Review on Green Synthesis of Silver Nanoparticles through Plants.

Nature has the potential to reduce metal salts to their relative nanoparticles. Traditionally, physical and chemical methods were used for the synthesis of nanoparticles but due to the use of toxic chemicals, non-ecofriendly methods and other harmful effects, green chemistry approaches are now employed for synthesizing nanoparticles which are basically the most cost effective, ecofriendly and non-hazardous methods. In this review, we aimed to evaluate and study the details of various mechanisms used for green synthesis of silver nanoparticles from plants, their size, shape and potential applications. A total of 150 articles comprising both research and review articles from 2009 to 2019 were selected and studied in detail to get in-depth knowledge about the synthesis of silver nanoparticles specifically through green chemistry approaches. Silver ions and their salts are well known for their antimicrobial properties and have been used in various medical and non-medical applications since the emergence of human civilization. Miscellaneous attempts have been made to synthesize nanoparticles using plants and such nanoparticles are more efficient and beneficial in terms of their antibacterial, antifungal, antioxidant, anti-biofilm and cytotoxic activities than nanoparticles synthesized through physical and chemical processes. Silver nanoparticles have been studied as an important research area due to their specific and tunable properties and their application in the field of biomedicine such as tissue and tumor imaging and drug delivery. These nanoparticles can be further investigated to find out their antimicrobial potential in cell lines and animal models.

In Vitro α-glucosidase Inhibition and Computational Studies of Kaempferol Derivatives from Dryopteris cycanida.

BACKGROUND: Dryopteris cycadina has diverse traditional uses in the treatment of various human disorders which are supported by pharmacological studies. Similarly, the phytochemical studies of this plant led to the isolation of numerous compounds. METHODOLOGY: The present study deals with α-glucosidase inhibition of various kaempferol derivates including kaempferol-3, 4/-di-O-α- L-rhamnopyranoside 1, kaempferol-3, 5-di-O-α-L-rhamnoside 2 and kaempferol-3,7-di-O-α- L-rhamnopyranoside 3. RESULTS: The results showed marked concentration-dependent inhibition of the enzyme when assayed at different concentrations and the IC50 values of compounds 1-3 were 137±9.01, 110±7.33, and 136±1.10 mM, respectively far better than standard compound, acarbose 290±0.54 mM. The computational studies revealed strong docking scores of these compounds and augmented the in vitro assay. CONCLUSION: In conclusion, the isolated kaempferol derivatives 1-3 from D. cycadina exhibited potent α- glucosidase inhibition.

Potent in Vitro α-Glucosidase Inhibition of Secondary Metabolites Derived from Dryopteris cycadina.

α-glucosidase is responsible for the hydrolysis of complex carbohydrates into simple absorbable glucose and causes postprandial hyperglycemia. α-glucosidase inhibition is thus the ideal target to prevent postprandial hyperglycemia. The present study was therefore designed to analyze the effects of various compounds isolated from Dryopteris cycadina against α-glucosidase including ß-Sitosterol 1, ß-Sitosterol3-O-ß-d-glucopyranoside 2, 3, 5, 7-trihydroxy-2-(p-tolyl) chorman-4-one 3, Quercetin-3-0-ß-d-glucopyranoside (3/→0-3///)- ß-d- Quercetin -3-0- ß â»d-galactopyranoside 4 and 5, 7, 4/-Trihydroxyflavon-3-glucopyranoid 5. The in vitro spectrophotometric method was used for the analysis of test compounds against possible inhibition. Similarly, molecular docking studies were performed using the MOE software. These compounds showed concentration-dependent inhibition on α-glucosidase, and compounds 1 (IC50: 143 ± 0.47 µM), 3 (IC50:133 ± 6.90 µM) and 5 (IC50: 146 ± 1.93 µM) were more potent than the standard drug, acarbose (IC50: 290 ± 0.54 µM). Computational studies of these compounds strongly supported the in vitro studies and showed strong binding receptor sensitivity. In short, the secondary metabolites isolated from D. cycadina demonstrated potent α-glucosidase inhibition that were supported by molecular docking with a high docking score.

Flavonoids as acetylcholinesterase inhibitors: Current therapeutic standing and future prospects.

BACKGROUND: Acetylcholinesterase (AChE), a serine hydrolase, is primarily responsible for the termination of signal transmission in the cholinergic system, owing to its outstanding hydrolyzing potential. Its substrate acetylcholine (ACh), is a neurotransmitter of the cholinergic system, with a predominant effect on motor neurons involved in memory formation. So, by decreasing the activity of this enzyme by employment of specific inhibitors, a number of motor neuron disorders such as myasthenia gravis, glaucoma, Lewy body dementia, and Alzheimer's disease, among others, can be treated. However, the current-available AChE inhibitors have several limitations in terms of efficacy, therapeutic range, and safety. SCOPE AND APPROACH: Primarily due to the non-compliance of current therapies, new, effective and safe inhibitors are being searched for, especially those which act through multiple receptor sites, but do not elicit undesirable effects. In this regard, the evaluation of phytochemicals such as flavonoids, can be a rational approach. The therapeutic potential of flavonoids has already been recognized agaisnt several ailments. This review deals with various plant-derived flavonoids, their preclinical potential as AChE inhibitors, in established assays, possible mechanisms of action, and structural activity relationship (SAR). RESULTS AND CONCLUSIONS: Subsequently, a number of plant-derived flavonoids with outstanding efficacy and potency as AChE inhibitors, the mechanistic, their safety profiles, and pharmacokinetic attributes have been discussed. Through derivatization of these reported flavonoids, some limitation in efficacy or pharmacokinetic parameters can be addressed. The selected flavonoids ought to be tested in clinical studies to discover new neuro-therapeutic candidates.

Targeting BDNF modulation by plant glycosides as a novel therapeutic strategy in the treatment of depression.

Current therapies in clinical practice face strong criticism regarding their efficacy, and side effects, which forced the neuro-researchers to discover novel agents with different mechanistic insights. Glycosides are naturally-occurring plant secondary metabolites with significant medicinal potential and clinical scope as antidepressant. The aim of this review is to focus on the antidepressant effects of glycosides in preclinical studies, with an emphasis on the possible mechanisms. The literature search revealed that only a few phytoglycosides have been evaluated for their relevance in depression alleviation. Through preclinical tests, it has come forth that the efficacy is mediated by the modulation of brain-derived neurotrophic factor (BDFN) in the hippocampus, that is known for promoting synaptic efficacy, neuronal connectivity and neuroplasticity. Thus, attempting the upregulation of BDNF expression by plant glycosides can be a novel therapeutic strategy for the treatment of depression. The outcome of this review can stimulate neuroscientists to evaluate plant-derived glycosides for the treatment of depression, as these structurally-complex and diverse molecules, might usher in a new paradigm in the treatment of depression, with a better efficacy and tolerability.

Plant bioactive molecules bearing glycosides as lead compounds for the treatment of fungal infection: A review.

Despite therapeutic advancement in the treatment of fungal infections, morbidity and mortality caused by these infections are still very high. There are approximately 300 fungal species that are infectious and can cause a variety of diseases. At present, several synthetic antifungal drugs are in clinical practice, many of them, however, are vulnerable to multidrug-resistant strains of microbes, and thus compromising the overall treatment outcomes. Glycosides are naturally occurring plant secondary metabolites with important therapeutic potential and clinical utility. The aim of this review was to focus on the antifungal effects of glycosides in preclinical studies with possible mechanism(s) wherein described. Published research show significant susceptibility of different fungi towards phytoglycosides, mediated through multiple mechanisms. Further detailed studies are needed to explain the clinical applications and limitations of these glycosides.

Antifungal Potential of Alkaloids As An Emerging Therapeutic Target.

BACKGROUND: Fungal infections have been causing serious problems in all age groups, especially in immune-compromised individuals. Various synthetic agents are in clinical practice for the treatment of these infections, however, resistance to these agents badly affected their therapeutic quality. OBJECTIVE: This review focuses on the antifungal activity of naturally occurring alkaloids, their source, chemical structure, and potency with a possible mechanism(s) of action. RESULTS: The results of available literature showed that at least 70 different plant derived alkaloids exhibited antifungal activity in vitro. These alkaloids are isolated from different plants and families showing their diverse distribution in plant kingdom. Additionally, the alkaloid from various classes depicted antifungal effects against a variety of fungi. CONCLUSIONS: Alkaloids could be a better therapeutic alternative to available therapies with fewer chances of resistance but more research and clinical trials are needed before final recommendations. Additionally, the details provided in this review will offer greater awareness of the excellent promise that natural alkaloids exhibit as antifungal agents.