Absolute configurations of griseorhodins A and C

Ortega, Humberto E.; Batista, João M.; Melo, Weilan Gomes da Paixão; Clardy, Jon; Pupo, Mônica Tallarico

doi:10.1016/j.tetlet.2017.11.008

Cited by 14 publications

(10 citation statements)

References 11 publications

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“…The stereocenter at carbon 6a has a dramatic effect on the calculated ECD spectrum, clearly supporting the assignment of carbon 6a as the S configuration, which is consistent with the previous reports within this structural class [23,24]. The calculated spectra for 6S,6aS and 6R,6aS, however, are indistinguishable by this method, leaving the configuration of C6 ambiguous.…”

Section: Absolute Configuration Of 78-dideoxygriseorhodin Csupporting

confidence: 89%

“…Two stereocenters are present in 1 at carbons 6 and 6a. Interestingly, previous reporting on the absolute configurations of griseorhodins A and C showed the configuration of carbon 6a to be S in both compounds, while carbon 6 is identified as S in griseorhodin A and R in griseorhodin C [23,24]. Despite being known for many years, no reports have been made on the absolute or relative configuration of 7,8-dideoxygriseorhodin C. Stereochemical assignment was done through a combination of calculated vs. experimental ECD spectra and through-space NOE correlations.…”

Section: Absolute Configuration Of 78-dideoxygriseorhodin Cmentioning

confidence: 85%

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Synergistic anti-methicillin-resistant Staphylococcus aureus (MRSA) activity and absolute stereochemistry of 7,8-dideoxygriseorhodin C

et al. 2020

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The emergence of antibiotic resistance necessitates not only the identification of new compounds with antimicrobial properties, but also new strategies and combination therapies to circumvent this growing problem. Here, we report synergistic activity against methicillin-resistant Staphylococcus aureus (MRSA) of the β-lactam antibiotic oxacillin combined with 7,8-dideoxygriseorhodin C in vitro. Ongoing efforts to identify antibiotics from marine mollusk-associated bacteria resulted in the isolation of 7,8-dideoxygriseorhodin C from a Streptomyces sp. strain cultivated from a marine gastropod tissue homogenate. Despite the long history of 7,8-dideoxygriseorhodin C in the literature, the absolute configuration has never been previously reported. A comparison of measured and calculated ECD spectra resolved the configuration of the spiroketal carbon C6, and 2D ROESY NMR spectroscopy established the absolute configuration as 6s,6aS. The compound is selective against Gram-positive bacteria including MRSA and Enterococcus faecium with an MIC range of 0.125-0.5 μg ml −1. Moreover, the compound synergizes with oxacillin against MRSA as observed in the antimicrobial microdilution and time-kill assays. Simultaneous treatment of the compound with oxacillin resulted in an approximately tenfold decrease in MIC with a combination index of <0.5, indicating synergistic anti-MRSA activity.

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Section: Absolute Configuration Of 78-dideoxygriseorhodin Csupporting

confidence: 89%

Section: Absolute Configuration Of 78-dideoxygriseorhodin Cmentioning

confidence: 85%

Synergistic anti-methicillin-resistant Staphylococcus aureus (MRSA) activity and absolute stereochemistry of 7,8-dideoxygriseorhodin C

et al. 2020

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“…Their AC was established as (6S,6aS,7S,8S)−192 and (6R,6aS,7S,8R)−193 using VCD and DFT calculations. 94 Dextrorotatory pennicitrinone A (194) ( Figure 53) is a citrinin dimeric derivative isolated from the marine-derived fungus Penicillium janthinellum. Due to the large distance between the stereogenic centers of the 2 monomer units, it was difficult to determine the AC, a task that was accomplished as (3R,4S,2'R,3'S)−194 by VCD combined with accurate quantum mechanical calculations.…”

Section: Polyketidesmentioning

confidence: 99%

Vibrational Circular Dichroism Absolute Configuration of Natural Products From 2015 to 2019

Río

Joseph‐Nathan

2021

Natural Product Communications

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Although demonstrated in 1975, vibrational circular dichroism (VCD) finally started to popularize during this century as a reliable tool to determine the absolute configuration (AC) of organic molecules. This research field continues to be a very dynamic one, in particular for the study of natural products which are a unlimited source of chiral molecules. It therefore turns of interest to summarize the accomplishments published in recent years and to comment on some eventual difficulties that emerged in rare cases to complete the AC determination task. Therefore the aim of this review is to update VCD results for the AC assignment of natural products published from 2015 to 2019, a period in which VCD was reported in some 126 publications involving almost 300 molecules. They are organized according the type of studied metabolite allowing an easily search. The molecules correspond to 28 monoterpenes concerning 17 papers, to 42 sesquiterpenes in 14 papers, to 51 diterpenes in 19 publications, to 5 other terpenoids in three papers, to 48 aromatic molecules in 15 reports, to 20 polyketides in 10 publications, to 27 miscellaneous formulas also in 10 papers, and to 76 nitrogen containing compounds, which include alkaloids and their synthetic analogs, in 38 articles. The landscape of reviewed molecules is quite wide as it goes from simple monoterpenes, like borneol or camphor, to very relevant biological molecules like the alkaloid cocaine or tadalafil samples to distinguish genuine and counterfeit Cialis®. In addition, 5 natural products and a simple derivative published outside the reviewed period, were used to illustrate some aspects of density functional theory calculations.

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“…The actinobacterium S. puniceus ICBG378, isolated from Acromyrmex rugosus rugosus ants, produces griseorhodin A (12) and griseorhodin C (13), natural products known by their cytotoxic activity against cancer cell lines [46], and dinactin (14), active against Escovopsis (▶ Fig. 2) [47].…”

Section: Natural Products Mediating Microbial Symbiosis Fungus-farminmentioning

confidence: 99%

Chemical Ecology in Insect-microbe Interactions in the Neotropics

2020

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Small molecules frequently mediate symbiotic interactions between microorganisms and their hosts. Brazil harbors the highest diversity of insects in the world; however, just recently, efforts have been directed to deciphering the chemical signals involved in the symbioses of microorganisms and social insects. The current scenario of natural products research guided by chemical ecology is discussed in this review. Two groups of social insects have been prioritized in the studies, fungus-farming ants and stingless bees, leading to the identification of natural products involved in defensive and nutritional symbioses. Some of the compounds also present potential pharmaceutical applications as antimicrobials, and this is likely related to their ecological roles. Microbial symbioses in termites and wasps are suggested promising sources of biologically active small molecules. Aspects related to public policies for insect biodiversity preservation are also highlighted.

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Absolute configurations of griseorhodins A and C

Cited by 14 publications

References 11 publications

Synergistic anti-methicillin-resistant Staphylococcus aureus (MRSA) activity and absolute stereochemistry of 7,8-dideoxygriseorhodin C

Synergistic anti-methicillin-resistant Staphylococcus aureus (MRSA) activity and absolute stereochemistry of 7,8-dideoxygriseorhodin C

Vibrational Circular Dichroism Absolute Configuration of Natural Products From 2015 to 2019

Chemical Ecology in Insect-microbe Interactions in the Neotropics

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