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

Natural STAT3 Inhibitors for Cancer Treatment: A Comprehensive Literature Review

Cancer is one of the leading causes of mortality and morbidity worldwide, affecting millions of people physically and financially every year. Over time, many anticancer treatments have been proposed and studied, including synthetic compound consumption, surgical procedures, or grueling chemotherapy. Although these treatments have improved the daily life quality of patients and increased their survival rate and life expectancy, they have also shown significant drawbacks, including staggering costs, multiple side effects, and difficulty in compliance and adherence to treatment. Therefore, natural compounds have been considered a possible key to overcoming these problems in recent years, and thorough research has been done to assess their effectiveness. In these studies, scientists have discovered a meaningful interaction between several natural materials and signal transducer and activator of transcription 3 molecules. STAT3 is a transcriptional protein that is vital for cell growth and survival. Mechanistic studies have established that activated STAT3 can increase cancer cell proliferation and invasion while reducing anticancer immunity. Thus, inhibiting STAT3 signaling by natural compounds has become one of the favorite research topics and an attractive target for developing novel cancer treatments. In the present article, we intend to comprehensively review the latest knowledge about the effects of various organic compounds on inhibiting the STAT3 signaling pathway to cure different cancer diseases.

Valuable pigments from microalgae: phycobiliproteins, primary carotenoids, and fucoxanthin

Phycobiliproteins, carotenoids and fucoxanthin are photosynthetic pigments extracted from microalgae and cyanobacteria with great potential biotechnological applications, as healthy food colorants and cosmetics. Phycocyanin possesses a brilliant blue color, with fluorescent properties making it useful as a reagent for immunological essays. The most important source of phycocyanin is the cyanobacterium Arthrospira platensis, however, recently, the Rhodophyta Galdieria sulphuraria has also been identified as such. The main obstacle to the commercialization of phycocyanin is represented by its chemical instability, strongly reducing its shelf-life. Moreover, the high level of purity needed for pharmaceutical applications requires several steps which increase both the production time and cost. Microalgae (Chlorella, Dunaliella, Nannochloropsis, Scenedesmus) produce several light harvesting carotenoids, and are able to manage with oxidative stress, due to their free radical scavenging properties, which makes them suitable for use as source of natural antioxidants. Many studies focused on the selection of the most promising strains producing valuable carotenoids and on their extraction and purification. Among carotenoids produced by marine microalgae, fucoxanthin is the most abundant, representing more than 10% of total carotenoids. Despite the abundance and diversity of fucoxanthin producing microalgae only a few species have been studied for commercial production, the most relevant being Phaeodactylum tricornutum. Due to its antioxidant activity, fucoxanthin can bring various potential benefits to the prevention and treatment of lifestyle-related diseases. In this review, we update the main results achieved in the production, extraction, purification, and commercialization of these important pigments, motivating the cultivation of microalgae as a source of natural pigments.

Recent advances in biological properties of brown algae-derived compounds for nutraceutical applications

The increasing demand for nutraceuticals in the circular economy era has driven the research toward studying bioactive compounds from renewable underexploited resources. In this regard, the exploration of brown algae has shown significant growth and maintains a great promise for the future. One possible explanation could be that brown algae are rich sources of nutritional compounds (polyunsaturated fatty acids, fiber, proteins, minerals, and vitamins) and unique metabolic compounds (phlorotannins, fucoxanthin, fucoidan) with promising biological activities that make them good candidates for nutraceutical applications with increased value-added. In this review, a deep description of bioactive compounds from brown algae is presented. In addition, recent advances in biological activities ascribed to these compounds through in vitro and in vivo assays are pointed out. Delivery strategies to overcome some drawbacks related to the direct application of algae-derived compounds (low solubility, thermal instability, bioavailability, unpleasant organoleptic properties) are also reviewed. Finally, current commercial and legal statuses of ingredients from brown algae are presented, considering future therapeutical and market perspectives as nutraceuticals.

Fucoxanthin: A Promising Phytochemical on Diverse Pharmacological Targets

Fucoxanthin (FX) is a special carotenoid having an allenic bond in its structure. FX is extracted from a variety of algae and edible seaweeds. It has been proved to contain numerous health benefits and preventive effects against diseases like diabetes, obesity, liver cirrhosis, malignant cancer, etc. Thus, FX can be used as a potent source of both pharmacological and nutritional ingredient to prevent infectious diseases. In this review, we gathered the information regarding the current findings on antimicrobial, antioxidant, anti-inflammatory, skin protective, anti-obesity, antidiabetic, hepatoprotective, and other properties of FX including its bioavailability and stability characteristics. This review aims to assist further biochemical studies in order to develop further pharmaceutical assets and nutritional products in combination with FX and its various metabolites.

Brown Algae as Functional Food Source of Fucoxanthin: A Review

Fucoxanthin is an algae-specific xanthophyll of aquatic carotenoid. It is prevalent in brown seaweed because it functions as a light-harvesting complex for algal photosynthesis and photoprotection. Its exceptional chemical structure exhibits numerous biological activities that benefit human health. Due to these valuable properties, fucoxanthin's potential as a potent source for functional food, feed, and medicine is being explored extensively today. This article has thoroughly reviewed the availability and biosynthesis of fucoxanthin in the brown seaweed, as well as the mechanism behind it. We included the literature findings concerning the beneficial bioactivities of fucoxanthin such as antioxidant, anti-inflammatory, anti-obesity, antidiabetic, anticancer, and other potential activities. Last, an additional view on its potential as a functional food ingredient has been discussed to facilitate a broader application of fucoxanthin as a promising bioactive compound.

Inhibiting STAT3 signaling pathway by natural products for cancer prevention and therapy: In vitro and in vivo activity and mechanisms of action

Signal transducer and activator of transcription 3 (STAT3) plays a critical role in signal transmission from the plasma membrane to the nucleus, regulating the expression of genes involved in essential cell functions and controlling the processes of cell cycle progression and apoptosis. Thus, STAT3 has been elucidated as a promising target for developing anticancer drugs. Many natural products have been reported to inhibit the STAT3 signaling pathway during the past two decades and have exhibited significant anticancer activities in vitro and in vivo. However, there is no FDA-approved STAT3 inhibitor yet. The major mechanisms of these natural product inhibitors of the STAT3 signaling pathway include targeting the upstream regulators of STAT3, directly binding to the STAT3 SH2 domain and inhibiting its activation, inhibiting STAT3 phosphorylation and/or dimerization, and others. In the present review, we have systematically discussed the development of these natural product inhibitors of STAT3 signaling pathway as well as their in vitro and in vivo anticancer activity and mechanisms of action. Outlooks and perspectives on the associated challenges are provided as well.

Synthetic and Naturally Occurring Heterocyclic Anticancer Compounds with Multiple Biological Targets

Cancer is a complex group of diseases initiated by abnormal cell division with the potential of spreading to other parts of the body. The advancement in the discoveries of omics and bio- and cheminformatics has led to the identification of drugs inhibiting putative targets including vascular endothelial growth factor (VEGF) family receptors, fibroblast growth factors (FGF), platelet derived growth factors (PDGF), epidermal growth factor (EGF), thymidine phosphorylase (TP), and neuropeptide Y4 (NY4), amongst others. Drug resistance, systemic toxicity, and drug ineffectiveness for various cancer chemo-treatments are widespread. Due to this, efficient therapeutic agents targeting two or more of the putative targets in different cancer cells are proposed as cutting edge treatments. Heterocyclic compounds, both synthetic and natural products, have, however, contributed immensely to chemotherapeutics for treatments of various diseases, but little is known about such compounds and their multimodal anticancer properties. A compendium of heterocyclic synthetic and natural product multitarget anticancer compounds, their IC50, and biological targets of inhibition are therefore presented in this review.

Silymarin (milk thistle extract) as a therapeutic agent in gastrointestinal cancer

Silymarin contains a group of closely-related flavonolignan compounds including silibinin, and is extracted from Silybum marianum species, also called milk thistle. Silymarin has been shown to protect the liver in both experimental models and clinical studies. The chemopreventive activity of silymarin has shown some efficacy against cancer both in vitro and in vivo. Silymarin can modulate apoptosis in vitro and survival in vivo, by interfering with the expression of cell cycle regulators and apoptosis-associated proteins. In addition to its anti-metastatic activity, silymarin has also been reported to exhibit anti-inflammatory activity. The chemoprotective effects of silymarin and silibinin (its major constituent) suggest they could be applied to reduce the side effects and increase the anti-cancer effects of chemotherapy and radiotherapy in various cancer types, especially in gastrointestinal cancers. This review examines the recent studies and summarizes the mechanistic pathways and down-stream targets of silymarin in the therapy of gastrointestinal cancer.

Anti-Inflammatory and Anticancer Effects of Microalgal Carotenoids

Acute inflammation is a key component of the immune system's response to pathogens, toxic agents, or tissue injury, involving the stimulation of defense mechanisms aimed to removing pathogenic factors and restoring tissue homeostasis. However, uncontrolled acute inflammatory response may lead to chronic inflammation, which is involved in the development of many diseases, including cancer. Nowadays, the need to find new potential therapeutic compounds has raised the worldwide scientific interest to study the marine environment. Specifically, microalgae are considered rich sources of bioactive molecules, such as carotenoids, which are natural isoprenoid pigments with important beneficial effects for health due to their biological activities. Carotenoids are essential nutrients for mammals, but they are unable to synthesize them; instead, a dietary intake of these compounds is required. Carotenoids are classified as carotenes (hydrocarbon carotenoids), such as α- and β-carotene, and xanthophylls (oxygenate derivatives) including zeaxanthin, astaxanthin, fucoxanthin, lutein, α- and β-cryptoxanthin, and canthaxanthin. This review summarizes the present up-to-date knowledge of the anti-inflammatory and anticancer activities of microalgal carotenoids both in vitro and in vivo, as well as the latest status of human studies for their potential use in prevention and treatment of inflammatory diseases and cancer.

Fucoxanthin induced apoptotic cell death in oral squamous carcinoma (KB) cells

Fucoxanthin (Fx) is an active compound commonly found in the many types of seaweed with numerous biological activities. The main goal of this investigation is to explore the effect of Fx against the cell proliferation, apoptotic induction and oxidative stress in the oral squamous (KB) cell line. Cytotoxicity of Fx was determined by MTT assay. The intracellular ROS production, mitochondrial membrane potential (MMP) and apoptosis induction in KB cells were examined through DCFH-DA, Rhodamine-123 and DAPI, and dual staining techniques. Effect of Fx on the antioxidant enzymes and lipid peroxidation in the KB cells was studied through the standard procedures. Fx treated KB cells showed morphological changes and reduced cell survival, which is exhibited by the cytotoxic activity of 50 µM/ml (IC50) Fx against the KB cells. The Fx treatment considerably induced the apoptotosis cells (EB/AO) and decreased the MMP (Rh-123) in KB cells. Further, it was pointed out that there was an increased lipid peroxidation (LPO) with decreased antioxidants (CAT, SOD and GSH). These results concluded that Fx has the cytotoxic effect against KB cells and has the potential to induce the apoptosis via increased oxidative stress. Hence, the Fx can be a promising agent for the treatment of oral cancer and it may lead to the development of cancer therapeutics.

Fucoxanthin, a Marine-Derived Carotenoid from Brown Seaweeds and Microalgae: A Promising Bioactive Compound for Cancer Therapy

Fucoxanthin is a well-known carotenoid of the xanthophyll family, mainly produced by marine organisms such as the macroalgae of the fucus genus or microalgae such as Phaeodactylum tricornutum. Fucoxanthin has antioxidant and anti-inflammatory properties but also several anticancer effects. Fucoxanthin induces cell growth arrest, apoptosis, and/or autophagy in several cancer cell lines as well as in animal models of cancer. Fucoxanthin treatment leads to the inhibition of metastasis-related migration, invasion, epithelial–mesenchymal transition, and angiogenesis. Fucoxanthin also affects the DNA repair pathways, which could be involved in the resistance phenotype of tumor cells. Moreover, combined treatments of fucoxanthin, or its metabolite fucoxanthinol, with usual anticancer treatments can support conventional therapeutic strategies by reducing drug resistance. This review focuses on the current knowledge of fucoxanthin with its potential anticancer properties, showing that fucoxanthin could be a promising compound for cancer therapy by acting on most of the classical hallmarks of tumor cells.

Protein kinases as targets for developing anticancer agents from marine organisms

Protein kinases play a fundamental role in the intracellular transduction because of their ability to phosphorylate plethora of proteins. Over the past three decades, numerous protein kinase inhibitors have been identified and are being used clinically successfully. The biodiversity of marine organisms provides a rich source for the discovery and development of novel anticancer agents in the treatment of human malignancies and a lot of bioactive ingredients from marine organisms display anticancer effects by affecting the protein kinases-mediated pathways. In the present mini-review, anticancer compounds from marine source were reviewed and discussed in context of their targeted pathways associated with protein kinases and the progress of these compounds as anticancer agents in recent five years were emphasized. The molecular entities and their modes of actions were presented. We focused on protein kinases-mediated signaling pathways including PI3K/Akt/mTOR, p38 MAPK, and EGFR. The marine compounds targeting special pathways of protein kinases were highlighted. We have also discussed the existing challenges and prospects related to design and development of novel protein kinase inhibitors from marine sources.

Nutraceutical characteristics of the brown seaweed carotenoid fucoxanthin

Fucoxanthin (Fx), a major carotenoid found in brown seaweed, is known to show a unique and wide variety of biological activities. Upon absorption, Fx is metabolized to fucoxanthinol and amarouciaxanthin, and these metabolites mainly accumulate in visceral white adipose tissue (WAT). As seen in other carotenoids, Fx can quench singlet oxygen and scavenge a wide range of free radicals. The antioxidant activity is related to the neuroprotective, photoprotective, and hepatoprotective effects of Fx. Fx is also reported to show anti-cancer activity through the regulation of several biomolecules and signaling pathways that are involved in either cell cycle arrest, apoptosis, or metastasis suppression. Among the biological activities of Fx, anti-obesity is the most well-studied and most promising effect. This effect is primarily based on the upregulation of thermogenesis by uncoupling protein 1 expression and the increase in the metabolic rate induced by mitochondrial activation. In addition, Fx shows anti-diabetic effects by improving insulin resistance and promoting glucose utilization in skeletal muscle.

The Yemeni Brown Algae Dictyota dichotoma Exhibit High In Vitro Anticancer Activity Independent of Its Antioxidant Capability

The aim of this study was to investigate the anticancer and antioxidant activities as well as the safety of the brown algae Dictyota dichotoma of the Western seacoast of Yemen. Cytotoxicity of methanol extract of D. dichotoma and several of its fractions, petroleum ether, chloroform, ethyl acetate, n-butanol, and aqueous extracts against seven different cancer cell lines was determined by crystal violet staining. The antioxidant activity was also assessed using the DPPH radical scavenging assay. Acute toxicity study was performed on rats at increasing doses of the methanol extract. Extracts of D. dichotoma exerted a significant dose-dependent cytotoxicity on the seven tumor cell lines but were generally more selective on MCF-7 and PC-3. Among all fractions, the chloroform fraction of the D. dichotoma displayed the highest cytotoxic activity and was most effective in MCF-7, PC3, and CACO cells (IC50 = 1.93 ± 0.25, 2.2 ± 0.18, and 2.71 ± 0.53 μg/mL, respectively). The petroleum ether fraction was also effective, particularly against MCF-7 and PC-3 (IC50 = 4.77 ± 0.51 and 3.93 ± 0.51 μg/mL, respectively) whereas the activity of the ethyl acetate fraction was more pronounced against HepG2 and CACO (IC50 = 5.06 ± 0.21 and 5.06 ± 0.23 μg/mL, respectively). Of all the extracts tested, the crude methanolic extract of the algae exhibited only a modest antioxidant potential (IC50 = 204.6 ± 8.3 μg/mL). Doses as high as 5000 mg/kg body weight of D. dichotoma methanolic extracts were safe and well tolerated by rats. The overall results showed that D. dichotoma exhibited a significant cytotoxic activity probably due to the occurrence of nonpolar cytotoxic compounds, which is independent of its antioxidant capability.

Bioactive Compounds from Seaweed with Anti-Leukemic Activity: A Mini-Review on Carotenoids and Phlorotannins

Chronic Myeloid Leukemia (CML) represents 15-20% of all new cases of leukemia and is characterized by an uncontrolled proliferation of abnormal myeloid cells. Currently, the first-line of treatment involves Tyrosine Kinase Inhibitors (TKIs), which specifically inhibits the activity of the fusion protein BCR-ABL. However, resistance, mainly due to mutations, can occur. In the attempt to find more effective and less toxic therapies, several approaches are taken into consideration such as research of new anti-leukemic drugs and "combination chemotherapy" where different drugs that act by different mechanisms are used. Here, we reviewed the molecular mechanisms of CML, the main mechanisms of drug resistance and current strategies to enhance the therapeutic effect of TKIs in CML. Despite major advances in CML treatment, new, more potent anticancer drugs and with fewer side effects are needed. Marine organisms, and particularly seaweed, have a high diversity of bioactive compounds with some of them having anticancer activity in several in vitro and in vivo models. The state-of-art suggests that their use during cancer treatment may improve the outcome. We reviewed here the yet few data supporting anti-leukemic activity of some carotenoids and phlorotannins in some leukemia models. Also, strategies to overcome drug resistance are discussed, particularly the combination of conventional drugs with natural compounds.

Chemopreventive Effect of β-Cryptoxanthin on Human Cervical Carcinoma (HeLa) Cells Is Modulated through Oxidative Stress-Induced Apoptosis

The present study was aimed to assess cellular and molecular events involved in the chemopreventive activities of β-cryptoxanthin derived from mandarin oranges (Citrus unshiu Marc.) on human cervical carcinoma (HeLa) cells. In vitro experiments established that β-cryptoxanthin significantly inhibited the proliferation of HeLa cells with the IC₅₀ value of 4.5 and 3.7 µM after 24 and 48 h of treatments, respectively. β-cryptoxanthin-treated HeLa cells exhibited enhanced levels of oxidative stress correlated with significant downregulation of anti-apoptotic Bcl-2, and upregulation of pro-apoptotic Bax mRNA expression. Moreover, β-cryptoxanthin triggered nuclear condensation and disruption of the integrity of the mitochondrial membrane, upregulated caspase-3, -7, and -9 mRNA, and enhanced activation of caspase-3 proteins, resulting in nuclei DNA damage and apoptosis of HeLa cells. Remarkably, TUNEL assay carried out to detect nuclei DNA damage showed 52% TUNEL-positive cells after treatment with a physiological concentration of β-cryptoxanthin (1.0 μM), which validates its potential as an anticancer drug of natural origin.

Targeting hallmarks of cancer with a food-system-based approach

Although extensive resources are dedicated to the development and study of cancer drugs, the cancer burden is expected to rise by about 70% over the next 2 decade. This highlights a critical need to develop effective, evidence-based strategies for countering the global rise in cancer incidence. Except in high-risk populations, cancer drugs are not generally suitable for use in cancer prevention owing to potential side effects and substantial monetary costs (Sporn, 2011). There is overwhelming epidemiological and experimental evidence that the dietary bioactive compounds found in whole plant-based foods have significant anticancer and chemopreventative properties. These bioactive compounds often exert pleiotropic effects and act synergistically to simultaneously target multiple pathways of cancer. Common bioactive compounds in fruits and vegetables include carotenoids, glucosinolates, and polyphenols. These compounds have been shown to target multiple hallmarks of cancer in vitro and in vivo and potentially to address the diversity and heterogeneity of certain cancers. Although many studies have been conducted over the past 30 y, the scientific community has still not reached a consensus on exactly how the benefit of bioactive compounds in fruits and vegetables can be best harnessed to help reduce the risk for cancer. Different stages of the food processing system, from "farm-to-fork," can affect the retention of bioactive compounds and thus the chemopreventative properties of whole foods, and there are opportunities to improve handling of foods throughout the stages in order to best retain their chemopreventative properties. Potential target stages include, but are not limited to, pre- and postharvest management, storage, processing, and consumer practices. Therefore, there is a need for a comprehensive food-system-based approach that not only taking into account the effects of the food system on anticancer activity of whole foods, but also exploring solutions for consumers, policymakers, processors, and producers. Improved knowledge about this area of the food system can help us adjust farm-to-fork operations in order to consistently and predictably deliver desired bioactive compounds, thus better utilizing them as invaluable chemopreventative tools in the fight to reduce the growing burden of cancer worldwide.

Characterizing fucoxanthin as a selective dopamine D3/D4 receptor agonist: Relevance to Parkinson's disease

Fucoxanthin and fucosterol are archetypal lipid components of edible brown algae that provide several health benefits. Lately, their protective role in Aβ1-42-induced cognitive dysfunction in animal models has been reported (Alghazwi et al., 2019; Oh et al., 2018). However, their role in the aminergic system and as a prime treatment approach for multifactorial neurodegenerative diseases still requires exploration. The main aims of the present study are to characterize the role of fucoxanthin and fucosterol in the aminergic pathway via in vitro human monoamine oxidase (hMAO) inhibition and cell-based functional G-protein coupled receptor (GPCR) assays and to underline their possible mechanisms of action via in silico molecular docking studies. Fucoxanthin displayed weak inhibition with IC50 values of 197.41 ± 2.20 and 211.12 ± 1.17 μM over two isoenzymes hMAO-A and hMAO-B, respectively. Fucosterol remained inactive up to 500 μM. In functional assay results, fucoxanthin showed a concentration-dependent agonist effect on dopamine D3 and D4 receptors. The half maximal effective concentration (EC50) of fucoxanthin for dopamine D3 and D4 receptors was 16.87 ± 3.41 and 81.87 ± 6.11 μM, respectively. For dopamine as a reference agonist, the EC50 values for these two receptors were 3.7 and 24 nM, respectively. Fucosterol showed no agonist activity on any of the tested receptors. Similarly, fucoxanthin showed a mild antagonist effect on dopamine D1 and tachykinin (NK1) receptor with inhibition of control agonist response by approximately 40% at 100 μM. Fucosterol displayed mild antagonist effects only on dopamine D1 and D4 receptors. In silico studies revealed potential mechanisms by which fucoxanthin binds to dopamine receptors to exert its agonist effects, including low binding energy and H-bond interactions with Ser196 and Thr115 at the D3 receptor and with Ser196 and Asp115 at the D4 receptor. Our results collectively suggest that fucoxanthin is a potential D3/D4 agonist for the management of neurodegenerative diseases, such as Parkinson's disease.

Combined using of paclitaxel and salinomycin active targeting nanostructured lipid carriers against non-small cell lung cancer and cancer stem cells

The existing of avidity cancer stem cells (CSCs) made it an optical strategy to kill cancer cells and CSCs at the same time. Here, we constructed a CSCs specific nanocarrier naming T-S-NLC using the CD133+ targeting peptide TISWPPR (TR) as the targeting moiety attached to the distal end of PEG on salinomycin (Sal) loaded nanostructured lipid carriers (NLC), its pharmaceutical characteristics proved it 128.73 ± 2.09 nm, anionic spheroid with sustained release profile. It's in vitro targeting effect in CD133+ CSCs indicated that it exhibited superior CSCs internalization over non-modified NLC or free drug. Afterwards, it was used in combination with previously designed EGFR specific A-P-NLC (AEYLR peptide-PEG-modified paclitaxel loaded NLC) to achieve the goal to kill the cancer cells and CSCs, simultaneously. The in vitro tumor targeting effect of T-S-NLC + A-P-NLC was affirmed by cellular uptake and proliferation inhibition effect in NCI-H1299 and S180 cell lines showing advanced results over single preparation groups. In vivo tumor targeting effect in S180 tumor-bearing mice also validated the better tumor accumulative effect of the combined group. Last but not least, the in vivo antitumor effect strongly identified the greater tumor suppression effect of T-S-NLC + A-P-NLC than single preparation groups or combined use of free drugs while maintaining a good living state of the mice. To sum up, the combined usage of PTX and Sal active targeting NLC naming A-P-NLC + T-S-NLC which killed cancer cells and CSCs at the same time was a promising drug delivery system.

An in vivo anti-tumor effect of eckol from marine brown algae by improving the immune response

The anti-cancer activities of brown algae and some active extracts or components from brown algae have been demonstrated. But the anti-tumor activities of eckol, a new natural phlorotannin derived from marine brown algae, are poorly understood. In order to investigate the in vivo anti-tumor effect and its potential mechanisms of eckol in a sarcoma 180 (S180) xenograft-bearing animal model, S180 xenograft-bearing mice were randomly divided into 4 groups: model control, and eckol low-dose (0.25 mg kg-1), middle-dose (0.5 mg kg-1) and high-dose (1.0 mg kg-1) groups. After eckol administration, the tumor inhibition, tumor tissue histology, thymus index and spleen index were measured. The apoptotic tumor cells were detected using the terminal deoxynucleotidyl transferase mediated dUTP nick end labelling (TUNEL) assay. The protein expression levels of cleaved Caspase-3 and Caspase-9 (two key apoptotic proteins), Bcl-2 and Bax (two key anti-apoptosis-related genes), as well as epidermal growth factor receptor (EGFR, a well-known cell proliferation-stimulating molecule in tumorigenesis) and p-EGFR in tumor tissues were determined by western blot. A carbon particle clearance test, measurement of serum cytokine levels, a splenic T lymphocyte proliferation test, and T lymphocyte subpopulation analysis were used to evaluate the effect of eckol on the immune function of tumor-bearing mice. Moreover, CD11c+-dendritic cell (DC) infiltration in tumor tissues was detected by immunohistochemistry, and the surface molecules on bone marrow-derived DCs were analyzed using flow cytometry. The pro-apoptosis and anti-proliferation activities of eckol were manifested by the increased TUNEL-positive apoptotic cells, the upregulated Caspase-3 and Caspase-9 expression, and the downregulated expression of Bcl-2, Bax, EGFR and p-EGFR in eckol-treated transplanted S180 tumors. Most importantly, eckol stimulated the mononuclear phagocytic system, recruited and activated DCs, promoted the tumor-specific Th1 responses, increased the CD4+/CD8+ T lymphocyte ratio, and enhanced cytotoxic T lymphocyte responses in the eckol-treated animals, suggesting its potent stimulatory property on innate and adaptive immune responses. This study suggested that eckol might act as a functional food constituent derived from marine brown algae with a potential in vivo anti-tumor effect achieved by improving the immune response.

Algae metabolites: from in vitro growth inhibitory effects to promising anticancer activity

Covering: 1957 to 2017 Algae constitute a heterogeneous group of eukaryotic photosynthetic organisms, mainly found in the marine environment. Algae produce numerous metabolites that help them cope with the harsh conditions of the marine environment. Because of their structural diversity and uniqueness, these molecules have recently gained a lot of interest for the identification of medicinally useful agents, including those with potential anticancer activities. In the current review, which is not a catalogue-based one, we first highlight the major biological events that lead to various types of cancer, including metastatic ones, to chemoresistance, thus to any types of current anticancer treatment relating to the use of chemotherapeutics. We then review algal metabolites for which scientific literature reports anticancer activity. Lastly, we focus on algal metabolites with promising anticancer activity based on their ability to target biological characteristics of cancer cells responsible for poor treatment outcomes. Thus, we highlight compounds that have, among others, one or more of the following characteristics: selectivity in reducing the proliferation of cancer cells over normal ones, potential for killing cancer cells through non-apoptotic signaling pathways, ability to circumvent MDR-related efflux pumps, and activity in vivo in relevant pre-clinical models.

Fucoxanthin inhibits tumour-related lymphangiogenesis and growth of breast cancer

Tumour lymphangiogenesis plays an important role in promoting the growth and lymphatic metastasis of tumours. The process is associated with cell proliferation, migration and tube-like structure formation in lymphatic endothelial cells (LEC), but no antilymphangiogenic agent is currently used in clinical practice. Fucoxanthin is a material found in brown algae that holds promise in the context of drug development. Fucoxanthin is a carotenoid with variety of pharmacological functions, including antitumour and anti-inflammatory effects. The ability of fucoxanthin to inhibit lymphangiogenesis remains unclear. The results of experiments performed as part of this study show that fucoxanthin, extracted from Undaria pinnatifida (Wakame), inhibits proliferation, migration and formation of tube-like structures in human LEC (HLEC). In this study, fucoxanthin also suppressed the malignant phenotype in human breast cancer MDA-MB-231 cells and decreased tumour-induced lymphangiogenesis when used in combination with a conditional medium culture system. Fucoxanthin significantly decreased levels of vascular endothelial growth factor (VEGF)-C, VEGF receptor-3, nuclear factor kappa B, phospho-Akt and phospho-PI3K in HLEC. Fucoxanthin also decreased micro-lymphatic vascular density (micro-LVD) in a MDA-MB-231 nude mouse model of breast cancer. These findings suggest that fucoxanthin inhibits tumour-induced lymphangiogenesis in vitro and in vivo, highlighting its potential use as an antilymphangiogenic agent for antitumour metastatic comprehensive therapy in patients with breast cancer.

Lutein derived from marigold (Tagetes erecta) petals triggers ROS generation and activates Bax and caspase-3 mediated apoptosis of human cervical carcinoma (HeLa) cells

The present investigation was designed to determine molecular and cellular events involved in anticancer properties of lutein derived from marigold (Tagetes erecta) petals using Human cervical carcinoma (HeLa) cell lines. In vitro experiments demonstrated that lutein at concentration of 10 μM significantly inhibited proliferation of HeLa cells by up to 62.85% after 24 h of treatment and 84.85% after 48 h of treatment. In addition, lutein inhibited proliferation of HeLa cells in a dose-dependent manner by inducing apoptosis. Lutein-treated HeLa cells also showed enhanced accumulation of reactive oxygen species (ROS) correlated with significant downregulation of Bcl-2 (anti-apoptotic) expression and upregulation of Bax (pro-apoptotic) expression. Furthermore, lutein mediated activation of caspase-3 and imbalance between Bax and Bcl-2 expression, causing significant loss of mitochondrial membrane potential of HeLa cells. TUNEL assays revealed significant damage of nuclei DNA in lutein-treated HeLa cells, demonstrating a critical role of lutein in the final stage of apoptosis. Taken together, the results indicate that lutein-induced apoptosis of HeLa cells occurs through enhanced ROS production, interaction with mitochondrial factors, and upregulation of caspase-3-mediated pathway, leading to fragmentation of nuclei DNA. Therefore, lutein could be potentially useful as a chemotherapeutic and/or chemopreventive biomolecule against Human cervical carcinoma.

Leathesia difformis Extract Inhibits α-MSH-Induced Melanogenesis in B16F10 Cells via Down-Regulation of CREB Signaling Pathway

Leathesia difformis (L.) Areschoug (L. difformis) is a species of littoral brown algae of the class Phaeophyceae. Only a few studies on the apoptotic, antiviral, and antioxidant properties of L. difformis have been reported, and its inhibitory effect on melanin synthesis has not been studied. The aim of this study was to investigate the anti-melanogenic effect of L. difformis extract on α-melanocyte-stimulating hormone (α-MSH)-induced B16F10 melanocytes and its mechanism of action. L. difformis was extracted using 80% ethanol (LDE) and then fractioned between ethyl acetate (LDE-EA) and water (LDE-A). Our data demonstrated that LDE-EA significantly inhibited melanin level and cellular tyrosinase activity in α-MSH-stimulated B16 cells. In addition, the expression of genes associated with melanin synthesis, such as microphthalmia-associated transcription factor (Mitf), tyrosinase (Tyr), tyrosinase-related protein-1 (Trp-1), dopachrome tautomerase (Dct), and melanocortin 1 receptor (Mc1r) was down-regulated by LDE-EA treatment. Moreover, LDE-EA decreased p-CREB levels, which suggests that the inhibition of the cAMP/PKA/CREB pathways may be involved in the anti-melanogenic effect of LDE-EA. Thus, this study revealed that LDE-EA is an effective inhibitor of hyperpigmentation through inhibition of CREB pathways and may be considered as a potential therapeutic agent for hyperpigmentation disorders.

The anticancer effects and mechanisms of fucoxanthin combined with other drugs

PURPOSE

Fucoxanthin (Fx) is a characteristic carotenoid present in brown seaweed that has been shown to have various benefits, including anticancer effects. In vitro studies demonstrated these various effects, including the suppression of cell viability, the promotion of apoptosis, and antiangiogenic, antiproliferative, and antimetastatic activity. Interestingly, combinations of Fx with other drugs have better effects than either Fx or other drugs alone. Although the antiproliferative and cancer prevention activities of the combination of Fx and other drugs are still unclear, several effects have been discovered, including the induction of apoptosis, cell cycle arrest at G1/G0, enhanced gap junctional intercellular communication, and the induction of autophagy via various mechanisms, such as decreasing P-gp, activating the CYP3A4 promoter, increasing reactive oxygen species and cellular uptake and suppressing the PI3K/Akt/NFκB pathway. In this review, we address the anticancer effects and mechanisms of the combination of Fx and other drugs in different types of cancer.

METHODS

The relevant literature from PubMed and Web of Science databases is reviewed in this article.

RESULTS

Fx combined with other drugs could enhance the effect of both Fx and the other drug or reduce the dose without reducing the effect, which may create more effective and less harmful therapeutic strategies.

CONCLUSION

Fx combined with other drugs has significant anticancer effects by various mechanisms and could be a potential therapeutic strategy for different types of cancer.

Optical properties and antiangiogenic activity of a chalcone derivate

Chalcones and their derivatives exhibit numerous pharmacological activities such as antibacterial, antifungal, cytotoxic, antinociceptive and anti-inflammatory. Recently, they have been assessed aiming for novel application in nonlinear optics and in the treatment of immune diseases and cancers. In this study, we investigate the optical properties of synthetic chalcona 1E,4E-1-(4-chlorophenyl)-5-(2,6,6-trimethylcyclohexen-1-yl)penta-1,4-dien-3-one (CAB7β) and its antiangiogenic potential using the chorioallantoic membrane (CAM) with the S180 sarcoma cell line. Experimental and theoretical results show intense absorption in the UVA-UVC region, which is associated with a π → π* transition with intramolecular charge transfer from the trimethyl-cyclohexen-1-yl ring to the chlorophenyl ring. Quantum chemical calculations of the first hyperpolarizability, accounting for both solvent and frequency dispersion effects, are in very good concordance with hyper-Rayleigh scattering measurements. In addition, two-photon absorption allowed band centered at 650 nm was observed. Concerning antiangiogenic activity, CAB7β causes a significant reduction in the total number, junctions, length and caliber of blood vessels stimulated by S180 cells reducing the presence of blood vessels, inflammatory cells and others elements related to angiogenic process. It is found that CAB7β is a versatile compound and a promising candidate for linear and nonlinear optical applications, in therapy against sarcoma and phototherapy.

Seaweed Secondary Metabolites In Vitro and In Vivo Anticancer Activity

Isolation, finding or discovery of novel anticancer agents is very important for cancer treatment, and seaweeds are one of the largest producers of chemically active metabolites with valuable cytotoxic properties, and therefore can be used as new chemotherapeutic agents or source of inspiration to develop new ones. Identification of the more potent and selective anticancer components isolated from brown, green and red seaweeds, as well as studies of their mode of action is very attractive and constitute a small but relevant progress for pharmacological applications. Several researchers have carried out in vitro and in vivo studies in various cell lines and have disclosed the active metabolites among the terpenoids, including carotenoids, polyphenols and alkaloids that can be found in seaweeds. In this review the type of metabolites and their cytotoxic or antiproliferative effects will be discussed additionally their mode of action, structure-activity relationship and selectivity will also be revealed. The diterpene dictyolactone, the sterol cholest-5-en-3β,7α-diol and the halogenated monoterpene halomon are among the reported compounds, the ones that present sub-micromolar cytotoxicity. Additionally, one dimeric sesquiterpene of the cyclolaurane-type, three bromophenols and one halogenated monoterpene should be emphasized because they exhibit half maximal inhibitory concentration (IC₅₀) values between 1–5 µM against several cell lines.

Effects of fucoxanthin on autophagy and apoptosis in SGC-7901cells and the mechanism

Autophagy and apoptosis are involved in the development of a variety of cancers. Fucoxanthin is a natural compound known to have antitumor effects, so we aimed to explore its effects on autophagy and apoptosis in gastric cancer SGC7901 cells. Specifically, we performed methyl thiazolyl tetrazolium assay, transmission electron microscopy, real-time polymerase chain reaction, Western blot analysis, immunofluorescence assay, and cell apoptosis analysis to clarify the role of fucoxanthin in SGC-7901 cells. Our results indicate that fucoxanthin significantly inhibits the viability of SGC-7901 cells, effectively inducing both autophagy and apoptosis by up-regulating the expressions of beclin-1, LC3, and cleaved caspase-3 (CC3), and by down regulating Bcl-2. Fucoxanthin-induced autophagy also seems to occur before, and may promote apoptosis.

Hyperthermia with different temperatures inhibits proliferation and promotes apoptosis through the EGFR/STAT3 pathway in C6 rat glioma cells

Malignant gliomas are a group of aggressive neoplasms among human cancers. The curative effects of current treatments are finite for improving the prognosis of patients. Hyperthermia (HT) is an effective treatment for cancers; however, the effects of HT with different temperatures in treatment of MG and relevant mechanisms remain unclear. MTT assay and Annexin V-fluorescein isothiocyanate/propidium iodide staining were used for investigating the proliferation and apoptosis of C6 cells, respectively. Western blotting was applied to detect the expression of proteins. Ultrasonography was employed to evaluate the tumor formation rate, growth rate, angiogenesis rate and degree of hardness of tumors in vivo. The authors certified that HT with 42–46°C × 1 h, 1 t could inhibit proliferation, promote apoptosis, reduce tumor formation rate, growth rate, angiogenesis rate, degree of hardness of tumors, ischemic tolerance and anoxic tolerance, and have synergy with temozolomide in C6 cells. Long-term HT (43°C × 1 h, 1 t/5 d, 90 d) did not cut down the sensitivity of C6 cells to HT, and sustainably inhibited the proliferation of C6 cells. Furthermore, the authors proved HT produced these effects primarily through inhibition of the EGFR/STAT3/HIF-1A/VEGF-A pathway.

Antitumor Effects of Laminaria Extract Fucoxanthin on Lung Cancer

Lung cancer is the leading cause of cancer mortality worldwide and non-small-cell lung cancer (NSCLC) is the most common type. Marine plants provide rich resources for anticancer drug discovery. Fucoxanthin (FX), a Laminaria japonica extract, has attracted great research interest for its antitumor activities. Accumulating evidence suggests anti-proliferative effects of FX on many cancer cell lines including NSCLCs, but the detailed mechanisms remain unclear. In the present investigation, we confirmed molecular mechanisms and in vivo anti-lung cancer effect of FX at the first time. Flow cytometry, real-time PCR, western blotting and immunohistochemistry revealed that FX arrested cell cycle and induced apoptosis by modulating expression of p53, p21, Fas, PUMA, Bcl-2 and caspase-3/8. These results show that FX is a potent marine drug for human non-small-cell lung cancer treatment.

Synergistic antitumor efficacy of antibacterial helvolic acid from Cordyceps taii and cyclophosphamide in a tumor mouse model

The antibacterial agent helvolic acid, which was isolated from the active antitumor fraction of Cordyceps taii, showed potent cytotoxicity against different human cancer cells. In the present study, the in vivo antitumor effect of helvolic acid was investigated in murine sarcoma S180 tumor-bearing mice. Doses of 10 and 20 mg/kg/day helvolic acid did not exert significant antitumor activity. Interestingly, co-administration of 10 mg/kg/day helvolic acid and 20 mg/kg/day cyclophosphamide (CTX) - a well-known chemotherapy drug - showed promising antitumor activity with a growth inhibitory rate of 70.90%, which was much higher than that of CTX alone (19.5%). Furthermore, the combination markedly prolonged the survival of tumor-bearing mice. In addition, helvolic acid enhanced the immune organ index. The protein expression levels of β-catenin, cyclin D1, and proliferating cell nuclear antigen were significantly suppressed in mice treated with 20 mg/kg/day helvolic acid and in those receiving combination therapy. Taken together, these results indicated that helvolic acid in combination with CTX showed potent in vivo synergistic antitumor efficacy, and its mechanism of action may involve the Wnt/ β-catenin signaling pathway.

Kinetics and molecular docking studies of fucosterol and fucoxanthin, BACE1 inhibitors from brown algae Undaria pinnatifida and Ecklonia stolonifera

Since the action of β-site amyloid precursor protein cleaving enzyme 1 (BACE1) is strongly correlated with the onset of Alzheimer's disease (AD), the development of BACE1 inhibitors as therapeutic agents is being vigorously pursued. In our ongoing research aimed at identifying anti-AD remedies derived from maritime plants, we evaluated the BACE1 inhibitory activities of fucosterol and fucoxanthin from Ecklonia stolonifera and Undaria pinnatifida. In vitro anti-AD activities were performed via BACE1 inhibition assays, as well as enzyme kinetic and molecular docking predictions. Based on enzyme-based assays, fucosterol and fucoxanthin showed noncompetitive and mixed-type inhibition, respectively, against BACE1. In addition, docking simulation results demonstrated that the Lys224 residue of BACE1 interacted with one hydroxyl group of fucosterol, while two additional BACE1 residues (Gly11 and Ala127) interacted with two hydroxyl groups of fucoxanthin. Moreover, the binding energy of fucosterol and fucoxanthin was negative (-10.1 and -7.0 kcal/mol), indicating that hydrogen bonding may stabilize the open form of the enzyme and potentiate tight binding of the active site of BACE1, resulting in more effective BACE1 inhibition. The results suggest that fucosterol and fucoxanthin may be used beneficially in the treatment of AD and provide potential guidelines for the design of new BACE1 inhibitors.

Inhibition of Ultraviolet B-Induced Expression of the Proinflammatory Cytokines TNF-α and VEGF in the Cornea by Fucoxanthin Treatment in a Rat Model

Ultraviolet B (UVB) irradiation is the most common cause of radiation damage to the eyeball and is a risk factor for human corneal damage. We determined the protective effect of fucoxanthin, which is a carotenoid found in common edible seaweed, on ocular tissues against oxidative UVB-induced corneal injury. The experimental rats were intravenously injected with fucoxanthin at doses of 0.5, 5 mg/kg body weight/day or with a vehicle before UVB irradiation. Lissamine green for corneal surface staining showed that UVB irradiation caused serious damage on the corneal surface, including severe epithelial exfoliation and deteriorated epithelial smoothness. Histopathological lesion examination revealed that levels of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF), significantly increased. However, pretreatment with fucoxanthin inhibited UVB radiation-induced corneal disorders including evident preservation of corneal surface smoothness, downregulation of proinflammatory cytokine expression, and decrease of infiltrated polymorphonuclear leukocytes from UVB-induced damage. Moreover, significant preservation of the epithelial integrity and inhibition of stromal swelling were also observed after UVB irradiation in fucoxanthin-treated groups. Pretreatment with fucoxanthin may protect against UVB radiation-induced corneal disorders by inhibiting expression of proinflammatory factors, TNF-α, and VEGF and by blocking polymorphonuclear leukocyte infiltration.

Fucoxanthin and Its Metabolite Fucoxanthinol in Cancer Prevention and Treatment

Fucoxanthin is a carotenoid present in the chloroplasts of brown seaweeds. When ingested, it is metabolized mainly to fucoxanthinol by digestive enzymes of the gastrointestinal tract. These compounds have been shown to have many beneficial health effects, including anti-mutagenic, anti-diabetic, anti-obesity, anti-inflammatory and anti-neoplastic actions. In every cancer tested, modulatory actions of fucoxanthinol on viability, cell-cycle arrest, apoptosis and members of the NF-κB pathway were more pronounced than that of fucoxanthin. Anti-proliferative and cancer preventing influences of fucoxanthin and fucoxanthinol are mediated through different signalling pathways, including the caspases, Bcl-2 proteins, MAPK, PI3K/Akt, JAK/STAT, AP-1, GADD45, and several other molecules that are involved in cell cycle arrest, apoptosis, anti-angiogenesis or inhibition of metastasis. In this review, we address the mechanisms of action of fucoxanthin and fucoxanthinol according to different types of cancers. Current findings suggest that these compounds could be effective for treatment and/or prevention of cancer development and aggressiveness.

Fucoxanthin: A Promising Medicinal and Nutritional Ingredient

Fucoxanthin, an allenic carotenoid, can be isolated from edible brown seaweeds. Recent studies have reported that fucoxanthin has many physiological functions and biological properties, such as antiobesity, antitumor, antidiabetes, antioxidant, anti-inflammatory, and hepatoprotective activities, as well as cardiovascular and cerebrovascular protective effects. Therefore, fucoxanthin can be used as both medicinal and nutritional ingredient to prevent and treat chronic diseases. Although fucoxanthin possesses many medicinal ingredient and nutritional qualities, studies indicated that its structure was unstable. In this paper, we consulted the current documents and reviewed structural properties and factors affecting the stability of fucoxanthin. We also reported the metabolism, safety, pharmacological activities, and the methods of improving the bioavailability of fucoxanthin. Based on these studies providing essential background knowledge, fucoxanthin can be developed into marine drugs and nutritional products.

A novel anticancer diarylurea derivative HL-40 as a multi-kinases inhibitor with good pharmacokinetics in Wistar rats

HL-40, N-(4-(1-(4-chlorine indazole)) phenyl)-N-(4-chloro-3-three fluorine methyl phenyl) urea, is a novel diarylurea derivative. In this study, we investigated the kinases activities and binding constants, pharmacokinetics of HL-40, and then evaluated its anticancer efficacy by both in vitro and in vivo methods. Enzyme activities assays in vitro were employed to identify eight candidate kinase targets. The competition binding assays against eight candidate kinases suggested that HL-40 showed strong affinity to c-Kit, PDGFRβ and FLT3. The pharmacokinetic studies in Wistar rats showed that HL-40 could maintain high compound concentration and long residence time in the blood circulation. HL-40 possessed strong inhibition activities against 12 human cancer cells. Meanwhile, HL-40 effectively delayed the growth of cancer xenografts without significant toxicity to mice. Based on these in vitro and in vivo results, we suggested that HL-40 might be developed as a potential multi-kinases inhibitor for cancer treatment.

Reactive oxygen species and autophagy modulation in non-marine drugs and marine drugs

It is becoming more understandable that an existing challenge for translational research is the development of pharmaceuticals that appropriately target reactive oxygen species (ROS)-mediated molecular networks in cancer cells. In line with this approach, there is an overwhelmingly increasing list of many non-marine drugs and marine drugs reported to be involved in inhibiting and suppressing cancer progression through ROS-mediated cell death. In this review, we describe the strategy of oxidative stress-based therapy and connect the ROS modulating effect to the regulation of apoptosis and autophagy. Finally, we focus on exploring the function and mechanism of cancer therapy by the autophagy modulators including inhibitors and inducers from non-marine drugs and marine drugs.

Inhibitory effects of fucoxanthinol on the viability of human breast cancer cell lines MCF-7 and MDA-MB-231 are correlated with modulation of the NF-kappaB pathway

Fucoxanthin is a carotenoid present in the chloroplasts of brown seaweeds. When ingested, it is metabolized mainly to fucoxanthinol in the gastrointestinal tract by digestive enzymes. These compounds have been shown to have many beneficial health effects. The present study was designed to evaluate the molecular mechanisms of action of fucoxanthin and/or of its metabolite fucoxanthinol against viability of estrogen-sensitive MCF-7 and estrogen-resistant MDA-MB-231 breast cancer cell lines. Fucoxanthin and fucoxanthinol reduced the viability of MCF-7 and MDA-MB-231 cells in dose- and time-dependent manners as a result of increased apoptosis. Furthermore, fucoxanthinol-induced apoptosis was more potent than that of fucoxanthin and correlated, for MDA-MB-231 cells, with inhibitory actions on members of the NF-κB pathway p65, p50, RelB, and p52. Being overexpressed and regulated by NF-κB in different types of cancers, the transcription factor SOX9 was also decreased at the nuclear level by fucoxanthin and fucoxanthinol in MDA-MB-231. Taken together, the current results suggest that fucoxanthinol and fucoxanthin could be potentially effective for the treatment and/or prevention of different types of cancers, including breast cancer.

Fucoxanthin: a marine carotenoid exerting anti-cancer effects by affecting multiple mechanisms

Fucoxanthin is a marine carotenoid exhibiting several health benefits. The anti-cancer effect of fucoxanthin and its deacetylated metabolite, fucoxanthinol, is well documented. In view of its potent anti-carcinogenic activity, the need to understand the underlying mechanisms has gained prominence. Towards achieving this goal, several researchers have carried out studies in various cell lines and in vivo and have deciphered that fucoxanthin exerts its anti-proliferative and cancer preventing influence via different molecules and pathways including the Bcl-2 proteins, MAPK, NFκB, Caspases, GADD45, and several other molecules that are involved in either cell cycle arrest, apoptosis, or metastasis. Thus, in addition to decreasing the frequency of occurrence and growth of tumours, fucoxanthin has a cytotoxic effect on cancer cells. Some studies show that this effect is selective, i.e., fucoxanthin has the capability to target cancer cells only, leaving normal physiological cells unaffected/less affected. Hence, fucoxanthin and its metabolites show great promise as chemotherapeutic agents in cancer.