Phytostilbenes as agrochemicals: biosynthesis, bioactivity, metabolic engineering and biotechnology

Covering: 1976 to 2020. Although constituting a limited chemical family, phytostilbenes represent an emblematic group of molecules among natural compounds. Ever since their discovery as antifungal compounds in plants and their ascribed role in human health and disease, phytostilbenes have never ceased to arouse interest for researchers, leading to a huge development of the literature in this field. Owing to this, the number of references to this class of compounds has reached the tens of thousands. The objective of this article is thus to offer an overview of the different aspects of these compounds through a large bibliography analysis of more than 500 articles. All the aspects regarding phytostilbenes will be covered including their chemistry and biochemistry, regulation of their biosynthesis, biological activities in plants, molecular engineering of stilbene pathways in plants and microbes as well as their biotechnological production by plant cell systems.

Epigenetics of glioblastoma multiforme: From molecular mechanisms to therapeutic approaches

Glioblastoma multiforme (GBM) is the most common form of brain cancer and one of the most aggressive cancers found in humans. Most of the signs and symptoms of GBM can be mild and slowly aggravated, although other symptoms might demonstrate it as an acute ailment. However, the precise mechanisms of the development of GBM remain unknown. Due to the improvement of molecular pathology, current researches have reported that glioma progression is strongly connected with different types of epigenetic phenomena, such as histone modifications, DNA methylation, chromatin remodeling, and aberrant microRNA. Furthermore, the genes and the proteins that control these alterations have become novel targets for treating glioma because of the reversibility of epigenetic modifications. In some cases, gene mutations including P16, TP53, and EGFR, have been observed in GBM. In contrast, monosomies, including removals of chromosome 10, particularly q23 and q25-26, are considered the standard markers for determining the development and aggressiveness of GBM. Recently, amid the epigenetic therapies, histone deacetylase inhibitors (HDACIs) and DNA methyltransferase inhibitors have been used for treating tumors, either single or combined. Specifically, HDACIs are served as a good choice and deliver a novel pathway to treat GBM. In this review, we focus on the epigenetics of GBM and the consequence of its mutations. We also highlight various treatment approaches, namely gene editing, epigenetic drugs, and microRNAs to combat GBM.

Nutritional and health beneficial properties of saffron (Crocus sativus L): a comprehensive review

Saffron (Crocus sativus L., family Iridaceae) is used traditionally for medicinal purpose in Chinese, Ayurvedic, Persian and Unani medicines. The bioactive constituents such as apocarotenoids, monoterpenoids, flavonoids, phenolic acids and phytosterols are widely investigated in experimental and clinical studies for a wide range of therapeutic effects, especially on the nervous system. Some of the active constituents of saffron have high bioavailability and bioaccessibility and ability to pass the blood-brain barrier. Multiple preclinical and clinical studies have supported neuroprotective, anxiolytic, antidepressant, learning and memory-enhancing effect of saffron and its bioactive constituents (safranal, crocin, and picrocrocin). Thus, this plant and its active compounds could be a beneficial medicinal food ingredient in the formation of drugs targeting nervous system disorders. This review focuses on phytochemistry, bioaccessibility, bioavailability, and bioactivity of phytochemicals in saffron. Furthermore, the therapeutic effect of saffron against different nervous system disorders has also been discussed in detail.

Molecular mechanism of zinc neurotoxicity in Alzheimer's disease

Zinc (Zn) is an essential trace element for most organisms, including human beings. It plays a crucial role in several physiological processes such as catalytic reaction of enzymes, cellular growth, differentiation and metabolism, intracellular signaling, and modulation of nucleic acid structure. Zn containing above 50 metalloenzymes is responsible for proteins, receptors, and hormones synthesis and has a critical role in neurodevelopment. Zn also regulates excitatory and inhibitory neurotransmitters such as glutamate and GABA and is found in high concentration in the synaptic terminals of hippocampal mossy fibers that maintains cognitive function. It regulates LTP and LTD by regulation of AMPA and NMDA receptors. But an excess or deficiency of Zn becomes neurotoxic or cause impairment in growth or sexual maturation. There is mounting evidence that supports this idea of Zn becoming neurotoxic and being involved in the pathogenesis of AD. Zn dyshomeostasis in AD is an area that needs attention as moderate concentration of Zn is involved in the memory regulation via regulation of amyloid plaque. Dyshomeostasis of Zn is involved in the pathogenesis of diseases like AD, ALS, depression, PD, and schizophrenia.

Neuroprotective Effects of Ellagic Acid in Alzheimer's Disease: Focus on Underlying Molecular Mechanisms of Therapeutic Potential

Neurodegeneration is a multifactorial process involved the different cytotoxic pathways that lead to neuronal cell death. Alzheimer's disease (AD) is a persistent neurodegenerative disorder that normally has a steady onset and gradually worsens. Neuropathology, AD is characterized by the presence of neuroinflammation, mitochondrial dysfunction, increased oxidative stress, decreased antioxidant defense as well as increased acetylcholinesterase activity. Moreover, enhanced expression of amyloid precursor proteins leads to neural apoptosis, which has a vital role in the degeneration of neurons. The inability of commercial therapeutics to treat a single feature of AD pathology leads to the attraction towards organic drugs. Ellagic acid is a dimer of gallic acid; latest studies revealed that ellagic acid can initiate numerous cell signaling transmissions and decrease the progression of neurodegeneration. The neuroprotective effects of ellagic acid to protect the neurons against neurodegenerative events are due to its antioxidant effect, iron chelating, and mitochondrial protective effect. The main goal of this review is to critically analyze the molecular mechanism of action of ellagic acid against AD.

Emerging Potential of Naturally Occurring Autophagy Modulators Against Neurodegeneration

BACKGROUND

Naturally-occurring products derived from living organisms have been shown to modulate various pharmacological and biological activities. Natural products protect against various diseases, which could be used for therapeutic assistance. Autophagy, a lysosome-mediated self-digestion pathway, has been implicated in a range of pathophysiological conditions and has recently gained attention for its role in several neurodegenerative diseases.

METHODS

In this current review, we emphasized the recent progress made in our understanding of the molecular mechanism of autophagy in different cellular and mouse models using naturally-occurring autophagy modulators for the management of several neurodegenerative diseases.

RESULTS

Accumulating evidence has revealed that a wide variety of natural compounds such as alkaloids, polyphenols, terpenoids, xanthonoids, flavonoids, lignans, disaccharides, glycolipoproteins, and saponins are involved in the modulation of the autophagy signaling pathway. These natural products have been used to treat various neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis, spinocerebellar ataxia, neuroblastoma, and glioblastoma. Although a number of synthetic autophagy regulators have been recognized as encouraging neurodegenerative therapeutic candidates, natural autophagy- regulating compounds have been of further interest as potential disease therapeutics, as they cause insignificant side effects.

CONCLUSION

Existing in vitro and in vivo data are promising and highlight that naturally-occurring autophagyregulating compounds play an important role in the prevention and treatment of neurodegenerative disorders.

Untying the correlation between apolipoproteins and rheumatoid arthritis

AIM AND OBJECTIVE

The concentration of lipoproteins and apolipoprotein are extremely low in the synovial fluid of any healthy person as compared to the concentrations in plasma. However, in the synovial fluid of any diseased patient the amount of cholesterol and lipids is sharply increased. The current review defines the role of various apolipoproteins and lipoproteins and their constituent subfractions in the synovial fluid embarking its principal role in rheumatoid arthritis. It also explains the need to define synovial fluid lipids, lipoprotein particle subfractions and their constituent apolipoproteins in synovial fluid.

MATERIALS AND METHODS

Various research and review articles highlighting the role of apolipoproteins and lipoproteins were procured from medical websites mainly Pubmed, Medline, Science Direct, etc., and studied for the writing of the review paper.

CONCLUSION

Mainly apolipoproteins A-1, B and E are prominently increased in chronic inflammatory joint disorders. Several theories have been proposed to understand the source of increase of lipids and apolipoproteins in synovial fluid of the diseased patients compared to healthy individuals, yet the precise mechanism is still not lucid. Lipoproteins are believed to play both functional role and pathological role in the synovial fluid. The activated T-lymphocytes in patients of RA lead to activation of inflammatory cytokines such as tumor necrosis factor and interleukins which embark to be the principal mechanism for induction of the disease. It can be thus concluded that the apolipoproteins prevent the activation of monocytes by blocking their contact of activation and thus play critical role in management of RA by inhibiting the production of proinflammatory cytokines.

COVID-19 Outbreak: Pathogenesis, Current Therapies, and Potentials for Future Management

At the end of 2019, a novel coronavirus (CoV) was found at the seafood market of Hubei province in Wuhan, China, and this virus was officially named coronavirus diseases 2019 (COVID-19) by World Health Organization (WHO). COVID-19 is mainly characterized by severe acute respiratory syndrome coronavirus-2 (SARS-CoV2) and creates public health concerns as well as significant threats to the economy around the world. Unfortunately, the pathogenesis of COVID-19 is unclear and there is no effective treatment of this newly life-threatening and devastating virus. Therefore, it is crucial to search for alternative methods that alleviate or inhibit the spread of COVID-19. In this review, we try to find out the etiology, epidemiology, symptoms as well as transmissions of this novel virus. We also summarize therapeutic interventions and suggest antiviral treatments, immune-enhancing candidates, general supplements, and CoV specific treatments that control replication and reproduction of SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV).

Available Compounds With Therapeutic Potential Against COVID-19: Antimicrobial Therapies, Supportive Care, and Probable Vaccines

The recent outbreak of the COVID-2019 (coronavirus disease 2019) due to the infectious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has realized the requirement of alternative therapeutics to mitigate and alleviate this lethal infection. These alternative therapies are effective when they are started at the initial stage of the infection. Some drugs that were used in previous other related infections SARS-CoV-2003 and Middle East respiratory syndrome coronavirus (MERS-CoV)-2012 could be potentially active against currently emerging SARS-CoV-2. This fact imparts some rationale of current interventions, in the absence of any specific therapeutics for SARS-CoV-2. It is imperative to focus on the available antimicrobial and adjunct therapies during the current emergency state and overcome the challenges associated with the absence of robust controlled studies. There is no established set of drugs to manage SARS-CoV-2 infected patients. However, closely following patients’ conditions and responding with the dosage guidelines of available drugs may significantly impact our ability to slow down the infection. Of note, it depends upon the condition of the patients and associated comorbid; therefore, the health workers need to choose the drug combinations judiciously until COVID-19 specific drug or vaccine is developed with the collective scientific rigor. In this article, we reviewed the available antimicrobial drug, supportive therapies, and probable high importance vaccines for the COVID-19 treatment.

The pharmacological basis of Cuscuta reflexa whole plant as an antiemetic agent in pigeons

Cuscuta reflexa has been traditionally used as an antiemetic. Additionally, it has been used in various herbal formulations for the treatment of emesis. So far, there is no scientific evidence of the plant extract as antiemetic. Therefore, this study was intended to assess the antiemetic activity of Juice (JCR), aqueous (CRAE) and methanolic extract (CRME) of C. reflexa in pigeons. Emesis was induced through GIT irritants like ampicillin (300 mg/kg, IM), copper sulphate (100 mg/kg, PO), conc. sodium chloride solution (1600 mg/kg, PO) and cisplatin (5-HT3 receptor stimulator) (6 mg/kg, IM). Dimenhydrinate acted as a positive control (2 mg/kg; IM). JCR [(1 ml/kg (1 %) and 1 ml/kg (2 %)], CRAE, and CRME were administered intramuscularly at different doses (50, 100 and 200 mg/kg) to each pigeon (n = 6). In each group, calculation of total number of jerks & vomiting episodes, and vomiting-weight was carried out to evaluate its antiemetic activity. The JCR exhibited a significant (p < 0.05) antiemetic impact on both the frequency and onset of emesis at 1 ml/kg (2 %) against various emesis mediator, except sodium chloride. Similarly, CRAE and CRME elicited marked dose dependent inhibition both on onset and frequency of emesis with highly significant (p < 0.001) effect at 200 mg/kg. The study reflects that juice, aqueous and methanolic extract of C. reflexa have significant antiemetic potential and possess pharmacological active constituent(s) that interfered with the emetic mediators by acting through GIT irritation and 5-HT3 receptor stimulations. Results of this study provide a scientific background to its traditional antiemetic uses.

Perspective Design of Chalcones for the Management of CNS Disorders: A Mini-Review

The development of chalcone-based compounds for CNS disorders has been explored by many research groups. Chalcones are being considered as a potent organic scaffold with widespread applications in the field of drug discovery and medicinal chemistry. The planar or semi-planar geometry of chalcones with various functionalities impinged on the terminal aromatic systems renders the molecule its bio-activity including anti-cancer, anti-malarial, anti-microbial, anti-fungal, antileishmanial, anti-viral, anti-diabetic, anti-hypertensive properties, etc. Moreover, cutting-edge research has been executed in the domain of Central Nervous System (CNS) based scheme, further, their identification and classifications also remain of high interest in the field of medicinal chemistry but the specific reviews are limited. Hence, the present review highlights the significance of chalcones toward their CNS activities (up to 2019), which include anti-depressant activity, anxiolytic activity, activity with GABA receptors, acetylcholinesterase (AChE) and butyryl cholinesterase (BChE) inhibitions, activity as adenosine receptor antagonists anti-Alzheimer's agents, β-amyloid plaques imaging agents, monoamine oxidase inhibition. To our knowledge, this is the first review exclusively for CNS activity profile of chalcones.

Withdrawal Notice: Reconnoitering the Role of Endothelin in Obesity

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The dual impact of ACE2 in COVID-19 and ironical actions in geriatrics and pediatrics with possible therapeutic solutions

The novel corona virus disease has shaken the entire world with its deadly effects and rapid transmission rates, posing a significant challenge to the healthcare authorities to develop suitable therapeutic solution to save lives on earth. The review aims to grab the attention of the researchers all over the globe, towards the role of ACE2 in COVID-19 disease. ACE2 serves as a molecular target for the SARS-CoV-2, to enter the target cell, by interacting with the viral glycoprotein spikes. However, the complexity began when numerous studies identified the protective response of ACE2 in abbreviating the harmful effects of vasoconstrictor, anti-inflammatory peptide, angiotensin 2, by mediating its conversion to angiotensin-(1-7), which exercised antagonistic actions to angiotensin 2. Furthermore, certain investigations revealed greater resistance among children as compared to the geriatrics, towards COVID-19 infection, despite the elevated expression of ACE2 in pediatric population. Based upon such evidences, the review demonstrated possible therapeutic interventions, targeting both the protective and deleterious effects of ACE2 in COVID-19 disease, primarily inhibiting ACE2-virus interactions or administering soluble ACE2. Thus, the authors aim to provide an opportunity for the researchers to consider RAAS system to be a significant element in development of suitable treatment regime for COVID-19 pandemic.

Multi-Target Drug Candidates for Multifactorial Alzheimer's Disease: AChE and NMDAR as Molecular Targets

Alzheimer's disease (AD) is one of the most common forms of dementia among elder people, which is a progressive neurodegenerative disease that results from a chronic loss of cognitive activities. It has been observed that AD is multifactorial, hence diverse pharmacological targets that could be followed for the treatment of AD. The Food and Drug Administration has approved two types of medications for AD treatment such as cholinesterase inhibitors (ChEIs) and N-methyl-D-aspartic acid receptor (NMDAR) antagonists. Rivastigmine, donepezil, and galantamine are the ChEIs that have been approved to treat AD. On the other hand, memantine is the only non-competitive NMDAR antagonist approved in AD treatment. As compared with placebo, it has been revealed through clinical studies that many single-target therapies are unsuccessful to treat multifactorial Alzheimer's symptoms or disease progression. Therefore, due to the complex nature of AD pathophysiology, diverse pharmacological targets can be hunted. In this article, based on the entwined link of acetylcholinesterase (AChE) and NMDAR, we represent several multifunctional compounds in the rational design of new potential AD medications. This review focus on the significance of privileged scaffolds in the generation of the multi-target lead compound for treating AD, investigating the idea and challenges of multi-target drug design. Furthermore, the most auspicious elementary units for designing as well as synthesizing hybrid drugs are demonstrated as pharmacological probes in the rational design of new potential AD therapeutics.

Aptamers in Drug Design: An Emerging Weapon to Fight a Losing Battle

Implementation of novel and biocompatible polymers in drug design is an emerging and rapidly growing area of research. Even though we have a large number of polymer materials for various applications, the biocompatibility of these materials remains as a herculean task for researchers. Aptamers provide a vital and efficient solution to this problem. They are usually small (ranging from 20 to 60 nucleotides, single-stranded DNA or RNA oligonucleotides which are capable of binding to molecules possessing high affinity and other properties like specificity. This review focuses on different aspects of Aptamers in drug discovery, starting from its preparation methods and covering the recent scenario reported in the literature regarding their use in drug discovery. We address the limitations of Aptamers and provide valuable insights into their future potential in the areas regarding drug discovery research. Finally, we explained the major role of Aptamers like medical imaging techniques, application as synthetic antibodies, and the most recent application, which is in combination with nanomedicines.

Correction to: Exploring the Role of CLU in the Pathogenesis of Alzheimer's Disease

The original article has been corrected. Author Md. Ghulam Md Ashraf" should be "Ghulam Md Ashraf".

Sesquiterpenes and their derivatives-natural anticancer compounds: An update

Sesquiterpenes belong to the largest group of plant secondary metabolites, which consist of three isoprene building units. These compounds are widely distributed in various angiosperms, a few gymnosperms and bryophytes. Sesquiterpenes and their allied derivatives are bio-synthesized in various plant parts including leaves, fruits and roots. These plant-based metabolites are predominantly identified in the Asteraceae family, wherein up to 5000 complexes have been documented to date. Sesquiterpenes and their derivatives are characteristically associated with plant defence mechanisms owing to their antifungal, antibacterial and antiviral activities. Over the last two decades, these compounds have been reportedly demonstrated health promoting perspectives against a wide range of metabolic syndromes i.e. hyperglycemia, hyperlipidemia, cardiovascular complications, neural disorders, diabetes, and cancer. The high potential of sesquiterpenes and their derivatives against various cancers like breast, colon, bladder, pancreatic, prostate, cervical, brain, liver, blood, ovarium, bone, endometrial, oral, lung, eye, stomach and kidney are the object of this review. Predominantly, it recapitulates the literature elucidating sesquiterpenes and their derivatives while highlighting the mechanistic approaches associated with their potent anticancer activities such as modulating nuclear factor kappa (NF-kB) activity, inhibitory action against lipid peroxidation and retarding the production of reactive oxygen & nitrogen species (ROS&RNS).

Mechanistic insights into the role of pyroptosis in rheumatoid arthritis

Cell death is ascribed as an essential biological process that is fundamental for the development of an organism along with its survival. The procedure comprises of apoptosis and pyroptosis. Pyroptosis is a programmed procedure for cell death which is inflammatory in nature and this pathway gets activated via human caspase-4, human caspase-11 and human caspase-5. The activation of this process leads to release of pro-inflammatory mediators including cytokines, alarmins, IL-18 and IL-1β. The pro-inflammatory mediators released via interaction of intracellular kinases direct the development of Rheumatoid arthritis. Rheumatoid arthritis is characterized as disorder/disease that is auto-immune and chronic in nature. It involves erosions in marginal bone along with articular cartilage which is responsible for joint destruction. The cytokine along with its complex network is responsible for inflammation. The process of pyroptosis is linked with the destruction of plasma membrane, that releases these mediators and excessive release of these mediators is linked with rheumatoid arthritis.

Revisiting the Amyloid Cascade Hypothesis: From Anti-Aβ Therapeutics to Auspicious New Ways for Alzheimer's Disease

Alzheimer’s disease (AD) is the most prevalent neurodegenerative disorder related to age, characterized by the cerebral deposition of fibrils, which are made from the amyloid-β (Aβ), a peptide of 40–42 amino acids. The conversion of Aβ into neurotoxic oligomeric, fibrillar, and protofibrillar assemblies is supposed to be the main pathological event in AD. After Aβ accumulation, the clinical symptoms fall out predominantly due to the deficient brain clearance of the peptide. For several years, researchers have attempted to decline the Aβ monomer, oligomer, and aggregate levels, as well as plaques, employing agents that facilitate the reduction of Aβ and antagonize Aβ aggregation, or raise Aβ clearance from brain. Unluckily, broad clinical trials with mild to moderate AD participants have shown that these approaches were unsuccessful. Several clinical trials are running involving patients whose disease is at an early stage, but the preliminary outcomes are not clinically impressive. Many studies have been conducted against oligomers of Aβ which are the utmost neurotoxic molecular species. Trials with monoclonal antibodies directed against Aβ oligomers have exhibited exciting findings. Nevertheless, Aβ oligomers maintain equivalent states in both monomeric and aggregation forms; so, previously administered drugs that precisely decrease Aβ monomer or Aβ plaques ought to have displayed valuable clinical benefits. In this article, Aβ-based therapeutic strategies are discussed and several promising new ways to fight against AD are appraised.

Exploring the therapeutic promise of targeting HMGB1 in rheumatoid arthritis

High mobility group box-1 (HMGB1) protein is a diverse, single polypeptide moiety, present in mammalian eukaryotic cells. In response to stimuli, this nuclear protein is actively secreted in to the extracellular compartment or passively released by the necrotic cells, in order to mediate inflammatory responses, by forming complexes with IL-1α, IL-1β, LPS and other moieties, and binding to RAGE, TLR and other receptor ligands, initiating downstream, signaling processes. This molecule acts as a proinflammatory cytokine and contributes to the progression of diseases like, acute lung injury, autoimmune liver damage, graft rejection immune response and arthritis. Small concentrations of HMGB1 are released during apoptosis, which facilitates oxidative regulation on Cys106, and propagates immune inactivating tolerogenic signals in the body. The review portrays the role of HMGB1 in rheumatoid arthritis, evidently supported by pre-clinical and clinical investigations, demonstrating extensive HMGB1 expression in synovial tissue and fluid as well as serum, excessive expression of transduction receptor signaling molecules, bone remodeling and uncontrolled expression of bone destroying osteoclastogenesis, resulting in destruction of articular cartilage, bone deformation and synovial proliferation, alleviating the pathogenesis in RA disease. Moreover, the review highlights the therapeutic regime targeting HMGB1, facilitating inhibition of its actions and release into the extracellular compartment, to ameliorate the destructive events that prevail in rheumatoid arthritis.