Current Drug Metabolism - Volume 22, Issue 4, 2021

Impressive research steps have been taken for the treatment of neurological disorders in the last few decades. Still, effective treatments of brain related disorders are very less due to problems associated with crossing the blood-brain barrier (BBB), non-specific therapies, and delay in functional recovery of the central nervous system (CNS) after treatment. Striving for novel treatment options for neurological disorders, nanotechnology- derived materials, and devices have gained ground due to inherent features of derivatization/encapsulation with drugs as per the neurological ailments and pharmacological targets. Facile developments/syntheses of the nanomaterials-drug conjugates have also been the driving force for researchers to get into this field. Moreover, the tunable size and hydro/lipophilicity of these nanomaterials are the added advantages that make these materials more acceptable for CNS disorders. These nano-neurotherapeutics (NNTs) systems provide the platform for diagnosis, theranostics, treatments, restoration of CNS disorders, and encourage the translation of NNTs from “bench to bedside”. Still, these techniques are in the primary stages of medical development. This review describes the latest advancements and future scenarios of developmental and clinical aspects of polymeric NNTs.

Background: Form last few decades, nanoparticles have witnessed breakthroughs in the treatment of neurological disorders due to their unique physiochemical properties, which make them an effective drug delivery system. However, there is not much information available on the toxicity of nanoparticles in neuronal disorders. The toxic effect of nanoparticles on brain disorders and their regulatory issues are the primary concerns of the healthcare industry. Methods: A strategical literature search was performed on various bibliographic databases such as Scopus, PubMed, SciFinder, Google Scholar, Medline, Google Patent, Derwent Innovation, and Orbit Intelligence for retrieval of peer-reviewed articles and patents on regulatory issues and toxicity of nanoparticles in neuronal disorders for last decade. The relevant hits of articles and patents were analyzed, and citation search for the relevant documents was carried out. Results: The literature documents have been summarized regarding the existing regulatory issues and toxicity of nanoparticles on neuronal disorders with a focus on the detailed mechanism of the developmental toxicity of nanoparticles. The focus of this report is to emphasize the negative effects of nanoparticle on neuronal disorders, which may partially contribute to the management of toxicity of nanoparticles. Conclusion: Although nanoparticles have unique physical and chemical properties that explain the broad range of application for the central nervous system, they can also manifest neurotoxic effects due to cell necrosis, generation of free radicals, immune responses and neuroinflammation. Thus, this review highlights risk assessment, safety regulations and regulatory guidelines of nanoparticles, which may reduce adverse reactions in humans and animals.

Background: Human immunodeficiency virus (HIV)/AIDS is one of the principal concerns contributing to the global burden and the accompanying deleterious outcomes could not be left unattended. Despite significant advances and innovative research being conducted throughout the globe in order to improve the therapeutic profile of conventionally available antiretroviral (ARV) drugs in the eradication of HIV virus reservoirs, its penetration across the blood-brain barrier (BBB) is still a formidable mission. This makes the central nervous system a dominant and vulnerable site for virus propagation, which ultimately affects the therapeutic potential of the drug administered. Therefore there is an upsurge in the prerequisite of novel technologies to come into play, paving the way for nanotechnology. Methods: This review primarily provides a comprehensive outline and emphasizes on the nanotechnological techniques employed for the delivery of ARV drugs and their stupendous advantages in overcoming the hurdles associated with the same. Results: The nanotechnological approach bears the potential of site-specific delivery across the BBB via targeting explicit transport processes and provides a sustained release mechanism. Furthermore, different routes of administration explored have also yielded beneficial outcomes for the delivery of ARV drugs. Conclusion: The futuristic holistic nanotechnology methods, however, should focus on increasing drug trafficking and permeability across the BBB to ameliorate the therapeutic effect of ARV drugs. Additionally, the domain warrants clinical studies to be undertaken to make the technology commercially viable and a success to deal with the problems of the treatment strategy.

Parkinson’s disease (PD) is believed to be one of the commonly found adult-onset movement disorder occurring due to neurodegeneration and striatal dopamine deficiency. Although clinical diagnosis depends on the occurrence of bradykinesia and other cardinal motor features, PD is linked with many non-motor symptoms that are responsible for overall disability. Among several factors, genetic and environment-related factors are thought to be the major ones accountable for PD. Comprehensive research has shown that a number of drugs are effective in providing symptomatic relief to the patients suffering from PD. But some drug molecules suffer from significant drawbacks such as poor bioavailability and instability, therefore, they sometimes fail to deliver the expected results. Hence, to resolve these issues, new promising novel drug delivery systems have been developed. Liposomes, solid lipid nanoparticles, nanoemulsion, self-emulsifying drug delivery system (SEDDS), niosomes are some of the novel drug delivery system (NDDS) carriers that have been explored for enhancing the CNS concentration of levodopa, apomorphine, resveratrol, and other numerous drugs. This paper elucidates various drugs that have been studied for their potential contribution to the treatment and management of PD and also reviews and acknowledges the efforts of several scientists who successfully established various NDDS approaches for these drugs for the management of PD.

Background: Aluminum toxicity induces neurodegenerative changes in the brain and results in Alzheimer’s disease (AD). Objective: Here, the aim was to evaluate the antioxidant therapeutic effects of ellagic acid (EA) and EA-loaded nanoparticles (EA-NP) in an aluminum chloride-induced AD rat model. Methods: The nanoparticles’ loading of EA was 0.84/1 w/w. The in vitro release kinetics of EA from EA-NP in fetal bovine serum showed 60% release in the first 1-5 hours, followed by sustained release at 60-70% over 6-24 hours. Six groups were implemented; group 1 served as the control, group 2 received EA, group 3 received EA-NP, group 4 was the AD rat model administered AlCl3 (50 mg/kg) for 4 weeks, groups 5 (AD+EA) and 6 (AD+EA-NP) were treated with EA and EA-NP, respectively, for 2 weeks after AlCl3 was stopped. The neurotoxicity in the rat brain was examined by measuring the brain antioxidant biomarkers catalase, glutathione, and total antioxidant activity and lipid peroxidation (thiobarbituric acid, TBA). Histopathological studies using hematoxylin and eosin, cresyl violet, silver stains, and the novel object recognition test were examined. Results: Data revealed significant increase of antioxidant biomarkers and decreased TBA in the EA-NP group. The pathological hallmarks of AD-vacuolation of the neurons, chromatolysis, neurofibrillary tangles, and the senile plaques in brains of the AD rat model were decreased and restoration of Nissl granules was noted. The calculated discrimination index in the behavioral test increased more in cases treated with EA-NP. Conclusion: The treatment of AD with EA-NP was more effective than EA in alleviating the oxidative neurotoxic effects on AD rat brains.

Background: The glutathione S-transferases (GSTs) are family of enzymes that are notable for their role in phase II detoxification reactions. Antibiotics have been reported to have several adverse effects on the activity of the enzymes in mammals. Aim: The aim of this study was the structural and biochemical characterization of rat erythrocyte GST and understanding the effects of gentamicin, clindamycin, cefazolin, ampicillin and scopolamine butylbromide on the activity of human erythrocyte GST using rat as a model. Methods: The enzyme was purified by GSH-agarose affinity chromatography. In vitro GST enzyme activity was measured at 25°C using CDNB as a model substrate. IC50 of drugs was measured by activity % vs compound concentration graphs. Lineweaver Burk graphs were drawn to determine the inhibition type and Ki constants for the drugs. The structure of the enzyme was predicted via Protein Homology/analogy Recognition Engine. Results: In this study, GST was purified from rat erythrocyte with a specific activity of 6.3 EU/mg protein, 44 % yield and 115 fold. Gentamicin and clindamycin inhibited the enzymatic activity with IC50 of 1.69 and 6.9 mM and Ki of 1.70 and 2.36 mM, respectively. Ampicillin and scopolamine butylbromide were activators of the enzyme, while the activity of the enzyme was insensitive to cefazolin. The enzyme was further characterized by homology modeling and sequence alignment revealing similarities with human GST. Conclusion: Collectively, it could be concluded that gentamicin and clindamycin are the inhibitors of erythrocyte GST.

Aims: We aim to demonstrate why deeming diffusible reactive oxygen species (DROS) as toxic wastes do not afford a comprehensive understanding of cytochrome P450 mediated microsomal xenobiotic metabolism (mXM). Background: Current pharmacokinetic investigations consider reactive oxygen species formed in microsomal reactions as toxic waste products, whereas our works (Manoj et al., 2016) showed that DROS are the reaction mainstay in cytochrome P450 mediated metabolism and that they play significant roles in explaining several unexplained physiologies. Objective: Herein, we strive to detail the thermodynamic and kinetic foundations of murburn precepts of cytochrome P450 mediated drug metabolism. Methods: Primarily, in silico approaches (using pdb crystal structure files), murburn reaction chemistry logic and thermodynamic calculations to elucidate the new model of CYP-mediated drug metabolism. The theoretical foundations are used to explain experimental observations. Results: We visually elucidate how murburn model better explains- (i) promiscuity of the unique P450-reductase; (ii) prolific activity and inhibitions of CYP3A4; (iii) structure-function correlations of important key CYP2 family isozymes- 2C9, 2D6 and 2E1; and (iv) mutation studies and mechanism-based inactivation of CYPs. Several other miscellaneous aspects of CYP reaction chemistry are also addressed. Conclusion: In the light of our findings that DROS are crucial for explaining reaction outcomes in mXM, approaches for understanding drug-drug interactions and methodologies for lead drug candidates' optimizations should be revisited.