Flavonoids as a scaffold for development of novel anti-angiogenic agents: An experimental and computational enquiry

Apigenin and its combination with Vorinostat induces apoptotic-mediated cell death in TNBC by modulating the epigenetic and apoptotic regulators and related miRNAs

Triple-negative breast cancer (TNBC) is a metastatic disease and a formidable treatment challenge as it does not respond to existing therapies. Epigenetic regulators play a crucial role in the progression and metastasis by modulating the expression of anti-apoptotic, pro-apoptotic markers and related miRNAs in TNBC cells. We have investigated the anti-TNBC potential of dietary flavonoid 'Apigenin' and its combination with Vorinostat on MDA-MB-231 cells. At Apigenin generated ROS, inhibited cell migration, arrested the cell cycle at subG0/G1 phases, and induced apoptotic-mediated cell death. Apigenin reduced the expression of the class-I HDACs at the transcriptomic and proteomic levels. In the immunoblotting study, Apigenin has upregulated pro-apoptotic markers and downregulated anti-apoptotic proteins. Apigenin inhibited the enzymatic activity of HDAC/DNMT and increased HAT activity. Apigenin has manifested its effect on miRNA expression by upregulating the tumor-suppressor miR-200b and downregulation oncomiR-21. Combination study reduced the growth of TNBC cells synergistically by modulating the expression of epigenetic and apoptotic regulators. Molecular docking and MD simulations explored the mechanism of catalytic inhibition of HDAC1 and HDAC3 and supported the in-vitro studies. The overall studies demonstrated an anti-TNBC potential of Apigenin and may help to design an effective strategy to treat metastatic phenotype of TNBC.

Pharmacognostic Evaluation of Monarda didyma L. Growing in Trentino (Northern Italy) for Cosmeceutical Applications

Monarda didyma L. (Lamiaceae) is a medicinal and aromatic herb native to eastern North America and now is also cultivated in Northern Italy, which shows terminal heads of bright scarlet-red flowers, subtended by a whorl of red-tinged leafy bracts. Starting from 2018, M. didyma flowering tops have been included in the Belfrit List of botanicals. However, to date studies on the crude extract of this plant are still lacking. The aim of the present study was to investigate the morphological and anatomical features of the flowering tops and the phytochemical profile of their ethanolic and hydroglyceric extracts (EE and HGE, respectively). HGE was the richest in total phenols (105.75 ± 5.91 vs. 64.22 ± 3.45 mg/100 mL) and especially in flavonoids (71.60 ± 5.09 vs. 47.70 ± 1.27 mg/100 mL), as confirmed also by LC-DAD-ESI-MS. Fifty-three polyphenols were identified and quantified. Even if they showed a common polyphenolic profile, EE and HGE showed quantitative differences. Flavan-3-ols and anthocyanins were the most expressed metabolites in HGE, whereas flavonols were the most expressed metabolites in EE. These features confer to HGE the highest antioxidant, anti-inflammatory, and anti-angiogenic properties, detected by several in vitro and in vivo assays, highlighting a promising use of this plant extract for skincare applications.

Ethanol extract of basil (Ocimum Basilicum L.) leaves inhibits endometriosis growth in a mouse model by modulating vascular endothelial growth factor (VEGF) expression

The objective of this study was to examine the effect of administering an ethanol extract obtained from basil leaves on the expression of vascular endothelial growth factor (VEGF) and the severity of endometriosis lesions in a mouse model. A total of 28 female mice, aged 2-3 months and weighing 20-30 grams, were randomly divided into four groups: the control group (C), treatment group 1 (T1) receiving a dose of basil leaf ethanol extract (0.21 mg/g-BW), treatment group 2 (T2) receiving a higher dose (0.42 mg/g BW), and treatment group 3 (T3) receiving the highest dose (0.84 mg/g-BW). Each group underwent a 14-day treatment period, and tissue samples were collected on the 29th day. An immunohistochemical examination was conducted to assess the expression of VEGF and evaluate the severity of endometriosis lesions. The statistical analysis of VEGF expression revealed a significant difference (p=0.026; p<0.05), with the most pronounced effects observed when administering basil leaf ethanol extract at doses of 0.21 mg/g-BW and 0.42 mg/g-BW. Although not statistically significant (p=0.271; p<0.05), a reduction in the severity of endometriosis lesions was observed following the administration of basil leaf ethanol extract at doses of 0.21 mg/g-BW and 0.42 mg/g-BW. Administering basil leaf ethanol extract at doses of 0.21 mg/g-BW and 0.42 mg/g-BW effectively decreased VEGF expression and limited the severity of endometriosis lesions.

Repurposing of neprilysin inhibitor 'sacubitrilat' as an anti-cancer drug by modulating epigenetic and apoptotic regulators

Modifications in the epigenetic landscape have been considered a hallmark of cancer. Histone deacetylation is one of the crucial epigenetic modulations associated with the aggressive progression of various cancer subtypes. Herein, we have repurposed the neprilysin inhibitor sacubitrilat as a potent anticancer agent using in-silico protein-ligand interaction profiler (PLIP) analysis, molecular docking, and in vitro studies. The screening of PLIP profiles between vorinostat/panobinostat and HDACs/LTA4H followed by molecular docking resulted in five (Sacubitrilat, B65, BDS, BIR, and NPV) FDA-approved, experimental and investigational drugs. Sacubitrilat has demonstrated promising anticancer activity against colorectal cancer (SW-480) and triple-negative breast cancer (MDA-MB-231) cells, with IC₅₀ values of 14.07 μg/mL and 23.02 μg/mL, respectively. FACS analysis revealed that sacubitrilat arrests the cell cycle at the G0/G1 phase and induces apoptotic-mediated cell death in SW-480 cells. In addition, sacubitrilat inhibited HDAC isoforms at the transcriptomic level by 0.7-0.9 fold and at the proteomic level by 0.5-0.6 fold as compared to the control. Sacubitrilat increased the protein expression of tumor-suppressor (p53) and pro-apoptotic makers (Bax and Bid) by 0.2-2.5 fold while decreasing the expression of anti-apoptotic Bcl2 and Nrf2 proteins by 0.2-0.5 fold with respect to control. The observed cleaved PARP product indicates that sacubitrilat induces apoptotic-mediated cell death. This study may pave the way to identify the anticancer potential of sacubitrilat and can be explored in human clinical trials.

High-resolution liquid chromatography and mass spectrometry (HR-LCMS) assisted phytochemical profiling and an assessment of anticancer activities of Gracilaria foliifera and Turbinaria conoides using in vitro and molecular docking analysis

Marine algae's, owing to diverse range of secondary metabolites, opening up the new avenues in new drug development and can be used efficiently in anticancer research. Two seaweeds Gracilaria foliifera and Turbinaria conoides are subjected to phytochemical investigation by HR-LCMS and NMR which confirms presence of different bioactive compounds. The cytotoxicity of the dichloromethane (DCM) fraction of Gracilaria foliifera and Turbinaria conoides was determined using an in vitro methyl thiazolyl tetrazolium (MTT) test and showed considerable dose-dependent cytotoxicity on tumour cell lines. In MCF7, Gracilaria foliifera had an IC₅₀ of 100 μg/ml, while Turbinaria conoides had an IC₅₀ of 200 μg/ml and both the DCM fraction had IC₅₀ values of 100 μg/ml in the A549 cell line. MTT assay for anticancer activity suggest that Gracilaria foliifera has potent anticancer activity in both breast and lung cell lines, while the DCM fraction of Turbinaria conoides has potent activity in lung cell lines and moderate activity in breast cell lines. The anticancer effects of the discovered drugs targeting the most prevalent enzymes VEGFR and AXL tyrosine kinases were confirmed using a computational technique. We believe that residues from VEGFR, like Lys868, Asn923, Asp1046, and Phe1047 and Asp690 from Axl kinase may have contributed to the plausible anti-cancer benefit seen in this study. Communicated by Ramaswamy H. Sarma.

Halogenated Flavonoid Derivatives Display Antiangiogenic Activity

Antiangiogenic agents attenuate tumours' growth and metastases and are therefore beneficial as an adjuvant or standalone cancer regimen. Drugs with dual antiproliferative and antiangiogenic activities can achieve anticancer efficacy and overcome acquired resistance. In this study, synthetic flavones (5a,b) with reported anticancer activity, and derivatives (4b and 6a), exhibited significant inhibition of endothelial cell tube formation (40-55%, 12 h) at 1 µM, which is comparable to sunitinib (50% inhibition at 1 µM, 48 h). Flavones (4b, 5a,b and 6a) also showed 25-37% reduction in HUVECs migration at 10 µM. In a Western blotting assay, 5a and 5b subdued VEGFR2 phosphorylation by 37% and 57%, respectively, suggesting that VEGFR2 may be their main antiangiogenic target. 5b displayed the best docking fit with VEGFR2 in an in silico study, followed by 5a, emphasizing the importance of the 7-hydroxyl group accompanied by a 4-C=S for activity. Conversely, derivatives with a 4-carbonyl moiety fitted poorly into the target's binding pocket, suggesting that their antiangiogenic activity depends on a different target. This study provides valuable insight into the Structure Activity Relationships (SAR) and modes of action of halogenated flavones with VEGFR2 and highlights their therapeutic potential as antiangiogenic/anticancer lead compounds.

Microvascular Experimentation in the Chick Chorioallantoic Membrane as a Model for Screening Angiogenic Agents including from Gene-Modified Cells

The chick chorioallantoic membrane (CAM) assay model of angiogenesis has been highlighted as a relatively quick, low cost and effective model for the study of pro-angiogenic and anti-angiogenic factors. The chick CAM is a highly vascularised extraembryonic membrane which functions for gas exchange, nutrient exchange and waste removal for the growing chick embryo. It is beneficial as it can function as a treatment screening tool, which bridges the gap between cell based in vitro studies and in vivo animal experimentation. In this review, we explore the benefits and drawbacks of the CAM assay to study microcirculation, by the investigation of each distinct stage of the CAM assay procedure, including cultivation techniques, treatment applications and methods of determining an angiogenic response using this assay. We detail the angiogenic effect of treatments, including drugs, metabolites, genes and cells used in conjunction with the CAM assay, while also highlighting the testing of genetically modified cells. We also present a detailed exploration of the advantages and limitations of different CAM analysis techniques, including visual assessment, histological and molecular analysis along with vascular casting methods and live blood flow observations.

Antiangiogenic Activity of Flavonoids: A Systematic Review and Meta-Analysis

Abstract: An imbalance of angiogenesis contributes to many pathologies such as cancer, arthritis and retinopathy, hence molecules that can modulate angiogenesis are of considerable therapeutic importance. Despite many reports on the promising antiangiogenic properties of naturally occurring flavonoids, no flavonoids have progressed to the clinic for this application. This systematic review and meta-analysis therefore evaluates the antiangiogenic activities of a wide range of flavonoids and is presented in two sections. The first part of the study (Systematic overview) included 402 articles identified by searching articles published before May 2020 using ScienceDirect, PubMed and Web of Science databases. From this initial search, different classes of flavonoids with antiangiogenic activities, related pathologies and use of in vitro and/or in/ex vivo angiogenesis assays were identified. In the second part (Meta-analysis), 25 studies concerning the antiangiogenic evaluation of flavonoids using the in vivo chick chorioallantoic membrane (CAM) assay were included, following a targeted search on articles published prior to June 2020. Meta-analysis of 15 out of the 25 eligible studies showed concentration dependent antiangiogenic activity of six compared subclasses of flavonoids with isoflavones, flavonols and flavones being the most active (64 to 80% reduction of blood vessels at 100 µM). Furthermore, the key structural features required for the antiangiogenic activity of flavonoids were derived from the pooled data in a structure activity relationship (SAR) study. All in all, flavonoids are promising candidates for the development of antiangiogenic agents, however further investigations are needed to determine the key structural features responsible for their activity.

Evaluation of the status quo of polyphenols analysis: Part I-phytochemistry, bioactivity, interactions, and industrial uses

Phytochemicals, especially polyphenols, are gaining more attention from both the scientific community and food, pharmaceutical, and cosmetics industries due to their implications in human health. In this line, lately new applications have emerged, and of great importance is the selection of accurate and reliable analytical methods for better evaluation of the quality of the end-products, which depends on diverse process variables as well as on the matrices and on the physicochemical properties of different polyphenols. The first of a two-part review on polyphenols will address the phytochemistry and biological activities of different classes of polyphenols including flavonoids, lignans and flavanolignans, stilbenoids, tannins, curcuminoids, and coumarins. Moreover, the possible interactions of polyphenols and current and potential industrial applications of polyphenols are discussed.

FlavoDb: a web-based chemical repository of flavonoid compounds

There are many online resources that focus on chemical diversity of natural compounds, but only handful of resources exist that focus solely on flavonoid compounds and integrate structural and functional properties; however, extensive collated flavonoid literature is still unavailable to scientific community. Here we present an open access database 'FlavoDb' that is focused on providing physicochemical properties as well as topological descriptors that can be effectively implemented in deducing large scale quantitative structure property models of flavonoid compounds. In the current version of database, we present data on 1, 19,400 flavonoid compounds, thereby covering most of the known structural space of flavonoid class of compounds. Moreover, effective structure searching tool presented here is expected to provide an interactive and easy-to-use tool for obtaining flavonoid-based literature and allied information. Data from FlavoDb can be freely accessed via its intuitive graphical user interface made available at following web address: http://bioinfo.net.in/flavodb/home.html.

Design, synthesis and in silico study of pyridine based 1,3,4-oxadiazole embedded hydrazinecarbothioamide derivatives as potent anti-tubercular agent

Development of novel, safe and effective drug candidates combating the emerging drug resistance has remained a major focus in the mainstream of anti-tuberculosis research. Here, we inspired to design and synthesize series of new pyridin-4-yl-1,3,4-oxadiazol-2-yl-thio-ethylidene-hydrazinecarbothioamide derivatives as potential anti-tubercular agents. The anti-tubercular bioactive assay demonstrated that the synthesized compounds exhibit potent anti-tubercular activity (MIC = 3.9-7.81 μg/mL) in comparison with reference drugs Rifampicin and Isoniazid.We employed pharmacophore probing approach for the identification of CYP51 as a possible drug target for the synthesized compounds. To understand the preferable binding mode, the synthesized molecules were docked onto the active site of Sterol 14 α-demethylases (CYP51) target. From the binding free energy of the docking results it was revealed that the compounds were effective CYP51 inhibitors and acts as antitubercular agent.

Dietary flavonoids inhibit the glycation of lens proteins: implications in the management of diabetic cataract

The intervention of functional foods as complementary therapeutic approach for the amelioration of diabetes and sugar induced cataractogenesis is more appreciated over the present day chemotherapy agents owing to their nontoxic and increased bioavailability concerns. Dietary flavonoids, a class of bioactive phytochemicals is known to have wide range of biological activities against variety of human ailments. In the present study, we demonstrate anti-cataract effect of eight dietary flavonoids in sugar induced lens organ culture study. We present data on processes like inhibition of glycation-induced lens cloudiness, lens protein aggregation, glycation reaction and advanced glycation end products formation that can act as biochemical markers for this disease. The selected flavonoids were also tested for their aldose reductase (AR) inhibition (experimental and in silico). The molecular dynamics simulation results shed light on mechanistic details of flavonoid induced AR inhibition. The outcome of the present study clearly focuses the significance of kaempferol, taxifolin and quercetin as potential candidates for controlling diabetic cataract.

Didymin by suppressing NF-κB activation prevents VEGF-induced angiogenesis in vitro and in vivo

Although didymin, a dietary flavonoid glycoside from citrus fruits, known to be a potent antioxidant with anti-cancer activities, its role in angiogenesis is not known. In this study, we examined the effect of didymin on VEGF-induced angiogenesis in vitro and in vivo models. Our results suggest that treatment of human umbilical vein endothelial cell (HUVECs) with didymin significantly prevented the VEGF-induced cell proliferation, migration, and invasion. Further, didymin significantly prevented the VEGF-induced endothelial tube formation in culture. Didymin also attenuated the VEGF-induced generation of ROS, activation of NF-κB and the expression of adhesion molecules such as VCAM-1, ICAM-1, and E-selectin in HUVECs. Further, didymin also prevented the VEGF-induced microvessel sprouting in ex vivo mouse aortic rings. Most importantly, didymin significantly prevented the invasion of endothelial cells and formation of blood capillary-like structures in Matrigel plug model of angiogenesis in mice. Thus, our results suggest a novel antiangiogenic efficacy of didymin in addition to its reported anti-cancer properties, which warrant further development of this agent for cancer therapy.

Reversion of in vivo fibrogenesis by novel chromone scaffolds

BACKGROUND

Myofibroblasts are known to play a key role in the development of idiopathic pulmonary fibrosis (IPF). Two drugs, pirfenidone and nintedanib, are the only approved therapeutic options for IPF, but their applications are limited due to their side effects. Thus, curative IPF drugs represent a huge unmet medical need.

METHODS

A mouse hepatic stellate cell (HSC) line was established that could robustly differentiate into myofibroblasts upon treatment with TGF-β. Eupatilin was assessed in diseased human lung fibroblasts from IPF patients (DHLFs) as well as in human lung epithelial cells (HLECs). The drug's performance was extensively tested in a bleomycin-induced lung fibrosis model (BLM). Global gene expression studies and proteome analysis were performed.

FINDINGS

Eupatilin attenuated disease severity of BLM in both preventative and therapeutic studies. The drug inhibited the in vitro transdifferantiation of DHLFs to myofibroblasts upon stimulation with TGF-β. No such induction of the in vitro transdifferantiation was observed in TGF-β treated HLECs. Specific carbons of eupatilin were essential for its anti-fibrotic activity. Eupatilin was capable of dismantling latent TGF-β complex, specifically by eliminating expression of the latent TGF-β binding protein 1 (LTBP1), in ECM upon actin depolymerization. Unlike eupatilin, pirfenidone was unable to block fibrosis of DHLFs or HSCs stimulated with TGF-β. Eupatilin attenuated phosphorylation of Smad3 by TGF-β. Eupatilin induced myofibroblasts to dedifferentiate into intermediate HCS-like cells.

INTERPRETATION

Eupatilin may act directly on pathogenic myofibroblasts, disarming them, whereas the anti-fibrotic effect of pirfenidone may be indirect. Eupatilin could increase the efficacy of IPF treatment to curative levels.

Design, synthesis, and preliminary biological evaluation of 3′,4′,5′-trimethoxy flavonoid salicylate derivatives as potential anti-tumor agents

According to the combination principle, target compounds were designed; compound10vmight be a promising multiple target anti-tumor agent candidate.

Polyphenolic profile and biological activities of black carrot crude extract (Daucus carota L. ssp. sativus var. atrorubens Alef.)

Black carrot (Daucus carota L. ssp. sativus var. atrorubens Alef.) is a valuable source of carbohydrates, minerals and vitamins and contains also high amounts of anthocyanins giving the characteristic deep-purple color. These latter compounds are known as natural dyes used in the food and pharmaceutical industry that have recently attracted much attention for their healthful properties. The aim of this work was to investigate for the first time the polyphenolic profile and biological properties of a black carrot crude extract (BCCE) through an in-depth analysis of the main polyphenolic classes evaluating its antioxidant, cytoprotective and anti-angiogenic properties. Twenty five polyphenols were quantified by LC-DAD-FLD-MS/MS analysis (anthocyanins 78.06%, phenolic acids 17.89% and other flavonoids 4.06%) with polyglycosylated cyanidins as major components. In addition, BCCE showed a strong antioxidant and free radical scavenging activity particularly in the hydrogen transfer-based assays (ORAC and β-carotene bleaching) and a significant increase in the cell viability. Furthermore, BCCE exhibited a strong anti-angiogenic activity at the highest concentration assayed on the chick chorioallantoic membrane (50μg/egg). In conclusion, the obtained results demonstrated the antioxidant, cytoprotective and anti-angiogenic properties of BCCE, which highlight that the higher biological activity of BCCE is probably due to the synergic effects exerted by various polyphenolic classes.

Pharmacophore Mapping Approach for Drug Target Identification: A Chemical Synthesis and in Silico Study on Novel Thiadiazole Compounds

INTRODUCTION

Compounds containing thiadiazole moiety are cognized to possess with variety of clinical and therapeutic activity. Finding a suitable drug target for newly synthesized compounds remain a major bottle neck in current high throughout medicinal chemistry era.

AIM

To effectively synthesize di substituted thiadiazole compounds and demonstrate drug target identification using an in silico pharmacophore probing approach. Moreover, we also aim to validate the suitability of identified drug target.

MATERIALS AND METHODS

A cost-effective and environmental friendly chemical synthesis scheme for production of di substituted thiadiazole compounds was employed. Target identification was conducted by Pharmmapper software. Validation was accomplished by performing molecular docking and further Molecular Hydrophobic Potential (MHP) analysis.

RESULTS

Pharmacophore probing base approach identified hepatocyte growth factor receptor (c-Met) as a suitable biological target for newly synthesized compounds. Binding free energy values indicate that compound 4b, 4e, 4g and 4h has tremendous potential to be further used as lead compound to design selective inhibitors of c-Met receptor. MHP data from current study supports the possibility that hydrophobic contacts might act as major factor stabilizing thiadiazole- c-Met complex. Moreover, in silico observations of current study are in absolute accordance with previously described in vitro and crystallographic analysis.

CONCLUSION

We demonstrate that thiadiazole compounds synthesized in current investigation has high potential to act in modulation of hepatocyte growth factor receptor (c-Met) activity and thereby act as putative therapeutic agent in cancer therapy.