Bioactive lipids from the sponge Spirastrella abata

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.

Antiviral Cyclopropane Acids from Deep-Sea-Derived Fungus Aspergillus sydowii

Four novel monocyclic cyclopropane acids, namely, sydocyclopropanes A–D (1–4), along with one known congener hamavellone B (5), were isolated from the Aspergillus sydowii MCCC 3A00324 fungus, which was isolated from the deep-sea sediment. The gross structures of novel compounds were established by detailed analyses of the spectroscopic data (HRESIMS and NMR spectra), and their absolute configurations were resolved on the basis of the quantum chemical calculations of ECD and NMR data, in association with DP4+ probability analyses. Sydocyclopropanes A–D, featuring the 1,1,2,3-tetrasubstituted cyclopropane nucleus with different lengthy alkyl side chains, were discovered in nature for the first time. All compounds exhibited antiviral activities against A/WSN/33 (H1N1), with IC₅₀ values ranging from 26.7 to 77.2 μM, of which compound 1 exhibited a moderate inhibitory effect (IC₅₀ = 26.7 μM).

Cytotoxic Alkylynols of the Sponge Cribrochalina vasculum: Structure, Synthetic Analogs and SAR Studies

A series of twenty-three linear and branched chain mono acetylene lipids were isolated from the Caribbean Sea sponge Cribrochalina vasculum. Seventeen of the compounds, 1–17, are new, while six, 18–23, were previously characterized from the same sponge. Some of the new acetylene-3-hydroxy alkanes 1, 6, 7, 8, 10 were tested for selective cytotoxicity in non-small cell lung carcinoma (NSCLC) cells over WI-38 normal diploid lung fibroblasts. Compound 7, presented clear tumor selective activity while, 1 and 8, showed selectivity at lower doses and 6 and 10, were not active towards NSCLC cells at all. The earlier reported selective cytotoxicity of some acetylene-3-hydroxy alkanes (scal-18 and 23), in NSCLC cells and/or other tumor cell types were also confirmed for 19, 20 and 22. To further study the structure activity relationships (SAR) of this group of compounds, we synthesized several derivatives of acetylene-3-hydroxy alkanes, rac-18, scal-S-18, R-18, rac-27, rac-32, R-32, S-32, rac-33, rac-41, rac-42, rac-43, rac-45, rac-48 and rac-49, along with other 3-substituted derivatives, rac-35, rac-36, rac-37, rac-38, rac-39 and rac-40, and assessed their cytotoxic activity against NSCLC cells and diploid fibroblasts. SAR studies revealed that the alcohol moiety at position 3 and its absolute R configuration both were essential for the tumor cell line selective activity while for its cytotoxic magnitude the alkyl chain length and branching were of less significance.

Natural Enantiomers: Occurrence, Biogenesis and Biological Properties

The knowledge that natural products (NPs) are potent and selective modulators of important biomacromolecules (e.g., DNA and proteins) has inspired some of the world’s most successful pharmaceuticals and agrochemicals. Notwithstanding these successes and despite a growing number of reports on naturally occurring pairs of enantiomers, this area of NP science still remains largely unexplored, consistent with the adage “If you don’t seek, you don’t find”. Statistically, a rapidly growing number of enantiomeric NPs have been reported in the last several years. The current review provides a comprehensive overview of recent records on natural enantiomers, with the aim of advancing awareness and providing a better understanding of the chemical diversity and biogenetic context, as well as the biological properties and therapeutic (drug discovery) potential, of enantiomeric NPs.

Identification of potential antimicrobials against Salmonella typhimurium and Listeria monocytogenes using Quantitative Structure-Activity Relation modeling

The shelf-life of fresh carcasses and produce depends on the chemical and physical properties of antimicrobials currently used for treatment. For many years the gold standard of these antimicrobials has been Cetylpyridinium Chloride (CPC) a quaternary ammonium compound (QAC). CPC is very effective at removing bacterial pathogens from the surface of chicken but has not been approved for other products due to a toxic residue left behind after treatment. Currently there is also a rising trend in QAC resistant bacteria. In order to find new compounds that can combat both antimicrobial resistance and the toxic residue we have developed two Quantitative Structure-Activity Relationship (QSAR) models for Salmonella typhimurium and Listeria monocytogenes. These models have been shown to be accurate and reliable through multiple internal and external validation techniques. In processing these models we have also identified important descriptors and structures that may be key in producing a viable compound. With these models, development and testing of new compounds should be greatly simplified.

Cytotoxic Compounds Derived from Marine Sponges. A Review (2010-2012)

Abstract: This extensive review covers research published between 2010 and 2012 regarding new compounds derived from marine sponges, including 62 species from 60 genera belonging to 33 families and 13 orders of the Demospongia class (Porifera). The emphasis is on the cytotoxic activity that bioactive metabolites from sponges may have on cancer cell lines. At least 197 novel chemical structures from 337 compounds isolated have been found to support this work. Details on the source and taxonomy of the sponges, their geographical occurrence, and a range of chemical structures are presented. The compounds discovered from the reviewed marine sponges fall into mainly four chemical classes: terpenoids (41.9%), alkaloids (26.2%), macrolides (8.9%) and peptides (6.3%) which, along with polyketides, sterols, and others show a range of biological activities. The key sponge orders studied in the reviewed research were Dictyoceratida, Haplosclerida, Tetractinellida, Poecilosclerida, and Agelasida. Petrosia, Haliclona (Haplosclerida), Rhabdastrella (Tetractinellida), Coscinoderma and Hyppospongia (Dictyioceratida), were found to be the most promising genera because of their capacity for producing new bioactive compounds. Several of the new compounds and their synthetic analogues have shown in vitro cytotoxic and pro-apoptotic activities against various tumor/cancer cell lines, and some of them will undergo further in vivo evaluation.

Potential inhibitors for isocitrate lyase of Mycobacterium tuberculosis and non-M. tuberculosis: a summary

Isocitrate lyase (ICL) is the first enzyme involved in glyoxylate cycle. Many plants and microorganisms are relying on glyoxylate cycle enzymes to survive upon downregulation of tricarboxylic acid cycle (TCA cycle), especially Mycobacterium tuberculosis (MTB). In fact, ICL is a potential drug target for MTB in dormancy. With the urge for new antitubercular drug to overcome tuberculosis treat such as multidrug resistant strain and HIV-coinfection, the pace of drug discovery has to be increased. There are many approaches to discovering potential inhibitor for MTB ICL and we hereby review the updated list of them. The potential inhibitors can be either a natural compound or synthetic compound. Moreover, these compounds are not necessary to be discovered only from MTB ICL, as it can also be discovered by a non-MTB ICL. Our review is categorized into four sections, namely, (a) MTB ICL with natural compounds; (b) MTB ICL with synthetic compounds; (c) non-MTB ICL with natural compounds; and (d) non-MTB ICL with synthetic compounds. Each of the approaches is capable of overcoming different challenges of inhibitor discovery. We hope that this paper will benefit the discovery of better inhibitor for ICL.

Marine natural products

This review covers the literature published in 2012 for marine natural products, with 1035 citations (673 for the period January to December 2012) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1241 for 2012), together with the relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.