Application of dietary supplements in the prevention of type 2 diabetes-related cardiovascular complications

Joint review by the Leicester Institute for Pharmaceutical Innovation and the Institute for Allied Health Sciences Research, based on invited plenary lecture presented by Prof. Randolph Arroo at the conference 'Natural Products in Drug Discovery and Human Health' in Lisbon, 28-31 July, 2019 The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Type 2 diabetes, which accounts for the vast majority of diabetes worldwide is the result of a lowered sensitivity of the insulin receptors, resulting in impaired sugar metabolism is and chronic hyperglycaemia. There is no cure for type 2 diabetes, though some people with pre-diabetes and diabetes manage to reach and hold normal blood sugar levels, thus avoiding most of the complications that come with chronic hyperglycaemia; this is sometimes referred to as ‘reversing diabetes’. A healthy diet, with sufficient amounts of fruits, nuts, and vegetables is positively correlated with maintaining glycaemic control and prevention of diabetes-related complications. Whereas many different dietary phytochemicals have been considered to play a role in the glycaemic control and in prevention of degenerative diseases, there is currently no consensus on a particular mode of action. In this review, a range of pre-clinical studies and intervention studies, including randomised double-blind, placebo controlled clinical studies, are considered that investigate the role of dietary compounds in the prevention of type 2 diabetes-related complications. Three generic mechanisms of action can be discerned: compounds that reduce sugar uptake, compounds that restore insulin function, and compounds that attenuate the effects of oxidative stress and chronic inflammation. Particularly the latter has received wide attention in the form of activation of the Nrf2-antioxidant response element signalling pathway by various polyphenolic or triterpenoid compounds. Although individual reports may present models with clear looking signalling cascades, an overall review shows that many biologically active compounds in the human diet are pan assay interference substances that alter several cell functions simultaneously, which makes them less attractive for drug development

Analysis of plant secondary metabolism using stable isotope‐labelled precursors

Special issue of Phytochemical Analysis on NMR-based analytical techniques. open access articleIntroduction Analysis of biochemical pathways typically involves feeding a labelled precursor to an organism, and then monitoring the metabolic fate of the label. Initial studies used radioisotopes as a label and then monitored radioactivity in the metabolic products. As analytical equipment improved and became more widely available, preference shifted the use stable ‘heavy’ isotopes like deuterium (2H)‐, carbon‐13 (13C)‐ and nitrogen‐15 (15N)‐atoms as labels. Incorporation of the labels could be monitored by mass spectrometry (MS), as part of a hyphenated tool kits, e.g. Liquid chromatography (LC)–MS, gas chromatography (GC)–MS, LC–MS/MS. MS offers great sensitivity but the exact location of an isotope label in a given metabolite cannot always be unambiguously established. Nuclear magnetic resonance (NMR) can also be used to pick up signals of stable isotopes, and can give information on the precise location of incorporated label in the metabolites. However, the detection limit for NMR is quite a bit higher than that for MS. Objectives A number of experiments involving feeding stable isotope‐labelled precursors followed by NMR analysis of the metabolites is presented. The aim is to highlight the use of NMR analysis in identifying the precise fate of isotope labels after precursor feeding experiments. As more powerful NMR equipment becomes available, applications as described in this review may become more commonplace in pathway analysis. Conclusion and Prospects NMR is a widely accepted tool for chemical structure elucidation and is now increasingly used in metabolomic studies. In addition, NMR, combined with stable isotope feeding, should be considered as a tool for metabolic flux analyses

Effect of the Citrus Flavone Nobiletin on Circadian Rhythms and Metabolic Syndrome

Invited review paper for a special issue of Molecules on "Biological Activities of Natural Products III" (Halina Ekiert & Agnieszka Szopa, eds.) open access articleThe importance of the circadian clock in maintaining human health is now widely acknowledged. Dysregulated and dampened clocks may be a common cause of age-related diseases and metabolic syndrome Thus, circadian clocks should be considered as therapeutic targets to mitigate disease symptoms. This review highlights a number of dietary compounds that positively affect the maintenance of the circadian clock. Notably the polymethoxyflavone nobiletin has shown some encouraging results in pre-clinical experiments. Although many more experiments are needed to fully elucidate its exact mechanism of action, it is a promising candidate with potential as a chronotherapeutic agent

Design, synthesis and antitrypanosomal activities of 2,6-disubstituted-4,5,7-Trifluorobenzothiophenes

Current treatments for Human African Trypanosomiasis (HAT) are limited in their application, have undesirable dosing regimens and unsatisfactory toxicities highlighting the need for the development of a safer drug pipeline. Our medicinal chemistry programme in developing rapidly accessible and modifiable heterocyclic scaffolds led to the design and synthesis of novel substituted benzothiophenes, with 6-benzimidazol-1-ylbenzothiophene derivatives demonstrating significant antitrypanosomal activities (IC50 <1 μM) against Trypanosoma brucei rhodesiense and no toxicity towards mammalian cells

A Brief Overview of Potential Treatments for Viral Diseases Using Natural Plant Compounds: The Case of SARS-Cov

Review paper, jointly written by experts from Universiti Putra Malaysia, Taras Shevchenko National University of Kyiv (Ukraine), Kermanshah University of Medical Sciences (Iran), Federal University of Maranhão (Brazil), Central University of Punjab (India), Federal Scientific Center of the East Asia Terrestrial Biodiversity (Russia), De Montfort University (UK), University of Orléans (France) open access articleThe COVID-19 pandemic, as well as the more general global increase in viral diseases, has led researchers to look to the plant kingdom as a potential source for antiviral compounds. Since ancient times, herbal medicines have been extensively applied in the treatment and prevention of various infectious diseases in different traditional systems. The purpose of this review is to highlight the potential antiviral activity of plant compounds as effective and reliable agents against viral infections, especially by viruses from the coronavirus group. Various antiviral mechanisms shown by crude plant extracts and plant-derived bioactive compounds are discussed. The understanding of the action mechanisms of complex plant extract and isolated plant-derived compounds will help pave the way towards the combat of this life-threatening disease. Further, molecular docking studies, in silico analyses of extracted compounds, and future prospects are included. The in vitro production of antiviral chemical compounds from plants using molecular pharming is also considered. Notably, hairy root cultures represent a promising and sustainable way to obtain a range of biologically active compounds that may be applied in the development of novel antiviral agents

Absorption, Distribution, Metabolism and Excretion (ADME) of Dietary Flavones and Their Glycosides

open access bookEpidemiological studies have long indicated a possible role for dietary flavonoids, notably flavones and flavonols, in the prevention of a range of degenerative diseases, e.g. cancer, diabetes, cardiovascular diseases and neurological disorders like Parkinson’s and Alzheimer’s disease. The flavonoids are a large and variable group of compounds, comprising thousands of different structures. The bulk of the dietary flavonoids occur as glycosides. The effect of flavonoid aglycones and their corresponding glycosides on cell metabolism and aetiology of degenerative diseases has been a topic of interest for a number of decades. In contrast, the role of the metabolic products of dietary flavonoid that reach all parts of the human body through systemic circulation, has received much less attention. Many detailed ADME studies focus specifically on quercetin and its glycosides, due to their abundant availability. Dietary quercetin occurs almost exclusively as β-glycosides, where the aglycone can be bound to a variety of sugars depending on the food source, e.g. apples are rich in galactosides, rhamnosides, and arabinosides, whereas in onions glucosides are the main glycosidic form. The sugar moiety was shown to be an important determinant of the bioavailability of quercetin from foods. The compounds that directly play a role in the prevention of degenerative diseases are most likely not dietary flavones themselves, but rather their metabolites and conjugation products

Artemisinin Cocrystals for Bioavailability Enhancement. Part 1: Formulation Design and Role of the Polymeric Excipient

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Artemisinin (ART) is a most promising antimalarial agent, which is both effective and well-tolerated in patients, though it has therapeutic limitations due to its low solubility, bioavailability and short half-life. The objective of this work was to explore the possibility of formulating ART cocrystals, i.e., artemisinin-orcinol (ART-ORC) and artemisinin-resorcinol (ART2-RES) as oral dosage forms to deliver ART molecules for bioavailability enhancement. This is the first part of the study, aiming to develop a simple and effective formulation which can then be tested on an appropriate animal model (i.e. mouse selected for in vivo study) to evaluate their preclinical pharmacokinetics for further development. In the current work, the physicochemical properties (i.e., solubility and dissolution rate) of ART cocrystals were measured to collect information necessary for the formulation development strategy. It was found that the ART solubility can be increased significantly by its cocrystals, i.e., 26-fold by ART-ORC and 21-fold by ART2-RES respectively. Screening a set of polymers widely used in pharmaceutical products, including Polyvinylpyrrolidone, Hydroxypropyl Methylcellulose and Hydroxypropyl Methylcellulose Acetate Succinate, based on the powder dissolution performance parameter analysis, revealed that Polyvinylpyrrolidone/vinyl Acetate (PVP-VA) was the most effective crystallisation inhibitor. The optimal concentration of PVP-VA at 0.05 mg/mL for the formulation was then determined by a dissolution/permeability method which represented a simplified permeation model to simultaneously evaluate the effects of a crystallization inhibitor on the dissolution and permeation performance of ART cocrystals. Furthermore, experiments, including surface dissolution of single ART cocrystals monitored by Raman spectroscopy and SEM and diffusion properties of ART in solution measured by 1H and diffusion-ordered spectroscopy (DOSY) nuclear magnetic resonance (NMR) spectroscopy, provided insight into how the excipient affects the ART cocrystal dissolution performance and bioavailability

Artemisinin Cocrystals for Bioavailability Enhancement: Part 2. In-vivo Bioavailability and PBPK Modelling

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.We report the evaluation and prediction of the pharmacokinetic (PK) performance of artemisinin (ART) cocrystal formulations, i.e., 1:1 Artemisinin-Orcinol (ART-ORC) and 2:1 Artemisinin-Resorcinol (ART2-RES), using in vivo murine animal and PBPK (physiological based pharmacokinetic) models. The efficacy of the ART cocrystal formulations along with the parent drug ART were tested in mice infected with Plasmodium berghei. When given at the same dose, the ART-cocrystal formulation showed a significant reduction in parasitaemia at day 4 post infection compared to ART alone. The PK parameters including Cmax (maximum plasma concentration), Tmax (time to Cmax), AUC (area under the curve) were obtained by determining drug concentrations in the plasma using LC-HRMS (Liquid Chromatography-High Resolution Mass Spectrometry), showing enhanced ART levels after dosage with the cocrystal formulations. The dose-response tests revealed that a significantly lower dose of the ART cocrystals in the formulation was required to achieve a similar therapeutic effect as ART alone. A PBPK model was developed using a PBPK mouse simulator to accurately predict the in vivo behaviour of the cocrystal formulations by combining in vitro dissolution profiles with the properties of the parent drug ART. The study illustrated that information from classical in vitro and in vivo experimental investigations of the parent drug of ART formulation can be coupled with PBPK modelling to predict the PK parameters of an ART cocrystal formulation in an efficient manner. Therefore, the proposed modelling strategy could be used to establish in vitro and in vivo correlations for different cocrystals intended to improve dissolution properties and to support clinical candidate selection, contributing to assessment of cocrystal developability and formulation development

Biosynthesis of podophyllotoxin in Linum album cell cultures

Cell cultures of Linum album Kotschy ex Boiss. (Linaceae) showing high accumulation of the lignan podophyllotoxin (PTOX) were established. Enzymological studies revealed highest activities of phenylalanine ammonia-lyase, cinnamyl alcohol dehydrogenase, 4-hydroxycinnamate:CoA ligase and cinnamoyl-CoA:-NADP oxidoreductase immediately prior to PTOX accumulation. To investigate PTOX biosynthesis, feeding experiments were performed with [2- 13 C]3¢,4¢-dimethoxycinnamic acid, [2-13 C]3¢,4¢-methylenedioxycinnamic acid (MDCA), [2-13C]3¢,4¢,5¢-trimethoxycinnamic acid,[2- 13C]sinapic acid, [2-13C]- and [2,3-13C2]ferulic acid.Analysis of the metabolites by HPLC coupled to tandem mass spectrometry revealed incorporation of label from ferulic acid into PTOX and deoxypodophyllotoxin (DOP). In addition, MDCA was also unambiguously incorporated intact into PTOX. These observations suggest that in L. album both ferulic acid and methylenedioxy-substituted cinnamic acid can be incorporated into lignans. Furthermore, it appears that, in this species, the hydroxylation of DOP is a rate-limiting point in the pathway leading to PTOX