Current Pharmaceutical Design - Volume 24, Issue 19, 2018

Plants and crops contain a staggering diversity of compounds, many of which have pharmacological activity towards a variety of diseases. These properties have been exploited by traditional and modern medicine providing important sources of healthcare to this day. The contribution of natural products (such as plant-derived) to the modern pharmacopeia is indeed significant; however, the process of identifying novel bioactive compounds from biological sources has been a central challenge in the discovery of natural products. The resolution of these challenges relied extensively on the use of hyphenated Mass Spectrometry (MS) and Nuclear Magnetic Resonance (NMR)-based analytical technologies for the structural elucidation and annotation of novel compounds. Technical developments in instrumentation and data processing have fostered the development of the field of metabolomics which provides a wealth of tools with the huge potential for application in the process of drug/bioactive discovery from plant tissues. This manuscript provides an overview of the metabolomics toolbox available for the discovery of novel bioactive compounds and the integration of these tools in the bioprospection and drug discovery workflows.

Neurodegenerative Diseases (ND) are a major threat to the aging population and the lack of a single preventive or disease-modifying agent only serves to increase their impact. In the past few years, protein misfolding and the subsequent formation of neurotoxic oligomeric/aggregated protein species have emerged as a unifying theme underlying the pathology of these complex diseases. Recently developed microbial genetic screens and selection systems for monitoring ND-associated protein misfolding have allowed the establishment of highthroughput assays for the identification of cellular factors and processes that are important mediators of NDassociated proteotoxicities. In addition, such systems have facilitated the discovery of synthetic and natural compounds with the ability to rescue the misfolding and the associated pathogenic effects of aggregation-prone proteins associated with NDs. This review outlines such available systems in bacteria and yeast, whose usage will likely accelerate the pre-clinical discovery process for effective drugs against a variety of NDs with high socioeconomic impact.

Our society is currently experiencing increased lifespan; one of the top causes for the high incidence of neurodegenerative disorders. The lack of effective treatments delaying or blocking disease progression has encouraged the active search for novel therapies. Many evidences support the protective role of phytochemicals in the prevention of neurodegenerative diseases, particularly (poly)phenols. In this review, we described the use of cellular-based models of neurodegenerative diseases and the benefits of their use as potent tools in the search for bioactive molecules, particularly (poly)phenols. Studies to assess the biological activity of (poly)phenols involve experimentation with in vitro and in vivo systems. In vitro systems are a useful tool as a first approach to test the underlined molecular mechanisms of candidate molecules. They can provide valuable information about biological activity, which can be then used to design animal and human intervention studies.

Polyphenols constitute a group of compounds that have been highly investigated for their beneficial effects against various pathologic and non-pathologic conditions and diseases. Among their multi-faceted properties, their anti-oxidant potential nominates them as ideal protective candidates for conditions characterized by elevated levels of oxidative stress, including aging and age-related diseases. The nematode Caenorhabditis elegans is a multicellular model organism that is highly exploited in studies related to aging and age-associated pathologies. In this review, we will summarize studies where polyphenolic compounds have been tested for their anti-aging potential and their protective role against the progression of age-related diseases using C. elegans as their main model.

Nasopharyngeal Cancer (NPC) is a rare type of head and neck cancer that is mainly treated by radiotherapy, but sometimes it is radioresistant. Curcumin is a polyphenolic natural product with established anticancer effects in various human cancers. Recent studies have shown that curcumin has therapeutic and radiosensitizing effects on NPC cells. In fact, it has been found that curcumin can sensitize NPC cells to radiation through different mechanisms, including modulation of ROS generation, Jab1/CSN5 and non-coding RNAs. As curcumin is safe and lacks systemic toxic effects in humans, it may be considered as a potential candidate to enhance the therapeutic effects of radiation and potentiate the efficacy of chemotherapy in the context of combination regimens.

Curcumin quite possibly represents one of the most diverse therapeutic agents yet isolated from natural sources. Therapeutic benefits of this extraordinary natural compound have been demonstrated during treatment of a variety of diseases, including cancer, inflammatory processes, immunological disorders, Diabetes, and oxidative stress often associated with hyperlipidemia. Due to its unique molecular chemical structure and functional groups, curcumin may bind with and subsequently either inhibit or activate a variety of endogenous biomolecules, including enzymes, receptors, signaling molecules, metals, transcription factors, and even certain proteins located in cell membranes. In fact, curcumin exerts pharmacologically useful effects through non-covalent interactions with biomolecules. With so many varied biological targets, curcumin (a polyphenol) elicits numerous pleiotropic effects, which is therapeutically advantageous owing to the fact that many pathological disease states involve more than one signaling pathway, receptor, protein/enzyme, or gene. In this paper, we will discuss the underlying mechanisms responsible for the chemical interaction of curcumin with selected classes of biomolecules, rather than attempt to provide an exhaustive list of each and every biomolecule with which curcumin may chemically interact.

Polyphenols are natural compounds present in fruits and vegetables that can exert beneficial effects on human health and notably, on the cardiovascular system. Some of these compounds showed significant protective activities toward atherosclerosis, hypertension, myocardial infarction, anthracyclin-induced cardiomyopathy, angiogenesis as well as heart failure. Polyphenols can act through systemic effects as well as through modulation of signaling pathways such as redox signaling, inflammation, autophagy and cell death in the heart and vessels. These effects can be mediated by changes in expression level and by post-translational modifications of proteins (e.g. Stat1, CaMKII, Sirtuins, BCL-2 family members, PDEs, TRF2, eNOS and SOD). This non-comprehensive short review aims to summarize recent knowledge on the main pharmacological effects and mechanisms of cardioprotection of pure polyphenols, using different approaches such as cell culture, animal models and human studies.

Hydroxytyrosol (HT) and its derivatives represent the minor components of Virgin Olive Oil (VOO) that are of great interest for their pharmacological properties and among the most widely researched natural antioxidant compounds. In this review, the occurrence and metabolic fate of HT and its precursors are presented prior to discussing its beneficial effects on health. Bioavailability studies show that the metabolites detected in plasma depend on the model used (animal or human), the HT source (simple molecule or complex precursors) and the dose administered. However, in all cases HT sulphate appears to be the most ubiquitous metabolite in biofluids and it seems probable that it is responsible to a great extent for HT biological effects. Epidemiological evidence of HT and its derivatives against such lifestyle-associated pathologies as cancer, cardiovascular and neurodegenerative diseases is reviewed together with the newest perspectives on the mechanisms of action based on in-vitro and animal studies. According to the reviewed data, HT and its precursors could have the potential clinical use in cardiovascular diseases; more epidemiological data is needed to demonstrate their neurodegenerative diseases and cancer prevention.

Diabetic Retinopathy (DR) is one of the leading causes of decreased vision and blindness in developed countries. Diabetes-induced metabolic disorder is believed to increase oxidative stress in the retina. This results in deleterious change through dysregulation of cellular physiology that damages both neuronal and vascular cells. In this review, we first highlight the evidence of potential metabolic sources and pathways which increase oxidative stress that contribute to retinal pathology in diabetes. As oxidative stress is a central factor in the pathophysiology of DR, antioxidants therapy would be beneficial towards preventing the retinal damage. A number of experimental studies by our group and others showed that dietary flavonoids cause reduction in increased oxidative stress and other beneficial effects in diabetic retina. We then discuss the beneficial effects of the six major flavonoid families, such as flavanones, flavanols, flavonols, isoflavones, flavones and anthocyanins, which have been studied to improve retinal damage. Flavanoids, being known antioxidants, may ameliorate the retinal degenerative factors including apoptosis, inflammation and neurodegeneration in diabetes. Therefore, intake of potential dietary flavonoids would limit oxidative stress and thereby prevent the retinal damage, and subsequently the development of DR.

In this non-comprehensive review, the potential of natural polyphenols as lead compounds for the design and synthesis of new molecules with potential application in several diseases was highlighted. Organic synthesis has been essential for the development of new analogues of naturally found polyphenols, providing a wide range of structural modifications for structure-activity relationship studies and improving or modulating the biological activity of the promising compounds.

Polyphenols form a group of important natural bioactive compounds with numerous ascribed healthbeneficial attributes (e.g. antioxidant, anti-inflammatory, anti-microbial and tumor-suppressing properties). Some polyphenols can also be used as natural dyes or plastic precursors. Notwithstanding their relevance, production of most of these compounds still relies on extraction from plant material, which for most of it is a costly and an inefficient procedure. The use of microbial cell factories for this purpose is an emerging alternative that could allow a more efficient and sustainable production. The most recent advances in molecular biology and genetic engineering, combined with the ever-growing understanding of microbial physiology have led to multiple success stories. Production of multiple polyphenolic compounds or their direct precursors has been achieved not only in the common production hosts, such as Escherichia coli and Saccharomyces cerevisiae, but also in Corynebacterium glutamicum and Lactococcus lactis. However, boosting production of native compounds or introduction of heterologous biosynthetic pathways also brings certain challenges, such as the need to express, balance and maintain efficient precursor supply. This review will discuss the most recent advances in the field of metabolic engineering of microorganisms for polyphenol biosynthesis and its future perspectives, as well as outlines their potential health benefits and current production methods.