Phytosterols and triterpenes from Morinda lucida Benth. exhibit binding tendency against class I HDAC and HDAC7 isoforms

Phytosterol and phytostanol-mediated epigenetic changes in cancer and other non-communicable diseases: a systematic review

Phytosterols/phytostanols are bioactive compounds found in vegetable oils, nuts and seeds and added to a range of commercial food products. Consumption of phytosterols/phytostanols reduces levels of circulating LDL-cholesterol, a causative biomarker of CVD, and is linked to a reduced risk of some cancers. Individuals who consume phytosterols/phytostanols in their diet may do so for many years as part of a non-pharmacological route to lower cholesterol or as part of a healthy diet. However, the impact of long term or high intakes of dietary phytosterols/phytostanols has not been on whole-body epigenetic changes before. The aim of this systematic review was to identify all publications that have evaluated changes to epigenetic mechanisms (post-translation modification of histones, DNA methylation and miRNA expression) in response to phytosterols/phytostanols. A systematic search was performed that returned 226 records, of which eleven were eligible for full-text analysis. Multiple phytosterols were found to inhibit expression of histone deacetylase (HDAC) enzymes and were also predicted to directly bind and impair HDAC activity. Phytosterols were found to inhibit the expression and activity of DNA methyl transferase enzyme 1 and reverse cancer-associated gene silencing. Finally, phytosterols have been shown to regulate over 200 miRNA, although only five of these were reported in multiple publications. Five tissue types (breast, prostate, macrophage, aortic epithelia and lung) were represented across the studies, and although phytosterols/phytostanols alter the molecular mechanisms of epigenetic inheritance in these mammalian cells, studies exploring meiotic or transgenerational inheritance were not found.

Exploring the potential of Andrographis paniculata for developing novel HDAC inhibitors: an in silico approach

Cancer is one of the dreaded diseases of the twentieth century, emerging the major global causes of human morbidity. Cancer research in the last 15 years has provided unprecedented information on the role of epigenetics in cancer initiation and progression. Histone deacetylases (HDACs) are recognized as important epigenetic markers in cancer, whose overexpression leads to increased metastasis and angiogenesis. In the current study, thirty-four (34) compounds from Andrographis paniculata were screened for the identification of potential candidate drugs, targeting three Class I HDACs (Histone deacetylases), namely HDAC1 (PDB id 5ICN), HDAC3 (PDB id 4A69) and HDAC8 (PDB id 5FCW) through computer-assisted drug discovery study. Results showed that some of the phytochemicals chosen for this study exhibited significant drug-like properties. In silico molecular docking study further revealed that out of 34 compounds, the flavonoid Andrographidine E had the highest binding affinities towards HDAC1 (-9.261 Kcal mol-1) and 3 (-9.554 Kcal mol-1) when compared with the control drug Givinostat (-8.789 and -9.448 Kcal mol-1). The diterpenoid Andrographiside displayed the highest binding affinity (-9.588 Kcal mol-1) to HDAC8 compared to Givinostat (-8.947 Kcal mol-1). Statistical analysis using Principal Component Analysis tool revealed that all 34 phytocompounds could be clustered in four statistical groups. Most of them showed high or comparable inhibitory potentials towards HDAC target protein. Finally, the stability of top-ranked complexes (Andrographidine E-HDAC1 and HDAC3; Andrographiside-HDAC8) at the physiological condition was validated by Molecular Dynamic Simulation and MM-PBSA study.Communicated by Ramaswamy H. Sarma.

Computational studies on the cholinesterase, beta-secretase 1 (BACE1) and monoamine oxidase (MAO) inhibitory activities of endophytes-derived compounds: towards discovery of novel neurotherapeutics

Cholinesterases, beta-secretase 1 (BACE1) and monoamine oxidase (MAO) are significant in the etiology of neurodegenerative diseases. Inhibition of these enzymes is therefore a major strategy for the development of neurotherapeutics. Even though, this strategy has birthed some approved synthetic drugs, they are characterized by adverse effects. It is therefore, imperative to explore promising alternatives. Consequently, we assessed the inhibitory activities of some endophytes-derived compounds against selected targets towards discovery of novel neurotherapeutics. Standard inhibitors and 83 endophytes-derived compounds were docked against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), BACE 1 and MAO using AutodockVina while the molecular interactions between the selected targets and the compounds with notable binding affinity were viewed through Discovery Studio Visualizer. Druglikeness and Absorption-Distribution-Metabolism-Excretion-Toxicity (ADMET) and blood brain barrier (BBB) properties of the top 4 compounds were evaluated using the Swiss online ADME web tool and OSIRIS server; ligands-enzymes complex stability was assessed through molecular dynamics (MD) simulation. From the 83 compounds, asperflavin, ascomfurans C, camptothecine and corynesidone A exhibited remarkable inhibitory activity against all the four target enzymes compared to the respective standard inhibitors. However, only corynesidone A could transverse the BBB and predicted to be safe. MD simulation of the unbound and complexed enzymes with corynesidone A showed that the complexes were stable throughout the simulation time. Given the exceptional inhibitory activity of endophytes-derived corynesidone A against the four selected targets, its ability to permeate the BBB, excellent drugability properties as well as its stability when complexed with the enzymes, it is a good candidate for further studies towards development of new neurotherapeutics.Communicated by Ramaswamy H. Sarma.

In silico profiling of histone deacetylase inhibitory activity of compounds isolated from Cajanus cajan

Background

Cancer is responsible for high morbidity and mortality globally. Because the overexpression of histone deacetylases (HDACs) is one of the molecular mechanisms associated with the development and progression of some diseases such as cancer, studies are now considering inhibition of HDAC as a strategy for the treatment of cancer. In this study, a receptor-based in silico screening was exploited to identify potential HDAC inhibitors among the compounds isolated from Cajanus cajan, since reports have earlier confirmed the antiproliferative properties of compounds isolated from this plant.

Results

Cajanus cajan-derived phytochemicals were docked with selected HDACs, with givinostat as the reference HDAC inhibitor, using AutodockVina and Discovery Studio Visualizer, BIOVIA, 2020. Furthermore, absorption, distribution, metabolism and excretion (ADME) drug-likeness analysis was done using the Swiss online ADME web tool. From the results obtained, 4 compounds; betulinic acid, genistin, orientin and vitexin, were identified as potential inhibitors of the selected HDACs, while only 3 compounds (betulinic acid, genistin and vitexin) passed the filter of drug-likeness. The molecular dynamic result revealed the best level of flexibility on HDAC1 and HDAC3 compared to the wild-type HDACs and moderate flexibility of HDAC7 and HDAC8.

Conclusions

The results of molecular docking, pharmacokinetics and molecular dynamics revealed that betulinic acid might be a suitable HDAC inhibitor worthy of further investigation in order to be used for regulating conditions associated with overexpression of HDACs. This knowledge can be used to guide experimental investigation on Cajanus cajan-derived compounds as potential HDAC inhibitors.

Identification of potential histone deacetylase inhibitory biflavonoids from Garcinia kola (Guttiferae) using in silico protein-ligand interaction

Overactivity of histone deacetylases (HDACs) is the underlying cause of some cancers, thus, inhibiting their overactivities is a rational treatment option. However, endeavors to employ current anti-HDACs agents in cancer treatment have yielded limited success. Consequently, there is need to explore anti-HDACs natural products, especially from plants sources, because of the intimate relationship plant products and drug discovery have enjoyed over the centuries. To identify possible HDACs inhibitors, Garcinia kola (Guttiferae) seed-derived compounds were screened in silico for HDAC-inhibitory tendencies because of their reported anticancer potentials. Fifteen G. kola-derived compounds and givinostat were docked with five selected HDACs using AutodockVina, while the binding interactions of the compounds with high binding affinities for the five HDACs were viewed with Discovery Studio Visualizer BIOVIA, 2016. Results indicated that four of the compounds studied, including amentoflavone, Garcinia biflavonoid 1, Garcinia biflavonoid 2 and kolaflavanone have higher binding propensity for all the five HDACs relative to givinostat, the standard HDAC inhibitor. This study indicated that inhibition of HDAC might be another key mechanism accountable for the bioactivities of G. kola and its intrinsic compounds. The results from this study implied that the compounds could be further investigated as drugable HDAC inhibitors with potential pharmacological applications in the treatment of cancers.

Antimicrobial Importance of Medicinal Plants in Nigeria

Despite the success of antibiotic discovery, infectious diseases remain the second leading source of death worldwide, while the resistance to antibiotics is among the significant problems in the twenty-first century. Medicinal plants are very rich in phytochemicals which can be structurally optimized and processed into new drugs. Nigeria enjoys a diverse collection of medicinal plants, and joint research has ascertained the efficacy of these plants. Plants such as guava (Psidium guajava), ginger (Zingiber officinale), neem (Azadirachta indica), and moringa (Moringa oleifera) have been found to exhibit broad range of antimicrobial activities. Studies on Nigerian plants have shown that they contain alkaloids, polyphenols, terpenes, glycosides, and others with possible therapeutic potentials. The antimicrobial activities of some new compounds such as alloeudesmenol, hanocokinoside, orosunol, and 8-demethylorosunol, identified from medicinal plants in Nigeria, are not yet explored. Further investigation and optimization of these compounds will facilitate the development of new sets of pharmacologically acceptable antimicrobial agents. This review study revealed the efficacy of medicinal plants as an alternative therapy in combating and curtailing the development and survival of multidrug-resistant pathogens coupled with the toxic effects of some antibiotics. Due to enormous therapeutic possibilities buried in medicinal plants, there is a need for more research into unique fingerprints and novel compounds that can provide cure to the neglected tropical diseases (NTDs) of humans and animals facing Africa, especially Nigeria.

Natural Products Impacting DNA Methyltransferases and Histone Deacetylases

Epigenetics refers to heritable changes in gene expression and chromatin structure without change in a DNA sequence. Several epigenetic modifications and respective regulators have been reported. These include DNA methylation, chromatin remodeling, histone post-translational modifications, and non-coding RNAs. Emerging evidence has revealed that epigenetic dysregulations are involved in a wide range of diseases including cancers. Therefore, the reversible nature of epigenetic modifications concerning activation or inhibition of enzymes involved could be promising targets and useful tools for the elucidation of cellular and biological phenomena. In this review, emphasis is laid on natural products that inhibit DNA methyltransferases (DNMTs) and histone deacetylases (HDACs) making them promising candidates for the development of lead structures for anticancer-drugs targeting epigenetic modifications. However, most of the natural products targeting HDAC and/or DNMT lack isoform selectivity, which is important for determining their potential use as therapeutic agents. Nevertheless, the structures presented in this review offer the well-founded basis that screening and chemical modifications of natural products will in future provide not only leads to the identification of more specific inhibitors with fewer side effects, but also important features for the elucidation of HDAC and DNMT function with respect to cancer treatment.

Biosynthesis of cycloartenol by expression of plant and bacterial oxidosqualene cyclases in engineered Rhodobacter capsulatus

Cyclic triterpenes are a large group of secondary metabolites produced by plants, fungi and bacteria. They have diverse biological functions, and offer potential health benefits for humans. Although various terpenes from the mono-, sesqui- and diterpene classes are easy to produce in engineered bacteria, heterologous synthesis of cyclic triterpenes is more challenging. We have recently shown that the triterpene cycloartenol can be produced in Rhodobacter capsulatus SB1003 but initial titers were low with 0.34mgL^-1. To assess, if this phototrophic α-proteobacterium can be engineered for enhanced triterpene production, we followed two alternative strategies by comparing the performance of the R. capsulatus SB1003 wildtype strain with two recombinant strains carrying either a mevalonate pathway implemented from Paracoccus zeaxanthinifaciens or a deletion in the intrinsic carotenoid biosynthesis gene crtE. These strains are thus engineered for an enhanced isoprenoid biosynthesis or a suppressed precursor conversion by the competing carotenoid pathway. Moreover, three different cycloartenol synthase (CAS) genes from Arabidopsis thaliana or the myxobacterial strains Stigmatella aurantiaca Sga15 and DW4/3-1 were tested for heterologous cycloartenol synthesis. We found that the heterologous expression of mevalonate pathway enzymes had little impact on cycloartenol levels irrespective of the chosen CAS. In contrast, the use of the newly constructed carotenoid-deficient crtE deletion strain showed threefold increased cycloartenol product titers. We conclude that R. capsulatus is a promising alternative host for the functional expression of triterpene biosynthetic enzymes from plants and microbes. Apparently, product titers can also be improved by suppression of competing precursor consumption.