Nephroprotective effects of honokiol in a high-fat diet-streptozotocin rat model of diabetic nephropathy.

AIMS: Diabetic nephropathy (DN) is the foremost basis of end-stage kidney failure implicating endoplasmic reticulum (ER) stress and dysregulation of Rho kinase/Rock pathway. Magnolia plants are used in traditional medicine systems in Southeast Asia owing to bioactive phytoconstituents. Earlier, honokiol (Hon) exhibited therapeutic potential in experimental models of metabolic, renal, and brain disorders. In the present study, we evaluated potential of Hon against DN and possible molecular mechanisms. MAIN METHODS: In the existing experiments, high-fat diet (HFD) (17 weeks) and streptozotocin (STZ) (40 mg/kg once) induced DN rats were orally treated with Hon (25, 50, 100 mg/kg) or metformin (150 mg/kg) for 8 weeks. KEY FINDINGS: Hon attenuated albuminuria, blood biomarkers (e.g., urea nitrogen, glucose, C-reactive protein, and creatinine) and ameliorated lipid profile, electrolytes levels (Na+/K+), and creatinine clearance against DN. Hon significantly decreased renal oxidative stress and inflammatory biomarkers against DN. Histomorphometry and microscopic analysis revealed nephroprotective effects of Hon marked by a decrease in leukocyte infiltration, renal tissue damage, and urine sediments. RT-qPCR showed that Hon treatment attenuated mRNA expression of transforming growth factor-ß1 (TGF-ß1), endothelin-1 (ET-1), ER stress markers (GRP78, CHOP, ATF4, and TRB3), and Rock 1/2 in DN rats. Data from ELISA supported a decrease in levels of TGF-ß1, ET-1, ER stress markers, and Rock1/2 by Hon. SIGNIFICANCE: Hon attenuated hyperglycemia, redox imbalance, and inflammation and improved renal functions in rats. Hon alleviates DN pathogenesis possibly by attenuating ER stress and Rock pathway.

A comparative physicochemical and pharmacological evaluation of dexamethasone sodium phosphate and betamethasone sodium phosphate mucoadhesive gels for the treatment of oral submucous fibrosis in rats

Abstract The present study is aimed to formulate steroidal oral mucoadhesive gels of dexamethasone sodium phosphate and betamethasone sodium phosphate. Six gel formulations each of dexamethasone sodium phosphate and betamethasone sodium phosphate prepared using two different polymers carboxymethyl cellulose sodium and hydroxypropyl methylcellulose, in variable proportions. All the formulations subjected for assessment of various physicochemical parameters and mechanical properties. The formulations BSP5 and DSP5, both containing 1.25 % carboxymethyl cellulose sodium, 1.25 % hydroxypropyl methylcellulose, exhibiting mucoadhesive strength of 12.300 ± 0.004 and 12.600 ± 0.01, adhesiveness of 28.04 ± 00 and 30.02 ± 00, cohesiveness of 28.04 ± 00 and 30.02 ± 00, drug release of 86.869 ± 0.380 % and 88.473 ± 0.457 % respectively were considered as promising ones and were further subjected for stability studies and in vivo study in male albino rats. Formulation DSP5 upon oral application for 4 months in arecoline induced oral submucous fibrosis rats, showed more than 80 % reduction in fibrosis as compared with BSP5 which showed nearly 50 % reduction. These results were concluded on the basis of histopathological profile and weight gain among the experimental animals during in vivo study. Hence, DSP5 by minimizing the painful injuries and morbidities justifies being suitable noninvasive model for OSMF treatment.

Arbutin protects brain against middle cerebral artery occlusion-reperfusion (MCAo/R) injury.

Focal ischemia causes irreversible brain damage if cerebral blood flow is not restored promptly. Acute phase excitotoxicity and pro-oxidant and inflammatory events in the sub-chronic phase elicit coagulative necrosis, vascular injury, cerebral oedema, and neurobehavioral deficits. Earlier, in pre-clinical studies arbutin protected behavioral functions and improved therapeutic outcomes in different models of brain and metabolic disorders. Arbutin is natural hydroquinone that might protect against ischemia-reperfusion (I/R) injury. In this study, cerebro-protective effects of arbutin were evaluated in the middle cerebral artery occlusion-reperfusion (MCAo/R) mouse model. Mice were administered arbutin (50, 100 mg/kg, i.p.) for 21 days, and subjected to MCAo/R or sham surgery on day 14. Results showed brain infarction, blood-brain barrier dysfunction, oedema, and neurological deficits 24 h post-MCAo/R injury that were prevented by arbutin. Behavioral evaluations over the sub-chronic phase revealed MCAo/R triggered spatial and working memory deficits. Arbutin protected the memory against MCAo/R injury and decreased hydroxy-2'-deoxyguanosine, protein carbonyls, inflammatory cytokines (tumor necrosis factor-α, myeloperoxidase, matrix metalloproteinase-9, inducible nitric oxide synthase), and enhanced glutathione levels in the ischemia ipsilateral hemisphere. Arbutin decreased brain acetylcholinesterase activity, glutamate, and enhanced GABA levels against MCAo/R. Arbutin can alleviate I/R pathogenesis and protects neurobehavioral functions in the MCAo/R mouse model.

In vitro and in vivo effects of morin on the intestinal absorption and pharmacokinetics of olmesartan medoxomil solid dispersions.

PURPOSE: In-situ evaluation to corroborate morin effects on the intestinal absorption and pharmacokinetic behavior of freeze-dried OLM-loaded solid dispersions with Caco-2 and in-vivo studies Methods: Intestinal transport and absorption studies were examined by Caco-2 permeability, in-situ single pass perfusion and closed-loop models along with in-vivo pharmacokinetic studies to evaluate and confirm the effect of P-gp-mediated activity of morin. We evaluated the intestinal membrane damage in the presence of morin by measuring the release of protein and lactate dehydrogenase (LDH) followed by using qualitative and quantitative morphometric analysis to describe the surface characteristics of intestinal epithelium. RESULTS: Morin showed the highest Peff value 13.8 ± 0.34 × 10-6 cm/s in jejunum than ileum (p < .01) at 100 µM with absorption enhancement of 1.31-fold together with enhanced (p < .01) secretory transport of 6.27 ± 0.27 × 10 -6 cm/s in Caco-2 monolayer cells. Our findings noticed 2.37 (in-situ); 2.39 (in-vivo) and 1.43 (in-situ); 1.36 (in-vivo) fold increase in AUC0-t with elevated Cmax and shortened Tmax for freeze-dried solid dispersion in the presence of morin as compared to pure OLM and freeze-dried solid dispersions without morin, respectively. CONCLUSIONS: Our study demonstrated that increased solubilization through freeze-dried OLM-loaded solid dispersion together with efflux inhibition improved intestinal permeability to one system that might lead to novel solubilization and efflux pump inhibition as a novel alternative potential to increase oral absorption and bioavailability of OLM.

Novel tablet formulation of amorphous candesartan cilexetil solid dispersions involving P-gp inhibition for optimal drug delivery: in vitro and in vivo evaluation.

OBJECTIVE: The aim of this study was to develop a novel tablet formulation of amorphous candesartan cilexetil (CAN) solid dispersion involving effective P-gp inhibition for optimal drug delivery by direct compression (DC) method. METHODS: To accomplish DC, formulation blends were evaluated for micromeritic properties. The Carr index, Hausner ratio, flow rate and cotangent of the angle α were determined. The tablets with and without naringin prepared by DC technique were evaluated for average weight, hardness, disintegration time and friability assessments. The drug release profiles were determined to study the dissolution kinetics. In vivo pharmacokinetic studies were conducted in rabbits. Accelerated stability studies were performed for tablets at 40 ± 2 °C/75% RH ± 5% for 6 months. RESULTS: FTIR studies confirmed no discoloration, liquefaction and physical interaction between naringin and drug. The results indicated that tablets prepared from naringin presented a dramatic release (82%) in 30 min with a similarity factor (76.18), which is most likely due to the amorphous nature of drug and the higher micromeritic properties of blends. Our findings noticed 1.7-fold increase in oral bioavailability of tablet prepared from naringin with mean Cmax and AUC0-12 h values as 35.81 ± 0.13 µg/mL and 0.14 ± 0.09 µg h/mL, respectively. The tablets with and without naringin prepared by DC technique were physically and chemically stable under accelerated stability conditions upon storage for 6 months. CONCLUSION: These results are attractive for further development of an oral tablet formulation of CAN through P-gp inhibition using naringin, a natural flavonoid as a pharmaceutical excipient.

Safety evaluation of naringenin upon experimental exposure on rat gastrointestinal epithelium for novel optimal drug delivery.

OBJECTIVE: To assess the effect of naringenin on the intestinal biochemical composition, function and histology for gastrointestinal toxicity since it has not yet been adequately exploited for safety through standard assays. METHODS: Here, we describe naringenin (1 mM, 10 mM and 100 mM, respectively) or sodium deoxycholate (10 mM) effects on isolated brush border membrane from intestinal segments with single pass intestinal perfusion using lactate dehydrogenase, alkaline phosphatase and protein assays. MTT assay was used for cytotoxicity studies. Everted gut sac studies were used for evaluating the transport of nutrients across the intestinal segments. Lucifer yellow was used for paracellular permeability, followed by histological changes and surface characteristic studies of intestinal sacs. RESULTS: The results indicated no significant alterations with naringenin, although significant (p < 0.01) changes were noticed with sodium deoxycholate in the activity of the rat intestinal brush border associated enzymes such as LDH, followed by intact cell viability with marked decrease in the villi height of the intestinal segments. CONCLUSIONS: These observations indicate that naringenin was harmless upon exposure to rat gastrointestinal epithelium, clearly demonstrating the potential use of naturally occurring bioflavonoid as safe and novel pharmaceutical adjuvant in oral dosage forms as P-gp inhibitor.

Comprehensive cytotoxic evaluation of morin, a bioflavonoid against verapamil on rat gastrointestinal epithelium for novel pharmaceutical application involving P-glycoprotein inhibition.

OBJECTIVE: In this study, a comprehensive and comparative cytotoxic evaluation of morin against verapamil on rat intestinal epithelium as P-gp inhibitors through in-vitro gastrointestinal short-term toxicity assays involving permeability studies for safety evaluation was investigated. METHODS: In this study, the effect of morin (1 mM or 10 mM) or verapamil (1 mM or 10 mM) or sodium deoxycholate (10 mM) was investigated on intestinal epithelium and isolated brush border membrane using biomarker assays. Cytotoxicity was determined using 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay. The nutrients transport was assessed using everted sacs studies. Paracellular permeability was measured using Lucifer yellow, followed by morphometric analysis of intestinal sacs. KEY FINDINGS: Our results indicated that morin was effective in maintaining cell viability with no significant changes (P > 0.05) in the activity of intestinal brush border markers, membrane integrity and morphometric analysis as compared with control. On the contrary, dramatic (P < 0.01) changes were noticed in the release of membrane markers, cell viability and surface characteristics of intestinal segments when treated with verapamil or sodium deoxycholate as compared with control or morin. CONCLUSIONS: Our findings confirm that morin is non-toxic to rat intestinal epithelium against verapamil demonstrating the potential use of bioflavonoid as safe and novel pharmaceutical adjuvant as P-gp inhibitor.

Corroboration of naringin effects on the intestinal absorption and pharmacokinetic behavior of candesartan cilexetil solid dispersions using in-situ rat models.

OBJECTIVE: The aim of this study was to corroborate the effects of naringin, a P-glycoprotein inhibitor, on the intestinal absorption and pharmacokinetics of candesartan (CDS) from candesartan cilexetil (CAN) solid dispersions using in-situ rat models. MATERIALS AND METHODS: Intestinal transport and absorption studies were examined by in-situ single pass perfusion and closed-loop models. We evaluated the intestinal membrane damage in the presence of naringin by measuring the release of protein and alkaline phosphatase (ALP). RESULTS AND DISCUSSION: We noticed 1.47-fold increase in Peff of CDS from freeze-dried CAN-loaded solid dispersions with naringin (15 mg/kg, w/w) when compared with freeze-dried solid dispersion without naringin using in-situ single pass intestinal perfusion model. However, no intestinal membrane damage was observed in the presence of naringin. Our findings from in-situ closed-loop pharmacokinetic studies showed 1.34-fold increase in AUC with elevated Cmax and shortened tmax for freeze-dried solid dispersion with naringin as compared to freeze-dried solid dispersion without naringin. CONCLUSION: This study demonstrated that increased solubilization (favored by freeze-dried solid dispersion) and efflux pump inhibition (using naringin), the relative bioavailability of CDS can be increased, suggesting an alternative potential for improving oral bioavailability of CAN.