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Mass Spectrometric Analysis
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
The avermectins are a group of four major and four minor components extracted from the mycelia of Streptomyces avermitilis. The structures, elucidated with the help of exact masses of the molecular and fragment ions [184], have a common pentacyclic 16-membered macrolactone with a disaccharide side chain. An LC-MS method using nonaqueous reversed-phase liquid chromatography was developed to monitor fermentation broths for the avermectin components [129]. The authors also sought to identify other components by LC-MS in an effort to understand the fermentation process that may ultimately be used to improve fermentation conditions.
Distribution
Published in Paul Pumpens, Single-Stranded RNA Phages, 2020
Without any doubt, future developments by the search for the RNA phage sources relate to the coming of the next-generation sequencing era. By performing weekly metagenomic sequencing of organisms in San Francisco wastewater, full-length genomes of two novel RNA phages, EC and MB, were assembled (Greninger and DeRisi 2015). The EC and MB phages comprised the typical Leviviridae genome organization. Absolutely novel RNA phage sequences were found by Krishnamurthy et al. (2016). These novel sequences were present in samples collected from a range of ecological niches worldwide, including invertebrates and extreme microbial sediment, demonstrating that the RNA phages were more widely distributed than was recognized previously. One RNA phage was detected in the transcriptome of a pure culture of Streptomyces avermitilis, suggesting for the first time that the known tropism of the RNA phages may include Gram-positive bacteria. Then, two RNA phages were found in stool samples from a longitudinal cohort of macaques, suggesting that they were generally acutely present rather than persistent (Krishnamurthy et al. 2016).
On Biocatalysis as Resourceful Methodology for Complex Syntheses: Selective Catalysis, Cascades and Biosynthesis
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Andreas Sebastian Klein, Thomas Classen, Jörg Pietruszka
The important groups of neurotoxins avermectins 32 and ivermectins 33 are pesticides and are used to treat ectoparasites (lice, mites and ticks) and nematodes (Pitterna et al., 2009). For the discovery and development of these compounds, the Nobel Prize for Physiology or Medicine was awarded in 2015. These natural products are polyketides, which are produced from acyl building blocks by a modularly clustered enzyme machinery. Some avermectins 32 are obtained by fermentation of Streptomyces avermitilis, other derivatives are only chemically addressable.
Alpha-mangostin attenuates the apoptotic pathway of abamectin in the fetal rats’ brain by targeting pro-oxidant stimulus, catecholaminergic neurotransmitters, and transcriptional regulation of reelin and nestin
Published in Drug and Chemical Toxicology, 2022
Khairy A. Ibrahim, Mohammed Eleyan, Soad A. Khwanes, Rania A. Mohamed, Basim M. Ayesh
Abamectin (ABM), a member of avermectins, is naturally generated by the soil bacterium Streptomyces avermitilis (Campbell et al.1983). ABM has insecticidal and anthelmintic activities and is broadly used in agriculture and veterinary medicine, due to its low cost, high efficacy, and environmental stability (Batiha et al.2020). The insecticidal action of ABM occurs by interfering with the insects' nervous system and stimulation of glutamate-gated chloride channel involved in its antiparasitic activity (Cully et al.1994). ABM has a highly lipophilic nature and is ineffectively metabolized in mammals (Sun et al.2005). The biotransformation of this pesticide occurs via cytochromes P450 and biodistribution depends on the affluence of P-glycoprotein which prevents neurotoxicity by restricting the entrance of poisonous compounds over the blood-brain barrier (Roulet et al.2003).
Intentional avermectin pesticide ingestion: a retrospective multicenter study
Published in Clinical Toxicology, 2022
Yi-Kan Wu, Chia-Hau Chang, Jiun-Hao Yu, Kai-Ping Lan, Tzung-Hai Yen, Shu-Sen Chang, Chen-June Seak, Hsing-Yuan Chang, Hsien-Yi Chen
Avermectins are macrocyclic lactones, produced naturally through fermentation of Streptomyces avermitilis [6]. They are commonly used as antiparasitics, pesticides, and acaricides. Avermectins can interact with invertebrate glutamate-gated chloride channels and γ-aminobutyric acid (GABA) receptors, causing paralysis and death [7,8]. Mammals are less susceptible because of the protection afforded by the blood-brain barrier (BBB) [7,9]. Ivermectin was the first commercialized avermectin used for the treatment of parasitic infections. It has been widely administered in Africa to treat millions of onchocerciasis patients [10]. Other derivatives, including abamectin and emamectin, were later commercialized as pesticides or acaricides, or as antiparasitics for pets [11].
Ivermectin: recent approaches in the design of novel veterinary and human medicines
Published in Pharmaceutical Development and Technology, 2022
Maiara Callegaro Velho, Diego Fontana de Andrade, Ruy Carlos Ruver Beck
Ivermectin (IVM) is a member of the avermectin family (Figure 1), an isolated class of fermentation products from Streptomyces avermitilis, which consists of a mixture of two homologues, 22,23-dihydro-avermectin B1a (80%) and 22,23-dihydro-avermectin B1b (20%) (Errecalde et al. 2021). IVM was discovered in the 1970s and was initially intended to treat parasitic diseases in animals. However, after being introduced to the animal health market in 1981, IVM was approved for human use in 1987 for the treatment of onchocerciasis. Since then, millions of people worldwide have used it to overcome many parasitic diseases, such as strongyloidiasis, filariasis, and scabies (Ashour 2019).