Theaflavin Induces Apoptosis of A375 Human Melanoma Cells and Inhibits Tumor Growth in Xenograft Zebrafishes Through P53- and JNK-Related Mechanism

Therapeutic potential of ASK1 activators in cancer treatment: Current insights and future directions

Apoptosis signal-regulated kinase 1 (ASK1) is a member of the mitogen-activated protein kinase kinase (MAP3K) family, whose activation and regulation are intricately associated with apoptosis. ASK1 is activated in response to oxidative stress, among other stimuli, subsequently triggering downstream JNK, p38 MAPK, and mitochondria-dependent apoptotic signaling, which participate in the initiation of tumor cell apoptosis induced by various stimuli. Research has shown that ASK1 plays a crucial role in the apoptosis of lung cancer, breast cancer, and liver cancer cells. Currently, the investigation of effective ASK1 activators is a hot topic in research on tumor cell apoptosis. Synthetic compounds such as human β-defensin, triazolothiazide derivatives and heat shock protein 27 inhibitors; natural compounds such as quercetin, Laminarina japonica polysaccharide-1 peptide and theabrownin; and nanomedicines such as cerium oxide nanoparticles, magnetite FeO nanoparticles and silver nanoparticles can activate ASK1 and induce apoptosis in various tumor cells. This review extensively investigates the roles and activation mechanisms of ASK1, explores its impact on a variety of apoptotic signaling pathways, and discusses the potential therapeutic applications of various ASK1 activators in cancer treatment. In addition, this paper provides an in-depth discussion of the future development of this field and proposes a promising method for further research and clinical progress.

Pharmacological Property and Cytotoxic Effect Showing Antiproliferative Potency in Human Melanoma Cell Lines (A375) of Combretum racemosum P. Beauv. Leaf and Root Extracts Used in Benin

Combretum racemosum, a plant from the Combretaceae family, is traditionally used in Benin for various health problems. However, scientific research on Beninese samples of this plant is limited. The aim of this study was to identify and assess the bioactive compounds in the plant's leaves and roots. Initial screening involved analyzing powders derived from these parts for total polyphenols, flavonoids, and both condensed and hydrolyzable tannins. The polyphenolic compounds were analyzed using HPLC-DAD-ESI-MS. To evaluate the plant's antimicrobial properties, the agar diffusion method was employed, while FRAP and DPPH assays were used to determine its antioxidant capacity. For anti-inflammatory activity, the study utilized tests for in vitro protein denaturation inhibition and in vivo acute edema induced by carrageenan. Additionally, an antiproliferative assay was conducted using the human melanoma cell line A375. The analysis revealed the presence of significant polyphenolic compounds in both the leaf and root extracts of C. racemosum. Notably, compounds like Pedunculagin, Vescalagin, Casuarictin, and Digalloyl-glucoside were abundant in the leaves, with Vescalagin being especially predominant in the roots. The study also found that the dichloromethane extracts from the leaves and roots exhibited bactericidal effects on a substantial percentage of meat-isolated strains. Moreover, the antioxidant activities of these extracts were confirmed through FRAP and DPPH methods. Interestingly, the dichloromethane root extract showed strong activity in inhibiting thermal albumin denaturation, while the water-ethanol leaf extract demonstrated significant edema inhibition. Finally, the study observed that C. racemosum extracts reduced cell viability in a dose-dependent manner, with leaf extracts showing more pronounced antiproliferative effects than root extracts. These findings highlight the potential of C. racemosum leaves and roots as sources of compounds with diverse and significant biological activities. In conclusion, C. racemosum's leaves and roots exhibit promising biological activities, highlighting their potential medicinal value.

Biological Potential and Mechanisms of Tea's Bioactive Compounds in Tea: An Updated Review

BACKGROUND

Tea (Camellia sinensis) has a rich history and is widely consumed across many countries, and is categorized into green tea, white tea, oolong tea, yellow tea, black tea, and dark tea based on the level of fermentation. Based on a review of previous literature, the commonly recognized bioactive substances in tea include tea polyphenols, amino acids, polysaccharides, alkaloids, terpenoids, macro minerals, trace elements, and vitamins, which have been known to have various potential health benefits, such as anticancer, antioxidant, anti-inflammatory, anti-diabetes, and anti-obesity properties, cardiovascular protection, immune regulation, and control of the intestinal microbiota. Most studies have only pointed out the characteristics of tea's bioactivities, so a comprehensive summary of the pharmacological characteristics and mechanisms of tea's bioactivities and their use risks are vital.

AIM

of Review The aim of this paper is to summarize the bioactive substances of tea and their pharmacological characteristics and mechanisms, providing a scientific basis for the application of bioactive substances in tea and outlining future research directions for the study of bioactive substances in tea. Key Scientific Concepts of Review This review summarizes the main biologically active substances, pharmacological effects, and mechanisms and discusses the potential risks. It may help researchers to grasp more comprehensive progress in the study of tea bioactive substances to further promote the application of tea as a natural bioactive substance in the medical field.

Application of Zebrafish as a Model for Anti-Cancer Activity Evaluation and Toxicity Testing of Natural Products

Developing natural product-based anti-cancer drugs/agents is a promising way to overcome the serious side effects and toxicity of traditional chemotherapeutics for cancer treatment. However, rapid assessment of the in vivo anti-cancer activities of natural products is a challenge. Alternatively, zebrafish are useful model organisms and perform well in addressing this challenging issue. Nowadays, a growing number of studies have utilized zebrafish models to evaluate the in vivo activities of natural compounds. Herein, we reviewed the application of zebrafish models for evaluating the anti-cancer activity and toxicity of natural products over the past years, summarized its process and benefits, and provided future outlooks for the development of natural product-based anti-cancer drugs.

Melanoma Cellular Signaling Transduction Pathways Targeted by Polyphenols Action Mechanisms

Melanoma is the most aggressive type of skin cancer. Although different anti-melanoma treatments are available, their efficacy is still improvable, and the number of deaths continues to increase worldwide. A promising source of antitumor agents could be presented by polyphenols-natural plant-based compounds. Over the past decades, many studies have described multiple anticancer effects of polyphenols in melanoma, presenting their potential interactions with targeted molecules from different signaling pathways. However, to our knowledge, there is no comprehensive review on polyphenols-regulated mechanisms in melanoma cells available in the literature. To fulfill this gap, this article aims to summarize the current knowledge of molecular mechanisms of action regulated by polyphenols involved in melanoma initiation and progression. Here, we focus on in vitro and in vivo effects of polyphenol treatments on tumor-essential cellular pathways, such as cell proliferation, apoptosis, autophagy, inflammation, angiogenesis, and metastasis. Moreover, emerging studies regarding the well-marked role of polyphenols in the regulation of microRNAs (miRNAs), highlighting their contribution to melanoma development, are also epitomized. Finally, we hope this review will provide a firm basis for developing polyphenol-based therapeutic agents in melanoma treatment.

Targeting regulated cell death with plant natural compounds for cancer therapy: A revisited review of apoptosis, autophagy-dependent cell death, and necroptosis

Regulated cell death (RCD) refers to programmed cell death regulated by various protein molecules, such as apoptosis, autophagy-dependent cell death, and necroptosis. Accumulating evidence has recently revealed that RCD subroutines have several links to many types of human cancer; therefore, targeting RCD with pharmacological small-molecule compounds would be a promising therapeutic strategy. Moreover, plant natural compounds, small-molecule compounds synthesized from plant sources, and their derivatives have been widely reported to regulate different RCD subroutines to improve potential cancer therapy. Thus, in this review, we focus on updating the intricate mechanisms of apoptosis, autophagy-dependent cell death, and necroptosis in cancer. Moreover, we further discuss several representative plant natural compounds and their derivatives that regulate the above-mentioned three subroutines of RCD, and their potential as candidate small-molecule drugs for the future cancer treatment.

Novel diosgenin-amino acid-benzoic acid mustard trihybrids exert antitumor effects via cell cycle arrest and apoptosis

In discovering new powerful antitumor agents, two series of novel diosgenin-amino acid-benzoic acid mustard trihybrids (7a-7 g and 12a-12 g) were designed and synthesized. The antiproliferative activities were tested against five human tumor cell lines and one normal cell line using CCK-8 assays. Among the trihybrids, 12e was the most promising compound, which inhibited T24 cells with IC₅₀ value of 6.96 μM, and was stronger than its parent compound diosgenin (IC₅₀ = 32.33 μM). In addition, 12e had weak cytotoxicity on the normal GES-1 cell line (IC₅₀ = 213.74 μM). Moreover, 12e could cause G2/M cell cycle arrest, increase the percentage of apoptosis, induce mitochondrial depolarization, and promote reactive oxygen species generation in T24 cells. Further studies on antitumor mechanism demonstrated that 12e triggered the intrinsic (mitochondrial) and extrinsic (death receptor) apoptotic pathways. More importantly, 12e could inhibit T24 cell proliferation in an in vivo zebrafish xenograft model. Therefore, 12e, as a novel trihybrid with potent cytotoxicity, might be applied as a promising skeleton for antitumor agents, which deserved further optimization.

Treatment with b-AP15 to Inhibit UCHL5 and USP14 Deubiquitinating Activity and Enhance p27 and Cyclin E1 for Tumors with p53 Deficiency

Background: TP53 protein is lost or mutated in about half of all types of human cancers and small molecules to regulate mutant p53 repair, or interrupt ubiquitination degradation of p53 induced by E3-ubiquitin ligase Mdm2 have a potential application in clinical application. Methods: To inhibit the deubiquitinase activity of 19S proteasome and restore the p53 protein level, in this study, we utilized p53 knockout mice to test the anti-cancer effect of a specific USP14 and UCH37 inhibitor b-AP15. Results: Our results show that UCHL5, USP14 and COPS5 are upregulated in p53-related tumors, and higher expression of these genes results in a shorter overall survival in patients with p53 deficiency. Treatment with b-AP15, a UCHL5 and USP14 deubiquitinating activity inhibitor in 19S regulatory subunit, induces tumor regression and prolong the survival period of tumor-loaded mice through down-regulation of COPS5 and its downstream AP-1 and E2F1, and up-regulation of the cell cycle-related proteins p27 and Cyclin E1. Conclusions: Thus, our results suggested that inhibition of UCHL5 and USP14 deubiquitinating activity in 19S proteasome may contribute an extensive approach to preventing tumor progress due to p53 deficiency.

Anticancer Effects and Molecular Target of Theaflavins from Black Tea Fermentation in Vitro and in Vivo

Black tea is one of the most popular beverages in the world, and numerous epidemiological studies have shown that drinking black tea is good for health. As a natural tea pigment formed during the fermentation of black tea, the content of theaflavins accounts for only 2-6% of the dry weight of black tea, but they have a great impact on the color and taste of black tea soup. Recently, a large number of studies have shown that theaflavins have a significant anticancer effect. In this Perspective, we first state the physical and chemical properties, separation and purification methods, and biological formation pathways of theaflavins and analyze their safety and oral bioavailability and the structure-activity relationship of their antioxidant and anticancer activities; then, we describe in detail their anticancer effect in vitro and in vivo and highlight their various molecular targets involved in cancer inhibition. The anticancer molecular targets of theaflavins are mainly cell-cycle regulatory proteins, apoptosis-related proteins, cell-migration-related proteins, and growth transcription factors. Finally, the possibility of developing new health-care food based on theaflavins is discussed. This Perspective is expected to provide a theoretical basis for the anticancer application of theaflavins in the future.

The Challenging Melanoma Landscape: From Early Drug Discovery to Clinical Approval

Melanoma is recognized as the most dangerous type of skin cancer, with high mortality and resistance to currently used treatments. To overcome the limitations of the available therapeutic options, the discovery and development of new, more effective, and safer therapies is required. In this review, the different research steps involved in the process of antimelanoma drug evaluation and selection are explored, including information regarding in silico, in vitro, and in vivo experiments, as well as clinical trial phases. Details are given about the most used cell lines and assays to perform both two- and three-dimensional in vitro screening of drug candidates towards melanoma. For in vivo studies, murine models are, undoubtedly, the most widely used for assessing the therapeutic potential of new compounds and to study the underlying mechanisms of action. Here, the main melanoma murine models are described as well as other animal species. A section is dedicated to ongoing clinical studies, demonstrating the wide interest and successful efforts devoted to melanoma therapy, in particular at advanced stages of the disease, and a final section includes some considerations regarding approval for marketing by regulatory agencies. Overall, considerable commitment is being directed to the continuous development of optimized experimental models, important for the understanding of melanoma biology and for the evaluation and validation of novel therapeutic strategies.

Recent Advances in Phenolic Metabolites and Skin Cancer

Skin cancer represents any tumor development from the cutaneous structures within the epidermis, dermis or subcutaneous tissue, and is considered to be the most prevalent type of cancer. Compared to other types of cancer, skin cancer is proven to have a positive growth rate of prevalence and mortality. There are available various treatments, including chemotherapy, immunotherapy, radiotherapy and targeted therapy, but because of the multidrug resistance development, a low success has been registered. By this, the importance of studying naturally occurring compounds that are both safe and effective in the chemoprevention of skin cancer is emphasized. This review focuses on melanoma because it is the deadliest form of skin cancer, with a significantly increasing incidence in the last decades. As chemopreventive agents, we present polyphenols and their antioxidant activity, anti-inflammatory effect, their ability to balance the cell cycle and to induce apoptosis and their various other effects on skin melanoma. Besides chemoprevention, studies suggest that polyphenols can have treating abilities in some conditions. The limitations of using polyphenols are also pointed out, which are related to their poor bioavailability and stability, but as the technology is well developed, it is possible to augment the efficacy of polyphenols in the case of melanoma.