Three-dimensional quantitative structure–activity relationship study on antioxidant capacity of curcumin analogues

Promising Potential of Curcumin and Related Compounds for Antiviral Drug Discovery

Viruses are acellular, microscopic, and mobile particles containing genetic particles, either DNA/RNA strands as nucleoproteins, responsible for 69,53,743 deaths till the year 2023. Curcumin and related compounds are among the areas of pivotal interest for researchers because of their versatile pharmacological profile. Chemically known as diferuloylmethane, which is a main constituent of turmeric along with demethoxycurcumin and bisdemethoxycurcumin, they have a broad spectrum of antiviral activity against viruses such as human immunodeficiency virus, herpes simplex virus, influenza virus (Avian influenza) and Hepatitis C virus HIV. The possible role of curcumin as an antiviral agent may be attributed to the activation of the 20S proteasome, a cellular machinery responsible for degrading unfolded or misfolded proteins in a ubiquitin-independent manner. It shows suppression of HBV entry at various infection stages by inhibiting cccDNA replication by inhibiting the Wnt/β-catenin signaling pathway to attenuate IAV-induced myocarditis.

Bioactive Diarylpentanoids: Insights into the Biological Effects beyond Antitumor Activity and Structure-Activity Relationships

Diarylpentanoids, a class of natural products and their synthetic analogs which are structurally related to chalcones, have gained increasing attention due to their wide array of biological activities, including antitumor, anti-infective, antioxidant, anti-inflammatory, antidiabetic, anti-hyperuricemic, and neuroprotective properties. Previously, we reviewed diarylpentanoids with promising antitumor activity. However, in view of the wide range of biological activities described for this class of compounds, the purpose of this review is to provide a more detailed overview of the synthetic bioactive diarylpentanoids that have been described over the last two decades, beyond simply their antitumor effects. A total of 745 compounds were found, highlighting the main synthetic methodologies used in their synthesis as well as the structure-activity relationship studies and structural features for all activities reported. Collectively, this review highlights the diarylpentanoid scaffold as a promising starting point for the development of new therapeutic agents.

Curcumin-Synthetic Analogs Library Screening by Docking and Quantitative Structure-Activity Relationship Studies for AXL Tyrosine Kinase Inhibition in Cancers

AXL is an important drug target for cancers. Two-dimensional quantitative structure-activity relationship (2D-QSAR) tests were performed to elucidate a relationship between molecular structures and the activity of a series of 400 curcumin derivatives subjected to AXL kinase by ATP competition in the catalytic site. The partial least square regression method implanted in molecular operating environment software was applied to develop QSAR models, which were further validated for statistical significance by internal and external validation. The best model has proven to be statistically robust with a good predictive correlation of R ²  = 0.996 and a significant cross-validation correlation coefficient of q ²  = 0.707. Docking analysis reveled that three curcumin derivatives have the best affinity for AXL and formed a hydrogen bond with the important amino acid residues in the binding pocket. As treated in this article, the docking studies and 2D-QSAR approach will pave the way for the development of new drugs while highlighting curcumin and its derivatives.

Biological Potential of Novel Methoxy and Hydroxy Substituted Heteroaromatic Amides Designed as Promising Antioxidative Agents: Synthesis, 3D-QSAR Analysis, and Biological Activity

This paper discusses antioxidative and biological activities of 25 novel amidino substituted benzamides with a variety of heteroaromatic nuclei attached to the benzamide moiety and with a variable number of methoxy or hydroxy substituents. Targeted compounds, bearing either amidino or 2-imidazolinyl substituent, were obtained in the Pinner reaction from cyano precursors. 3D-QSAR models were generated to predict antioxidative activity of the 25 novel aromatic and heteroaromatic benzamide derivatives. The compounds were tested for antioxidative activity using in vitro spectrophotometric assays. Direct validation of 3D-QSAR approach for predicting activities of novel benzamide derivatives was carried out by comparing experimental and computationally predicted antioxidative activity. Experimentally determined activities for all novel compounds were found to be within a standard deviation of error of the models. Following this, structure-activity relationships among the synthesized compounds are discussed. Furthermore, antiproliferative activity in vitro against HeLa cells as well as antibacterial and antifungal activity was tested to confirm the other biological activities of the prepared compounds.

Immunosuppressive Effects of Natural α,β-Unsaturated Carbonyl-Based Compounds, and Their Analogs and Derivatives, on Immune Cells: A Review

The immune system is complex and pervasive as it functions to prevent or limit infections in the human body. In a healthy organism, the immune system and the redox balance of immune cells maintain homeostasis within the body. The failure to maintain the balance may lead to impaired immune response and either over activity or abnormally low activity of the immune cells resulting in autoimmune or immune deficiency diseases. Compounds containing α,β-unsaturated carbonyl-based moieties are often reactive. The reactivity of these groups is responsible for their diverse pharmacological activities, and the most important and widely studied include the natural compounds curcumin, chalcone, and zerumbone. Numerous studies have revealed the mainly immunosuppressive and anti-inflammatory activities of the aforesaid compounds. This review highlights the specific immunosuppressive effects of these natural α,β-unsaturated carbonyl-based compounds, and their analogs and derivatives on different types of immune cells of the innate (granulocytes, monocytes, macrophages, and dendritic cells) and adaptive (T cells, B cells, and natural killer cells) immune systems. The inhibitory effects of these compounds have been comprehensively studied on neutrophils, monocytes and macrophages but their effects on T cells, B cells, natural killer cells, and dendritic cells have not been well investigated. It is of paramount importance to continue generating experimental data on the mechanisms of action of α,β-unsaturated carbonyl-based compounds on immune cells to provide useful information for ensuing research to discover new immunomodulating agents.

QSAR of Antioxidants

Antioxidants are substances that protect cells from the damaging effects of oxygen radicals, which are chemicals that play a part in some diseases such as cancer and others. Antioxidants are expected to be promising drugs in the management of these diseases by removing oxidative stress. Most of the modeling approaches involved in designing new antioxidants is based on Quantitative Structure-Activity Relationship (QSAR). A number of QSAR studies have been conducted to elucidate the structural requirements of antioxidants for their activities in order to predict the potency of these compounds with regard to the targeted activity and to direct the synthesis of more potent analogues. The main focus of this chapter is on the QSAR modeling of antioxidant compounds. The authors provide different QSAR studies of antioxidant compounds and try to compare between them in terms of the best models obtained and their use in designing potential new drugs.

Establishment of tandem mass spectrometric fingerprint of novel antineoplastic curcumin analogues using electrospray ionization

RATIONALE

Curcumin analogues are antineoplastic agents, designed based on the structure of the spice turmeric with structural modifications aiming at enhancing potency. The goal is to identify the common tandem mass spectrometric (MS/MS) behavior of 13 novel curcumin analogues. Such knowledge is critical for their biological assessment, including metabolite identification and pharmacokinetic evaluation.

METHODS

Both detection of the protonated molecules [M + H](+) of the synthesized compounds and determination of their exact molecular masses were achieved with hybrid quadrupole orthogonal time-of-flight mass spectrometry (QqTOF-MS). Low-energy collision-induced dissociation (CID)-MS/MS analysis was performed using triple quadrupole linear ion trap mass spectrometry (QqLIT-MS). Both instruments were equipped with an electrospray ionization (ESI) source. MS(3) and neutral loss experiments were performed using QqLIT-MS to confirm the genesis of the observed product ions.

RESULTS

Abundant [M + H](+) molecules were formed using the QqTOF-MS hybrid instrument with mass accuracies below 6 ppm. CID-MS/MS dissociation studies were centered on the piperidone ring of curcumin analogues; twelve common product ions have been identified from the fission of the various bonds within the piperidone moiety. There was a tendency for the formation of highly conjugated product ions, stabilized via resonance. The variety of the side-chain substituents at the nitrogen atom resulted in side-chain-specific product ions.

CONCLUSIONS

The ESI-CID-MS/MS analysis of curcumin analogues revealed a common fragmentation behavior of all tested compounds, which gave diagnostic product ions identified for each molecule. The established MS/MS behavior will be applied to determine metabolic by-products of curcumin analogues as well as to develop targeted identification/quantification methods within biological extracts.

Synthesis and assessment of the antioxidant and antitumor properties of asymmetric curcumin analogues

In this study, 12 asymmetric curcumin (CUR) analogues and 5 symmetric curcumin derivatives were synthesized, the antioxidant activity of these derivatives were evaluated by radicals 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay, 2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) assay, ROO (TRAP) assay and O(2-) (NET) assay and anti-proliferative activities of these analogues were assessed against the human hepatoma cell line (SMMC-7721), the human breast cancer cell line (MCF-7) and the human prostate cancer cell lines (PC-3). Most of the asymmetric compounds showed stronger antioxidant activities than Vitamin C (Vc). Curcumin analogues reducing free radicals contain two reaction mechanisms: H-atom and electron transfer mechanisms. Compound 14 showed the most significant antioxidant activity compared with curcumin and other derivatives. Shorted the carbon chain of 14 can reduce the O-H bond dissociation enthalpy (BED) to improve the antioxidant activity. The antioxidant activity of 25 was similar to curcumin. All of the compounds performed better in an anti-proliferate assay than curcumin, especially compound 25, which exhibited the preferential cytotoxic activity against MCF-7 cells(25, IC50 = 9.11 μM, curcumin, IC50 = 70.2 μM). Considering these data, future studies should be performed to assess the therapeutic values of these asymmetric curcumin analogues.

Curcumin improves liver damage in male mice exposed to nicotine

The color of turmeric (薑黃 jiāng huáng) is because of a substance called curcumin. It has different pharmacological effects, such as antioxidant and anti-inflammatory properties. Nicotine is a major pharmacologically active substance in cigarette smoke. It is mainly metabolized in the liver and causes devastating effects. This study was designed to evaluate the protective role of curcumin against nicotine on the liver in mice.

Forty-eight mice were equally divided into eight groups; control (normal saline), nicotine (2.5 mg/kg), curcumin (10, 30, and 60 mg/kg) and curcumin plus nicotine-treated groups. Curcumin, nicotine, and curcumin plus nicotine (once a day) were intraperitoneally injected for 4 weeks. The liver weight and histology, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and serum nitric oxide levels have been studied.

The results indicated that nicotine administration significantly decreased liver weight and increased the mean diameter of hepatocyte, central hepatic vein, liver enzymes level, and blood serum nitric oxide level compared with the saline group (p < 0.05). However, curcumin and curcumin plus nicotine administration substantially increased liver weight and decreased the mean diameter of hepatocyte, central hepatic vein, liver enzymes, and nitric oxide levels in all groups compared with the nicotine group (p < 0.05).

Curcumin demonstrated its protective effect against nicotine-induced liver toxicity.

Pharmacological evaluation and docking studies of α,β-unsaturated carbonyl based synthetic compounds as inhibitors of secretory phospholipase A₂, cyclooxygenases, lipoxygenase and proinflammatory cytokines

Arachidonic acid and its metabolites have generated high level of interest among researchers due to their vital role in inflammation. The inhibition of enzymes involved in arachidonic acid metabolism has been considered as synergistic anti-inflammatory effect. A series of novel α,β-unsaturated carbonyl based compounds were synthesized and evaluated for their inhibitory activity on secretory phospholipase A₂ (sPLA₂), cyclooxygenases (COX), soybean lipoxygenase (LOX) in addition to proinflammatory cytokines comprising IL-6 and TNF-α. Six α,β-unsaturated carbonyl based compounds (2, 3, 4, 12, 13 and 14) exhibited strong inhibition of sPLA₂ activity, with IC₅₀ values in the range of 2.19-8.76 μM. Nine compounds 1-4 and 10-14 displayed inhibition of COX-1 with IC₅₀ values ranging from 0.37 to 1.77 μM (lower than that of reference compound), whereas compounds 2, 10, 13 and 14 strongly inhibited the COX-2. The compounds 10-14 exhibited strong inhibitory activity against LOX enzyme. All compounds were evaluated for the inhibitory activities against LPS-induced TNF-α and IL-6 release in the macrophages. On the basis of screening results, five active compounds 3, 4, 12, 13 and 14 were found strong inhibitors of TNF-α and IL-6 release in a dose-dependent manner. Molecular docking experiments were performed to clarify the molecular aspects of the observed COX and LOX inhibitory activities of the investigated compounds. Present findings increases the possibility that these α,β-unsaturated carbonyl based compounds might serve as beneficial starting point for the design and development of improved anti-inflammatory agents.