Najeeb Ullah

Neuroprotection with metformin and thymoquinone against ethanol-induced apoptotic neurodegeneration in prenatal rat cortical neurons.

BackgroundExposure to ethanol during early development triggers severe neuronal death by activating multiple stress pathways and causes neurological disorders, such as fetal alcohol effects or fetal alcohol syndrome. This study investigated the effect of ethanol on intracellular events that predispose developing neurons for apoptosis via calcium-mediated signaling. Although the underlying molecular mechanisms of ethanol neurotoxicity are not completely determined, mitochondrial dysfunction, altered calcium homeostasis and apoptosis-related proteins have been implicated in ethanol neurotoxicity. The present study was designed to evaluate the neuroprotective mechanisms of metformin (Met) and thymoquinone (TQ) during ethanol toxicity in rat prenatal cortical neurons at gestational day (GD) 17.5.ResultsWe found that Met and TQ, separately and synergistically, increased cell viability after ethanol (100 mM) exposure for 12 hours and attenuated the elevation of cytosolic free calcium [Ca2+]c. Furthermore, Met and TQ maintained normal physiological mitochondrial transmembrane potential (ΔψM), which is typically lowered by ethanol exposure. Increased cytosolic free [Ca2+]c and lowered mitochondrial transmembrane potential after ethanol exposure significantly decreased the expression of a key anti-apoptotic protein (Bcl-2), increased expression of Bax, and stimulated the release of cytochrome-c from mitochondria. Met and TQ treatment inhibited the apoptotic cascade by increasing Bcl-2 expression. These compounds also repressed the activation of caspase-9 and caspase-3 and reduced the cleavage of PARP-1. Morphological conformation of cell death was assessed by TUNEL, Fluoro-Jade-B, and PI staining. These staining methods demonstrated more cell death after ethanol treatment, while Met, TQ or Met plus TQ prevented ethanol-induced apoptotic cell death.ConclusionThese findings suggested that Met and TQ are strong protective agents against ethanol-induced neuronal apoptosis in primary rat cortical neurons. The collective data demonstrated that Met and TQ have the potential to ameliorate ethanol neurotoxicity and revealed a possible protective target mechanism for the damaging effects of ethanol during early brain development.

Amorphous amphiphilic P(3HV-co-4HB)-b-mPEG block copolymer synthesized from bacterial copolyester via melt transesterification: Nanoparticle preparation, cisplatin-loading for cancer therapy and in vitro evaluation

Cisplatin is a chemotherapeutic agent used against a variety of tumors. We determined the efficacy and bioavailability of cisplatin in the form of cisplatin-loaded self-assembled amphiphilic copolymer nanoparticles (NPs). Non-crystallizing bacterial copolyester was employed as hydrophobic segment to increase drug loading efficiency. Novel amorphous amphiphilic block copolymer P(3HV-co-4HB)-b-mPEG was synthesized from bacterial copolyester poly(3-hydroxyvalerate-co-4-hydroxybutyrate) coupled via transesterification reaction using bis(2-ethylhexanoate) tin catalyst to monomethoxypoly(ethylene glycol). The product was characterized, and core-shell particles with nanometer size range were prepared by emulsification-solvent evaporation method. Transmission electron microscopy (TEM) examination revealed that the NPs took the shape of spheres with inner concealed core of hydrophobic P(3HV-co-4HB) polymer and the outer shell formed by hydrophilic mPEG segment. The in vitro release profile of cisplatin from the core hydrophobic domain showed a sustained release of the drug. TEM and confocal microscopy examination revealed clearly the internalization of cisplatin-loaded NPs into the tumor cells. MTT assay, flow cytometry, western blot and confocal microscopy revealed a suppression effect by the NPs on tumor cell growth, and enhancement of apoptotic process of the tumor cells compared to free drug treated cells. The amorphous polymeric NPs could be effective vehicles for the sustained delivery of toxic anticancer drugs.