Three novel polyene macrolides isolated from cultures of Streptomyces lavenduligriseus

Abstract

Actinomycetes have evolved in the process of ecological interactions between animals, plants and microorganisms in the environment to produce new classes of secondary metabolites with novel structures, 1-3 of which polyene macrolides are very interesting bioactive compounds with a wide range of biological activities and subject to a relatively low incidence of resistance. 4,5 Many of these molecules have been successfully isolated and turned into useful drugs and other organic chemicals. In our study aimed at the discovering of novel antifungals, the soil actinomycete, Streptomyces lavenduligriseus, was found to produce strong antifungal components. Bioactivity-guided isolation and purification yielded filipin III 1 and three novel polyene macrolides, compound 2, 3 and 4 ( Figure 1). Details of the isolation, structure elucidation and the antifungal activities of these compounds are presented below.The strain of S. lavenduligriseus was cultivated in 250-ml Erlenmeyer flasks containing 30 ml of seed medium (2% glucose, 3% soybean meal, 2% soluble starch, 2% glycerol, 0.02% MgSO 4 ·7H 2 O and 0.02% KH 2 PO 4 , pH 7.5). The flasks were shaken at 220 r.p.m. on a rotary shaker at 28°C for 2 days. The seed culture (8%) was transferred into 500-ml Erlenmeyer flasks containing 50 ml of production medium (4% cornstarch, 0.8% glucose, 2.2% soybean meal, 0.1% MgSO 4 ·7H 2 O, 0.02% KH 2 PO 4 and 0.2% NaCl). The flasks were incubated at 220 r.p.m. on a rotary shaker at 28°C for 7 days. The cells were lysed with EtOH, which was then removed by concentration in vacuo. The resulting aqueous concentrate was partitioned successively with EtOAc (3 × 3 l) and BuOH (3 × 3 l). The combined extracts were concentrated under reduced pressure to yield 68 g of brown gum. This material was subjected to silica gel chromatography using a gradient mixture of CHCl 3 -MeOH (from 100:0 to 0:100), yielding nine fractions (A-I). A fraction (5.65 g) was identified as containing polyene macrolides by assaying for bioactivity against Candida albicans and by a diode array detector (DAD)/UV spectra with three characteristic λ max at 289, 303, 319 nm. 6 The fraction was further fractionated by successive preparative HPLC (YMC-Pack RP-C18 (YMC, Tokyo, Japan), 30 × 250 mm 2 , 35% MeCN in H 2 O, 10 mlmin − 1 ), yielding fractions 1-8. Fraction 3 (26.5 mg) was further purified by semi-prep RP-HPLC (YMC-Pack RP-C18, 20 × 250 mm 2 , 35% MeCN in H 2 O, 7 ml min − 1 ) to attain compound 4 (23.6 mg; t R = 20.1 min). Using the same procedure, purification of fraction 6 (56.5 mg) yielded compounds 3 (8.3 mg; t R = 72.6 min) and 2 (7.3 mg; t R = 81.2 min), fraction 8 (69.5 mg) afforded compound 1 (12.6 mg; t R = 63.5 min).Compound 1 was identified as filipin III by comparing its NMR and MS data with those previously reported. 7 The molecular formula of compound 2 was determined to be C 38 H 64 O 13 (seven degrees of unsaturation) on the basis of its positive HR-ESI-MS at the m/z value = 751.4226 [M+Na] + , 74 a.m.u. higher than that of compound 1, in agreement with ...

In vitro and in vivo Assay for Assessment of the Biological Control Potential of Streptomyces sp. KT

“…From these results, KT was identified as Streptomyces sp., which closely related to strain S. lavenduligriseus NRRL B-3173 T . S. lavenduligriseus is known to produces pentenomycin and polyene macrolides (Jiayue et al, 2016). Pentenomycin is antibacterial compound and is not effective against fungi.…”

The nesting preference of an invasive ant is associated with the cues produced by actinobacteria in soil

“…One of the most striking features of actinobacteria is that they can produce antifungal compounds [ 26 ]. Actinobacteria with antifungal activity are reported to show high species richness in certain types of soil [ 27 – 29 ]. Because entomopathogenic fungi are also widely distributed in soil [ 30 – 33 ], we hypothesize that some soil-dwelling insects may choose soil types with the highest abundance of actinobacteria for nest building to avoid being infected by some soil-derived entomopathogenic fungi.…”

Molecular-Based Identification of Actinomycetes Species That Synthesize Antibacterial Silver Nanoparticles

“…MBE174 is unknown. Moreover, based on the EzTaxon-e database search result, the sequence of KDT32 isolate showed 99.8% sequence similarity with S. lavenduligriseus strain NRRL ISP-5487 that produced polyene macrolides (pentenomycine II, pentenomycine III, and narangomycine) [40].…”