Chemistry of Essential Oils
K. Hüsnü Can Başer, Gerhard Buchbauer in Handbook of Essential Oils, 2020
Figure 6.3 shows how condensation of polyketides can lead to phenolic rings. Intramolecular aldol condensation of the tri-keto-octanoic acid and subsequent enolization leads to orsellinic acid (6). Polyketide phenols can be distinguished from the phenolic systems of the shikimates by the fact that the former usually retain evidence of oxygenation on alternate carbon atoms, either as acids, ketones, phenols, or as one end of a double bond. The most important natural products containing polyketide phenols are the extracts of oakmoss and tree moss (Evernia prunastri). The most significant in odor terms is methyl 3-methylorsellinate (7) and ethyl everninate (8), which is usually also present in reasonable quantity. Atranol (9) and chloratranol (10) are minor components but they are skin sensitizers and so limit the usefulness of oakmoss and tree moss extracts, unless they are removed from them. Dimeric esters of orsellinic and everninic acids and analogues also exist in mosses. They are known as depsides and hydrolysis yields the monomers, thus increasing the odor of the sample. However, some depsides, such as atranorin (11), are allergens and thus contribute to safety issues with the extracts.
Natural Polyketides to Prevent Cardiovascular Disease
Catherina Caballero-George in Natural Products and Cardiovascular Health, 2018
This chapter will not attempt to address the numerous controversies that surround the use of statins with relation to cardiovascular disease and their associated side effects. Rather, the focus of this chapter is on the nature of statins, their structure and how they interact with relevant biological processes. This should provide some perspective on the use of polyketides as pharmaceuticals. While statin intervention may be straightforward life-or-death in a microbial world, these molecules operate in the context of a more complex system, the human body, which has carefully regulated mechanisms to maintain function. It becomes more difficult to predict how the introduction of statins will affect the organism as a whole. Regardless, statins have proven to be the most consistent and effective lipid-lowering agent on the market since their introduction and are a valuable case study for the role of polyketides in disease prevention.
On Biocatalysis as Resourceful Methodology for Complex Syntheses: Selective Catalysis, Cascades and Biosynthesis
Peter Grunwald in Pharmaceutical Biocatalysis, 2019
Polyketide synthases (PKS) are particularly suitable for the approach of combinatorial biosynthesis, since the exchange of homologous genes is simplified by the modular character in order to generate new derivatives. For some avermectins 32 it could be shown that an exchange of reducing enzymes from module 2 (DH: dehydratase; KR: ketoreductase) with enzymes from a rapamycin-producing PKS of Streptomyces hygroscopicus (DH: dehydratase; KR: ketoreductase; ER: enoyl reductase) led to products with reduced double bond (Fig. 21.13) (Gaisser et al., 2003).
Inhibition of heterotrophic bacterial biofilm in the soil ferrosphere by Streptomyces spp. and Bacillus velezensis
Published in Biofouling, 2022
Nataliia Tkachuk, Liubov Zelena
Although antagonistic properties of S. canus strain NUChC F2 have not been observed, various strains of S. canus have been studied in the past and a number of compounds with antifungal and bactericidal activity have been identified (Zhang et al. 2013). In particular S. canus strain C-509 (ATCC 12647) was found to produce telomycin, an antibiotic with marked bactericidal activity (Hooper et al. 1962; Fu et al. 2015). S. canus strain IMCC 34906 was indicated among microorganisms with antimicrobial potential and isolated from Nepalese Soil (Khadayat et al. 2020). Liu et al. (2016) performed whole genome sequence of S. canus strain ATCC 12647. Twelve secondary metabolite biosynthetic gene clusters were identified, of which three were nonribosomal peptides, six were polyketides, one was another hybrid peptide-polyketide, and two were other metabolites. The complete nonribosomal peptide gene cluster responsible for the production of telomycin and its associated analogues was identified. Researchers also observed gene clusters with high homology scores corresponding to those known to produce coelichelin and albaflavenone. Other remaining nonribosomal peptide, polyketide, and hybrid clusters of substantial size are also present with yet-unknown identity (Liu et al. 2016).
Cytogenotoxic evaluation of the acetonitrile extract, citrinin and dicitrinin-A from Penicillium citrinum
Published in Drug and Chemical Toxicology, 2022
José Williams Gomes de Oliveira Filho, Teresinha de Jesus Aguiar dos Santos Andrade, Rosália Maria Tôrres de Lima, Dulce Helena Siqueira Silva, Antonielly Campinho dos Reis, José Victor de Oliveira Santos, Ag-Anne Pereira Melo de Meneses, Ricardo Melo de Carvalho, Ana Maria Oliveira da Mata, Marcus Vinícius Oliveira Barros de Alencar, Ana Carolina Soares Dias, Felipe Cavalcanti Carneiro da Silva, Muhammad Torequl Islam, Cain C. T. Clark, João Marcelo de Castro e Sousa, Ana Amélia de Carvalho Melo-Cavalcante
Polyketides are evident to induce apoptosis and MN formation (Yu et al.2006, Chan 2007, Dönmez-Altuntas et al.2007). CIT induces DNA damage via ROS formation through mitogen-activated protein kinase (MAPK) activation (Chan et al.2007, Farrugia and Balzan 2012). In rats, CIT at high doses was seen to increase mRNA expression for Ccna2, Ccnb1 and E2f1 transcription factors, leading to cell cycle modifications, CA and genotoxicity (Liu et al.2003, Knasmüller et al.2004, Bouslimi et al.2008, Folkmann et al.2009, Chang et al.2011, Kuroda et al.2013). In addition, the induction of MN, mediated by CIT, and several other damages caused to DNA were observed in HepG2 cells (Knasmüller et al.2004). A good candidate for an antitumor agent should have the ability to induce cytotoxic, genotoxic and mutagenic effects in neoplastic cells, generating blocking effects of the neoplastic process. CIT is capable of causing clastogenic effects in in vivo and in vitro test systems (Liu et al.2017).
Recent advances and future perspectives in the pharmacological treatment of Candida auris infections
Published in Expert Review of Clinical Pharmacology, 2021
Daniele R. Giacobbe, Laura Magnasco, Chiara Sepulcri, Malgorzata Mikulska, Philipp Koehler, Oliver A. Cornely, Matteo Bassetti
Turbinmicin was discovered through the screening of 1482 actinobacteria from marine invertebrates and subsequent challenge in vitro for activity against C. albicans. Turbinmicin was isolated from a sea squirt microbiome constituent, Micromonospora spp., and belongs to highly oxidized type II polyketides [112]. Its antifungal activity was tested against 39 fungi, including one isolate of fluconazole-resistant and micafungin-resistant C. auris, showing a MIC of 0.25 mg/L [112]. Turbinmicin was also evaluated in a neutropenic murine model of C. auris bloodstream infection, showing a greater reduction in fungal load in comparison with micafungin. Sec14p, a transfer protein essential for cellular trafficking, was identified as the antifungal target of turbinmicin [112].
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