Catellatolactams A–C, Plant Growth-Promoting Ansamacrolactams from a Rare Actinomycete of the Genus Catellatospora

Abstract

Catellatolactams A–C (1–3), three novel ansamacrolactams, were isolated from the culture extract of an underexplored rare actinomycete of the genus Catellatospora. Spectroscopic and spectrometric analyses by NMR and MS elucidated the structure of 1 to be a lactamized pentaketide presumably extended on a 3-amino-5-hydroxybenzoic acid starter unit. Compounds 2 and 3 further received epoxidation and intramolecular cross-linking to incorporate a 2-indolinone unit, with a 3-amino-5-hydroxybenzoic acid pendant on 3. The absolute configurations of 2 and 3 were unequivocally established to both be 2S,6R,7R by comparison of the experimental NMR chemical shifts and ECD spectra with those predicted by DFT-based quantum chemical calculation. While 1–3 showed no appreciable antimicrobial activity or cytotoxicity, root elongation of germinated lettuce seeds was promoted by 2 and 3 at 1–10 μM.

Krasilnikolides A and B and Detalosylkrasilnikolide A, Cytotoxic 20-Membered Macrolides from the Genus Krasilnikovia: Assignment of Anomeric Configuration by J-Based Configuration Analysis

“…Krasilnikolides A ( 1 ) and B ( 2 ) and detalosylkrasilnikolide A ( 3 ) are unique macrolides characterized by a ( Z )-2-(m)­ethyl-2-butenyl side chain. Glycosylation by 6dTal is unprecedented for macrolides, though modified 6dTal are seen in maduralide, callipeltosides, , or mandelalides. − Along with a series of results from our investigation on rare actinomycetes, the present work supports an idea that phylogenetically distant actinomycetes, even at the genus level, possess different secondary metabolite biosynthetic gene clusters, and hence unexplored or underexplored genera are promising as a source of unreported natural products. − The newly introduced diagnostic criteria of the JBCA method, used for the assignment of the α-glycosidic linkage of l -6dTal, complements the scope of this nonempirical and nondestructive stereochemical analysis. The updated JBCA method is especially useful when an aldohexopyranoside under study has a small anomeric 1 H– 1 H coupling constant.…”

Complete Genome Sequence Analysis of Kribbella sp. CA-293567 and Identification of the Kribbellichelins A & B and Sandramycin Biosynthetic Gene Clusters

“…Some of these genera are well known as producers of relevant antibiotics with clinical applications, including rifamycins from Amycolatopsis mediterranei , vancomycin from Amycolatopsis orientalis , erythromycin from Saccharopolyspora erythraea , teicoplanin from Actinoplanes teichomyceticus , and gentamicin from Micromonospora purpurea [ 17 ]. The importance of minor genera of actinomycetes has been corroborated by the discovery of several novel compounds in the last years [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ], such as kongjuemycins [ 23 ], catellatolactams [ 24 ], and persicamidines [ 25 ], so these genera represent an untapped resource of potential new bioactive natural products [ 17 , 26 ].…”

Double Bond Geometric Isomers of Pentaketide Ansamycins from Streptomyces sp. S008

“…Generally, structures of pentaketide ansamycins are unique due to their smallest ansa-skeletons, diverse extender units, and post-PKS modifications. To date, six types of skeletons of pentaketide ansamycins have been reported, including cebulactams, 10 ansaetherones and tetrapetalones, 11,12 microansamycins, 13 aminoansamycins, 14 catellatolactams, 15 and dimacrolactam juanlimycins. 16 Herein, we report the identification of six new pentaketide ansamycins, namely, shengliangmycins A−F (1−6, respectively) (Figure 2), through activation of the slm gene cluster.…”