Anticancer activity of synthetic (±)-kusunokinin and its derivative (±)-bursehernin on human cancer cell lines

The Emerging Role of Natural Products in Cancer Treatment

The exploration of natural products as potential agents for cancer treatment has garnered significant attention in recent years. In this comprehensive review, we delve into the diverse array of natural compounds, including alkaloids, carbohydrates, flavonoids, lignans, polyketides, saponins, tannins, and terpenoids, highlighting their emerging roles in cancer therapy. These compounds, derived from various botanical sources, exhibit a wide range of mechanisms of action, targeting critical pathways involved in cancer progression such as cell proliferation, apoptosis, angiogenesis, and metastasis. Through a meticulous examination of preclinical and clinical studies, we provide insights into the therapeutic potential of these natural products across different cancer types. Furthermore, we discuss the advantages and challenges associated with their use in cancer treatment, emphasizing the need for further research to optimize their efficacy, pharmacokinetics, and delivery methods. Overall, this review underscores the importance of natural products in advancing cancer therapeutics and paves the way for future investigations into their clinical applications.

Role of CSF1R 550th-tryptophan in kusunokinin and CSF1R inhibitor binding and ligand-induced structural effect

Binding affinity is an important factor in drug design to improve drug-target selectivity and specificity. In this study, in silico techniques based on molecular docking followed by molecular dynamics (MD) simulations were utilized to identify the key residue(s) for CSF1R binding affinity among 14 pan-tyrosine kinase inhibitors and 15 CSF1R-specific inhibitors. We found tryptophan at position 550 (W550) on the CSF1R binding site interacted with the inhibitors' aromatic ring in a π-π way that made the ligands better at binding. Upon W550-Alanine substitution (W550A), the binding affinity of trans-(-)-kusunokinin and imatinib to CSF1R was significantly decreased. However, in terms of structural features, W550 did not significantly affect overall CSF1R structure, but provided destabilizing effect upon mutation. The W550A also did not either cause ligand to change its binding site or conformational changes due to ligand binding. As a result of our findings, the π-π interaction with W550's aromatic ring could be still the choice for increasing binding affinity to CSF1R. Nevertheless, our study showed that the increasing binding to W550 of the design ligand may not ensure CSF1R specificity and inhibition since W550-ligand bound state did not induce significantly conformational change into inactive state.

Trans-(±)-TTPG-B Attenuates Cell Cycle Progression and Inhibits Cell Proliferation on Cholangiocarcinoma Cells

This research aimed to determine the target protein and molecular mechanism of trans-(±)-kusunokinin ((±)-KU) derivatives (trans-(±)-ARC and trans-(±)-TTPG-B). Molecular docking was used to predict potential synthesized (±)-KU targets among 22 proteins. The (±)-TTPG-B bound HSP90α better than EC44, native (±)-KU and (-)-KU, and (±)-KU and (-)-ARC. In contrast, (-)-ARC bound PI3K more strongly than any other test compound. CSF1R and AKR1B1 were not supposed to be the target of (±)-TTPG-B and (±)-ARC, unlike native (±)-KU. The (±)-TTPG-B bound Tyr139 and Trp162 of HSP90α. Moreover, (-)-ARC bound PI3K via hydrogen bonds and π-π stacking at distinct amino acids, which was different from the other tested compounds. Using half of the IC50 concentration, (±)-TTPG-B, (±)-KU and (±)-ARC enhanced cell cycle arrest at the G0/G1 phase after 12 h and 24 h on KKU-M213 (CCA) cells. The (±)-TTPG-B showed a stronger inhibitory effect than (±)-ARC and (±)-KU on HSP90α, PI3K, HSP90β, c-Myc, AKT, MEK1, CyclinB1, CyclinD1, and CDK1 for 24 and 48 h after treatment with the same concentration (0.015 µM). Thus, trans-(±)-TTPG-B, a newly synthesized compound, has pharmacological potential for development as a target therapy for CCA treatment.

Modern Photocatalytic Strategies in Natural Product Synthesis

Modern photocatalysis has proven its generality for the development and functionalization of native functionalities. To date, the field has found broad applications in diverse research areas, including the total synthesis of natural products. This contribution covers recent reports of total syntheses involving as a key step a photocatalytic reaction. Among the selected examples, the photocatalytic processes proceed in a highly chemo-, regio-, and stereoselective manner, thereby allowing the rapid access to structurally complex architectures under light-driven conditions.

Combination effect of cold atmospheric plasma with green synthesized zero-valent iron nanoparticles in the treatment of melanoma cancer model

Green synthesized zero-valent iron nanoparticles (nZVI) have high potential in cancer therapy. Cold atmospheric plasma (CAP) is also an emerging biomedical technique that has great potential to cure cancer. Therefore, the combined effect of CAP and nZVI might be promising in treatment of cancer. In this study, we evaluated the combined effect of CAP and nZVI on the metabolic activity of the surviving cells and induction of apoptosis in malignant melanoma in comparison with normal cells. Therefore, the effect of various time exposure of CAP radiation, different doses of nZVI, and the combined effect of CAP and nZVI were evaluated on the viability of malignant melanoma cells (B16-F10) and normal fibroblast cells (L929) at 24 h after treatment using MTT assay. Then, the effect of appropriate doses of each treatment on apoptosis was evaluated by fluorescence microscopy and flow cytometry with Annexin/PI staining. In addition, the expression of BAX, BCL2 and Caspase 3 (CASP3) was also assayed. The results showed although the combined effect of CAP and nZVI significantly showed cytotoxic effects and apoptotic activity on cancer cells, this treatment had no more effective compared to CAP or nZVI alone. In addition, evaluation of gene expression showed that combination therapy didn't improve expression of apoptotic genes in comparison with CAP or nZVI. In conclusion, combined treatment of CAP and nZVI does not seem to be able to improve the effect of monotherapy of CAP or nZVI. It may be due to the resistance of cancer cells to high ROS uptake or the accumulation of saturated ROS in cells, which prevents the intensification of apoptosis.

Anticancer Activity of (±)-Kusunokinin Derivatives towards Cholangiocarcinoma Cells

This study aimed to investigate the cytotoxicity and anticancer activity of (±)-kusunokinin derivatives ((±)-TTPG-A and (±)-TTPG-B). The cytotoxicity effect was performed on human cancer cells, including breast cancer, cholangiocarcinoma, colon and ovarian cancer-cells, compared with normal cells, using the MTT assay. Cell-cycle arrest and apoptosis were detected using flow-cytometry analysis. We found that (±)-TTPG-B exhibited the strongest cytotoxicity on aggressive breast-cancer (MDA-MB-468 and MDA-MB-231) and cholangiocarcinoma (KKU-M213), with an IC50 value of 0.43 ± 0.01, 1.83 ± 0.04 and 0.01 ± 0.001 µM, respectively. Interestingly, (±)-TTPG-A and (±)-TTPG-B exhibited less toxicity than (±)-kusunokinin (9.75 ± 0.39 µM) on L-929 cells (normal fibroblasts). Moreover, (±)-TTPG-A predominated the ell-cycle arrest at the S phase, while (±)-TTPG-B caused cell arrest at the G0/G1 phase, in the same way as (±)-kusunokinin in KKU-M213 cells. Both (±)-TTPG-A and (±)-TTPG-B induced apoptosis and multi-caspase activity more than (±)-kusunokinin. Taken together, we conclude that (±)-TTPG-A and (±)-TTPG-B have a strong anticancer effect on cholangiocarcinoma. Moreover, (±)-TTPG-B could be a potential candidate compound for breast cancer and cholangiocarcinoma in the future.

Trans-(±)-Kusunokinin Binding to AKR1B1 Inhibits Oxidative Stress and Proteins Involved in Migration in Aggressive Breast Cancer

Synthetic trans-(±)-kusunokinin ((±)KU), a potential anticancer substance, was revealed to have an inhibitory effect on breast cancer. According to the computational modeling prediction, AKR1B1, an oxidative stress and cancer migration protein, could be a target protein of trans-(-)-kusunokinin. In this study, we determined the binding of (±)KU and AKR1B1 on triple-negative breast and non-serous ovarian cancers. We found that (±)KU exhibited a cytotoxic effect that was significantly stronger than zopolrestat (ZP) and epalrestat (EP) (known AKR1B1 inhibitors) on breast and ovarian cancer cells. (±)KU inhibited aldose reductase activity that was stronger than trans-(-)-arctiin ((-)AR) but weaker than ZP and EP. Interestingly, (±)KU stabilized AKR1B1 on SKOV3 and Hs578T cells after being heated at 60 and 75 °C, respectively. (±)KU decreased malondialdehyde (MDA), an oxidative stress marker, on Hs578T cells in a dose-dependent manner and the suppression was stronger than EP. Furthermore, (±)KU downregulated AKR1B1 and its downstream proteins, including PKC-δ, NF-κB, AKT, Nrf2, COX2, Twist2 and N-cadherin and up-regulated E-cadherin. (±)KU showed an inhibitory effect on AKR1B1 and its downstream proteins, similar to siRNA-AKR1B1. Interestingly, the combination of siRNA-AKR1B1 with EP or (±)KU showed a greater effect on the suppression of AKR1B1, N-cadherin, E-cadherin and NF-κB than single treatments. Taken together, we concluded that (±)KU-bound AKR1B1 leads to the attenuation of cellular oxidative stress, as well as the aggressiveness of breast cancer cell migration.

Review of lignans from 2019 to 2021: Newly reported compounds, diverse activities, structure-activity relationships and clinical applications

Lignans, with various biological activities, such as antitumor, antioxidant, antibacterial, and antiviral activities, are widely distributed in nature and mainly exist in the xylem of plants. In this paper, we summarized the structures and bioactivities of lignans reported in recent years (2019-2021) from five parts, including (1) a summary and classification of newly reported compounds; (2) the pharmacological activities of lignans; (3) molecular resources and activity distribution; (4) the structure-activity relationships; and (5) the clinical application of lignans. This review covers all undescribed compounds that were reported within the covered period of time and all bioactivity data about previously isolated lignans. The distribution of lignans in different plants and families is visualized, which improves the efficiency of searching for specific molecules. The diverse activities of different types of lignans provide an important reference for the rapid screening of these compounds. Discussion about the structure-activity relationships of lignans provides a direction for the structural modification of skeleton molecules. Combined with the clinical application of such molecules, this work will provide a valuable reference for pharmaceutical chemists.

Potential Stereoselective Binding of Trans-(±)-Kusunokinin and Cis-(±)-Kusunokinin Isomers to CSF1R

Breast cancer cell proliferation and migration are inhibited by naturally extracted trans-(−)-kusunokinin. However, three additional enantiomers of kusunokinin have yet to be investigated: trans-(+)-kusunokinin, cis-(−)-isomer and cis-(+)-isomer. According to the results of molecular docking studies of kusunokinin isomers on 60 breast cancer-related proteins, trans-(−)-kusunokinin was the most preferable and active component of the trans-racemic mixture. Trans-(−)-kusunokinin targeted proteins involved in cell growth and proliferation, whereas the cis-(+)-isomer targeted proteins involved in metastasis. Trans-(−)-kusunokinin targeted CSF1R specifically, whereas trans-(+)-kusunokinin and both cis-isomers may have bound AKR1B1. Interestingly, the compound’s stereoisomeric effect may influence protein selectivity. CSF1R preferred trans-(−)-kusunokinin over trans-(+)-kusunokinin because the binding pocket required a ligand planar arrangement to form a π-π interaction with a selective Trp550. Because of its large binding pocket, EGFR exhibited no stereoselectivity. MD simulation revealed that trans-(−)-kusunokinin, trans-(+)-kusunokinin and pexidartinib bound CSF1R differently. Pexidartinib had the highest binding affinity, followed by trans-(−)-kusunokinin and trans-(+)-kusunokinin, respectively. The trans-(−)-kusunokinin-CSF1R complex was found to be stable, whereas trans-(+)-kusunokinin was not. Trans-(±)-kusunokinin, a potential racemic compound, could be developed as a selective CSF1R inhibitor when combined.

Low Piperine Fractional Piper nigrum Extract Enhanced the Antitumor Immunity via Regulating the Th1/Th2/Treg Cell Subsets on NMU-Induced Tumorigenesis Rats

Cancer is one of the major causes of death worldwide. In addition to standard regimens, tumor suppression ability has been demonstrated in many types of natural products, including Piper nigrum, or black pepper. In previous reports, we demonstrated the antitumor effect of low piperine fractional Piper nigrum extract in vitro and in vivo. However, the effects of low piperine fractional P. nigrum extract in the aspect of antitumor immunity has not yet been investigated. In this study, tumor-bearing rats were fed with 100 mg/kg BW or 200 mg/kg BW of low piperine fractional P. nigrum extract 3 times per week for 4 weeks. Tumor burden and hematological data were then evaluated. Immunological data was investigated using a cytokine array and flow cytometry. The results showed that both doses of low piperine fractional P. nigrum extract significantly suppressed tumor progression in N-nitrosomethylurea-induced mammary tumor rats. There were no significant changes observed in the total white blood cells, red blood cells, and hemoglobin. Low piperine fractional P. nigrum extract suppressed some cytokine and chemokine levels including CXCL7, sICAM-1, and L-selectin 0.2- to 0.6-fold. Interestingly, 200 mg/kg BW of low piperine fractional P. nigrum extract significantly promoted type 1 T helper cell, and suppressed neutrophil, basophil, type 2 T helper cell, and regulatory T cell compared to the control group. In summary, these results indicate that low piperine fractional P. nigrum extract had a high efficacy in supporting antitumor activity at immunological levels via regulating Th1/Th2/Treg cells.

Effects of trans-(±)-kusunokinin on chemosensitive and chemoresistant ovarian cancer cells

Ovarian cancer ranks eighth in cancer incidence and mortality among women worldwide. Cisplatin-based chemotherapy is commonly used for patients with ovarian cancer. However, the clinical efficacy of cisplatin is limited due to the occurrence of adverse side effects and development of cancer chemoresistance during treatment. Trans-(±)-kusunokinin has been previously reported to inhibit cell proliferation and induce cell apoptosis in various cancer cell types, including breast, colon and cholangiocarcinoma. However, the potential effects of (±)-kusunokinin on ovarian cancer remains unknown. In the present study, chemosensitive ovarian cancer cell line A2780 and chemoresistant ovarian cancer cell lines A2780cis, SKOV-3 and OVCAR-3 were treated with trans-(±)-kusunokinin to investigate its potential effects. MTT, colony formation, apoptosis and multi-caspase assays were used to determine cytotoxicity, the ability of single cells to form colonies, induction of apoptosis and multi-caspase activity, respectively. Moreover, western blot analysis was performed to determine the proteins level of topoisomerase II, cyclin D1, CDK1, Bax and p53-upregulated modulator of apoptosis (PUMA). The results demonstrated that trans-(±)-kusunokinin exhibited the strongest cytotoxicity against A2780cis cells with an IC₅₀ value of 3.4 µM whilst also reducing the colony formation of A2780 and A2780cis cells. Trans-(±)-kusunokinin also induced the cells to undergo apoptosis and increased multi-caspase activity in A2780 and A2780cis cells. This compound significantly downregulated topoisomerase II, cyclin D1 and CDK1 expression, but upregulated Bax and PUMA expression in both A2780 and A2780cis cells. In conclusion, trans-(±)-kusunokinin suppressed ovarian cancer cells through the inhibition of colony formation, cell proliferation and the induction of apoptosis. This pure compound could be a potential targeted therapy for ovarian cancer treatment in the future. However, studies in an animal model and clinical trial need to be performed to support the efficacy and safety of this new treatment.

Cytotoxicity of synthetic derivatives against breast cancer and multi-drug resistant breast cancer cell lines: a literature-based perspective study

Cancer is the second most killer worldwide causing millions of people to lose their lives every year. In the case of women, breast cancer takes away the highest proportion of mortality rate than other cancers. Due to the mutation and resistance-building capacity of different breast cancer cell lines against conventional therapies, this death rate is on the verge of growth. New effective therapeutic compounds and treatment method is the best way to look out for in this critical time. For instance, new synthetic derivatives/ analogues synthesized from different compounds can be a ray of hope. Numerous synthetic compounds have been seen enhancing the apoptosis and autophagic pathway that directly exerts cytotoxicity towards different breast cancer cell lines. To cease the ever-growing resistance of multi-drug resistant cells against anti-breast cancer drugs (Doxorubicin, verapamil, tamoxifen) synthetic compounds may play a vital role by increasing effectivity, showing synergistic action. Many recent and previous studies have reported that synthetic derivatives hold potentials as an effective anti-breast cancer agent as they show great cytotoxicity towards cancer cells, thus can be used even vastly in the future in the field of breast cancer treatment. This review aims to identify the anti-breast cancer properties of several synthetic derivatives against different breast cancer and multi-drug-resistant breast cancer cell lines with their reported mechanism of action and effectivity.

Trans-(-)-Kusunokinin: A Potential Anticancer Lignan Compound against HER2 in Breast Cancer Cell Lines?

Trans-(−)-kusunokinin, an anticancer compound, binds CSF1R with low affinity in breast cancer cells. Therefore, finding an additional possible target of trans-(−)-kusunokinin remains of importance for further development. Here, a computational study was completed followed by indirect proof of specific target proteins using small interfering RNA (siRNA). Ten proteins in breast cancer were selected for molecular docking and molecular dynamics simulation. A preferred active form in racemic trans-(±)-kusunokinin was trans-(−)-kusunokinin, which had stronger binding energy on HER2 trans-(+)-kusunokinin; however, it was weaker than the designed HER inhibitors (03Q and neratinib). Predictively, trans-(−)-kusunokinin bound HER2 similarly to a reversible HER2 inhibitor. We then verified the action of (±)-kusunokinin compared with neratinibon breast cancer cells (MCF-7). (±)-Kusunokinin exhibited less cytotoxicity on normal L-929 and MCF-7 than neratinib. (±)-Kusunokinin and neratinib had stronger inhibited cell proliferation than siRNA-HER2. Moreover, (±)-kusunokinin decreased Ras, ERK, CyclinB1, CyclinD and CDK1. Meanwhile, neratinib downregulated HER, MEK1, ERK, c-Myc, CyclinB1, CyclinD and CDK1. Knocking down HER2 downregulated only HER2. siRNA-HER2 combination with (±)-kusunokinin suppressed HER2, c-Myc, CyclinB1, CyclinD and CDK1. On the other hand, siRNA-HER2 combination with neratinib increased HER2, MEK1, ERK, c-Myc, CyclinB1, CyclinD and CDK1 to normal levels. We conclude that trans-(±)-kusunokinin may bind HER2 with low affinity and had a different action from neratinib.

Phyto-Phospholipid Complexation as a Novel Drug Delivery System for Management of Cancer with Better Bioavailability: Current Perspectives and Future Prospects

Cancer is the foremost cause of death, and it supports the need for the identification of novel anticancer drugs to improve the efficacy of current-therapy. While the synthetic anticancer drug is associated with numerous side effects. Hence the plant active or phytoconstituents are in high demand for the treatment of cancer due to minimum side effects. But the polar nature of phytoconstituents hindered the absorption of the drug and lowered the therapeutic efficacy. The plant activity incorporated into Phyto-phospholipid Complexation can enhance bioavailability and improved therapeutic efficacy. In this review article, advantages, limitation and application of Phyto-phospholipid complexes have been illustrated. The article highlights the application of Phyto-phospholipid complexes as a promising drug carrier system to treat cancer.

(-)-Kusunokinin as a Potential Aldose Reductase Inhibitor: Equivalency Observed via AKR1B1 Dynamics Simulation

(-)-Kusunokinin performed its anticancer potency through CFS1R and AKT pathways. Its ambiguous binding target has, however, hindered the next development phase. Our study thus applied molecular docking and molecular dynamics simulation to predict the protein target from the pathways. Among various candidates, aldo-keto reductase family 1 member B1 (AKR1B1) was finally identified as a (-)-kusunokinin receptor. The predicted binding affinity of (-)-kusunokinin was better than the selected aldose reductase inhibitors (ARIs) and substrates. The compound also had no significant effect on AKR1B1 conformation. An intriguing AKR1B1 efficacy, with respect to the known inhibitors (epalrestat, zenarestat, and minalrestat) and substrates (UVI2008 and prostaglandin H₂), as well as a similar interactive insight of the enzyme pocket, pinpointed an ARI equivalence of (-)-kusunokinin. An aromatic ring and a γ-butyrolactone ring shared a role with structural counterparts in known inhibitors. The modeling explained that the aromatic constituent contributed to π-π attraction with Trp111. In addition, the γ-butyrolactone ring bound the catalytic His110 using hydrogen bonds, which could lead to enzymatic inhibition as a consequence of substrate competitiveness. Our computer-based findings suggested that the potential of (-)-kusunokinin could be furthered by in vitro and/or in vivo experiments to consolidate (-)-kusunokinin as a new AKR1B1 antagonist in the future.

(-)-Kusunokinin inhibits breast cancer in N-nitrosomethylurea-induced mammary tumor rats

Natural and synthetic (-)-kusunokinin inhibited breast cancer, colon cancer and cholangiocarcinoma cells at the G2/M phase and induced apoptosis. However, there is no report on the action and adverse effects of (-)-kusunokinin in animal models. In this study, we investigated the cytotoxic effect of (-)-kusunokinin from Piper nigrum on cancer cells. NMU-induced rat mammary tumors, an ER positive breast cancer model, were treated with (-)-kusunokinin. Proteins of interest related to cell cycle, angiogenesis, migration and signaling proteins were detected in tumor tissues. Results showed that (-)-kusunokinin exhibited strong cytotoxicity against breast, colon and lung cancer cells and caused low toxicity against normal fibroblast cells. For in vivo study, 7.0 mg/kg and 14.0 mg/kg of (-)-kusunokinin reduced tumor growth without side effects on body weight, internal organs and bone marrow. Combination of (-)-kusunokinin with a low effective dose of doxorubicin significantly inhibited tumor growth and provoked cell death in cancer tissues. Mechanistically, 14.0 mg/kg of (-)-kusunokinin decreased cell proliferation (c-Src, PI3K, Akt, p-Erk1/2 and c-Myc), cell cycle (E2f-1, cyclin B1 and CDK1), and metastasis (E-cadherin, MMP-2 and MMP-9) proteins in tumor tissues, which supports its anticancer effect. We further confirmed the antimigration effect of (-)-kusunokinin; the results show that this compound inhibited breast cancer cell (MCF-7) migration in a dose-dependent manner. In conclusion, the results suggest that 14 mg/kg of (-)-kusunokinin inhibited tumors through the reduction of signaling proteins and their downstream molecules. Therefore, (-)-kusunokinin becomes an intriguing candidate for cancer treatment as it provides a strong potency in cancer inhibition.

Inhibition of CSF1R and AKT by (±)-kusunokinin hinders breast cancer cell proliferation

Kusunokinin, a lignan compound, inhibits cancer cell proliferation and induces apoptosis; however, the role of kusunokinin is not fully understood. Here, we aimed to identify a target protein of (-)-kusunokinin and determine the protein levels of its downstream molecules. We found that (-)-kusunokinin bound 5 possible target proteins, including CSF1R, MMP-12, HSP90-α, CyclinB1 and MEK1 with ΔG_bind less than -10.40 kcal/mol. MD simulation indicated (-)-kusunokinin and pexidartinib (P31, a specific CSF1R binding compound) shared some extents of functional similarity in which (-)-kusunokinin bound CSF1R at the juxtamembrane (JM) region with aromatic amino acids similar to pexidartinib using π-π interaction, as well as hydrogen bond. Both P31 and (-)-kusunokinin moved into the same CSF1R region and W7 was a mutual key residue. However, the P31 binding site differed from the (-)-kusunokinin binding site. For in vitro study, the synthetic (±)-kusunokinin exhibited stronger cytotoxicity than picropodophyllotoxin, silibinin and etoposide on MCF-7 cells and represented less toxicity than picropodophyllotoxin and doxorubicin on L-929 and MCF-12A cells. Knocking down CSF1R using a specific siRNA combination with (±)-kusunokinin demonstrated levels of cell proliferation proteins slightly higher than siRNA-CSF1R treatment. However, siRNA-CSF1R combination with P31 represented the number of cell viability and cell proliferation proteins, like in the control groups (Lipofectamine and siRNA-Luciferase). Moreover, (±)-kusunokinin suppressed CSF1R and its downstream proteins, including AKT, CyclinD1 and CDK1. Meanwhile, both P31 and siRNA-CSF1R dramatically suppressed CSF1R, MEK1, AKT, ERK, CyclinB1, CyclinD1 and CDK1. Our overall results indicate that the mechanism of (±)-kusunokinin differed fairly from P31. We have concluded that (±)-kusunokinin inhibited breast cancer cell proliferation partially through the binding and suppression of CSF1R, which consequently affected AKT and its downstream molecules.