Abstract
Bacteria of Streptomyces genus are a promising source of biologically active products, with applications in medicine, industry and agriculture. Therefore, the objective of this work was to evaluate the cytotoxic, antioxidant and antimicrobial activities of fermented rice extract and their semipurified fractions from Streptomyces spp. isolated of the rhizosphere of Paullinia cupana, Amazon-Brazil. For this, a bioguided study was carried out by the cytotoxic activity with methanolic extract of Streptomyces sp. ACTMS-12H UFPEDA 3405 (EMeOH-12H) partitioned with n-hexane, ethyl acetate and 2-butanol. The antioxidant activity was analyzed using the DPPH, ABTS and phosphomolybdenum methods, while the antimicrobial activity was investigated by microdilution method to determine the minimum inhibitory concentration (MIC) against species of bacteria and yeast. In the cytotoxicity test, the butanolic phase (FbuOH-12H) presented IC50 of 1.1 µg/mL against MOLT-4, with cell death probably by apoptosis, but did not cause cytotoxicity on peripheral blood mononuclear cell (PBMC) or human erythrocytes. Chemical prospecting detected the presence of saponins and reducing sugars on 2-butanol fraction (FBuOH-12H), which can be related to cytotoxicity. On the antioxidant activity by ABTS, the partition with ethyl acetate (FAcOEt-12H) showed antioxidant capacity of 1161.7 ± 0.04 µM of Trolox/g of extract, indicating an expressive reactivity of the phase with this radical. The aqueous phases (from hexane, ethyl acetate and methanol extracts) were active in all tested microorganisms, except E. faecalis.
Highlights
Bacteria of the genus Streptomyces are known to produce a wide variety of antibiotics and other bioactive compounds, being this genus the major producer in number and diversity of new antibiotics when compared to other bacterial genera
The objective of this work was to investigate the antimicrobial, antioxidant and cytotoxic activities of Streptomyces spp. secondary metabolites isolated of the rhizosphere of Paullinia cupana from Amazon-Brazil region
Micromorphological, biochemical characterizations and antibiotic resistance, strain isolated from the rhizosphere soil of P. cupana (Kunth) var. sorbilis (Mart.) Ducke, Amazonas-Brasil, belong to the genus Streptomyces
Summary
Bacteria of the genus Streptomyces are known to produce a wide variety of antibiotics and other bioactive compounds, being this genus the major producer in number and diversity of new antibiotics when compared to other bacterial genera (Rashad et al, 2015). Secondary metabolites produced by Streptomyces are described in the literature as antifungal (Sharma, Manhas, 2020), antiviral (Jakubiec-Krzesniak et al, 2018), anticancer (Tan et al, 2015; Nguyen et l., 2020), antioxidants (Tan et al, 2018) and cytotoxic agents (Lima et al, 2017). There is a range of antibiotic drugs of various chemical classes; it is still necessary to investigate new molecules due to the indiscriminate use of these drugs and the increasingly frequent emergence of multiresistant bacterial strains. Many of these antibiotics are used in the fight against cancer. Pre-clinical tests in animal models and in vitro tests on cells, tissues or biochemical functions are fundamental to guarantee the safety and continuity of the prospection of new drugs in humans (Scott, Peters, Dragan, 2013)
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