Rational approaches for toxicological assessments of nanobiomaterials

Cellular uptake, intracellular behavior, and acute/sub-acute cytotoxicity of a PEG-modified quantum dot with promising in-vivo biomedical applications

Quantum Dots (QDs) modified with branched Polyethylene Glycol-amine (6- or 8-arm PEG-amine) coupled with methoxy PEG (mPEG) hold great promise for in vivo biomedical applications due to a long half-life in blood and negligible toxicity. However, the potential risks regarding their concomitant prolonged co-incubation with cardiovascular and blood cells remains inconclusive. In the present study, the feasible, effective and convenient proliferating-restricted cell line models representing the circulatory system were established to investigate the cellular internalization followed by intracellular outcomes and resulting acute/sub-acute cytotoxicity of the 6-arm PEG-amine/mPEG QDs. We found a dose-, time- and cell type-dependent cellular uptake of the 6-arm PEG-amine/mPEG QDs, which was ten-fold lower compared to the traditional linear PEG-modified counterpart. The QDs entered cells via multiple endocytic pathways and were mostly preserved in Golgi apparatus for at least one week instead of degradation in lysosomes, resulting in a minimal acute cytotoxicity, which is much lower than other types of PEG-modified QDs previously reported. However, a sub-acute cytotoxicity of QDs were observed several days post exposure using the concentrations eliciting no-significant acute cytotoxic effects, which was associated with elevated ROS generation caused by QDs remained inside cells. Finally, a non-cytotoxic concentration of the QDs was identified at the sub-acute cytotoxic level. Our study provided important information for clinical translation of branched PEG-amine/mPEG QDs by elucidating the QDs-cell interactions and toxicity mechanism using the proliferation-restricted cell models representing circulatory system. What's more, we emphasized the indispensability of sub-acute cytotoxic effects in the whole biosafety evaluation process of nanomaterials like QDs.

Novel therapeutic interventions for combating Parkinson's disease and prospects of Nose-to-Brain drug delivery

Parkinson disease (PD) is a progressive neurodegenerative disorder prevalent mainly in geriatric population. While, L-DOPA remains one of the major choices for the therapeutic management of PD, various motor and non-motor manifestations complicate the management of PD. In the last two decades, exhaustive research has been carried out to explore novel therapeutic approaches for mitigating motor and non-motor symptoms of PD. These approaches majorly include receptor-based, anti-inflammatory, stem-cell and nucleic acid based. The major limitations of existing therapeutic interventions (of commonly oral route) are low efficacy due to low brain bioavailability and associated side effects. Nanotechnology has been exploited and has gained wide attention in the recent years as an approach for enhancement of bioavailability of various small molecule drugs in the brain. To address the challenges associated with PD therapy, nose-to-brain delivery utilizing nanomedicine-based approaches has been found to be encouraging in published evidence. Therefore, the present work summarises the major challenges and limitations with antiparkinsonian drugs, novel therapeutic interventions, and scope of nanomedicine-based nose-to-brain delivery in addressing the current challenges of antiparkinsonian therapy. The manuscript tries to sensitize the researchers for designing brain-targeted nanomedicine loaded with natural/synthetic scaffolds, biosimilars, and nucleic acids that can bypass the first-pass effect for the effective management of PD.

Role of Flavonoids in Neurodegenerative Diseases: Limitations and Future Perspectives

BACKGROUND

Flavonoids, a group of natural dietary polyphenols, are known for their beneficial effects on human health. By virtue of their various pharmacological effects, like anti-oxidative, antiinflammatory, anti-carcinogenic and neuroprotective effects, flavonoids have now become an important component of herbal supplements, pharmaceuticals, medicinals and cosmetics. There has been enormous literature supporting neuroprotective effect of flavonoids. Recently their efficacy in various neurodegenerative diseases, like Alzheimer's disease and Parkinson diseases, has received particular attention.

OBJECTIVE

The mechanism of flavanoids neuroprotection might include antioxidant, antiapoptotic, antineuroinflammatory and modulation of various cellular and intracellular targets. In in-vivo systems, before reaching to brain, they have to cross barriers like extensive first pass metabolism, intestinal barrier and ultimately blood brain barrier. Different flavonoids have varied pharmacokinetic characteristics, which affect their pharmacodynamic profile. Therefore, brain accessibility of flavonoids is still debatable.

METHODS

This review emphasized on current trends of research and development on flavonoids, especially in neurodegenerative diseases, possible challenges and strategies to encounter using novel drug delivery system.

RESULTS

Various flavonoids have elicited their therapeutic potential against neurodegenerative diseases, however by using nanotechnology and novel drug delivery systems, the bioavailability of favonoids could be enhanced.

CONCLUSION

This study bridges a significant opinion on medicinal chemistry, ethanopharmacology and new drug delivery research regarding use of flavonoids in management of neurodegeneration.

Effect of hesperidin on fluoride-induced neurobehavioral and biochemical changes in rats

Fluoride is the second largest contaminant of drinking water. Fluoride toxicity is a major concern in the endemic areas where a high amount of fluoride is present in ground water. Oxidative stress has been proposed to be one of the mechanisms of fluoride-induced toxicity. Antioxidant-rich food has been found to alleviate fluoride-induced toxicity. Therefore, in this study, we have examined the effect of hesperidin on fluoride-induced neurobehavioral changes in rats. In the current study, male Sprague-Dawley rats were exposed to sodium fluoride through drinking water (120 ppm). Hesperidin (200 mg kg^-1  d^-1 ; per os) was administered either alone or in combination with fluoride-containing drinking water. Bisphinol A diglycidyl ether (BADGE) was used as peroxisome proliferator-activated receptor-γ (PPAR-γ) antagonist and was administered (10 mg kg^-1  d^-1 ; intraperitoneal injection) with/without hesperidin along with fluoride-containing drinking water. The behavioral changes in the animals were assessed by analyzing rotarod test, novel object recognition test, and forced swim test (FST). After 8 weeks, animals were killed to isolate blood and brain for monitoring biochemical changes. The 8-week exposure of fluoride resulted in motor impairment as observed with reduced fall time in rotarod test, memory impairment as observed with reduced preference index in novel object recognition test, and depression-like behavior as observed with reduced mobility index in the FST. Treatment with hesperidin improved neurobehavioral impairment along with restoration in brain biochemical changes (ie, acetylcholinesterase activity and antioxidant and oxidative stress parameters). The protective effect of hesperidin was reversed by coadministration of BADGE. The neuroprotective effect of hesperidin appears to be contributed through PPAR-γ receptor.

Role of curcumin and its nanoformulations in neurotherapeutics: A comprehensive review

Curcumin, a dietary polyphenol and major constituent of Curcuma longa (Zingiberaceae), is extensively used as a spice in Asian countries. For ages, turmeric has been used in traditional medicine systems to treat various diseases, which was possible because of its anti-inflammatory, antioxidant, anticancerous, antiepileptic, antidepressant, immunomodulatory, neuroprotective, antiapoptotic, and antiproliferative effects. Curcumin has potent antioxidant, anti-inflammatory, antiapoptotic, neurotrophic activities, which support its plausible neuroprotective effects in neurodegenerative disease. However, there is limited information available regarding the clinical efficacy of curcumin in neurodegenerative cases. The low oral bioavailability of curcumin may be speculated as a plausible factor that limits its effects in humans. Therefore, utilization of several approaches for the enhancement of bioavailability may improve clinical outcomes. Furthermore, the use of nanotechnology and a targeted drug delivery system may improve the bioavailability of curcumin. The present review is designed to summarize the molecular mechanisms pertaining to the neuroprotective effects of curcumin and its nanoformulations.