New secosteroids from a gorgonian of the genus Muricella

Immunosuppressive 9,10-Secosteroids from the Gorgonian Verrucella umbraculum Collected in the South China Sea

Four new 9,10-secosteroids, verrucellols A-D (1-4), together with 12 known derivatives (5-16) were isolated from the gorgonian Verrucella umbraculum collected in the South China Sea. The structures of the new compounds were established by spectroscopic analysis and comparison with reported data. These compounds exhibited significant suppressive effects on CD4+ T lymphocyte cell differentiation in an in vitro bioassay. This is the first report of 9,10-secosteroids exhibiting immunomodulation activity.

Subergorgiaols A-L, 9,10-secosteroids from the South China Sea gorgonian Subergorgia rubra

Twelve new 9,10-secosteroids designated as subergorgiaols A-L (1-12), along with four known analogues (13-16), were isolated from the gorgonian Subergorgia rubra collected from the South China Sea. Their planar structures and the relative configurations were elucidated by comprehensive spectroscopic methods including NOESY spectra. The absolute configuration of 1 was established by a dimolybdenum tetraacetate [Mo2(AcO)4] induced circular dichroism (ICD) procedure and the modified Mosher's method. Compounds 1-12 represent the first series of 9,10-secosteroids characterized with a hydroxy group at C-8, which are 8-OH derivatives of astrogorgiadiols/calicoferols. Compound 4 exhibited cytotoxicity against the cervical carcinoma cell line (CaSki) with an IC50 value of 2.4 μM, and 6 showed toxicity toward brine shrimp Artemia salina with an LC50 value of 2.0 μM.

A click chemistry approach to secosteroidal macrocycles

A new synthetic pathway towards secosteroidal macrocycles was described via a reaction of cycloaddition as the key step. The characteristic (1)H and (13)C NMR spectroscopic features of the synthesized compounds are reported.

Cytotoxic and cytolytic cnidarian venoms. A review on health implications and possible therapeutic applications

The toxicity of Cnidaria is a subject of concern for its influence on human activities and public health. During the last decades, the mechanisms of cell injury caused by cnidarian venoms have been studied utilizing extracts from several Cnidaria that have been tested in order to evaluate some fundamental parameters, such as the activity on cell survival, functioning and metabolism, and to improve the knowledge about the mechanisms of action of these compounds. In agreement with the modern tendency aimed to avoid the utilization of living animals in the experiments and to substitute them with in vitro systems, established cell lines or primary cultures have been employed to test cnidarian extracts or derivatives. Several cnidarian venoms have been found to have cytotoxic properties and have been also shown to cause hemolytic effects. Some studied substances have been shown to affect tumour cells and microorganisms, so making cnidarian extracts particularly interesting for their possible therapeutic employment. The review aims to emphasize the up-to-date knowledge about this subject taking in consideration the importance of such venoms in human pathology, the health implications and the possible therapeutic application of these natural compounds.

Cytotoxic 9,11-secosteroids from the South China Sea gorgonian Subergorgia suberosa

Ten new 9,11-secosteroids, subergorgols A-J (1-10), including two pairs of epimers (3/4, and 6/7), along with three known analogues (11-13) were isolated from the South China Sea gorgonian Subergorgia suberosa. The structures of these compounds were elucidated on the basis of extensive spectroscopic analyses and comparison with the literature data. The cytotoxicities in vitro against three selected human tumor cell lines for all the compounds were evaluated. Compound 9 showed significant cytotoxicities toward both K562 and MDA-MB-231 cell lines with IC50 values of 5.5 and 6.2μM, respectively, and compound 10 also showed inhibitory activity against K562 cell line with an IC50 value of 6.5μM.

Synthesis of various secosteroidal macrocycles by ring-closing metathesis

We set out to describe an efficient and versatile method for preparing secosteroidal macrocycles from cholic acid, via an oxidative ring-expansion/ring-opening sequence and a ring-closing metathesis reaction as the key steps. The characteristic ¹H and ¹³C NMR spectroscopic features of the synthesized compounds are reported.

Natural product chemistry of gorgonian corals of the family Plexauridae distributed in the Indo-Pacific Ocean

The structures, names, bioactivities and references of 105 natural products obtained from gorgonian corals belonging to the family Plexauridae with an Indo-Pacific distribution are described in this review. All compounds mentioned in this review were obtained from gorgonian corals belonging to the genera Astrogorgia, Bebryce, Echinomuricea, Euplexaura and Menella.

Secosteroids of marine origin

This review describes the isolation from marine organisms of all secosteroids reported in the literature from 1972 to 2004. Secosteroids are highly oxidized metabolites with bond cleavage in the rings of the steroid tetracyclic nucleus. All secosteroids are grouped in accordance with their ring joined to side chain as 5,6-, 9,11-, 9,10- 8,9-, 8,14- and 13,17-secosteroids and the structures and the synthetic works, where available, are reported. Furthermore, this review gives details on the biological activities of the isolated secosteroids (e.g. antiproliferative, antifouling, antiinflammatory, antimicrobial, ichthyotoxic and antiviral).

Synthesis of 13,14-secotestosterone derivatives

A number of testosterone analogs with a 13,14-secosteroidal fragment have been prepared from (13S)-13-iodo-6beta-methoxy-3alpha, 5-cyclo-13,14-seco-5alpha-androstan-14,17-dione. The key steps involved stereoselective deiodination of the starting compound with triphenylphosphine and selective protection of the 17-keto group with trimethylsilylcyanide. Removal of iodine at C-13 proceeded with inversion of the configuration at C-13, which has been established by X-ray crystallography. 13,14-Secotestosterone analogues substituted and non-substituted at C-14 have been prepared. The obtained compounds containing flexible CD ring fragments are of great interest for comparative studies in biological tests together with testosterone and other steroids with a rigid tetracyclic skeleton.