Structure and Metabolically Oriented Efficacy of Fucoidan from Brown Alga Sargassum muticum in the Model of Colony Formation of Melanoma and Breast Cancer Cells.

This work reports the detailed structure of fucoidan from Sargassum miticum (2SmF2) and its ability to potentiate the inhibitory effect of glycolysis inhibitor 2-deoxy-d-glucose (2-DG). 2SmF2 was shown to be sulfated and acetylated galactofucan containing a main chain of alternating residues of 1,3- and 1,4-linked α-l-fucopyranose, fucose fragments with monotonous 1,3- and 1,4-type linkages (DP up to 3), α-d-Gal-(1→3)-α-L-Fuc disaccharides, and 1,3,4- and 1,2,4-linked fucose branching points. The sulfate groups were found at positions 2 and 4 of fucose and galactose residues. 2SmF2 (up to 800 µg/mL) and 2-DG (up to 8 mM) were not cytotoxic against MDA-MB-231 and SK-MEL-28 as determined by MTS assay. In the soft agar-based model of cancer cell colony formation, fucoidan exhibited weak inhibitory activity at the concentration of 400 µg/mL. However, in combination with low non-cytotoxic concentrations of 2-DG (0.5 or 2 mM), 2SmF2 could effectively inhibit the colony formation of SK-MEL-28 and MDA-MB-231 cells and decreased the number of colonies by more than 50% compared to control at the concentration of 200 µg/mL. Our findings reveal the metabolically oriented effect of fucoidan in combination with a glycolysis inhibitor that may be beneficial for a therapy for aggressive cancers.

The Combined Metabolically Oriented Effect of Fucoidan from the Brown Alga Saccharina cichorioides and Its Carboxymethylated Derivative with 2-Deoxy-D-Glucose on Human Melanoma Cells.

Melanoma is the most aggressive and treatment-resistant form of skin cancer. It is phenotypically characterized by aerobic glycolysis that provides higher proliferative rates and resistance to cell death. The glycolysis regulation in melanoma cells by means of effective metabolic modifiers represents a promising therapeutic opportunity. This work aimed to assess the metabolically oriented effect and mechanism of action of fucoidan from the brown alga Saccharina cichorioides (ScF) and its carboxymethylated derivative (ScFCM) in combination with 2-deoxy-D-glucose (2-DG) on the proliferation and colony formation of human melanoma cell lines SK-MEL-28, SK-MEL-5, and RPMI-7951. The metabolic profile of melanoma cells was determined by the glucose uptake and Lactate-GloTM assays. The effect of 2-DG, ScF, ScFCM, and their combination on the proliferation, colony formation, and activity of glycolytic enzymes was assessed by the MTS, soft agar, and Western blot methods, respectively. When applied separately, 2-DG (IC50 at 72 h = 8.7 mM), ScF (IC50 at 72 h > 800 µg/mL), and ScFCM (IC50 at 72 h = 573.9 µg/mL) inhibited the proliferation and colony formation of SK-MEL-28 cells to varying degrees. ScF or ScFCM enhanced the inhibiting effect of 2-DG at low, non-toxic concentrations via the downregulation of Glut 1, Hexokinase II, PKM2, LDHA, and pyruvate dehydrogenase activities. The obtained results emphasize the potential of the use of 2-DG in combination with algal fucoidan or its derivative as metabolic modifiers for inhibition of melanoma SK-MEL-28 cell proliferation.

The Discovery of the Fucoidan-Active Endo-1→4-α-L-Fucanase of the GH168 Family, Which Produces Fucoidan Derivatives with Regular Sulfation and Anticoagulant Activity.

Sulfated polysaccharides of brown algae, fucoidans, are known for their anticoagulant properties, similar to animal heparin. Their complex and irregular structure is the main bottleneck in standardization and in defining the relationship between their structure and bioactivity. Fucoidan-active enzymes can be effective tools to overcome these problems. In the present work, we identified the gene fwf5 encoding the fucoidan-active endo-fucanase of the GH168 family in the marine bacterium Wenyingzhuangia fucanilytica CZ1127T. The biochemical characteristics of the recombinant fucanase FWf5 were investigated. Fucanase FWf5 was shown to catalyze the endo-type cleavage of the 1→4-O-glycosidic linkages between 2-O-sulfated α-L-fucose residues in fucoidans composed of the alternating 1→3- and 1→4-linked residues of sulfated α-L-fucose. This is the first report on the endo-1→4-α-L-fucanases (EC 3.2.1.212) of the GH168 family. The endo-fucanase FWf5 was used to selectively produce high- and low-molecular-weight fucoidan derivatives containing either regular alternating 2-O- and 2,4-di-O-sulfation or regular 2-O-sulfation. The polymeric 2,4-di-O-sulfated fucoidan derivative was shown to have significantly greater in vitro anticoagulant properties than 2-O-sulfated derivatives. The results have demonstrated a new type specificity among fucanases of the GH168 family and the prospects of using such enzymes to obtain standard fucoidan preparations with regular sulfation and high anticoagulant properties.

The role of T-LAK cell-originated protein kinase in targeted cancer therapy.

Targeted therapy has gradually become the first-line clinical tumor therapy due to its high specificity and low rate of side effects. TOPK (T-LAK cell-originated protein kinase), a MAP kinase, is highly expressed in various tumor tissues, while it is rarely expressed in normal tissues, with the exceptions of testicular germ cells and some fetal tissues. It can promote cancer cell proliferation and migration and is also related to drug resistance. Therefore, TOPK is considered a good therapeutic target. Moreover, a number of studies have shown that targeting TOPK can inhibit the proliferation of cancer cells and promote their apoptosis. Here, we discussed the biological functions of TOPK in cancer and summarized its tumor-related signaling network and known TOPK inhibitors. Finally, the role of TOPK in targeted cancer therapy was concluded, and future research directions for TOPK were assessed.

Molecular Targets of Brown Algae Phlorotannins for the Therapy of Inflammatory Processes of Various Origins.

Inflammatory reactions are part of a complex biological response that plays a vital role in the appearance of various stimuli resulting from tissue and cell damage, the invasion of pathogenic bacteria, and the formation of the subsequent adaptive immune response. The production of many triggers and mediators of inflammation, which are inducers of pro-inflammatory factors, is controlled by numerous differentiation programs, through which inflammation is resolved and tissue homeostasis is restored. However, prolonged inflammatory responses or dysregulation of pro-inflammatory mechanisms can lead to chronic inflammation. Modern advances in biotechnology have made it possible to characterize the anti-inflammatory activity of phlorotannins, polyphenolic compounds from brown seaweed, and the mechanisms by which they modulate the inflammatory response. The purpose of this review is to analyze and summarize the results of numerous experimental in vitro and in vivo studies, illustrating the regulatory mechanisms of these compounds, which have a wide range of biological effects on the body. The results of these studies and the need for further research are discussed.

Disulfated Ophiuroid Type Steroids from the Far Eastern Starfish Pteraster marsippus and Their Cytotoxic Activity on the Models of 2D and 3D Cultures.

New steroidal 3ß,21-disulfates (2-4), steroidal 3ß,22-disulfate (5), and the previously known related steroidal 3ß,21-disulfate (1) were isolated from the ethanolic extract of the Far Eastern starfish Pteraster marsippus, collected off Urup Island in the Sea of Okhotsk. The structures of these compounds were determined by intensive NMR and HRESIMS techniques as well as by chemical transformations. Steroids 2 and 3 have an oxo-group in the tetracyclic nucleus at position C-7 and differ from each other by the presence of the 5(6)-double bond. The Δ24-22-sulfoxycholestane side chain of the steroid 5 has not been found previously in the starfish or ophiuroid steroids. The cytotoxic activities of 1, 4, 5, and the mixture of 2 and 3 were determined on the models of 2D and 3D cultures of human epithelial kidney cells (HEK293), melanoma cells (SK-MEL-28), small intestine carcinoma cells (HuTu80), and breast carcinoma cells (ZR-75-1). The mixture of 2 and 3 revealed a significant inhibitory effect on the cell viability of human breast carcinoma ZR-75-1 cells, but other tested compounds were less effective.

Combined Anticancer Effect of Sulfated Laminaran from the Brown Alga Alaria angusta and Polyhydroxysteroid Glycosides from the Starfish Protoreaster lincki on 3D Colorectal Carcinoma HCT 116 Cell Line.

Colorectal cancer is one of the most frequent types of malignancy in the world. The search for new approaches of increasing the efficacy of cancer therapy is relevant. This work was aimed to study individual, combined anticancer effects, and molecular mechanism of action of sulfated laminaran AaLs of the brown alga Alaria angusta and protolinckiosides A (PL1), B (PL2), and linckoside L1 (L1) of the starfish Protoreaster lincki using a 3D cell culture model. The 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS), soft agar, 3D spheroids invasion, and Western blotting assays were performed to determine the effect and mechanism of the action of investigated compounds or their combinations on proliferation, colony formation, and the invasion of 3D HCT 116 spheroids. AaLs, PL1, PL2, and L1 individually inhibited viability, colony growth, and the invasion of 3D HCT 116 spheroids in a variable degree with greater activity of linckoside L1. AaLs in combination with L1 exerted synergism of a combined anticancer effect through the inactivation of protein kinase B (AKT) kinase and, consequently, the induction of apoptosis via the regulation of proapoptotic/antiapoptotic proteins balance. The obtained data about the efficacy of the combined anticancer effect of a laminaran derivative of brown algae and polyhydroxysteroid glycosides of starfish open up prospects for the development of new therapeutic approaches for colorectal cancer treatment.

In Vitro Anti-Orthohantavirus Activity of the High-and Low-Molecular-Weight Fractions of Fucoidan from the Brown Alga Fucus evanescens.

The Hantaan orthohantavirus (genovariant Amur-AMRV) is a rodent-borne zoonotic virus; it is the causative agent of haemorrhagic fever with renal syndrome in humans. The currently limited therapeutic options require the development of effective anti-orthohantavirus drugs. The ability of native fucoidan from Fucus evanescens (FeF) and its enzymatically prepared high-molecular-weight (FeHMP) and low-molecular-weight (FeLMP) fractions to inhibit different stages of AMRV infection in Vero cells was studied. The structures of derivatives obtained were determined using nuclear magnetic resonance (NMR) spectroscopy. We found that fucoidan and its derivatives exhibited significant antiviral activity by affecting the early stages of the AMRV lifecycle, notably virus attachment and penetration. The FeHMP and FeLMP fractions showed the highest anti-adsorption activity by inhibiting AMRV focus formation, with a selective index (SI) > 110; FeF had an SI of ~70. The FeLMP fraction showed a greater virucidal effect compared with FeF and the FeHMP fraction. It was shown by molecular docking that 2O-sulphated fucotetrasaccharide, a main component of the FeLMP fraction, is able to bind with the AMRV envelope glycoproteins Gn/Gc and with integrin ß3 to prevent virus-cell interactions. The relatively small size of these sites of interactions explains the higher anti-AMRV activity of the FeLMP fraction.

Antiparasitic Effects of Sulfated Polysaccharides from Marine Hydrobionts.

This review presents materials characterizing sulfated polysaccharides (SPS) of marine hydrobionts (algae and invertebrates) as potential means for the prevention and treatment of protozoa and helminthiasis. The authors have summarized the literature on the pathogenetic targets of protozoa on the host cells and on the antiparasitic potential of polysaccharides from red, brown and green algae as well as certain marine invertebrates. Information about the mechanisms of action of these unique compounds in diseases caused by protozoa has also been summarized. SPS is distinguished by high antiparasitic activity, good solubility and an almost complete absence of toxicity. In the long term, this allows for the consideration of these compounds as effective and attractive candidates on which to base drugs, biologically active food additives and functional food products with antiparasitic activity.

Extracts and Marine Algae Polysaccharides in Therapy and Prevention of Inflammatory Diseases of the Intestine.

Inflammatory bowel disease (IBD) is a serious public health problem worldwide. Current therapeutic strategies that use anti-inflammatory drugs, immunosuppressants, and biological treatments are often ineffective and have adverse health effects. In this regard, the use of natural compounds aimed at key pathogenic therapeutic targets in IBD attracts universal attention. Seaweed is a valuable source of structurally diverse biologically active compounds. The materials presented in the review indicate that seaweed extracts and polysaccharides are effective candidates for the development of drugs, biological food additives, and functional nutrition products for the treatment and prevention of IBD. The structural features of algal polysaccharides provide the possibility of exposure to therapeutic targets of IBD, including proinflammatory cytokines, chemokines, adhesion molecules, nuclear factor NF-kB, intestinal epithelial cells, reactive oxygen and nitrogen. Further study of the relationship between the effect of polysaccharides from different types of algae, with different structure and molecular weights on immune and epithelial cells, intestinal microorganisms will contribute to a deeper understanding of their mechanisms and will help in the development of drugs, dietary supplements, functional foods for the treatment of patients with IBD.

Functional Characterization of a New GH107 Endo-α-(1,4)-Fucoidanase from the Marine Bacterium Formosa haliotis.

Fucoidans from brown macroalgae are sulfated fucose-rich polysaccharides, that have several beneficial biological activities, including anti-inflammatory and anti-tumor effects. Controlled enzymatic depolymerization of the fucoidan backbone can help produce homogeneous, defined fucoidan products for structure-function research and pharmaceutical uses. However, only a few endo-fucoidanases have been described. This article reports the genome-based discovery, recombinant expression in Escherichia coli, stabilization, and functional characterization of a new bacterial endo-α-(1,4)-fucoidanase, Fhf1, from Formosa haliotis. Fhf1 catalyzes the cleavage of α-(1,4)-glycosidic linkages in fucoidans built of alternating α-(1,3)-/α-(1,4)-linked l-fucopyranosyl sulfated at C2. The native Fhf1 is 1120 amino acids long and belongs to glycoside hydrolase (GH) family 107. Deletion of the signal peptide and a 470 amino acid long C-terminal stretch led to the recombinant expression of a robust, minimized enzyme, Fhf1Δ470 (71 kDa). Fhf1Δ470 has optimal activity at pH 8, 37-40 °C, can tolerate up to 500 mM NaCl, and requires the presence of divalent cations, either Ca2+, Mn2+, Zn2+ or Ni2+, for maximal activity. This new enzyme has the potential to serve the need for controlled enzymatic fucoidan depolymerization to produce bioactive sulfated fucoidan oligomers.

Structures and Bioactivities of Quadrangularisosides A, A1, B, B1, B2, C, C1, D, D1-D4, and E from the Sea Cucumber Colochirus quadrangularis: The First Discovery of the Glycosides, Sulfated by C-4 of the Terminal 3-O-Methylglucose Residue. Synergetic Effect on Colony Formation of Tumor HT-29 Cells of these Glycosides with Radioactive Irradiation.

Thirteen new mono-, di-, and trisulfated triterpene glycosides, quadrangularisosides A-D4 (1-13) have been isolated from the sea cucumber Colochirus quadrangularis, which was collected in Vietnamese waters. The structures of these glycosides were established by 2D NMR spectroscopy and HR-ESI (High Resolution Electrospray Ionization) mass spectrometry. The novel carbohydrate moieties of quadrangularisosides D-D4 (8-12), belonging to the group D, and quadrangularisoside E (13) contain three sulfate groups, with one of them occupying an unusual position-at C(4) of terminal 3-O-methylglucose residue. Quadrangularisosides A (1) and D3 (11) as well as quadrangularisosides A1 (2) and D4 (12) are characterized by the new aglycones having 25-hydroperoxyl or 24-hydroperoxyl groups in their side chains, respectively. The cytotoxic activities of compounds 1-13 against mouse neuroblastoma Neuro 2a, normal epithelial JB-6 cells, erythrocytes, and human colorectal adenocarcinoma HT-29 cells were studied. All the compounds were rather strong hemolytics. The structural features that most affect the bioactivity of the glycosides are the presence of hydroperoxy groups in the side chains and the quantity of sulfate groups. The membranolytic activity of monosulfated quadrangularisosides of group A (1, 2) against Neuro 2a, JB-6 cells, and erythrocytes was relatively weak due to the availability of the hydroperoxyl group, whereas trisulfated quadrangularisosides D3 (11) and D4 (12) with the same aglycones as 1, 2 were the least active compounds in the series due to the combination of these two structural peculiarities. The erythrocytes were more sensitive to the action of the glycosides than Neuro 2a or JB-6 cells, but the structure-activity relationships observed for glycosides 1-13 were similar in the three cell lines investigated. The compounds 3-5, 8, and 9 effectively suppressed the cell viability of HT-29 cells. Quadrangularisosides A1 (2), C (6), C1 (7), and E (13) possessed strong inhibitory activity on colony formation in HT-29 cells. Due to the synergic effects of these glycosides (0.02 µM) and radioactive irradiation (1 Gy), a decreasing of number of colonies was detected. Glycosides 1, 3, and 9 enhanced the effect of radiation by about 30%.

The Comparative Analysis of Antiviral Activity of Native and Modified Fucoidans from Brown Algae Fucus evanescens In Vitro and In Vivo.

The enzymatic depolymerization of fucoidans from brown algae allowed the production of their standardized derivatives with different biological activities. This work aimed to compare the antiviral activities of native (FeF) and modified with enzyme (FeHMP) fucoidans from F. evanescens. The cytotoxicity and antiviral activities of the FeF and FeHMP against herpes viruses (HSV-1, HSV-2), enterovirus (ECHO-1), and human immunodeficiency virus (HIV-1) in Vero and human MT-4 cell lines were examined by methylthiazolyltetrazolium bromide (MTT) and cytopathic effect (CPE) reduction assays, respectively. The efficacy of fucoidans in vivo was evaluated in the outbred mice model of vaginitis caused by HSV-2. We have shown that both FeF and FeHMP significantly inhibited virus-induced CPE in vitro and were more effective against HSV. FeF exhibited antiviral activity against HSV-2 with a selective index (SI) > 40, and FeHMP with SI ˃ 20, when they were added before virus infection or at the early stages of the HSV-2 lifecycle. Furthermore, in vivo studies showed that after intraperitoneal administration (10 mg/kg), both FeF and FeHMP protected mice from lethal intravaginal HSV-2 infection to approximately the same degree (44-56%). Thus, FeF and FeHMP have comparable potency against several DNA and RNA viruses, allowing us to consider the studied fucoidans as promising broad-spectrum antivirals.

Immunoadjuvant Activity of Fucoidans from the Brown Alga Fucus evanescens.

Thе study presents the results of a comparative evaluation of the effect of structural modifications of fucoidans from the brown alga Fucus evanescens (native, highly purified рroduct of fucoidan enzymatic hydrolysis, a new regular 1→3;1→4-α-L-fucan, sulphated mainly at C2 and acetylated at C4 of the fucose residue) on the effector functions of innate and adaptive immunity cells in vitro and in vivo. Using flow cytometry, we found that all examined fucoidans induce the maturation of dendritic cells, enhance the ability of neutrophils to migrate and adhere, activate monocytes and enhance their antigen-presenting functions, and increase the cytotoxic potential of natural killers. Fucoidans increase the production of hepatitis B virus (HBs) specific IgG and cytokine Th1 (IFN-γ, TNF-α) and Th2 (IL-4) profiles in vivo. The data obtained suggest that in vitro and in vivo adjuvant effects of the products of fucoidan enzymatic hydrolysis with regular structural characteristics are comparable to those of the native fucoidan. Based on these data, the products of fucoidan enzymatic hydrolysis can be considered as an effective and safe candidate adjuvant to improve the efficacy of prophylactic and therapeutic vaccines.

In Vitro Anticancer and Radiosensitizing Activities of Phlorethols from the Brown Alga Costaria costata.

The anticancer and radiosensitizing effects of high-molecular-weight phlorethols CcPh (Mw = 2520 Da) isolated from the brown algae of Costaria costata on human colorectal carcinoma HCT 116 and HT-29 cells were investigated. Phlorethols CcPh possessed cytotoxic activity against HT-29 (IC50 = 92 µg/mL) and HCT 116 (IC50 = 94 µg/mL) cells. CcPh at non-toxic concentrations inhibited the colony formation in colon cancer cells and significantly enhanced their sensitivity to low non-toxic X-ray irradiation. The combinatory effect of radiation and CcPh was synergistic (Combination index < 0.7). Algal phlorethols might be prospective candidates as radiosensitizers to improve the scheme of radiotherapy.

Structures and Bioactivities of Six New Triterpene Glycosides, Psolusosides E, F, G, H, H1, and I and the Corrected Structure of Psolusoside B from the Sea Cucumber Psolus fabricii.

Seven sulfated triterpene glycosides, psolusosides B (1), E (2), F (3), G (4), H (5), H1 (6), and I (7), along with earlier known psolusoside A and colochiroside D have been isolated from the sea cucumber Psolus fabricii collected in the Sea of Okhotsk. Herein, the structure of psolusoside B (1), elucidated by us in 1989 as a monosulfated tetraoside, has been revised with application of modern NMR and particularly MS data and proved to be a disulfated tetraoside. The structures of other glycosides were elucidated by 2D NMR spectroscopy and HR-ESI mass-spectrometry. Psolusosides E (2), F (3), and G (4) contain holostane aglycones identical to each other and differ in their sugar compositions and the quantity and position of sulfate groups in linear tetrasaccharide carbohydrate moieties. Psolusosides H (5) and H1 (6) are characterized by an unusual sulfated trisaccharide carbohydrate moiety with the glucose as the second sugar unit. Psolusoside I (7) has an unprecedented branched tetrasaccharide disulfated carbohydrate moiety with the xylose unit in the second position of the chain. The cytotoxic activities of the compounds 2-7 against several mouse cell lines-ascite form of Ehrlich carcinoma, neuroblastoma Neuro 2A, normal epithelial JB-6 cells, and erythrocytes-were quite different, at that hemolytic effects of the tested compounds were higher than their cytotoxicity against other cells, especially against the ascites of Ehrlich carcinoma. Interestingly, psolusoside G (4) was not cytotoxic against normal JB-6 cells but demonstrated high activity against Neuro 2A cells. The cytotoxic activity against human colorectal adenocarcinoma HT-29 cells and the influence on the colony formation and growth of HT-29 cells of compounds 1-3, 5-7 and psolusoside A was checked. The highest inhibitory activities were demonstrated by psolusosides E (2) and F (3).

Total Syntheses and Preliminary Biological Evaluation of Brominated Fascaplysin and Reticulatine Alkaloids and Their Analogues.

A simple approach toward the synthesis of the marine sponge derived pigment fascaplysin was used to obtain the marine alkaloids 3-bromofascaplysin and 3,10-dibromofascaplysin. These compounds were used for first syntheses of the alkaloids 14-bromoreticulatate and 14-bromoreticulatine. Preliminary bioassays showed that 14-bromoreticulatine has a selective antibiotic (to Pseudomonas aeruginosa) activity and reveals cytotoxicity toward human melanoma, colon, and prostate cancer cells. 3,10-Dibromofascaplysin was able to target metabolic activity of the prostate cancer cells, without disrupting cell membrane's integrity and had a wide therapeutic window amongst the fascaplysin alkaloids.

Effects of Polar Steroids from the Starfish Patiria (=Asterina) pectinifera in Combination with X-Ray Radiation on Colony Formation and Apoptosis Induction of Human Colorectal Carcinoma Cells.

Despite significant advances in the understanding, prevention, and treatment of cancer, the disease continues to affect millions of people worldwide. Chemoradiation therapy is a rational approach that has already proven beneficial for several malignancies. However, the existence of toxicity to normal tissue is a serious limitation of this treatment modality. The aim of the present study is to investigate the ability of polar steroids from starfish Patiria (=Asterina) pectinifera to enhance the efficacy of radiation therapy in colorectal carcinoma cells. The cytotoxic activity of polar steroids and X-ray radiation against DLD-1, HCT 116, and HT-29 cells was determined by an MTS assay. The effect of compounds, X-ray, and their combination on colony formation was studied using the soft agar method. The molecular mechanism of the radiosensitizing activity of asterosaponin P1 was elucidated by western blotting and the DNA comet assay. Polar steroids inhibited colony formation in the tested cells, and to a greater extent in HT-29 cells. Asterosaponin P1 enhanced the efficacy of radiation and, as a result, reduced the number and size of the colonies of colorectal cancer cells. The radiosensitizing activity of asterosaponin P1 was realized by apoptosis induction through the regulation of anti- and pro-apoptotic protein expression followed by caspase activation and DNA degradation.

In Vitro Anticancer and Proapoptotic Activities of Steroidal Glycosides from the Starfish Anthenea aspera.

New marine glycoconjugates-the steroidal glycosides designated as anthenosides V⁻X (1⁻3)-and the seven previously known anthenosides E (4), G (5), J (6), K (7), S1 (8), S4 (9), and S6 (10) were isolated from the extract of the tropical starfish Anthenea aspera. The structures of 1⁻3 were elucidated by extensive NMR and ESIMS techniques. Glycoside 1 contains a rare 5α-cholest-8(14)-ene-3α,7ß,16α-hydroxysteroidal nucleus. Compounds 2 and 3 were isolated as inseparable mixtures of epimers. All investigated compounds (1⁻10) at nontoxic concentrations inhibited colony formation of human melanoma RPMI-7951, breast cancer T-47D, and colorectal carcinoma HT-29 cells to a variable degree. The mixture of 6 and 7 possessed significant anticancer activity and induced apoptosis of HT-29 cells. The molecular mechanism of the proapoptotic action of this mixture was shown to be associated with the regulation of anti- and proapoptotic protein expression followed by the activation of initiator and effector caspases.

Six New Polyhydroxysteroidal Glycosides, Anthenosides S1 - S6, from the Starfish Anthenea sibogae.

Six new polyhydroxysteroidal glycosides, anthenosides S1  - S6 (1 - 6), along with a mixture of two previously known related glycosides, 7 and 8, were isolated from the methanolic extract of the starfish Anthenea sibogae. The structures of 1 - 6 were established by NMR and HR-ESI-MS techniques as well as by chemical transformations. All new compounds have a 5α-cholest-8(14)-ene-3α,6ß,7ß,16α-tetrahydroxysteroidal nucleus and differ from majority of starfish glycosides in positions of carbohydrate moieties at C(7) and C(16) (1 - 4, 6) or only at C(16) (5). The 4-O-methyl-ß-d-glucopyranose residue (2) and Δ24 -cholestane side chain (3) have not been found earlier in the starfish steroidal glycosides. The mixture of 7 and 8 slightly inhibited the proliferation of human breast cancer T-47D cells and decreased the colony size in the colony formation assay.