In silico study of fucoxanthin as a tumor cytotoxic agent

Unlocking the Green Gold: Exploring the Cancer Treatment and the Other Therapeutic Potential of Fucoxanthin Derivatives from Microalgae

Fucoxanthin, a carotenoid widely studied in marine microalgae, is at the heart of scientific research because of its promising bioactive properties for human health. Its unique chemical structure and specific biosynthesis, characterized by complex enzymatic conversion in marine organisms, have been examined in depth in this review. The antioxidant, anti-inflammatory, and anti-cancer activities of fucoxanthin have been rigorously supported by data from in vitro and in vivo experiments and early clinical trials. Additionally, this review explores emerging strategies to optimize the stability and efficacy of fucoxanthin, aiming to increase its solubility and bioavailability to enhance its therapeutic applications. However, despite these potential benefits, challenges persist, such as limited bioavailability and technological obstacles hindering its large-scale production. The medical exploitation of fucoxanthin thus requires an innovative approach and continuous optimization to overcome these barriers. Although further research is needed to refine its clinical use, fucoxanthin offers promising potential in the development of natural therapies aimed at improving human health. By integrating knowledge about its biosynthesis, mechanisms of action, and potential beneficial effects, future studies could open new perspectives in the treatment of cancer and other chronic diseases.

Identification of Potential Poly (ADP-Ribose) Polymerase-1 Inhibitors Derived from Rauwolfia serpentina: Possible Implication in Cancer Therapy

Poly (ADP-ribose) polymerase-1 (PARP-1) has been recognized as a prospective target for the development of novel cancer therapeutics. Several PARP-1 inhibitors are currently being considered for anticancer drug development and clinical investigation. Lately, natural compounds seem to be excellent alternative drug candidates for cancer treatment. Rauwolfia serpentina is a medicinal plant traditionally used in Indian subcontinents to treat various diseases. This study has been designed to identify the bioactive compounds derived from R. serpentina for possible binding and inhibition of PARP-1 using the molecular docking approach. Thirteen compounds were found to interact with the target with a binding affinity greater than the value of -9.0 kcal/mol. After screening the physicochemical properties, only 5 ligands (ajmalicine, yohimbine, isorauhimbine, rauwolscine, and 1,2-dihydrovomilenine) were found to obey all the parameters of Lipinski's rule of five, showed maximum drug-likeness, and possess no significant toxicity. These ligands displayed strong interactions with target PARP-1 via several hydrogen bonds and hydrophobic interactions. Therefore, these identified compounds derived from R. serpentina can be considered for drug development against cancer-targeting PARP-1.

Elucidating Antiangiogenic Potential of Rauwolfia serpentina: VEGFR-2 Targeting-Based Molecular Docking Study

Angiogenesis plays a critical role in tumorigenesis as it provides the necessary blood supply to the newly grown solid tumor. It helps maintain the tumor microenvironment, promotes tumor development, progression, and metastasis. The vascular epithelial growth factor (VEGF), interacting with the tyrosine kinase receptor VEGFR-2 on endothelial cells, exerts its proangiogenic activity. Hence, targeting the VEGFR-2 signaling is considered a promising strategy to inhibit angiogenesis and thus cancer treatment. This study aims to identify the bioactive compounds derived from the medicinal herb Rauwolfia serpentina that effectively binds with VEGFR-2. The bioactive compounds of R. serpentina were first screened for their physicochemical properties using the DataWarrior program (version 5.5.0). Finally, 17 compounds that obeyed Lipinski's rule of five and showed good drug-likeness were selected for molecular docking studies. Molecular docking results showed that the ligands ajmalicidine, 1, 2-dihydrovomilenine, rauwolscine, yohimbine, ajmaline, and papaverine interact strongly with the target VEGFR-2 receptor. Hydrogen bonds and hydrophobic interactions stabilized the interactions of these compounds with VEGFR-2. These compounds showed favourable drug-like properties and possess no significant toxicity. Therefore, the findings of this study indicate that the compounds derived from R. serpentina can be considered for the development of antiangiogenic drug candidates by targeting VEGFR-2.

Molecular docking elucidates the plausible mechanisms underlying the anticancer properties of acetyldigitoxigenin from Adenium obesum

Adenium obesum (Forssk.) Roem. & Schult. is a promising medicinal plant belonging to the Apocynaceae family. It is a rich source of various phytochemicals such as cardiac glycosides, flavonoids, terpeniods, pregnanes etc. which have different pharmacological properties such as anticancer, antibacterial, acaricidal etc. While previous reports showed the anticancer activity of the aerial parts of the plant extract of A. obesum, the mechanisms of action of its chemical constituents are not known. The present study is aimed at elucidation of plausible mechanisms of anticancer activity of the plant by evaluating the binding interaction of its nine major selected compounds with macromolecular receptors implicated in the initiation and progression of cancer using various in silico approaches. Molecular docking results showed that the compound Δ16-3-Acetyldigitoxigenin (16-anhydro-3-acetylgitoxigenin) scored the best binding energy scores with the majority of the target proteins. The molecular binding of the compound was stabilized through hydrogen bonds as well as hydrophobic interactions, and also possesses favorable drug-like properties without significant toxicities.

Unravelling lead antiviral phytochemicals for the inhibition of SARS-CoV-2 Mpro enzyme through in silico approach

A new SARS coronavirus (SARS-CoV-2) belonging to the genus Betacoronavirus has caused a pandemic known as COVID-19. Among coronaviruses, the main protease (M^pro) is an essential drug target which, along with papain-like proteases catalyzes the processing of polyproteins translated from viral RNA and recognizes specific cleavage sites. There are no human proteases with similar cleavage specificity and therefore, inhibitors are highly likely to be nontoxic. Therefore, targeting the SARS-CoV-2 M^pro enzyme with small molecules can block viral replication. The present study is aimed at the identification of promising lead molecules for SARS-CoV-2 M^pro enzyme through virtual screening of antiviral compounds from plants. The binding affinity of selected small drug-like molecules to SARS-CoV-2 M^pro, SARS-CoV M^pro and MERS-CoV M^pro were studied using molecular docking. Bonducellpin D was identified as the best lead molecule which shows higher binding affinity (−9.28 kcal/mol) as compared to the control (−8.24 kcal/mol). The molecular binding was stabilized through four hydrogen bonds with Glu166 and Thr190 as well as hydrophobic interactions via eight residues. The SARS-CoV-2 M^pro shows identities of 96.08% and 50.65% to that of SARS-CoV M^pro and MERS-CoV M^pro respectively at the sequence level. At the structural level, the root mean square deviation (RMSD) between SARS-CoV-2 M^pro and SARS-CoV M^pro was found to be 0.517 Å and 0.817 Å between SARS-CoV-2 M^pro and MERS-CoV M^pro. Bonducellpin D exhibited broad-spectrum inhibition potential against SARS-CoV M^pro and MERS-CoV M^pro and therefore is a promising drug candidate, which needs further validations through in vitro and in vivo studies.

Theaflavin and epigallocatechin-3-gallate synergistically induce apoptosis through inhibition of PI3K/Akt signaling upon depolymerizing microtubules in HeLa cells

Theaflavin (TF) and epigallocatechin-3-gallate (EGCG) both have been reported previously as microtubule depolymerizing agents that also have anticancer effects on various cancer cell lines and in animal models. Here, we have applied TF and EGCG in combination on HeLa cells to investigate if they can potentiate each other to improve their anticancer effect in lower doses and the underlying mechanism. We found that TF and EGCG acted synergistically, in lower doses, to inhibit the growth of HeLa cells. We found the combination of 50 µg/mL TF and 20 µg/mL EGCG to be the most effective combination with a combination index of 0.28. The same combination caused larger accumulation of cells in the G ₂ /M phase of the cell cycle, potent mitochondrial membrane potential loss, and synergistic augmentation of apoptosis. We have shown that synergistic activity might be due to stronger microtubule depolymerization by simultaneous binding of TF and EGCG at different sites on tubulin: TF binds at vinblastine binding site on tubulin, and EGCG binds near colchicines binding site on tubulin. A detailed mechanistic analysis revealed that stronger microtubule depolymerization caused effective downregulation of PI3K/Akt signaling and potently induced mitochondrial apoptotic signals, which ultimately resulted in the apoptotic death of HeLa cells in a synergistic manner.

The role of gap junctions in inflammatory and neoplastic disorders (Review)

Gap junctions are intercellular channels made of connexin proteins, mediating both electrical and biochemical signals between cells. The ability of gap junction proteins to regulate immune responses, cell proliferation, migration, apoptosis and carcinogenesis makes them attractive therapeutic targets for treating inflammatory and neoplastic disorders in different organ systems. Alterations in gap junction profile and expression levels are observed in hyperproliferative skin disorders, lymphatic vessel diseases, inflammatory lung diseases, liver injury and neoplastic disorders. It is now recognized that the therapeutic effects mediated by traditional pharmacological agents are dependent upon gap junction communication and may even act by influencing gap junction expression or function. Novel strategies for modulating the function or expression of connexins, such as the use of synthetic mimetic peptides and siRNA technology are considered.

Identification of molecular descriptors for design of novel Isoalloxazine derivatives as potential Acetylcholinesterase inhibitors against Alzheimer's disease

In Alzheimer's disease (AD), the level of Acetylcholine (ACh) neurotransmitter is reduced. Since Acetylcholinesterase (AChE) cleaves ACh, inhibitors of AChE are very much sought after for AD treatment. The side effects of current inhibitors necessitate development of newer AChE inhibitors. Isoalloxazine derivatives have proved to be promising (AChE) inhibitors. However, their structure-activity relationship studies have not been reported till date. In the present work, various quantitative structure-activity relationship (QSAR) building methods such as multiple linear regression (MLR), partial least squares ,and principal component regression were employed to derive 3D-QSAR models using steric and electrostatic field descriptors. Statistically significant model was obtained using MLR coupled with stepwise selection method having r² = .9405, cross validated r² (q²) = .6683, and a high predictability (pred_r² = .6206 and standard error, pred_r²se = .2491). Steric and electrostatic contribution plot revealed three electrostatic fields E_496, E_386 and E_577 and one steric field S_60 contributing towards biological activity. A ligand-based 3D-pharmacophore model was generated consisting of eight pharmacophore features. Isoalloxazine derivatives were docked against human AChE, which revealed critical residues implicated in hydrogen bonds as well as hydrophobic interactions. The binding modes of docked complexes (AChE_IA1 and AChE_IA14) were validated by molecular dynamics simulation which showed their stable trajectories in terms of root mean square deviation and molecular mechanics/Poisson-Boltzmann surface area binding free energy analysis revealed key residues contributing significantly to overall binding energy. The present study may be useful in the design of more potent Isoalloxazine derivatives as AChE inhibitors.

Fucoxanthin induces growth arrest and apoptosis in human bladder cancer T24 cells by up-regulation of p21 and down-regulation of mortalin

Fucoxanthin, a natural carotenoid, has been reported to have anti-cancer activity in human colon cancer cells, human prostate cancer cells, human leukemia cells, and human epithelial cervical cancer cells. This study was undertaken to evaluate the molecular mechanisms of fucoxanthin against human bladder cancer T24 cell line. MTT analysis results showed that 5 and 10 μM fucoxanthin inhibited the proliferation of T24 cells in a dose- and time-dependent manner accompanied by the growth arrest at G0/G1 phase of cell cycle, which is mediated by the up-regulation of p21, a cyclin-dependent kinase (CDK)-inhibitory protein and the down-regulation of CDK-2, CDK-4, cyclin D1, and cyclin E. In addition, 20 and 40 μM fucoxanthin induced apoptosis of T24 cells by the abrogation of mortalin-p53 complex and the reactivation of nuclear mutant-type p53, which also had tumor suppressor function as wild-type p53. All these results demonstrated that the anti-cancer activity of fucoxanthin on T24 cells was associated with cell cycle arrest at G0/G1 phase by up-regulation of p21 at low doses and apoptosis via decrease in the expression level of mortalin, which is a stress regulator and a member of heat shock protein 70, followed by up-regulation of cleaved caspase-3 at high doses.

Cancer preventive efficacy of marine carotenoid fucoxanthin: cell cycle arrest and apoptosis

Epidemiological investigations have shown that overcoming the risk of cancer is related to the consumption of green vegetables and fruits. Many compounds from different origins, such as terrestrial plants and marine and microbial sources, have been reported to have therapeutic effects of which marine sources are the most important because the diversity of marine life is more varied than other sources. Fucoxanthin is one important compound with a marine origin and belongs to the group of carotenoids; it can be found in marine brown seaweeds, macroalgae, and diatoms, all of which have remarkable biological properties. Numerous studies have shown that fucoxanthin has considerable medicinal potential and promising applications in human health. In this review, we summarize the anticancer effects of fucoxanthin through several different mechanisms including anti-proliferation, induction of apoptosis, cell cycle arrest and anti-angiogenesis, and its possible role in the treatment of cancer.

In vivo induction of apoptosis by fucoxanthin, a marine carotenoid, associated with down-regulating STAT3/EGFR signaling in sarcoma 180 (S180) xenografts-bearing mice

Previous in vitro researches have showed that fucoxanthin, a natural carotenoid isolated from sargassum, can inhibit proliferation or induce apoptosis in human neuroblastoma, hepatoma, leukemia, colon carcinoma, prostate cancer or urinary bladder cancer cells. But the precise mechanism by which fucoxanthin exerts anticarcinogenic effects is not yet fully understood. In this study, we performed an in vivo study to investigate the anti-tumor effect and mechanisms of fucoxanthin on xenografted sarcoma 180 (S180) in mice. Results revealed that fucoxanthin significantly inhibited the growth of sarcoma at the dose of 50 or 100 mg/kg. TUNEL analysis showed that the number of positive cells in the fucoxanthin-treated group was higher than that in the control group. Western blotting analysis also revealed the suppressed expression of bcl-2 and enhanced expression of cleaved caspase-3 by fucoxanthin. In addition, immunohistochemistry analysis and Western blotting analysis showed that fucoxanthin significantly decreased the expressions of survivin and vascular endothelial growth factor (VEGF). Most importantly, fucoxanthin inhibited the expressions of the epidermal growth factor receptor (EGFR) and STAT3 and phosphorylated STAT3 proteins. These results indicated that in vivo induction of apoptosis by fucoxanthin is associated with down-regulating STAT3/EGFR signaling in S180 xenografts-bearing mice.