Abstract:O esclareolido (1) foi incubado com oito diferentes espécies de fungos filamentosos usados convencionalmente para bio-oxidações. O composto 1 metabolizado pelo fungo Aspergilus niger em um meio de cultura A forneceu o 3-cetoesclareolido (2) e 3b-hidroxiesclareolido (4). Quando em um meio de cultura B (mais rico em nutrientes em relação ao meio de cultura A), foram obtidos os compostos 2, 4, e ainda 3a,6b-diidroxiesclareolido (16), 1-cetoesclareolido (17), 3-ceto-15-hidroxiesclareolido (18) e 3b, 15-diidroxiesc… Show more
“…In addition, 62 mg of 23 (2.4% yield) resulting from oxidation at C-2 are also ob-tained. Despite the low yield of 23, its isolation can be regarded as significant since it had only been synthesized by means of biological methods, [21] which require high reaction times, and with Fe-pdpp [11] under very low temperature catalytic conditions. Overall, the mass balance of the reaction is moderate (~64%), but it should be considered as quite good for a C À H oxidation reaction of a complex molecule.…”
Section: Multigram Scale Oxidation Of Elaborated Moleculesmentioning
The efficient and selective oxidation of secondary C À H sites of alkanes is achieved by using low catalyst loadings of a non-expensive, readily available iron catalyst [Fe(II)-trans-1,2-diamine]}, and hydrogen peroxide (H 2 O 2 ) as oxidant, via a simple reaction protocol. Natural products are selectively oxidized and isolated in synthetically amenable yields. The easy access to large quantities of the catalyst and the simplicity of the C À H oxidation procedure make this system a particularly convenient tool to carry out alkane C À H oxidation reactions on the preparative scale, and in short reaction times.
“…In addition, 62 mg of 23 (2.4% yield) resulting from oxidation at C-2 are also ob-tained. Despite the low yield of 23, its isolation can be regarded as significant since it had only been synthesized by means of biological methods, [21] which require high reaction times, and with Fe-pdpp [11] under very low temperature catalytic conditions. Overall, the mass balance of the reaction is moderate (~64%), but it should be considered as quite good for a C À H oxidation reaction of a complex molecule.…”
Section: Multigram Scale Oxidation Of Elaborated Moleculesmentioning
The efficient and selective oxidation of secondary C À H sites of alkanes is achieved by using low catalyst loadings of a non-expensive, readily available iron catalyst [Fe(II)-trans-1,2-diamine]}, and hydrogen peroxide (H 2 O 2 ) as oxidant, via a simple reaction protocol. Natural products are selectively oxidized and isolated in synthetically amenable yields. The easy access to large quantities of the catalyst and the simplicity of the C À H oxidation procedure make this system a particularly convenient tool to carry out alkane C À H oxidation reactions on the preparative scale, and in short reaction times.
“…oligosporus , and F . moliniforme , were screened for their capabilities to metabolize compounds 1 – 9 at analytical scale (10 – 15 mg), and according with these results, experiments were carried out on a preparative scale (150 – 220 mg), following the same experimental processes . Erlenmeyer cell culture flasks (250 ml) containing 125 ml of medium A or medium B were inoculated with a dense suspension (2 ml) of the corresponding fungi.…”
Section: Methodsmentioning
confidence: 99%
“…Eight fungi, R. nigricans, B. bassiana, C. lunata, A. niger, C. blakesleeana, M. miehei, R. oligosporus, and F. moliniforme, were screened for their capabilities to metabolize compounds 1 -9 at analytical scale (10 -15 mg), and according with these results, experiments were carried out on a preparative scale (150 -220 mg), following the same experimental processes. [38] Erlenmeyer cell culture flasks (250 ml) containing 125 ml of medium A or medium B were inoculated with a dense suspension (2 ml) of the corresponding fungi. Incubation was maintained at 25°C with gyratory shaking (125 rpm) for 14 days after which the substrates (2 -4 ml) in acetone were added.…”
Section: Incubation Experiments Recovery and Purification Of Productsmentioning
confidence: 99%
“…[23 -27] Thus, with the aim of exploring the bioreactivity and bioactivity of several SLs, we carried out the transformations of arglanin (1), [28 -30] 11,13-dehydroeriolin (2), [31] [32] budlein B (3), [33] [34] ludovicin A (4), [28] santamarin (5), [28] , epoxysantamarin (6), [28] parthenolide (7), [35] sphaerocephalin (8) [36] and deacetylconfertiflorin (9) [37] by eight filamentous fungi previously used by our group. [38] The biotransformations afforded the products 10 -17, which were previously characterized as natural products. Therefore, these derivatizations imitate their natural biosynthesis.…”
Biotransformation is an economically and ecologically viable technology which has been used to modify the structures of many classes of biologically active products. Some fungi may be useful for the biotransformation of sesquiterpene lactones (SLs), leading to unusual structural changes that modify their biological activities, and other transformations mimic their biosynthetic pathways, generating evidences for the proposed biogenesis. Eight filamentous fungi were screened for their ability to transform different SLs (1 - 9), and microbial reactions yielded compounds 10 - 17, which in turn have been isolated as natural products, thus mimicking their biosynthesis. Their structures were identified based on NMR and MS spectroscopic analyses. The cytotoxicities of SLs 1, 4, 6, 7 and 9, and their biotransformed produts (10, 14, 15 and 17) against human cancer cell lines U251 (glia), PC3 (prostate), K562 (leukemia), HCT-15 (colon), MCF7 (breast), and SKLU-1 (lung), were determined, confirming that the presence of Michael acceptor is an important feature for the bioactivity.
“…An oxidation reaction of alcohols has been reported with whole cells of R. miehei. 28,29 With other filamentous fungi, regioselective oxidation of the hydroxy group has also been found in one of the hydroxy groups of entmanoyl oxides. 30,31 The reduction of the keto group in derivative 4, by action of a dehydrogenase present in R. miehei, would lead to compound 6 with the S-configuration for the 12-hydroxy derivative obtained (Figure 4).…”
Incubation of salpichrolide A (1) with Rhizomucor miehei produced hydroxylation in rings B and C (C-7 and C-12) and led to C-5-C-6 epoxide opening, while incubation of salpichrolides C (2) and G (3) with R. miehei led to epoxide opening at the C-24-C-25 and C-5-C-6 positions, respectively. Biotransformation of salpichrolide A (1) with Cunninghamella elegans produced stereoselective hydroxylated, oxidized, and reduced derivatives in different positions of the A, B, and C rings and C-5-C-6 epoxide opening. In addition, selective epoxide opening at the C-5-C-6 or C-24-C-25 positions was obtained from the incubation of salpichrolide A (1) with Curvularia lunata.
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