Recently confirmed apoptosis-inducing lead compounds isolated from marine sponge of potential relevance in cancer treatment

Anticancer potential of Spirastrella pachyspira (marine sponge) against SK-BR-3 human breast cancer cell line and in silico analysis of its bioactive molecule sphingosine

The rate of breast cancer is rapidly increasing and discovering medications with therapeutic effects play a significant role in women’s health. Drugs derived from marine sponges have recently received FDA approval for the treatment of malignant tumors, including metastatic breast cancer. Spirastrella pachyspira (marine sponge) is mainly obtained from the western coastal region of India, and its anticancer potential has not been explored. Hence, the present study aimed to evaluate the anticancer potential of Spirastrella pachyspira extracts and its bioactive molecule sphingosine. The extracts were prepared using hexane, chloroform, ethyl acetate, and ethanol. The cytotoxic potential of the extracts were determined by an in-vitro MTT assay using SK-BR-3 cancer cell line. Subsequently, acute toxicity investigation was conducted in Swiss albino mice. Then, the anticancer effects of the extract was investigated in a xenograft model of SK-BR-3 caused breast cancer. DAPI staining was used to assess the extract’s ability to induce apoptosis. In addition, in-silico study was conducted on sphingosine with extracellular site of HER2. The ethyl acetate extract of Spirastrella pachyspira (IC50: 0.04 µg/ml) showed comparable anticancer effects with standard doxorubicin (IC50: 0.054 µg/ml). The LD50 of the extracts in acute toxicity testing was fund to be 2000 mg/kg b.wt. The survival index of mice in ethanol extract was 83.33%, whereas that of standard doxirubicin was 100%, indicating that ethyl acetate extract Spirastrella pachyspira has good antiproliferative/cytotoxic properties. The results were well comparable with standard doxorubicin. Further, the docking studies of sphingosine against HER2 demonstrated that the bioactive molecule engage with the extracellular region of HER2 and block the protein as also shown by standard trastuzumab. The findings of this research suggest that Spirastrella pachyspira and sphingosine may be potential candidate for the treatments of breast cancer, particularly for HER2 positive cells. Overall, the present results demonstrate that sphingosine looks like a promising molecule for the development of new drugs for the treatment of cancer. However, in order to carefully define the sphingosine risk-benefit ratio, future research should focus on evaluating in-vivo and clinical anticancer studies. This will involve balancing both their broad-spectrum effectiveness and their toxicity.

Comparative Metagenomic Analysis of Biosynthetic Diversity across Sponge Microbiomes Highlights Metabolic Novelty, Conservation, and Diversification

Marine sponges and their microbial symbiotic communities are rich sources of diverse natural products (NPs) that often display biological activity, yet little is known about the global distribution of NPs and the symbionts that produce them. Since the majority of sponge symbionts remain uncultured, it is a challenge to characterize their NP biosynthetic pathways, assess their prevalence within the holobiont, and measure the diversity of NP biosynthetic gene clusters (BGCs) across sponge taxa and environments. Here, we explore the microbial biosynthetic landscapes of three high-microbial-abundance (HMA) sponges from the Atlantic Ocean and the Mediterranean Sea. This data set reveals striking novelty, with <1% of the recovered gene cluster families (GCFs) showing similarity to any characterized BGC. When zooming in on the microbial communities of each sponge, we observed higher variability of specialized metabolic and taxonomic profiles between sponge species than within species. Nonetheless, we identified conservation of GCFs, with 20% of sponge GCFs being shared between at least two sponge species and a GCF core comprised of 6% of GCFs shared across all species. Within this functional core, we identified a set of widespread and diverse GCFs encoding nonribosomal peptide synthetases that are potentially involved in the production of diversified ether lipids, as well as GCFs putatively encoding the production of highly modified proteusins. The present work contributes to the small, yet growing body of data characterizing NP landscapes of marine sponge symbionts and to the cryptic biosynthetic potential contained in this environmental niche. IMPORTANCE Marine sponges and their microbial symbiotic communities are a rich source of diverse natural products (NPs). However, little is known about the sponge NP global distribution landscape and the symbionts that produce them. Here, we make use of recently developed tools to perform untargeted mining and comparative analysis of sponge microbiome metagenomes of three sponge species in the first study considering replicate metagenomes of multiple sponge species. We present an overview of the biosynthetic diversity across these sponge holobionts, which displays extreme biosynthetic novelty. We report not only the conservation of biosynthetic and taxonomic diversity but also a core of conserved specialized metabolic pathways. Finally, we highlight several novel GCFs with unknown ecological function, and observe particularly high biosynthetic potential in Acidobacteriota and Latescibacteria symbionts. This study paves the way toward a better understanding of the marine sponge holobionts' biosynthetic potential and the functional and ecological role of sponge microbiomes.

Anti-inflammatory, anti-infectious and anti-cancer potential of marine algae and sponge: A review

Marine organisms are potentially a pretty good source of highly bioactive secondary metabolites that are best known for their anti-inflammation, anti-infection, and anti-cancer potential. The growing threat of bacterial resistance to synthetic antibiotics, is a potential source to screen terrestrial and marine natural organisms to discover promising anti-inflammatory and antimicrobial agents which can synergistically overcome the inflammatory and infectious disases. Algae and sponge have been studied enormously to evaluate their medicinal potential to fix variety of diseases, especially inflammation, infections, cancers, and diabetes. Cytarabine is the first isolated biomolecule from marine organism which was successfully practiced in clinical setup as chemotherapeutic agent against xylogenous leukemia both in acute and chronic conditions. This discovery opened the horizon for systematic evaluation of broad range of human disorders. This review is designed to look into the literature reported on anti-inflammatory, anti-infectious, and anti-cancerous potential of algae and sponge to refine the isolated compounds for value addition process.

Overcoming challenges of HERG potassium channel liability through rational design: Eag1 inhibitors for cancer treatment

Two decades of research have proven the relevance of ion channel expression for tumor progression in virtually every indication, and it has become clear that inhibition of specific ion channels will eventually become part of the oncology therapeutic arsenal. However, ion channels play relevant roles in all aspects of physiology, and specificity for the tumor tissue remains a challenge to avoid undesired effects. Eag1 (K_V 10.1) is a voltage-gated potassium channel whose expression is very restricted in healthy tissues outside of the brain, while it is overexpressed in 70% of human tumors. Inhibition of Eag1 reduces tumor growth, but the search for potent inhibitors for tumor therapy suffers from the structural similarities with the cardiac HERG channel, a major off-target. Existing inhibitors show low specificity between the two channels, and screenings for Eag1 binders are prone to enrichment in compounds that also bind HERG. Rational drug design requires knowledge of the structure of the target and the understanding of structure-function relationships. Recent studies have shown subtle structural differences between Eag1 and HERG channels with profound functional impact. Thus, although both targets' structure is likely too similar to identify leads that exclusively bind to one of the channels, the structural information combined with the new knowledge of the functional relevance of particular residues or areas suggests the possibility of selective targeting of Eag1 in cancer therapies. Further development of selective Eag1 inhibitors can lead to first-in-class compounds for the treatment of different cancers.

Inhibition of pathogenic Vibrio harveyi using calamenene, derived from the Indian gorgonian Subergorgia reticulata, and its synthetic analog

We report the synthesis and antimicrobial properties of a partially reduced dihydronathphthoquinone analogue of 2-methoxy, 5-acetoxy calamenene, extracted from Subergorgia reticulata. The growth of a pathogenic Vibrio harveyi strain was effectively controlled by the calamenene derivative 1 (Cala1) and its synthetic analog 2 (Cala2). Complete mortality of V. harveyi was observed with 2.5 and 0.5 µg mL-1 concentrations of Cala1 and Cala2, respectively. The metabolic assays demonstrated that Cala1 is a bacteriostatic agent while Cala2 showed bactericidal properties. It was confirmed that translocation of Cala2 into the cytoplasm does not induce any change to the integrity of the bacterial cell wall. The Cala2 induced damage to the genetic material of 70% of cells while genetic material of 91% of cells treated with Cala1 remained intact. The Cala2 is, therefore, proposed as a potential bactericidal compound against the aquaculture pathogen V. harveyi. The fact that the Cala2 exhibited minimal cytotoxicity to Artemia nauplii indicates its potential use as an antimicrobial agent for aquaculture operations.

Anticancer Activity of Gukulenin A Isolated from the Marine Sponge Phorbas gukhulensis In Vitro and In Vivo

Gukulenin A is a bis-tropolone tetraterpenoid isolated from the marine sponge Phorbas gukhulensis. In this study, we examined the anticancer activities of gukulenin A in ovarian cancer cell lines (A2780, SKOV3, OVCAR-3, and TOV-21G) and in an ovarian cancer mouse model generated by injecting A2780 cells. We found that gukulenin A suppressed tumor growth in A2780-bearing mice. Gukulenin A markedly inhibited cell viability in four ovarian cancer cell lines, including the A2780 cell line. Gukulenin A treatment increased the fraction of cells accumulated at the sub G1 phase in a dose-dependent manner and the population of annexin V-positive cells, suggesting that gukulenin A induces apoptotic cell death in ovarian cancer cells. In addition, gukulenin A triggered the activation of caspase-3, -8, and -9, and caspase inhibitors attenuated gukulenin A-induced A2780 cell death. The results suggest that gukulenin A may be a potential therapeutic agent for ovarian cancer.

Apoptosis induction on human breast cancer T47D cell line by extracts of Ancorina sp

Background: Breast cancer is the second leading cause of death in women. Alternative medicine with high efficacy is needed for breast cancer treatments, for example induction of apoptosis using natural products. It has been found that many natural apoptosis-inducing compounds are isolated from marine sponge. The objective of this study is to analyze the ability of extracts of the sponge Ancorina sp. to induce apoptosis on human breast cancer T47D cell line and find out its mechanism. Methods: T47D cells were treated with crude extracts of methanol, dichloromethane:methanol (1:1) and dichloromethane Ancorina sp. for 24 h, and doxorubicin was used as a positive control. Methods used for this study were MTT assay to examine cell viability and determine IC 50 of the three extracts, while the percentage of apoptosis and caspase-3 were investigated by flow cytometry. Results: IC 50 values of methanol, dichloromethane:methanol (1:1), and dichloromethane extract were 84.25, 121.45, and 99.85μg/mL respectively. The percentages of apoptotic cells after treatment with methanol, dichloromethane:methanol (1:1), and dichloromethane extracts were 88.68, 27.54 and 53.63% respectively, whereas the percentage of caspase-3 was 77.87, 12.66 and 12.97%, respectively. Conclusions: These results revealed that all extracts of Ancorina sp. have strong or moderate cytotoxicity and have the ability to induce apoptosis on T47D human breast cancer cell line. However, methanol crude extract has high efficacy to induce apoptosis through caspase-3 activation compared to the other extracts. Hence methanol extract warrants further investigation as a natural medicine for human breast cancer.

Apoptosis induction on human breast cancer T47D cell line by extracts of Ancorina sp

Background: Breast cancer is the second leading cause of death in women. Alternative medicine with high efficacy is needed for breast cancer treatments, for example induction of apoptosis using natural products. It has been found that many natural apoptosis-inducing compounds are isolated from marine sponge. The objective of this study is to analyze the ability of extracts of the sponge Ancorina sp. to induce apoptosis on human breast cancer T47D cell line and find out its mechanism. Methods: T47D cells were treated with crude extracts of methanol, dichloromethane:methanol (1:1) and dichloromethane Ancorina sp. for 24 h, and doxorubicin was used as a positive control. Methods used for this study were MTT assay to examine cell viability and determine IC 50 of the three extracts, while the percentage of apoptosis and caspase-3 were investigated by flow cytometry. Results: IC 50 values of methanol, dichloromethane:methanol (1:1), and dichloromethane extract were 84.25, 121.45, and 99.85μg/mL respectively. The percentages of apoptotic cells after treatment with methanol, dichloromethane:methanol (1:1), and dichloromethane extracts were 88.68, 27.54 and 53.63% respectively, whereas the percentage of caspase-3 was 77.87, 12.66 and 12.97%, respectively. Conclusions: These results revealed that all extracts of Ancorina sp. have strong or moderate cytotoxicity and have the ability to induce apoptosis on T47D human breast cancer cell line. However, methanol crude extract has high efficacy to induce apoptosis through caspase-3 activation compared to the other extracts. Hence methanol extract warrants further investigation as a natural medicine for human breast cancer.

New Drugs from the Sea: Pro-Apoptotic Activity of Sponges and Algae Derived Compounds

Natural compounds derived from marine organisms exhibit a wide variety of biological activities. Over the last decades, a great interest has been focused on the anti-tumour role of sponges and algae that constitute the major source of these bioactive metabolites. A substantial number of chemically different structures from different species have demonstrated inhibition of tumour growth and progression by inducing apoptosis in several types of human cancer. The molecular mechanisms by which marine natural products activate apoptosis mainly include (1) a dysregulation of the mitochondrial pathway; (2) the activation of caspases; and/or (3) increase of death signals through transmembrane death receptors. This great variety of mechanisms of action may help to overcome the multitude of resistances exhibited by different tumour specimens. Therefore, products from marine organisms and their synthetic derivates might represent promising sources for new anticancer drugs, both as single agents or as co-adjuvants with other chemotherapeutics. This review will focus on some selected bioactive molecules from sponges and algae with pro-apoptotic potential in tumour cells.

Novel pregnenolone derivatives modulate apoptosis via Bcl-2 family genes in hepatocellular carcinoma in vitro

A series of pregnenolone derivatives were synthesized and assessed for anti-cancer activity against hepatocellular carcinoma cell line (HepG2). The synthesized hetero-steroids (compounds 3, 4, 5, 6, 7, 8a and 8b) were evaluated for their cytotoxic activities using MTT (3-(4,5-Dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide) assay. Apoptotic activity was assessed using dual acridine orange/ethidium bromide staining method and DNA fragmentation assay. Pro-apoptotic genes (Bax and Bak) and anti-apoptotic genes (Bcl-2 and Bcl-xL) were analyzed using quantitative real time PCR. The results revealed that compounds 4 and 6 displayed cytotoxic activity (IC_50s, 36.97 ± 2.18 and 18.46 ± 0.64 μM, respectively), while compounds 5 and 7 exhibited weak cytotoxic activity (IC_50s, 93.87 ± 8.30 μM and 93.48 ± 4.14 μM, respectively). All synthesized heterocyclic pregnenolone derivatives induced apoptosis through DNA fragmentation. Compounds 4 and 6 increased early and late apoptotic cell percentages while compounds 3, 5, 7 and 8b increased either early or late apoptotic cell percentage. Moreover, compounds 3, 6 and 8b up-regulated the expression level of Bak gene. On the other hand, compounds 4, 5, 7 and 8a down-regulated the Bcl-2 expression level, besides, compounds 5, 7 and 8a down-regulated the Bcl-xL expression level. Compounds 5, 7, 8a and 8b increased the Bak/Bcl-xL ratio, besides, compound 8a raised the Bax/Bcl-xL ratio whereas compound 5 elevated Bax/Bcl-2 and Bak/Bcl-2 ratios. The present work introduced novel pro-apoptotic pregnenolone derivatives that acted against HepG2 cells through DNA fragmentation, apoptotic morphological changes and were able to increase the pro-apoptotic/anti-apoptotic ratios of Bcl-2 family genes. This study particularly revealed that the cytotoxic compound 4 is the most promising pro-apoptotic compound among other synthesized derivatives where it induced apoptosis (late and early) through the down-regulation of Bcl-2 gene expression level.

Sidr Kashmiry honey and its fractions induced apoptosis in hepatocellular carcinoma in vitro

Positive evidence for anticancer activities of honey is growing and the mechanism on how honey has anticancer characteristics is an area of great interest. Honey has been studied in various cancer cell lines for its ability to induce apoptosis, with several mechanisms of action being suggested. This study aims to evaluate the apoptotic activity of the non cytotoxic Sidr Kashmiry honey and its residue of successive fractionation as well as the cytotoxic chloroform-methanol and ethyl acetate fractions against hepatocellular carcinoma cells in vitro. Apoptosis was assessed by DNA fragmentation, diphenyl amine assay, and ultrastructure investigation. Micronuclei test was carried out to assess genotoxicity. Crude honey, residue, ethyl acetate and chloroform-methanol induced apoptosis, however, the residue and ethyl acetate caused high genotoxicity. Non cytotoxic Sidr Kashmiry honey and its cytotoxic chloroform-methanol fraction could be a powerful pro-apoptotic and non-genotoxic anticancer agent.

Evaluation of potential anti-cancer activity of cationic liposomal nanoformulated Lycopodium clavatum in colon cancer cells

Research dealing with early diagnosis and efficient treatment in colon cancer to improve patient's survival is still under investigation. Chemotherapeutic agent result in high systemic toxicity due to their non-specific actions on DNA repair and/or cell replication. Traditional medicine such as Lycopodium clavatum (LC) has been claimed to have therapeutic potentials against cancer. The present study focuses on targeted drug delivery of cationic liposomal nanoformulated LC (CL-LC) in colon cancer cells (HCT15) and comparing the efficacy with an anti-colon cancer drug, 7-ethyl-10-hydroxy-camptothecin (SN38) along with its nanoformulated form (CL-SN38). The colloidal suspension of LC was made using thin film hydration method. The drugs were characterised using ultraviolet, dynamic light scattering, scanning electron microscopy, energy, dispersive X-ray spectroscopy. Invitro drug release showed kinetics of 49 and 89% of SN38 and LC, whereas CL-SN38 and CL-LC showed 73 and 74% of sustained drug release, respectively. Studies on morphological changes, cell viability, cytotoxicity, apoptosis, cancer-associated gene expression analysis of Bcl-2, Bax, p53 by real-time polymerase chain reaction and western blot analysis of Bad and p53 protein were performed. Nanoformulated LC significantly inhibited growth and increased the apoptosis of colon cancer cells indicating its potential anti-cancer activity against colon cancer cells.

Selective Cytotoxicity of Luteolin and Kaempferol on Cancerous Hepatocytes Obtained from Rat Model of Hepatocellular Carcinoma: Involvement of ROS-Mediated Mitochondrial Targeting

To evaluate the cytotoxicity effects of luteolin (LUT) and kaempferol (KAE) via reactive oxygen species (ROS) mediated mitochondrial targeting on hepatocytes obtained from the liver of hepatocellular carcinoma (HCC) rats. In this study, HCC induced by diethylnitrosamine (DEN) and 2-acetylaminofluorene (2-AAF). In the following, rat liver hepatocytes and mitochondria were isolated and tested for every eventual apoptotic and anti-HCC effects of LUT and KAE. The results of MTT assay showed that LUT and KAE were able to induce selective cytotoxicity in hepatocytes of HCC group in a dose- and time-dependent manner. Treatment of mitochondria from hepatocytes of HCC group with LUT and KAE were accompanied by loss of mitochondrial membrane potential (MMP) and mitochondrial swelling and release of cytochrome c (P < 0.001) via reactive oxygen species (ROS) generation before cytotoxicity ensued. LUT and KAE also increased activation of caspase-3 (P < 0.001 and P < 0.01, respectively). Flow-cytometry analysis indicated that the mode of cell death induced by these flavonoids were mostly apoptosis. Importantly, LUT and KAE were nontoxic for healthy hepatocytes and mitochondria. Therefore, we suggest that LUT and KAE are a good candidate for the complementary therapeutic agent against HCC.

Discovery and characterization of Isofistularin-3, a marine brominated alkaloid, as a new DNA demethylating agent inducing cell cycle arrest and sensitization to TRAIL in cancer cells

We characterized the brominated alkaloid Isofistularin-3 (Iso-3), from the marine sponge Aplysina aerophoba, as a new DNA methyltransferase (DNMT)1 inhibitor. Docking analysis confirmed our in vitro DNMT inhibition data and revealed binding of Iso-3 within the DNA binding site of DNMT1. Subsequent increased expression of tumor suppressor gene aryl hydrocarbon receptor (AHR) could be correlated to decreased methylation of CpG sites within the essential Sp1 regulatory region of its promoter. Iso-3 induced growth arrest of cancer cells in G0/G1 concomitant with increased p21 and p27 expression and reduced cyclin E1, PCNA and c-myc levels. Reduced proliferation was accompanied by morphological changes typical of autophagy revealed by fluorescent and transmission electron microscopy and validated by LC3I-II conversion. Furthermore, Iso-3 strongly synergized with tumor-necrosis-factor related apoptosis inducing ligand (TRAIL) in RAJI [combination index (CI) = 0.22] and U-937 cells (CI = 0.21) and increased TRAIL-induced apoptosis via a mechanism involving reduction of survivin expression but not of Bcl-2 family proteins nor X-linked inhibitor of apoptosis protein (XIAP). Iso-3 treatment decreased FLIP_L expression and triggered activation of endoplasmatic reticulum (ER) stress with increased GRP78 expression, eventually inducing TRAIL receptor death receptor (DR)5 surface expression. Importantly, as a potential candidate for further anticancer drug development, Iso-3 reduced the viability, colony and in vivo tumor forming potential without affecting the viability of PBMCs from healthy donors or zebrafish development.

Synthesis of novel purpurealidin analogs and evaluation of their effect on the cancer-relevant potassium channel KV10.1

In the search for novel anticancer drugs, the potassium channel KV10.1 has emerged as an interesting cancer target. Here, we report a new group of KV10.1 inhibitors, namely the purpurealidin analogs. These alkaloids are produced by the Verongida sponges and are known for their wide variety of bioactivities. In this study, we describe the synthesis and characterization of 27 purpurealidin analogs. Structurally, bromine substituents at the central phenyl ring and a methoxy group at the distal phenyl ring seem to enhance the activity on KV10.1. The mechanism of action of the most potent analog 5 was investigated. A shift of the activation curve to more negative potentials and an apparent inactivation was observed. Since KV10.1 inhibitors can be interesting anticancer drug lead compounds, the effect of 5 was evaluated on cancerous and non-cancerous cell lines. Compound 5 showed to be cytotoxic and appeared to induce apoptosis in all the evaluated cell lines.

Marine Sponge Natural Products with Anticancer Potential: An Updated Review

Despite the huge investment into research and the significant effort and advances made in the search for new anticancer drugs in recent decades, cancer cure and treatment continue to be a formidable challenge. Many sources, including plants, animals, and minerals, have been explored in the oncological field because of the possibility of identifying novel molecular therapeutics. Marine sponges are a prolific source of secondary metabolites, a number of which showed intriguing tumor chemopreventive and chemotherapeutic properties. Recently, Food and Drug Administration-approved drugs derived from marine sponges have been shown to reduce metastatic breast cancer, malignant lymphoma, and Hodgkin's disease. The chemopreventive and potential anticancer activity of marine sponge-derived compounds could be explained by multiple cellular and molecular mechanisms, including DNA protection, cell-cycle modulation, apoptosis, and anti-inflammatory activities as well as their ability to chemosensitize cancer cells to traditional antiblastic chemotherapy. The present article aims to depict the multiple mechanisms involved in the chemopreventive and therapeutic effects of marine sponges and critically explore the limitations and challenges associated with the development of marine sponge-based anticancer strategy.

Chemistry of Renieramycins. 17. A New Generation of Renieramycins: Hydroquinone 5-O-Monoester Analogues of Renieramycin M as Potential Cytotoxic Agents against Non-Small-Cell Lung Cancer Cells

A series of hydroquinone 5-O-monoester analogues of renieramycin M were semisynthesized via bishydroquinonerenieramycin M (5) prepared from renieramycin M (1), a major cytotoxic bistetrahydroisoquinolinequinone alkaloid isolated from the Thai blue sponge Xestospongia sp. All 20 hydroquinone 5-O-monoester analogues possessed cytotoxicity with IC₅₀ values in nanomolar concentrations against the H292 and H460 human non-small-cell lung cancer (NSCLC) cell lines. The improved cytotoxicity toward the NSCLC cell lines was observed from the 5-O-monoester analogues such as 5-O-acetyl ester 6a and 5-O-propanoyl ester 7e, which exhibited 8- and 10-fold increased cytotoxicity toward the H292 NSCLC cell line (IC₅₀ 3.0 and 2.3 nM, respectively), relative to 1 (IC₅₀ 24 nM). Thus, the hydroquinone 5-O-monoester analogues are a new generation of the renieramycins to be further developed as potential marine-derived drug candidates for lung cancer treatment.

Selective Toxicity of Non Polar Bioactive Compounds of Persian Gulf Sea Squirt Phallusia Nigra on Skin Mitochondria Isolated from Rat Model of Melanoma

Background:

Skin cancer is the most prevalent cancer and one of the major causes of mortality worldwide. Marin animals have attracted much attention in recent years as useful substances having application in medicine. It was shown that Phallusia nigra (P. nigra) known as sea squirt could play an important role in cancer therapy.

Methods:

This study was designed to figure out the probable selective toxicity of n-hexane, diethyl ether, methanolic and aqueous extracts of P. nigra on cancerous mitochondria isolated from the skin of melanoma induced rats. In our study, mitochondria were isolated from the skin tissue of both melanoma induced and normal healthyrats. Different concentrations of four different extracts of P. nigra (250, 500 and 1000 µg/ml) were added to mitochondrial samples obtained from both groups, separately.

Results:

Our results showed that n-hexane, diethyl ether and methanolic extracts (but not aqueous extract) of P. nigra in all concentrations applied (250, 500 and 1000 µg/ml) significantly induced toxic alterations only in the cancerous but not normal healthy skin mitochondria including; increased reactive oxygen species (ROS) formation, mitochondrial swelling, decreased mitochondrial membrane potential (MMP) and cytochrome c release. Flow-cytometry analysis demonstrated that n-hexane, diethyl ether and methanolic extracts of P. nigra progressively induced apoptosis and necrosis only on melanoma cells but not healthy skin cells.

Conclusions:

Our results suggest that non polar bioactive compounds in P. nigra may be hopeful candidates for further studies including molecular identification, confirmatory in vivo experiments and finally clinical trials designed for new drug treatment of melanoma skin cancer.

Selective Toxicity of Persian Gulf Sea Cucumber (Holothuria parva) and Sponge (Haliclona oculata) Methanolic Extracts on Liver Mitochondria Isolated from an Animal Model of Hepatocellular Carcinoma

BACKGROUND

Natural products isolated from marine environments are well known for their pharmacodynamic potential in diverse disease treatments, such as for cancer or inflammatory conditions. Sea cucumbers are marine animals of the phylum Echinoderm and the class Holothuroidea, with leathery skin and gelatinous bodies. Sponges are important components of Persian Gulf animal communities, and the marine sponges of the genus Haliclona have been known to display broad-spectrum biological activity. Many studies have shown that sea cucumbers and sponges contain antioxidants and anti-cancer compounds.

OBJECTIVES

This study was designed to determine the selective toxicity of Persian Gulf sea cucumber (Holothuria parva) and sponge (Haliclona oculata) methanolic extracts on liver mitochondria isolated from an animal model of hepatocellular carcinoma, as part of a national project that hopes to identify novel potential anticancer candidates among Iranian Persian Gulf flora and fauna.

MATERIALS AND METHODS

To induce hepatocarcinogenesis, rats were given diethylnitrosamine (DEN) injections (200 mg/kg i.p. by a single dose), and then the cancer was promoted with 2-acetylaminofluorene (2-AAF) (0.02 w/w) for two weeks. Histopathological evaluations were performed, and levels of liver injury markers and a specific liver cancer marker (alpha-fetoprotein), were determined for confirmation of hepatocellular carcinoma induction. Finally, mitochondria were isolated from cancerous and non-cancerous hepatocytes.

RESULTS

Our results showed that H. parva methanolic extracts (250, 500, and 1000 µg/mL) and H. oculata methanolic extracts (200, 400, and 800 µg/mL) increased reactive oxygen species (ROS) formation, mitochondrial membrane potential (MMP), mitochondrial swelling, and cytochrome c release in the mitochondria obtained from cancerous hepatocytes, but not in mitochondria obtained from non-cancerous liver hepatocytes. These extracts also induced caspase-3 activation, which is known as a final mediator of apoptosis, in the hepatocytes obtained only from cancerous, not non-cancerous, rat livers.

CONCLUSIONS

Our results suggest that H. parva and H. oculata may be promising therapeutic candidates for the treatment of HCC, following further confirmatory in vivo experiments and clinical trials.

Significance of investigating allelopathic interactions of marine organisms in the discovery and development of cytotoxic compounds

Marine sessile organisms often inhabit rocky substrata, which are crowded by other sessile organisms. They acquire living space via growth interactions and/or by allelopathy. They are known to secrete toxic compounds having multiple roles. These compounds have been explored for their possible applications in cancer chemotherapy, because of their ability to kill rapidly dividing cells of competitor organisms. As compared to the therapeutic applications of these compounds, their possible ecological role in competition for space has received little attention. To select the potential candidate organisms for the isolation of lead cytotoxic molecules, it is important to understand their chemical ecology with special emphasis on their allelopathic interactions with their competitors. Knowledge of the ecological role of allelopathic compounds will contribute significantly to an understanding of their natural variability and help us to plan effective and sustainable wild harvests to obtain novel cytotoxic chemicals. This review highlights the significance of studying allelopathic interactions of marine invertebrates in the discovery of cytotoxic compounds, by selecting sponge as a model organism.

Antitumor Effects and Related Mechanisms of Penicitrinine A, a Novel Alkaloid with a Unique Spiro Skeleton from the Marine Fungus Penicillium citrinum

Penicitrinine A, a novel alkaloid with a unique spiro skeleton, was isolated from a marine-derived fungus Penicillium citrinum. In this study, the isolation, structure and biosynthetic pathway elucidation of the new compound were described. This new compound showed anti-proliferative activity on multiple tumor types. Among them, the human malignant melanoma cell A-375 was confirmed to be the most sensitive. Morphologic evaluation, apoptosis rate analysis, Western blot and real-time quantitative PCR (RT-qPCR) results showed penicitrinine A could significantly induce A-375 cell apoptosis by decreasing the expression of Bcl-2 and increasing the expression of Bax. Moreover, we investigated the anti-metastatic effects of penicitrinine A in A-375 cells by wound healing assay, trans-well assay, Western blot and RT-qPCR. The results showed penicitrinine A significantly suppressed metastatic activity of A-375 cells by regulating the expression of MMP-9 and its specific inhibitor TIMP-1. These findings suggested that penicitrinine A might serve as a potential antitumor agent, which could inhibit the proliferation and metastasis of tumor cells.

Structure elucidation and cytotoxic evaluation of new polyacetylenes from a marine sponge Petrosia sp

The sponge Petrosia sp. yielded five polyacetylenic compounds (1–5), including two new polyacetylenes, petrosianynes A (1) and B (2). The structures of these compounds were elucidated by detailed spectroscopic analysis and by comparison with the physical and spectral data of related known analogues. Compounds 1–5 exhibited significant cytotoxic activity against a limited panel of cancer cell lines.

Marine sponge derived natural products between 2001 and 2010: trends and opportunities for discovery of bioactives

Marine sponges belonging to the phylum Porifera (Metazoa), evolutionarily the oldest animals are the single best source of marine natural products. The present review presents a comprehensive overview of the source, taxonomy, country of origin or geographical position, chemical class, and biological activity of sponge-derived new natural products discovered between 2001 and 2010. The data has been analyzed with a view to gaining an outlook on the future trends and opportunities in the search for new compounds and their sources from marine sponges.

Synthesis and biological evaluation of novel 3-alkylpyridine marine alkaloid analogs with promising anticancer activity

Cancer continues to be one of the most important health problems worldwide, and the identification of novel drugs and treatments to address this disease is urgent. During recent years, marine organisms have proven to be a promising source of new compounds with action against tumoral cell lines. Here, we describe the synthesis and anticancer activity of eight new 3-alkylpyridine alkaloid (3-APA) analogs in four steps and with good yields. The key step for the synthesis of these compounds is a Williamson etherification under phase-transfer conditions. We investigated the influence of the length of the alkyl chain attached to position 3 of the pyridine ring on the cytotoxicity of these compounds. Biological assays demonstrated that compounds with an alkyl chain of ten carbon atoms (4c and 5c) were the most active against two tumoral cell lines: RKO-AS-45-1 and HeLa. Micronucleus and TUNEL assays showed that both compounds are mutagenic and induce apoptosis. In addition, Compound 5c altered the cellular actin cytoskeleton in RKO-AS-45-1 cells. The results suggest that Compounds 4c and 5c may be novel prototype anticancer agents.

The effects of bioactive compounds from plant foods on mitochondrial function: a focus on apoptotic mechanisms

Mitochondria are essential organelles for cellular integrity and functionality maintenance and their imparement is implicated in the development of a wide range of diseases, including metabolic, cardiovascular, degenerative and hyperproliferative pathologies. The identification of different compounds able to interact with mitochondria for therapeutic purposes is currently becoming of primary importance. Indeed, it is well known that foods, particularly those of vegetable origin, present several constituents with beneficial effects on health. This review summarizes and updates the most recent findings concerning the mechanisms through which different dietary compounds from plant foods affect mitochondria functionality in healthy and pathological in vitro and in vivo models, paying particular attention to the pathways involved in mitochondrial biogenesis and apoptosis.

5α,8α-Epidioxysterols from a Formosan Sponge, Axinyssa sp

One new 5α,8α-epidioxysterol, 3-acetylaxinysterol (1), along with one known sterol, axinysterol (2), were isolated from a Formosan sponge, Axinyssa sp.. The structures of the compounds were determined by spectroscopic methods and the absolute configuration of 2 was further confirmed by single-crystal X-ray diffraction analysis for the first time. Compound 2 exhibited significant cytotoxicity against K562 and Molt 4 cancer cell lines.

Triterpenoids of marine origin as anti-cancer agents

Triterpenoids are the most abundant secondary metabolites present in marine organisms, such as marine sponges, sea cucumbers, marine algae and marine-derived fungi. A large number of triterpenoids are known to exhibit cytotoxicity against a variety of tumor cells, as well as anticancer efficacy in preclinical animal models. In this review efforts have been taken to review the structural features and the potential use of triterpenoids of marine origin to be used in the pharmaceutical industry as potential anti-cancer drug leads.

Dragon exploration system on marine sponge compounds interactions

Background

Natural products are considered a rich source of new chemical structures that may lead to the therapeutic agents in all major disease areas. About 50% of the drugs introduced in the market in the last 20 years were natural products/derivatives or natural products mimics, which clearly shows the influence of natural products in drug discovery.

Results

In an effort to further support the research in this field, we have developed an integrative knowledge base on Marine Sponge Compounds Interactions (Dragon Exploration System on Marine Sponge Compounds Interactions - DESMSCI) as a web resource. This knowledge base provides information about the associations of the sponge compounds with different biological concepts such as human genes or proteins, diseases, as well as pathways, based on the literature information available in PubMed and information deposited in several other databases. As such, DESMSCI is aimed as a research support resource for problems on the utilization of marine sponge compounds. DESMSCI allows visualization of relationships between different chemical compounds and biological concepts through textual and tabular views, graphs and relational networks. In addition, DESMSCI has built in hypotheses discovery module that generates potentially new/interesting associations among different biomedical concepts. We also present a case study derived from the hypotheses generated by DESMSCI which provides a possible novel mode of action for variolins in Alzheimer’s disease.

Conclusion

DESMSCI is the first publicly available (http://www.cbrc.kaust.edu.sa/desmsci) comprehensive resource where users can explore information, compiled by text- and data-mining approaches, on biological and chemical data related to sponge compounds.

4-Methylenesterols from a sponge Theonella swinhoei

Three new 4-methylenesterols, theonellasterol K (1), acetyltheonellasterol (2) and acetyldehydroconicasterol (3), along with two known sterols, theonellasterol (4) and theonellasterone (5), were isolated from the sponge Theonella swinhoei. The structures of these compounds were elucidated on the basis of their spectroscopic data and comparison of the NMR data with those of known analogues. Compound 1 exhibited significant cytotoxic activity against HCT-116, K562 and Molt 4 cancer cell lines.