Current Drug Targets - Volume 19, Issue 2, 2018

Background: The central nervous system (CNS) is involved in organic integration. Nervous modulation via bioactive compounds can modify metabolism in order to prevent systemic noncommunicable diseases (NCDs). Concerning this, plant polyphenols are proposed as neurotropic chemopreventive/ therapeutic agents, given their redox and regulating properties. Objective: To review polyphenolic pharmacology and potential neurological impact on NCDs. Method: First, polyphenolic chemistry was presented, as well as pharmacology, i.e. kinetics and dynamics. Toxicology was particularly described. Then, functional relevance of these compounds was reviewed focusing on the metabolic CNS participation to modulate NCDs, with data being finally integrated. Results: Oxidative stress is a major risk factor for NCDs. Polyphenols regulate the redox biology of different organic systems including the CNS, which participates in metabolic homeostasis. Polyphenolic neurotropism is determined by certain pharmacological characteristics, modifying nervous and systemic physiopathology, acting on several biological targets. Nonetheless, because these phytochemicals can trigger toxic effects, they should not be recommended indiscriminately. Conclusion: Summing up, the modulating effects of polyphenols allow for the physiological role of CNS on metabolism and organic integration to be utilized in order to prevent NCDs, without losing sight of the risks.

Background: Staphylococcus aureus is a major bacterial pathogen capable of causing a range of infections in humans from gastrointestinal disease, skin and soft tissue infections, to severe outcomes such as sepsis. Staphylococcal infections in humans can be frequent and recurring, with treatments becoming less effective due to the growing persistence of antibiotic resistant S. aureus strains. Due to the prevalence of antibiotic resistance, and the current limitations on antibiotic development, an active and highly promising avenue of research has been to develop strategies to specifically inhibit the activity of virulence factors produced S. aureus as an alternative means to treat disease. Objective: In this review we specifically highlight several major virulence factors produced by S. aureus for which recent advances in antivirulence approaches may hold promise as an alternative means to treating diseases caused by this pathogen. Strategies to inhibit virulence factors can range from small molecule inhibitors, to antibodies, to mutant and toxoid forms of the virulence proteins. Conclusion: The major prevalence of antibiotic resistant strains of S. aureus combined with the lack of new antibiotic discoveries highlight the need for vigorous research into alternative strategies to combat diseases caused by this highly successful pathogen. Current efforts to develop specific antivirulence strategies, vaccine approaches, and alternative therapies for treating severe disease caused by S. aureus have the potential to stem the tide against the limitations that we face in the post-antibiotic era.

Background: The Notch pathway is an evolutionarily conserved, intercellular signalling system which is present in all multicellular organisms and mammals. The Notch pathway plays an important role in the embryonic development as it controls cell proliferation, cell differentiation and binary cell fate decisions. Objective: In the present review, we highlight the Notch signalling pathway components i.e. Notch receptors, ligands, effector, and their regulators. We also discuss the tumor biology of the Notch pathway involved in various cancers. Results: Interestingly, the Notch signalling pathway is dysregulated in many cancers. Notch may serve as oncogene or tumor suppressor and plays an important role in cancers of the liver, pancreas, endometrium of uterus, ovary, prostate, bladder and colon. The activation of Notch pathway plays a vital role in the progression of some cancer. In addition, Notch pathway activation was also shown to drive chemoresistance in cancer, as well. Chemotherapeutically, combined NOTCH1 inhibitor synergistically attenuated chemotherapy-enriched cancer stem cell population both in vitro and in vivo. This may prove to be beneficial in the treatment of cancer. Conclusion: The Notch inhibitors possess anti-proliferative effects on cancer, thereby serving as a new treatment for cancer.

Background: Peroxisome proliferator-activated receptors (PPAR) are nuclear receptors activated by endogenous fatty acids and prostaglandins that are classified into three types: α, γ and δ, which have different functions and tissue distribution. PPAR modulators have been exploited to the treatment of important metabolic diseases, such as type 2 diabetes mellitus and metabolic syndrome, which are considered relevant epidemic diseases currently. Along the last decades, several studies have reported structural differences between the three PPAR subtypes associated with the discovery of selective ligands, dual and pan-agonists. Nowadays, there are several approved drugs that activate PPARα (fibrates) and PPARγ (glitazones), but up to now there is none clinically used drug targeting PPARδ. Additionally, several side-effects associated with the use of PPARα and γ agonists are reported by regulatory agencies, which do not indicate anymore their use as first-line drugs. Objective: A significant new market has grown in the last years, focusing on the development of new PPARδ agonists as drug candidates to treat metabolic diseases and, in this sense, this study proposes to review the structural requirements to achieve selective PPARδ activation, as well to discuss the most relevant agonists in clinical trials, providing information on the current phase in the drug discovery and design targeting PPARδ. Conclusion: Several PPARδ ligands with high potency were reported in the literature and were designed or discovered by a combination of experimental and computational approaches. Furthermore, the reported importance of pockets and individual residues at PPARδ binding site as well as the importance of substituent and some physicochemical properties that could help to design of new classes of agonists.

Background: Alzheimer's disease (AD) is the most frequent age related neurodegenerative disorder. It represents 70% of all dementia. Millions of people have been affected by AD worldwide. It is a complex illness characterized pathologically by accumulation of protein aggregates of amyloid and neurofibrillary tangles containing hyperphosphorylated neuronal tau protein. AD requires drugs that can circumvent the blood–brain barrier (BBB) which is not a simple physical barrier between blood and brain, but acts as an iron curtain, allowing only selective molecules to enter the brain. Unfortunately, this dynamic barrier restricts transport of drugs to the brain; due to which, currently very few drugs are available for AD treatment. Objective: The present review focuses mainly on strategies used for administration of drug to the CNS by-passing BBB for the treatment of AD. Results: Many studies have proved to be effective in overcoming BBB and targeting drugs to CNS by using different strategies. Here we have discussed some of the most important drug permeability and drug targeting approaches. Conclusion: In conclusion, concentrating solely in development of drug discovery programs is not enough but it is important to maintain balance between the drug discovery and drug delivery systems that are more specific and effective in targeting CNS of AD patients.

Background: Cancer is one of the main causes of death in the world. It has not yet been cured in an efficient manner and has remained a major challenge for current chemotherapy. Objective: This review summarizes the latest investigations regarding the possible application of phytosome complexes for cancer therapy, their formulation techniques, and mechanism of transportation through phytosome. Results: Nanotechnology opened a pioneer field in cancer therapy by modifying significant properties of drugs and their carriers. Nanotechnology utilizes various nanostructures to transport anti-cancer agents to the site of action. The greater stability of nanophytosomes is due to formation of chemical links between phospholipid molecules and phytoactive agents. Among several new drug delivery systems, phytosomes depict an advanced technology to deliver phytoactive compounds to the target site of action, and at present, several phytosome formulations are in clinical use. Conclusion: Potential anti-cancer properties of phytoconstituents are enhanced by phytosomal formulations.

Background: Meis1 is a member of three-amino-acid loop extension (TALE) homeodomain transcription factors. Studies in the last decade have shown that Meis1 has crucial roles in cardiac regeneration, stem cell function, and tumorigenesis. Objective: We have recently demonstrated that knocking out of Meis1 in adult cardiomyocytes resulted in the induction of cardiomyocyte proliferation. This suggests that targeting of Meis1 might be utilized in the manipulation of cardiomyocyte cell cycle post cardiac injuries. In addition, hematopoietic stem cell (HSC) specific deletion of Meis1 leads to in vivo expansion of HSCs pool. Thus, targeting Meis1 may lead to not only cell cycle entry but also ex vivo and in vivo expansion of HSCs. On the other hand, Meis1 transcriptionally regulates the expression of hypoxic tumor markers, namely Hif-1α and Hif-2α. Hif-1α and Hif-2α are involved in the induction of cytoplasmic glycolysis and scavenging of reactive oxygen species (ROS), respectively. Conclusion: Studies highlight emerging roles of Meis1 towards development of new therapeutic approaches in the treatment of myocardial injuries, bone failure, and cancer.

Background: MiR-17-92 cluster is coded by MIR17HG in chromosome 13, which is highly conserved in vertebrates. Published literatures have proved that miR-17-92 cluster critically regulates tumorigenesis and metastasis. Recent researches showed that the miR-17-92 cluster also plays novel functions in the endocrine system. Objective: To summarize recent findings on the physiological and pathological roles of miR-17-92 cluster in bone, lipid and glucose metabolisms. Results: MiR-17-92 cluster plays significant regulatory roles in bone development and metabolism through regulating the differentiation and function of osteoblasts and osteoclasts. In addition, miR-17- 92 cluster is nearly involved in every aspect of lipid metabolism. Last but not the least, the miR-17-92 cluster is closely bound up with pancreatic beta cell function, development of type 1 diabetes and insulin resistance. However, whether miR-17-92 cluster is involved in the communication among bone, fat and glucose metabolisms remains unknown. Conclusion: Growing evidence indicates that miR-17-92 cluster plays significant roles in bone, lipid and glucose metabolisms through a variety of signaling pathways. Fully understanding its modulating mechanisms may necessarily facilitate to comprehend the clinical and molecule features of some metabolic disorders such as osteoporosis, arthrosclerosis and diabetes mellitus. It may provide new drug targets to prevent and cure these disorders.