Rosario Hernández-Galán

Secondary metabolites from species of the biocontrol agent Trichoderma

Trichoderma species are free-living fungi that are highly interactive in root, soil and foliar environments and have been used successfully in field trials to control many crop pathogens. Structural and biological studies of the metabolites isolated from Trichoderma species are reviewed. This review, encompassing all the literature in this field up to the present and in which 269 references are cited, also includes a detailed study of the biological activity of the metabolites, especially the role of these metabolites in biological control mechanisms. Some aspects of the biosynthesis of these metabolites and related compounds are likewise discussed.

THE PUTATIVE ROLE OF BOTRYDIAL AND RELATED METABOLITES IN THE INFECTION MECHANISM OF Botrytis cinerea

Phytotoxic assays, performed both in vitro and in vivo on leaves of Phaseolus vulgaris, with metabolites excreted by the fungus B. cinerea are evaluated. Exogenous application of the phytotoxin botrydial has been found to produce severe chlorosis and cell collapse and facilitated fungal penetration and colonization of plant tissue. The results also show a light-dependent action mechanism for the phytotoxin and seem to indicate that botrydial is a non-host-specific toxin involved in fungal infection of B. cinerea.

Structure-activity relationships of new phytotoxic metabolites with the botryane skeleton from Botrytis cinerea

Abstract The fungal antibiotic botrydial (1) and related compounds constitute an important group of metabolites whose biological activity was not previously known in depth. The isolation, in addition to known compounds, of three new epimer metabolites with the botryane structure has allowed us to study the structure-activity relationships. The results suggest that, in addition to the presence of the dialdehyde functionality, the antibiotic, phytotoxic and cytostatic activities shown by some of these compounds are strongly correlated with the stereochemistry of the C-1/C-8 dialdehyde moieties. The relative configuration (S) of the C-1 substituent seems to play a critical role in the binding of the substrate to the chemoreceptor.

Biologically active sesquiterpenoid metabolites from the fungus Botrytis cinerea

Five new sesquiterpenoid metabolites, botryendial, botryenalol, 10-epi-dihydrobotrydial, methyl acetyl botryenaloate and 10-dehydroxy dihydrobotrydialone, have been isolated from Botrytis cinerea. The structures were elucidated by extensive NMR studies of the natural products and their derivatives.

Effects of diterpenes from latex of Euphorbia lactea and Euphorbia laurifolia on human immunodeficiency virus type 1 reactivation

The persistence of latent HIV-infected cellular reservoirs represents the major hurdle to virus eradication in patients treated with highly active antiretroviral therapy, referred to as HAART. HIV-1 reservoirs are long-lived resting CD4+ memory cells containing the virus latently integrated. Since the HIV-1 reservoirs are not targeted by HAART, reactivation therapy has been suggested to purge viral latency. Bioassay-guided study of an ethyl acetate extract of Euphorbia laurifolia afforded two isomeric diterpenes that showed differential activity over HIV-1 reactivation. A previously reported compound was isolated too from Euphorbia lactea. This compound showed a potent HIV-1 reactivating effect. Bioassays results showed that HIV-1 reactivation activity is influenced by distinct structural characteristics.

Metabolites from a shake culture of Botrytis cinerea

Abstract Four new metabolites, 10-oxo-dihydrobotrydial, 4β-acetoxy-9β-10β-15α-trihydroxyprobotrydial, β - O -methyldihydrobotrydialone and α - O -methyldihydrobotrydialone, were isolated from a shake culture of Botrytis cenerea . The second compound, a tricyclic sesquiterpene, is a key biosynthetic intermediate and sheds light on the last steps of the biosynthesis of botrydial derivatives. A higher oxidation level was observed in the metabolites isolated. The structures were elucidated by extensive NMR investigations of the natural compounds and their derivatives.

Some metabolites of Botrytis cinerea related to botcinolide

Four new botcinolide derivatives 4-O-methylbotcinolide, 3-O-acetyl-5-O-methylbotcinolide, 3-O-acetyl-2-epibotcinolide and 2-epibotcinolide have been isolated from the plant pathogen, Botrytis cinerea. Their structures have been established by extensive spectroscopic methods.

An improved synthesis of 3-(1,1-dimethylallyl)coumarins

Abstract The syntheses of several 3-(1,1-dimethylallyl)coumarins, simple or bearing additional furan or pyran rings is achieved starting from the corresponding C-3 unsubstituted derivatives. The key step involves Ireland-Claisen rearrangements of allyl esters.

The biodegradation of the phytotoxic metabolite botrydial by its parent organism, Botrytis cinerea

The inhibition of the growth of Botrytis cinerea has been found to be directly proportional to the concentration of its metabolite, botrydial (1). The fungus transforms botrydial (1) to the less active phytotoxins dihydrobotrydial (2), botryenedial (3), and secobotrytrienediol (4). Two main biodegradative pathways of botrydial (1) and the interconversion of the botryane toxins excreted by B. cinerea are proposed.

SYNTHESIS AND ANTIFUNGAL ACTIVITY OF ANALOGUES OF NATURALLY OCCURRING BOTRYDIAL PRECURSORS

Analog compounds of the proposed intermediates of the biogenetic pathway to botrydial have been synthesized. These compounds were tested for their potential antifungal activity against the phytopathogenBotrytis cinerea. Our results showed a fungistatic effect of some compounds on mycelium growth. The most significant effect was exerted by 2-α-hydroxy-2,3-dihydro-1-epiprobotrydial, which inhibited growth ofB. cinerea. Some aspects of structure-activity relationships are discussed.