Synthesis, biological and computational studies of flavonoid acetamide derivatives

The synthesis and bioactivity of apigenin derivatives

BACKGROUND

Apigenin, a naturally occurring compound with a flavone core structure, is known for its diverse bioactivities, including anti-inflammation, anti-toxicant, anti-cancer and so on. There has been significant interest in the medicinal chemistry community. To address these challenges, researchers have developed various derivatives of apigenin to address challenges such as poor water-solubility and low intestinal absorption, aiming to enhance the pharmacological activities and pharmacokinetic properties of this compound.

OBJECTIVE

In recent years, there has been a proliferation of apigenin derivatives with enhanced bioactivity. However, there is a lack of comprehensive reviews on the function-based modification of these derivatives. In this paper, we provide an overview of the apigenin derivatives with varying bioactivities and explored their structure activity relationships. And the functions of different groups of apigenin derivatives were also analyzed.

CONCLUSION

This review summarized the current achievements that could provide some clues for further study of apigenin-based drugs.

Synthesis and Bioevaluation of New Stable Derivatives of Chrysin-8-C-Glucoside That Modulate the Antioxidant Keap1/Nrf2/HO-1 Pathway in Human Macrophages

Background/Objectives: The beneficial effects of the flavonoid chrysin can be reduced by its poor oral bioavailability. It has been shown that chrysin-8-C-glucoside (1) has a better absorption capability. The aim of this study was to evaluate the antioxidant and anti-inflammatory activity of this glucoside, as well as the respective hexa-acetate derivative 1a and the hexa-ethyl carbonate derivative 1b since the inclusion of moieties in bioactive molecules may increase or modify their biological effects. Methods: THP-1 macrophages were used to determine the viability in the presence of chrysin derivatives, and non-cytotoxic concentrations were selected. Subsequently, lipopolysaccharide (LPS)-induced reactive oxygen species (ROS) production and inflammatory mediators were examined. The involvement of chrysin derivatives with the Keap1 and Nrf2 antioxidant system was determined by docking and Western blotting studies. Results: Our data demonstrated, for the first time, that pretreatment with the three compounds caused a significant reduction in LPS-induced reactive oxygen species (ROS) production and pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin 1β (IL-1β) levels, as well as in cyclooxygenase 2 (COX-2) expression. The mechanisms underlying these protective effects were related, at least in part, to the competitive molecular interactions of these phenolic compounds with Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2), which would allow the dissociation of Nrf2 and its translocation into the nucleus and the subsequent up-regulation of hemo-oxygenase 1 (HO-1) expression. Conclusions: Compared to the 8-C-glucoside parent chrysin, compound 1a exhibited the strongest antioxidant and anti-inflammatory activity. We hypothesized that the incorporation of an acetate group (1a) may reduce its polarity and, thus, increase membrane permeability, leading to better pharmacological activity. These findings support the potential use of these phenolic compounds as Nrf2 activators against oxidative-stress-related inflammatory diseases.

From Hit to Lead: Discovery of First-In-Class Furanone Glycoside D228 Derived from Chimonanthus salicifolius for the Treatment of Inflammatory Bowel Disease

TNFα and related inflammatory factor antibody drugs have been orchestrated for the treatment of inflammatory bowel disease (IBD). However, antibody drugs elicited inevitable disadvantages and small molecule drugs are in an urgent need. Herein, we described the discovery, design, synthesis, and SAR studies from furanone glycoside compound Phoenicein (hit) isolated from Chimonanthus salicifolius to D228 (lead). Remarkably, D228 exhibited good inhibitory activity on B and T lymphocyte and excellent anti-IBD efficacy in vivo. Mechanistically, D228 alleviated the inflammation response by downregulating the MyD88/TRAF6/p38 signaling. Importantly, the relationship of D228, Phoenicein, and their aglycone 7a was deduced: D228 could be considered as a prodrug and metabolized to intermediate Phoenicein. In turn, Phoenicein released their shared active aglycone 7a. Additionally, D228 demonstrated good and balanced profiles of safety and efficacy both in vitro and in vivo. These results suggested that D228 could be used as an ideal lead and potentially utilized for IBD chemotherapy.

In-vitro and in-vivo investigation of wound healing efficacy of Syzygium cumini leaf extracts loaded carboxymethylcellulose film

The study focused on Syzygium cumini Leaf Extract (SCLE) loaded into Carboxymethylcellulose (CMC) film via Solution casting. Phytochemical screening revealed carbohydrates, and HPLC analysis identified quercetin, known for promoting wound healing. FT-IR spectroscopy confirmed various functional groups. X-Ray diffraction (XRD) determined the crystallite size to be 14.58 nm. Field Emission Scanning Electron Microscopy (FESEM) showed the dispersion of extracts, and Energy Dispersive X-ray (EDX) analysis detailed the weight percentages of components. Antibacterial activity tests revealed zones of inhibition for S. aureus (15 mm) and E. coli (11 mm). The film exhibited 63.11 % antioxidant activity at 517 nm with DPPH at a 750 μl sample concentration. Drug release kinetics were also studied. In-vitro wound healing using the L929 cell line showed 83 % healing at a 100 μl concentration. Over 14 days, the treatment group's wounds healed completely within 7 days, unlike the control groups which showed no recovery after 14 days. These findings indicate that the SCLE-CMC film is highly effective in promoting wound healing.

New sulfonamide derivatives based on 1,2,3-triazoles: synthesis, in vitro biological activities and in silico studies

Eight new hybrid constructs containing a series of sulfonamide and 1,2,3-triazole units were designed and synthesized. Anticancer, antioxidant and cholinesterase activities of these hybrid structures were investigated. In our design, the Cu(I)-catalyzed click reaction between N,4-dimethyl-N-(prop-2-yn-1-yl)benzenesulfonamide (6) and aryl azides 8a-h was used. Antioxidant activity values of 9f (IC50: 229.46 ± 0.001 μg/mL) and 9h (IC50: 254.32 ± 0.002 μg/mL) hybrid structures were higher than BHT (IC50: 286.04 ± 0.003 μg/mL) and lower than Ascorbic acid (IC50: 63.53 ± 0.001 μg/mL) and α-Tocopherol (IC50: 203.21 ± 0.002 μg/mL). We determined that the cytotoxic effects of hybrid constructs 9d (IC50: 3.81 ± 0.1084 µM) and 9g (IC50: 4.317 ± 0.0367 µM) against A549 and healthy cell line (HDF) are much better than standard cisplatin (IC50: 6.202 ± 0.0705 µM). It was determined that the AChE inhibitory activities of all synthesized compounds were much better than Galantamine used as a standard. In particular, 9c (IC50: 13.81 ± 0.0026 mM) had ten times better activity than the standard Galantamine (IC50: 136 ± 0.008 mM). The ADMET properties of the molecules have been thoroughly examined and met the criteria for drug-like substances. They also have a high oral absorption rate, as they can effectively cross the blood-brain barrier and are easily absorbed in the gastrointestinal tract. In vitro experiments were confirmed by in silico molecular docking studies.Communicated by Ramaswamy H. Sarma.

Inhibition of the predicted allosteric site of the SARS-CoV-2 main protease through flavonoids

Since its emergence in 2019, coronavirus infection (COVID-19) has become a global pandemic and killed several million people worldwide. Even though several types of vaccines are available against the COVID-19 virus, SARS-CoV-2, new strains are emerging that pose a constant danger to vaccine effectiveness. In this computational study, we identified and predicted potent allosteric inhibitors of the SARS-CoV-2 main protease (Mpro). Via molecular docking and simulations, more than 100 distinct flavonoids were docked with the allosteric site of Mpro. Docking experiments revealed four top hit compounds (Hesperidin, Schaftoside, Brickellin, and Marein) that bound strongly to the Mpro predicted allosteric site. Simulation analyses further revealed that these continually interacted with the enzyme's allosteric region throughout the simulation time. ADMET and Lipinski drug likenesses were calculated to indicate the therapeutic value of the top four hits: They were non-toxic and exhibited high human intestinal absorption concentrations. These novel allosteric site inhibitors provide a higher chance of drugging SARS-CoV2 Mpro due to the rapid mutation rate of the viral enzyme's active sites. Our findings provide a new avenue for developing novel allosteric inhibitors of SARS-CoV-2 Mpro.Communicated by Ramaswamy H. Sarma.

Triazole based novel molecules as potential therapeutic agents: Synthesis, characterization, biological evaluation, in-silico ADME profiling and molecular docking studies

In this study, eight new compounds (7a-h) based on triazole compounds containing ester groups were synthesized with high yields. The structures of the synthesized compounds (7a-h) were elucidated by various spectroscopic methods (element analysis, FT-IR, ¹H-(¹³C) NMR). Antioxidant, anticancer, and α-amylase enzyme inhibition activities of synthesized new triazole derivatives were carried out, and the effects of different groups on the activity were investigated. When the determined antioxidant properties of the compounds were examined, all synthesized compounds showed a moderate radical scavenging effect against radicals depending on the concentration (6.25-200 g/mL). All compounds except the three derivatives were found to have higher IC₅₀ values than the standard drug acarbose (IC₅₀: 891 μg/mL) according to the α-amylase enzyme inhibition results. Compound 7g (IC₅₀: 50 g/mL) was discovered to have nearly eighteen (18) times the activity of the conventional medication acarbose (IC₅₀: 891 μg/mL). Compounds synthesized for anticancer activity studies were screened against the Hela cell line, and the results were compared with standard cis-platinum (IC₅₀: 16.30 μg/mL). Compound 7g (IC₅₀: 19.78 μg/mL) was found to have almost the same activity as cis-platinum. Using Qikprop, the compounds were thoroughly tested for ADME qualities, and none violated any drug similarity standards. According to ADME data, whole physicochemical drug-likeness parameters of molecules remained within defined ranges as stipulated in the Lipinski rules (RO5) and revealed a high bioavailability profile. The molecular docking results with 2QV4 and 4GQR alpha-amylase enzymes demonstrated that all molecules have a high affinity, indicating polar and apolar interaction with critical amino acids in the α-amylase binding pocket.

Distribution and Stability of Polyphenols in Juices Made from Traditional Apple Cultivars Grown in Bosnia and Herzegovina

The present research was undertaken to investigate polyphenolic profiles of peel, pulp and juices made from two standard commercial and five traditional apple cultivars from Bosnia and Herzegovina. The main goal of the study was to monitor the distribution and changes of polyphenolic profiles through different phases of apples' processing into cloudy and clear juices, with regard to L-ascorbic acid pretreatment. Quantitative determination of phenolic compounds was carried out by using high-performance liquid chromatography with diode-array detection. The obtained results showed that traditional cultivars, namely 'Paradija' and 'Prijedorska zelenika', displayed significantly higher content of these compounds compared to commercial ones. Flavan 3-ols and flavonol glycosides were mostly found in peels of all cultivars (21.2-44.1 and 5.40-33.3%, respectively), while phenolic acids along with flavan 3-ols were predominant in the pulp (8.20-30.8 and 5.10-13.9%, respectively). Apples' processing into juices caused decrease (more than 90%) in the content of all polyphenols and the distribution of these compounds from fruits to final products had a negative trend, particularly evident in clear juices. The most drastic loss occurred in the flavonol glycosides and dihydrochalcones content, while chlorogenic acid displayed quite stable distribution from apples to final products due to its good solubility. Apple mash pretreatment with L-ascorbic acid had a positive impact on the preservation and retention of polyphenols.

Why Do Dietary Flavonoids Have a Promising Effect as Enhancers of Anthracyclines? Hydroxyl Substituents, Bioavailability and Biological Activity

Anthracyclines currently play a key role in the treatment of many cancers, but the limiting factor of their use is the widespread phenomenon of drug resistance and untargeted toxicity. Flavonoids have pleiotropic, beneficial effects on human health that, apart from antioxidant activity, are currently considered small molecules-starting structures for drug development and enhancers of conventional therapeutics. This paper is a review of the current and most important data on the participation of a selected series of flavonoids: chrysin, apigenin, kaempferol, quercetin and myricetin, which differ in the presence of an additional hydroxyl group, in the formation of a synergistic effect with anthracycline antibiotics. The review includes a characterization of the mechanism of action of flavonoids, as well as insight into the physicochemical parameters determining their bioavailability in vitro. The crosstalk between flavonoids and the molecular activity of anthracyclines discussed in the article covers the most important common areas of action, such as (1) disruption of DNA integrity (genotoxic effect), (2) modulation of antioxidant response pathways, and (3) inhibition of the activity of membrane proteins responsible for the active transport of drugs and xenobiotics. The increase in knowledge about the relationship between the molecular structure of flavonoids and their biological effect makes it possible to more effectively search for derivatives with a synergistic effect with anthracyclines and to develop better therapeutic strategies in the treatment of cancer.

Flavonoids Are Intra- and Inter-Kingdom Modulator Signals

Flavonoids are a broad class of secondary metabolites with multifaceted functionalities for plant homeostasis and are involved in facing both biotic and abiotic stresses to sustain plant growth and health. Furthermore, they were discovered as mediators of plant networking with the surrounding environment, showing a surprising ability to perform as signaling compounds for a multitrophic inter-kingdom level of communication that influences the plant host at the phytobiome scale. Flavonoids orchestrate plant-neighboring plant allelopathic interactions, recruit beneficial bacteria and mycorrhizal fungi, counteract pathogen outbreak, influence soil microbiome and affect plant physiology to improve its resilience to fluctuating environmental conditions. This review focuses on the diversified spectrum of flavonoid functions in plants under a variety of stresses in the modulation of plant morphogenesis in response to environmental clues, as well as their role as inter-kingdom signaling molecules with micro- and macroorganisms. Regarding the latter, the review addresses flavonoids as key phytochemicals in the human diet, considering their abundance in fruits and edible plants. Recent evidence highlights their role as nutraceuticals, probiotics and as promising new drugs for the treatment of several pathologies.

Synthesis, Structural Investigations, and In Vitro/In Silico Bioactivities of Flavonoid Substituted Biguanide: A Novel Schiff Base and Its Diorganotin (IV) Complexes

Quercetin is one of the most powerful bioactive dietary flavonoids. The in vivo biological study of quercetin is extremely difficult due to its very low solubility. However, diorganotin complexes of quercetin are more useful when contrasted with quercetin due to increased solubility. In the present study, quercetin, substituted biguanide synthesized in the form of Schiff base and its di-alkyl/aryl tin (IV) complexes were obtained by condensing Schiff base with respective di-alkyl/aryl tin (IV) dichloride. Advanced analytical techniques were used for structural elucidation. The results of biological screening against Gram-positive/Gram-negative bacteria and fungi showed that these diorganotin (IV) derivatives act as potent antimicrobial agents. The in silico investigation with dihydropteroate (DHPS) disclosed a large ligand-receptor interaction and revealed a strong relationship between the natural exercises and computational molecular docking results.

Selective Structural Derivatization of Flavonoid Acetamides Significantly Impacts Their Bioavailability and Antioxidant Properties

Flavonoids show abundant favorable physicochemical and drug related properties, leading to substantial biological applications which are limited by undesirable properties such as poor solubility, high polarity, low bioavailability, and enzymatic degradations. Chemical modification with bioisosteres can be used to address some of these challenges. We report the synthesis and characterization of partial flavonoid acetamide derivatives from quercetin, apigenin and luteolin and the evaluation of their structure-activity relationships based on antioxidant, bioavailability, drug likeness, and toxicity properties. The sequential synthesis was achieved with 76.67-87.23% yield; the structures of the compounds were confirmed using ¹H & ¹³C NMR characterizations. The purity of each compound was determined by HPLC while the molecular weights were determined by mass spectrometry. The % bioavailability was determined using the dialysis tubing procedure and the values were in the range 15.97-38.12%. The antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and expressed as the IC₅₀ values which were in the range 31.52-198.41 µM. The drug likeness and the toxicity properties of compounds 4, 5, 7, 11 and 15 were predicted using computational tools and showed satisfactory results. A structure-activity relationship evaluation reveals that hydroxyl and methylene groups attached on the 2-phenylchromen-4-one structure of the flavonoid play a colossal role in the overall antioxidant and bioavailability properties. The improved bioavailability and excellent drug relevance and toxicity properties present flavonoid acetamide derivatives as prospective drug candidates for further evaluations.