A multi-screening approach for marine-derived fungal metabolites and the isolation of cyclodepsipeptides from Beauveria felina

Abstract

Recebido em 9/5/07; aceito em 30/11/07; publicado na web em 21/7/08Extracts obtained from 57 marine-derived fungal strains were analyzed by HPLC-PDA, TLC and 1 H NMR. The analyses showed that the growth conditions affected the chemical profile of crude extracts. Furthermore, the majority of fungal strains which produced either bioactive of chemically distinctive crude extracts have been isolated from sediments or marine algae. The chemical investigation of the antimycobacterial and cytotoxic crude extract obtained from two strains of the fungus Beauveria felina have yielded cyclodepsipeptides related to destruxins. The present approach constitutes a valuable tool for the selection of fungal strains that produce chemically interesting or biologically active secondary metabolites.

Inhibition of Nitric Oxide and Tumour Necrosis Factor-α Production in Peritoneal Macrophages by <i>Aspergillus nidulans</i> Melanin

“…18) Among these, fungi represent an economically significant source of bioactive compounds because they are capable of producing high yields of substances with greatly diverse chemical structures, which exhibit a wide range of activi-ties. [19][20][21][22][23] However, only a small fraction of the estimated fungal biodiversity has been investigated for these compounds and there is great possibility to discover species that produce new bioactive metabolites. 22,23) The pigment melanin is found in organisms from all phylogenetic kingdoms, including fungi, and melanin exhibits thermoregulatory, photoprotective, antimicrobial, antiviral, antioxidant, cytotoxic, and anti-inflammatory activities.…”

“…[19][20][21][22][23] However, only a small fraction of the estimated fungal biodiversity has been investigated for these compounds and there is great possibility to discover species that produce new bioactive metabolites. 22,23) The pigment melanin is found in organisms from all phylogenetic kingdoms, including fungi, and melanin exhibits thermoregulatory, photoprotective, antimicrobial, antiviral, antioxidant, cytotoxic, and anti-inflammatory activities. 24,25) This pigment, formed by oxidative polymerization of phenolic or indolic compounds, is not essential for fungal growth or development but has been reported to act as 'fungal armour' because of its ability to protect the microorganisms from harmful environmental conditions such as ultraviolet (UV) radiation, extreme temperatures, hydrolytic enzymes, heavy metal toxicity, and antimicrobial drugs.…”

Evaluating methods for the isolation of marine-derived fungal strains and production of bioactive secondary metabolites

“…In the case of isolation and growth of marinederived fungal strains, the effect of seawater concentration in the media is also significantly relevant, as showed by Bugni & Ireland (2004), Yang et al (2007) as well as by our previous investigations (Vita-Marques et al, 2008;Pimenta et al, 2010). In general, high sea water concentration inhibits rather than promotes the growth and secondary metabolites production.…”

“…Media used in Petri dishes are provided below. Growth in Petri dishes were performed at 25 o C. All fungi growth media (pH 8.0) were prepared using artificial sea water (ASW: Vita-Marques et al, 2008): artificial sea water agar (ASW: 1 L of ASW; agar 15 g), glucose peptone yeast (GPY: glucose 1 g; soybean meat peptone 0.5 g; yeast extract 0.1 g; ASW 1L; agar 15 g), 2% malt (2%M: malt extract 20 g; ASW 1 L; agar 15 g); 3% malt (3%M: malt extract 30 g; mycological peptone 5 g; ASW 1 L; agar 15 g), Tubaki (TUB: glucose 30 g; yeast extract 1 g; peptone 1 g; K 2 HPO 4 1 g; MgSO 4 0.5 g; FeSO 4 0.01 g, ASW 1L pH 8.0; agar 15 g), potatocarrot medium (PCM: Potatoes cooked and smashed 20 g; carrots cooked and smashed 20g; ASW 1 L; agar 20 g); corn meal medium (CMM: 42 g of corn flour were stirred overnight in 500 mL of distilled H2O at 60 o C, filtered and the filtered medium was diluted to 1 L with ASW; agar 15 g), oat meal medium (OMM: 30 g of oat flakes were boiled in 500 mL of distilled H 2 O during one hour, filtrated and the filtered medium was diluted to 1 L with ASW; agar 20 g) and cellulose medium (CELM: cellulose 10 g, yeast extract 1 g; 1 L ASW; agar 15 g). Rifampicin was added in all media used for inoculation at a concentration of 300 mg/L in order to prevent bacterial contamination.…”

“…A number of new compounds have been previously reported by us (Hernandez et al, 2000;Hernandez et al, 2004;Lira et al, 2006;Pimenta et al, 2010). We have subsequently developed a multi-screening approach in order to obtain and select bioactive extracts from marine-derived fungi culture media (Vita-Marques et al, 2008). While a number of active extracts producing strains have been detected, such extracts have been obtained in only very limited amounts.…”