Biological and Chemical Control of <i>Sclerotinia sclerotiorum</i> using <i>Stachybotrys levispora</i> and Its Secondary Metabolite Griseofulvin

<i>Sclerotinia sclerotiorum</i> is responsible for the white mold of soybeans, and the difficulty to control the disease in Brazil is causing million-dollar damages. <i>Stachybotrys levispora</i> has shown activity against <i>S. sclerotiorum</i>. In our present investigation, we analyzed the chemical basis of this inhibition. Eight compounds were isolated, and using spectroscopic methods, we identified their structures as the known substances 7-dechlorogriseofulvin, 7-dechlorodehydrogriseofulvin, griseofulvin, dehydrogriseofulvin, 3,13-dihydroxy-5,9,11-trimethoxy-1-methylbenzophenone, griseophenone A, 13-hydroxy-3,5,9,11-tetramethoxy-1-methylbenzophenone, and 12-chloro-13-hydroxy-3,5,9,11-tetramethoxy-1-methylbenzophenone. Griseofulvin inhibited the mycelial growth of <i>S. sclerotiorum</i> at 2 μg mL^–1. Thus, the antagonistic effect of <i>S. levispora</i> to <i>S. sclerotiorum</i> may well be due to the presence of griseofulvins. Our results stimulate new work on the biosynthesis of griseofulvins, to locate genes that encode key enzymes in these routes and use them to increase the production of these compounds and thus potentiate the fungicide effect of this fungus. <i>S. levispora</i> represents an agent for biocontrol, and griseofulvin represents a fungicide to <i>S. sclerotiorum</i>

Isolation of Arginase Inhibitors from the Bioactivity-Guided Fractionation of <i>Byrsonima coccolobifolia</i> Leaves and Stems

<i>Byrsonima coccolobifolia</i> leaf and stem extracts were studied in the search for possible leishmanicidal compounds using arginase (ARG) from <i>Leishmania amazonensis</i> as a molecular target. Flavonoids <b>1b</b>, <b>1e</b>–<b>1g</b>, <b>2a</b>, <b>2b</b>, and <b>2d</b>–<b>2f</b> showed significant inhibitory activity, with IC₅₀ values ranging from 0.9 to 4.8 μM. The kinetics of the most active compounds were determined. Flavonoids <b>1e</b>, <b>1f</b>, <b>2a</b>, <b>2b</b>, and <b>2e</b> were characterized as noncompetitive inhibitors of ARG with dissociation constants (<i>K</i>_i) ranging from 0.24 to 3.8 μM, demonstrating strong affinity. Structure–activity relationship studies revealed some similarities in the structural features of flavonoids related to ARG activity