Fungal Strains

The present investigation was undertaken to study the sterol composition of 19 marine fungal strains; and then to assess their biological activities. Antimicrobial tests were perform against four Gram-positive bacteria; namely Staphylococcus aureusBacillus sp., Bacillus cereusListeria ivanovii and three Gram-negative ones; Escherichia coliCitrobacter freundii and Salmonella spp. However, for the cytotoxic activity; two breast and two lung cancer cell lines were chosen, namely MCF-7, MDA-MB-231, NSCLC-N6-L16 and A549.

The exploration of microorganisms as sources of new bioactive compounds has a much more recent history; in comparison to the use of plants or plant extracts in human medicine. However, the large number and variety of therapeutic agents isolated from microbial origins; and used to treat human diseases have greatly contribute to the improvement of human health during the past century.

, among microorganisms, steroid compounds isolate from marine fungi have demonstrate bioactivities such as cytotoxicity; against cancer cell lines. For example, a new sterol, ergosta-8(14),22-diene-3,5,6,7-tetraol(3β, 5α, 6β, 7α, 22E); isolate from a marine Penicillium sp., exhibited cytotoxicity with IC50 values of 23 μM against human liver cancer cell (Hep G).

Fungal strains from shellfish

Fungal strains are isolate from shellfish farming areas of the French Atlantic west coast. However, fungal identifications are perform on the basis of their morphological and microscopic features; and were completed for 11 strains by sequencing the internal transcribe spacers ITS1 and ITS2; and the 5.8S regions and deposited in GenBank. But the strains are conserve in the fungal collection of the MMS laboratory of the University of Nantes under the reference MMS + number.

But to explore sterol chemodiversity on marine strains; a screening was perform on Dextrose Casein Agar (DCA) culture media with 19 marine fungal strains. And they were select from the fungal collection of the laboratory either because they are representative of the major genera; of the Mer Molécules Santé (MMS) marine fungal strain collection or because an unusual biological active conjugate fatty acid; was previously isolate from the strain

Neoergosterol was report to be a metabolite of ergosterol. A fifth sterol was also observe in 13 out of the 19 strains study corresponding to a C31:2 sterol with m/z 440 [M]+●, most probably eburicol. However, two isomers are report in the literature; eburicol and euphorbol (7c) and even by using GC-MS analyses; it is still not possible to identify which isomer is produced by C. rosea MMS1090.

Antiproliferative Activity And Antimicrobial Activity

Until now, several studies have been carry out on the cytotoxicity of sterols; especially ergosterol and its derivatives. Therefore, eburicol was test against breast cancer cell lines (MCF-7 and MDA) and lung cancer cell lines (NSCLC-N6-L16 and A549); but to assess their antiproliferative activity using MTT assays. Eburicol exhibited cytotoxic activities on the four human cancer cell lines with IC50 lower than 40 µM. The most important activity was observe against the largely studied breast cancer cell; line MCF-7 with IC50 at 2 µM which is the lowest for a sterol compound compare to literature.

Lanostane triterpenes isolate from Fomitopsis rosea demonstrate only weak antibacterial activity against a S. aureus strain; at 400 µg/mL with an inhibition zone from 14 to 25 mm. Moreover, phytosterols, for example, sitosterol, campesterol and stigmasterol, with a Δ5 unsaturation; are known to present antibacterial activity against S. aureusS. albusStreptococcus viridansE. coliPseudomonas pyocyanea, and Klebsiella. Among Δ5 sterols, the most active one is the 24-propylidenecholest-5-en-3β-ol isolate; from Laurencia papillosa red seaweed which shows an antibacterial activity against S. aureus ATCC25923.

The present results show that eburicol had a weak antimicrobial activity; against S. aureus (but proved a significant cytotoxic effect against two breast human cancer cell lines; in particular against MCF-7 at 2 µM (IC50). This study of fungal sterols confirm the unusual profile of the marine-sourced Clonostachys roseaMMS1090 strains; and confirms its potential in the production of bioactive lipids.