Two series of pH-responsive biodegradable interpolymeric (IPN) hydrogels based on chitosan (Ch) and poly(vinyl alcohol) (PVA) were prepared for controlled drug release investigations. The first series was chemically crosslinked with different concentrations of glutaraldehyde and the second was crosslinked upon g-irradiation by different doses. The equilibrium swelling characteristics were investigated for the gels at 378C in buffer solutions of pH 2.1 and 7.4 as simulated gastric and intestinal fluids, respectively. 5-Fluorouracil (FU) was entrapped in the hydrogels, as a model therapeutic agent, and the in vitro release profiles of the drug were established at 378C in pH 2.1 and 7.4. FTIR, SEM, and X-ray diffraction analyses were used to characterize and investigate the structural changes of the gels with the variation of the blend composition and crosslinker content before and after the drug loading.
Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by gradual cognitive decline. Strong antioxidants that inhibit free radicals, such as polyphenols, reduce the likelihood of developing oxidative stress-related degenerative diseases such as AD. Naringin, a flavonoid found in citrus fruit shown to be neuroprotective, reduce oxidative damage and minimize histopathological changes caused by ischemic reperfusion, enhance the long-term memory in AD animal models. This work aimed to comprehend the role of naringin in the defense of the cerebellum against aluminum chloride (AlCl3)-induced AD in rats by investigating the behavioral, neurochemical, immunohistochemical, and molecular mechanisms that underpin its possible neuroprotective effects. Twenty-four adult albino rats were divided into four groups (n = 6/group): (i) Control (C) received saline per oral (p.o.), (ii) Naringin(N)-received naringin (100 mg/kg/d) p.o, (iii) AlCl3-recived AlCl3 (100 mg/kg/d) p.o and (iv) AlCl3 + Naringin (AlCl3 + N) received both AlCl3 and naringin p.o for 21 days. Behavioral tests showed an increase in the time to reach the platform in Morris water maze, indicating memory impairment in the AlCl3-treated group, but co-administration of naringin showed significant improvement. The Rotarod test demonstrated a decrease in muscle coordination in the AlCl3-treated group, while it was improved in the AlCl3 + N group. Neurochemical analysis of the hippocampus and cerebellum revealed that AlCl3 significantly increased lipid peroxidation and oxidative stress and decreased levels of reduced glutathione. Administration of naringin ameliorated these neurochemical changes via its antioxidant properties. Cerebellar immunohistochemical expression for microtubule assembly (tau protein) and oxidative stress (iNOS) increased in A1C13-treated group. On the other hand, the expression of the autophagic marker (LC3) in the cerebellum showed a marked decline in AlCl3-treated group. Western blot analysis confirmed the cerebellar immunohistochemical findings. Collectively, these findings suggested that naringin could contribute to the combat of oxidative and autophagic stress in the cerebellum of AlCl3-induced AD.
Graft copolymerization of 4-vinyl pyridine(4-VP) onto ethyl cellulose (EC) using ammonium persulfate (APS) as free radical initiator was studied in the toluene: DMSO (4:l v/v) solvent system. The weight conversion, grafting percentage and grafting efficiency were determined as functions of the polymerization temperature and of the concentration of monomer, ethyl cellulose and initiator. The homopolymerization of 4-VP in the presence ofAPS was also investigated. The graft copolymers were characterized by thin layer chromatography, IR spectroscopy, nuclear magnetic resonance and intrinsic viscosity measurements. The highest rate of propagation of graft copolymerization of 4-VP onto EC in the presence of APS observed was 0.06 %/min. A suitable mechanism of grafting reaction is discussed.
SynopsisThe oxidative degradation of polybutadiene-styrene-acrylonitrile (A=) copolymer was extensively investigated. Three factors were studied: the influence of ageing temperature on the rate of the oxidation of the copolymer; the efficiency of 8-carotene as chain breaking antioxidant; and the effect of butadiene content on the rate of the oxidative degradation of the ABS copolymer.
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