Neuroprotective effects of bergenin in Alzheimer's disease: Investigation through molecular docking, in vitro and in vivo studies.

Alzheimer's disease (AD) is an enervating and chronic progressive neurodegenerative disorder, occurring frequently in the elderly and adversely affecting intellectual capabilities and the cognitive processes. Bergenin possesses efficacious antioxidant, antiulcerogenic, anti-HIV, hepatoprotective, neuroprotective, anti-inflammatory and immunomodulatory activity along with antinociceptive effect and wound healing properties. Previous studies have shown that bergenin has in vitro bovine adrenal tyrosine hydroxylase inhibitory activity, mushroom tyrosinase inhibitory activities, ß-secretase (BACE-1) enzyme inhibitory activity and prevented neuronal death in the primary culture of rat cortical neurons. Protein tyrosine phosphatase-1B (PTP1B) is an intriguing target for anticancer and antidiabetic drugs and has recently been implicated to act as a positive regulator of neuroinflammation. Bergenin is also found to inhibit human protein tyrosine phosphatase-1B (hPTP1B) in vitro. Thus, bergenin was screened by molecular docking study using GOLD suite (version 5.2), CCDC for predicting its activity against targets of AD management like acetylcholinesterase (AChE) (1B41), butyrylcholinesterase (BuChE) (1P0I), Tau protein kinase 1 (GSK-3ß) (1J1B), BACE-1 (1FKN) wherein the GOLD score and fitness of bergenin were comparable to those of standard drugs like donepezil, galanthamine, physostigmine, etc. Bergenin demonstrated dose-dependent inhibition of both AChE and BuChE in vitro and found to be safe up to 50 µM when screened in vitro on SH-SY5Y cell lines by cytotoxicity studies using MTT and Alamar blue assays. It also led to dose-dependent prevention of NMDA induced toxicity in these cells. Pretreatment with bergenin (14 days) in rats at three dose levels (20, 40 and 80 mg/kg; p.o.) significantly (p < 0.01) and dose-dependently alleviated amnesia induced by scopolamine (2 mg/kg, i.p.). The therapeutic effect of bergenin supplementation for 28 days, at three dose levels, was also evaluated in streptozotocin (3 mg/kg, ICV, unilateral) induced AD model in Wistar rats using Morris water maze and Y maze on 7th, 14th, 21st and 28th days. STZ caused significant (p < 0.001) cognitive impairment and cholinergic deficit and increased oxidative stress in rats. Bergenin could significantly ameliorate STZ induced behavioral deficits, inhibit the AChE and BuChE activity in parallel with an increase in the diminished GSH levels in a dose-dependent fashion. The histopathological investigations were also supportive of this datum. The bergenin treatment at 80 mg/kg led to significant (p < 0.05) abatement of the raised Aß-1-42 levels and alleviated the perturbed p- tau levels leading to significantly low (p < 0.01) levels of p-tau in brain homogenates of rats as compared to ICV STZ injected rats. In conclusion, the observed effects might be attributed to the cholinesterase inhibitory activity of bergenin coupled with its antioxidant effect, anti-inflammatory activity and reduction of Aß-1-42 and p-tau levels which could have collectively helped in the attenuation of cognitive deficits. The current findings of the study are indicative of the promising preventive and ameliorative potential of bergenin in the management of AD through multiple targets.

Fabrication of peptide-linked albumin nanoconstructs for receptor-mediated delivery of asiatic acid to the brain as a preventive measure in cognitive impairment: optimization, in-vitro and in-vivo evaluation.

The aim of the study was to evaluate the neuroprotective activity of glutathione (GU)-conjugated asiatic acid (AA) loaded albumin nanoparticles and establishing the drug targeting efficiency (DTE) of GU as a selective ligand for brain-targeted delivery. Albumin nanoparticles were prepared by desolvation technique and optimized using quality by design (QbD) approach. GU was conjugated with nanoparticles by carbodiimide reaction and characterized by its size and zeta potential using dynamic light scattering phenomenon. Dialysis bag technique was employed for in-vitro release study and in-vivo brain targeting efficiency was evaluated in Sprague-Dawley rats (75 mg/kg, i.p.). Neuroprotective activity was evaluated against scopolamine-induced dementia in rats. Resultant brain bioavailability of nanoparticles with 100.2 nm size and 71.59% entrapment efficiency (EE), was found 7-fold higher than AA dispersion with 293% DTE for the brain. Conjugated nanoparticles showed significantly high percentage correct alternation (p < .05), low escape latency time (p < .01), cholinesterase inhibition (p < .01) and ameliorated GU levels (p < .01) as compared to diseased animals. GU showed potential to enhance the brain delivery of AA with ameliorated neuroprotective activity due to enhanced bioavailability. This concept can serve as a platform technology for similar potential neurotherapeutics, whose clinical efficacy is still challenging owing to poor bioavailability.

Neuroprotective effects of Bergenia ciliata on NMDA induced injury in SH-SY5Y cells and attenuation of cognitive deficits in scopolamine induced amnesia in rats.

Bergenia ciliata (Haw) Sternb. possess immunomodulatory, anti-inflammatory, antioxidant, anti-urolithiatic, wound healing, anti-malarial, anti-diabetic and anti-cancer properties. Moreover, the methanolic extracts of the rhizomes of the plant were found to demonstrate beneficial neuroprotective effects in the intracerebroventricular streptozotocin-induced model in rats. Thus, the present study was undertaken to further explore the neuroprotective potential of the aqueous (BA) and methanolic extracts (BM) of B. ciliata through various in-vitro and in-vivo studies. Both the extracts at all tested concentrations i.e. 50-50,000 ng/mL did not cause any significant reduction of cell viability of SH-SY5Y cells when tested for 48 h when assessed through MTT and resazurin metabolism- based cell viability assays. The pre-treatment with the extracts could confer significant (p < 0.001) and dose-dependent protective effects against NMDA induced injury in SH-SY5Y cells. BM [IC50: 5.7 and 5.19 µg/mL for acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) respectively] led to more potent inhibition of both the enzymes as compared to BA (IC50: 227.12 and 23.25 µg/mL for AChE and BuChE respectively). BM also proved to be a 1.85-fold better scavenger of the DPPH free radicals as compared to BA. Thus, BM was taken further for the evaluation of the beneficial effects of 14-day pre-treatment in rats in the scopolamine (2 mg/kg, i.p.) induced amnesia model at 125, 250 and 500 mg/kg, p.o. BM pre-treatment at 250 and 500 mg/kg could significantly ameliorate the cognitive impairment (p < 0.001), inhibit AChE (p < 0.001) and BuChE (p < 0.05) activity, restore GSH levels (p < 0.05) in serum and brain homogenates and recover the morphology of hippocampal neurons back to normal. Moreover, the BM administration at 500 mg/kg also showed beneficial effects through the significant (p < 0.05) reduction of Aß1-42, phosphorylated tau (p-tau) and GSK-3ß immunoreactivity in the brain homogenates of the intracerebroventricularly streptozotocin (ICV STZ) injected rats as observed from the results of the ELISA assays. The outcomes of the study unveiled that BM exerts its beneficial effects through prevention of NMDA induced excitotoxic cell death, dual cholinesterase inhibition, antioxidant activity coupled with the reduction of the immunoreactivity for the Aß1-42, p-tau and GSK-3ß indicating its potential to be screened further for various other models to determine the exact mechanism of action.

Bergenia ciliata ameliorates streptozotocin-induced spatial memory deficits through dual cholinesterase inhibition and attenuation of oxidative stress in rats.

Bergenia ciliata (Haw.) Sternb. rhizomes, family Saxifragaceae, are claimed to possess an array of beneficial effects like antioxidant, anti-inflammatory, immunomodulatory, antibacterial and anticancer activities. The plant has also been reported to be used by Nepalese folk to alleviate symptoms related to Parkinson's disease. Oxidative stress is one of the major reasons for cognitive decline observed in sporadic Alzheimer's disease (AD). Bergenia ciliata rhizomes have depicted potent antioxidant properties, but their role in the treatment of Alzheimer's disease is yet unexplored. Therefore, the present study was intended to explore the beneficial effects of methanolic extracts of rhizomes of B. ciliata (BM) in a streptozotocin-induced model of Alzheimer's disease in Wistar rats. Streptozotocin (STZ) was injected intracerebroventricularly (ICV) on day 1 (3 mg/kg, unilaterally) in Wistar rats. BM was thereafter administered (125, 250 and 500 mg/kg b.w./day p.o.), daily for 28 days. Morris water maze and Y maze test were used to evaluate learning and memory in rats on 7th, 14th, 21st and 28th days following initiation of dosing. Terminally, acetylcholinesterase activity, butyrylcholinesterase, and levels of oxidative stress markers were assessed in the serum as well as in brain homogenates of rats. Additionally, histopathological studies were carried out to observe effects in brain tissues at the cellular level. STZ produced significant (p < 0.001) learning and memory impairment, oxidative stress as well as a cholinergic deficit in rats. Whereas, BM treatment at various dose levels was able to significantly and dose-dependently diminish STZ induced behavioral deficits and biochemical anomalies in rats. The observed cognitive improvement following BM administration in STZ injected rats may be accredited to its antioxidant activity and refurbishment of cholinergic functions. The results of the study are indicative of the therapeutic potential of Bergenia ciliata in cognitive disorders such as AD as well as other such neurodegenerative disorders.