/mg) scavenging assays and by the restoration of cell cycle alterations. HPLC-DAD analysis revealed the presence quercetin, vitamin E, and catechin, which exhibited hepatoprotective activity.

Discussion and conclusions: A phytoextract of mustard seeds acts by suppressing the generation of ROS in response to APAP toxicity.