The compounds terrein (1), butyrolactone I (2), and butyrolactone V (3) were isolated from the ethyl acetate extract (EtOAc) of the endophytic fungus Aspergillus terreus-F7 obtained from Hyptis suaveolens (L.) Poit. The extract and the compounds presented schistosomicidal activity against Schistosoma mansoni; at 100 µg/mL for EtOAc extract, 1297.3 µM for compound 1, 235.6 µM for compound 2, and 454.1 µM for compound 3, they killed 100% of the parasites after 72 h of treatment. Compounds 1, 2, and 3 exerted moderate leishmanicidal activity against Leishmania amazonensis (IC ranged from 23.7 to 78.6 µM). At 235.6 and 227.0 µM, compounds 2 and 3, respectively, scavenged 95.92 and 95.12% of the DPPH radical (2,2-diphenyl-1-picryl-hydrazyl), respectively. Regarding the cytotoxicity against the breast tumor cell lines MDA-MB-231 and MCF-7, compound 2 gave IC of 34.4 and 17.4 µM, respectively, while compound 3 afforded IC of 22.2 and 31.9 µM, respectively. At 117.6 µM, compound 2 inhibited the growth of and killed the pathogen Escherichia coli (ATCC 25922). Compounds 1, 2, and 3 displayed low toxicity against the normal line of human lung fibroblasts (GM07492A cells), with IC of 15.3 × 10, 3.4 × 10, and 5.8 × 10 µM, respectively. This is the first report on (i) the in vitro schistosomicidal and leishmanicidal activities of the EtOAc extract of A. terreus-F7 and compounds 1, 2, and 3; and (ii) the antitumor activity of compounds 2 and 3 against MDA-MB-231 and MCF-7 cells.
We report the isolation and identification of endophytic fungi from Combretum lanceolatum Pohl ex Eichler. Further, we evaluated the relationships of fungi with the host plant and tested bioactivities of isolates. The fungi were isolated from disinfected root fragments and plated onto potato dextrose agar. Root pieces were also used to quantify fungal structures associated with the roots. Identification of fungi was carried out by characterization of morphological features and sequencing of the ITS region. Endophytism was confirmed by inoculation of endophyte-free seedlings followed by microscopic examination. The extract was obtained by maceration of the mycelium in ethyl acetate for antioxidant and antimicrobial evaluations. A total of 112 strains belonging to nine different species were isolated, the major classes were Dothideomycetes and Sordariomycetes. C. lanceolatum is colonized by dark septate endophytes (DSE), evidenced by the presence of microsclerotia and melanized hyphae. There is also co-colonization with mycorrhizal fungi in the same root fragments. Seedling inoculation experiments revealed that C. perangustum-95C and M. phaseolina-46C showed association with the seedlings of C. lanceolatum and differentiated microsclerotia and dark septate hyphae, indicating that these species are DSE. In the antimicrobial test, the D. phaseolorum-92C extract had the highest zones of inhibition against S. aureus and E. coli, respectively. The results showed that 100 % of the extracts have antioxidant activity ranging from low to moderate. All endophyte species had antioxidant and antimicrobial activities that were directly proportional to the dose-responses. Future research will involve chemical characterization and structural elucidation of bioactive compounds.
Chemical investigation of the ethyl acetate extract from the endophytic fungus Diaporthe phaseolorum-92C (92C) isolated from the roots of Combretum lanceolatum led to the isolation of 18-des-hydroxy Cytochalasin H (compound 1). The trypanocidal and schistosomicidal activity and cytotoxicity of the extract from 92C were evaluated. The schistosomicidal, leishmanicidal, antimicrobial, and antioxidant actions, as well as the antitumor activity against the breast cancer cells MDA-MB-231 and MCF-7, and the cytotoxicity towards normal human lung fibroblasts GM07492A of compound 1 was tested. The extract from 92C (20 μg/mL) exerted potent trypanocidal activity, reducing 82% of the number of amastigotes and trypomastigotes of Trypanosoma cruzi. Compound 1 at 50 μg/mL killed 50% of Schistosoma mansoni adult worms. Compound 1 reduced the viability of Leishmania amazonenses promastigotes (IC = 9.2 μg/mL) and of the cancer cells MDA-MB-231 and MCF-7 (IC = 17.5 and 8.88 μg/mL, respectively), presented moderate antioxidant activity, and gave IC of 2049.7 ± 39.9 μg/mL for the cytotoxicity towards normal cells GM07492A. This knowledge is highly relevant to the search for new promising compounds for therapeutic purposes.
The actinobacteria are the most abundant bacterial group in the soil, where they present different characteristics and antagonistic effects on other microorganisms. The objectives of this study were to characterize and evaluate the antagonistic effect of actinobacteria from the semiarid region on rhizobia from the same climatic region. Tests were performed to observe chromogenic and micro-morphological characteristics, tolerance to pH levels of melanin production, and use of carbon sources. This occurred due to the use of modified CDA culture media and basal medium supplemented with specific carbon sources, as well as the use of Ral color chat to observe the colonies. The in vitro antagonism on rhizobia was evaluated in yeast malt agar (YMA) culture medium for the observation of inhibition halo by actinobacteria. We observed different characteristics in relation to the color of aerial mycelium and reverse pigments; tolerance to media with acid and alkaline pH; and production of melanoid pigment occurred only in three strains. The morphological characteristics were described for genera Streptomyces and Saccharothrix, later confirmed by molecular sequencing. These genera were generalists in use of carbon sources, showing their physiological versatility. Regarding antagonism, nine strains of the genus Streptomyces were able to inhibit in vitro strains of Rhizobium tropici and Bradyrhizobium yuanmingense also coming from semiarid soils. The antagonism between actinobacteria and rhizobia can directly affect the symbiosis between nitrogen-fixing bacteria and leguminous plants. These results are pioneering in observing antagonism of these species of rhizobia under the climate condition of the semiarid region, and may contribute to agricultural biotechnology.
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