Examples
 |
| Name | =R1 | =R2 | –R3 |
|---|---|---|---|
| Milbemectin | –H, (β)–OH | –H, –H | –CH3 : –CH2CH3 = 3:7 |
| Milbemycin oxime | =NOH | –H, –H | –CH3 : –CH2CH3 = 3:7 |
| Moxidectin | –H, (β)–OH | =NOCH3 | (Z)–C(CH3)=CH–CH(CH3)2 [1] |
| Nemadectin | –H, (β)–OH | –H, (α)–OH | (Z)–C(CH3)=CH–CH(CH3)2 [1] |
The milbemycins are a group of macrolides chemically related to the avermectins and were first isolated in 1972 from Streptomyces hygroscopicus . They are used in veterinary medicine as antiparasitic agents against worms, ticks and fleas. [1]
Milbemycins have a similar mechanism of action, but a longer half-life than the avermectins. They open glutamate-sensitive chloride channels in neurons and myocytes of invertebrates, leading to hyperpolarisation of these cells and blocking of signal transfer. [ citation needed ]
Milbemycin is effective against some avermectin-resistant insects. [2]
Like avermectins, milbemycins are products of fermentation by Streptomyces species. A grand total of five species, namely S. hygroscopicus , S. griseochromogenes , S. cyaneogriseus , S. nanchanggensis and S. bingchenggensis , are known to produce this family of compounds. [2]
The biosynthetic cluster from S. bingchenggensis and S. nanchanggensis have been sequenced and analyzed, partly by analogy to the homologous biosynthetic cluster for avermectin. New regulatory elements that control how much milbemycins are being identified in hopes to improve the industrial fermentation yield of milbemycins, which (as of 2021) is much lower than that of avermectin. [2]
An alternative pathway to higher yields was demonstrated in 2017, when select genes from S. avermitilis were swapped out so the avermectin producer makes milbemycin instead. [2]
| |
| Name | =R1 | =R2 | –R3 |
|---|---|---|---|
| Milbemectin | –H, (β)–OH | –H, –H | –CH3 : –CH2CH3 = 3:7 |
| Milbemycin oxime | =NOH | –H, –H | –CH3 : –CH2CH3 = 3:7 |
| Moxidectin | –H, (β)–OH | =NOCH3 | (Z)–C(CH3)=CH–CH(CH3)2 [1] |
| Nemadectin | –H, (β)–OH | –H, (α)–OH | (Z)–C(CH3)=CH–CH(CH3)2 [1] |
Abamectin (also called avermectin B1) is a widely used insecticide and anthelmintic. Abamectin, is a member of the avermectin family and is a natural fermentation product of soil dwelling actinomycete Streptomyces avermitilis. Abamectin differs from ivermectin, the popular member of the avermectin family, by a double bond between carbons 22 and 25. Fermentation of Streptomyces avermitilis yields eight closely related avermectin homologs, with the B1a and B1b forms comprising the majority of the fermentation. The non-proprietary name, abamectin, refers to a mixture of B1a (~80%) and B1b (~20%). Out of all the avermectins, abamectin is the only one that is used both in agriculture and pharmaceuticals.
Streptomyces is the largest genus of Actinomycetota, and the type genus of the family Streptomycetaceae. Over 700 species of Streptomyces bacteria have been described. As with the other Actinomycetota, streptomycetes are gram-positive, and have very large genomes with high GC content. Found predominantly in soil and decaying vegetation, most streptomycetes produce spores, and are noted for their distinct "earthy" odor that results from production of a volatile metabolite, geosmin. Different strains of the same species may colonize very diverse environments.
Natamycin, also known as pimaricin, is an antifungal medication used to treat fungal infections around the eye. This includes infections of the eyelids, conjunctiva, and cornea. It is used as eyedrops. Natamycin is also used in the food industry as a preservative.
Production of antibiotics is a naturally occurring event, that thanks to advances in science can now be replicated and improved upon in laboratory settings. Due to the discovery of penicillin by Alexander Fleming, and the efforts of Florey and Chain in 1938, large-scale, pharmaceutical production of antibiotics has been made possible. As with the initial discovery of penicillin, most antibiotics have been discovered as a result of happenstance. Antibiotic production can be grouped into three methods: natural fermentation, semi-synthetic, and synthetic. As more and more bacteria continue to develop resistance to currently produced antibiotics, research and development of new antibiotics continues to be important. In addition to research and development into the production of new antibiotics, repackaging delivery systems is important to improving efficacy of the antibiotics that are currently produced. Improvements to this field have seen the ability to add antibiotics directly into implanted devices, aerosolization of antibiotics for direct delivery, and combination of antibiotics with non antibiotics to improve outcomes. The increase of antibiotic resistant strains of pathogenic bacteria has led to an increased urgency for the funding of research and development of antibiotics and a desire for production of new and better acting antibiotics.
Glufosinate is a naturally occurring broad-spectrum herbicide produced by several species of Streptomyces soil bacteria. Glufosinate is a non-selective, contact herbicide, with some systemic action. Plants may also metabolize bialaphos and phosalacine, other naturally occurring herbicides, directly into glufosinate. The compound irreversibly inhibits glutamine synthetase, an enzyme necessary for the production of glutamine and for ammonia detoxification, giving it antibacterial, antifungal and herbicidal properties. Application of glufosinate to plants leads to reduced glutamine and elevated ammonia levels in tissues, halting photosynthesis and resulting in plant death.
The avermectins are a series of drugs and pesticides used to treat parasitic worms and insect pests. They are a group of 16-membered macrocyclic lactone derivatives with potent anthelmintic and insecticidal properties. These naturally occurring compounds are generated as fermentation products by Streptomyces avermitilis, a soil actinomycete. Eight different avermectins were isolated in four pairs of homologue compounds, with a major (a-component) and minor (b-component) component usually in ratios of 80:20 to 90:10. Avermectin B1, a mixture of B1a and B1b, is the drug and pesticide abamectin. Other anthelmintics derived from the avermectins include ivermectin, selamectin, doramectin, eprinomectin.
The aminocyclitols are compounds related to cyclitols. They possess features of relative and absolute configuration that are characteristic of their class and have been extensively studied; but these features are not clearly displayed by general methods of stereochemical nomenclature, so that special methods of specifying their configuration are justified and have long been used. In other than stereochemical respects, their nomenclature should follow the general rules of organic chemistry.
Nogalamycin is an anthracycline antibiotic produced by the soil bacteria Streptomyces nogalater. It has antitumor properties but it is also highly cardiotoxic. The less cardiotoxic semisynthetic analog menogaril was developed in the 1970s. Currently nogalamycin and menogaril are not used clinically.
Milbemycin oxime, sold under the brand name Interceptor among others, is a veterinary medication from the group of milbemycins, used as a broad spectrum antiparasitic. It is active against worms (anthelmintic) and mites (miticide).
Emamectin is the 4″-deoxy-4″-methylamino derivative of abamectin, a 16-membered macrocyclic lactone produced by the fermentation of the soil actinomycete Streptomyces avermitilis. It is generally prepared as the salt with benzoic acid, emamectin benzoate, which is a white or faintly yellow powder. Emamectin is widely used in the US and Canada as an insecticide because of its chloride channel activation properties.
Streptomyces hygroscopicus is a bacterial species in the genus Streptomyces. It was first described by Hans Laurits Jensen in 1931.
Bialaphos is a natural herbicide produced by the bacteria Streptomyces hygroscopicus and Streptomyces viridochromogenes. Bialaphos is a protoxin and nontoxic as is. When it is metabolized by the plant, the glutamic acid analog glufosinate is released which inhibits glutamine synthetase. This results in the accumulation of ammonium and disruption of primary metabolism.
Streptomyces avermitilis is a species of bacteria in the genus Streptomyces. This bacterium was discovered by Satoshi Ōmura in Shizuoka Prefecture, Japan.
Streptomyces isolates have yielded the majority of human, animal, and agricultural antibiotics, as well as a number of fundamental chemotherapy medicines. Streptomyces is the largest antibiotic-producing genus of Actinomycetota, producing chemotherapy, antibacterial, antifungal, antiparasitic drugs, and immunosuppressants. Streptomyces isolates are typically initiated with the aerial hyphal formation from the mycelium.
The cyclothiazomycins are a group of natural products, classified as thiopeptides, which are produced by various Streptomyces species of bacteria.
Satoshi Ōmura is a Japanese biochemist. He is known for the discovery and development of hundreds of pharmaceuticals originally occurring in microorganisms. In 2015, he was awarded the Nobel Prize in Physiology or Medicine jointly with William C. Campbell for their role in the discovery of avermectins and ivermectin, the world's first endectocide and a safe and highly effective microfilaricide. It is believed that the large molecular size of ivermectin prevents it from crossing the blood/aqueous humour barrier, and renders the drug an important treatment of helminthically-derived blindness.
Streptomyces microflavus is a bacterium species from the genus of Streptomyces which has been isolated from soil. Streptomyces microflavus produces nemadectin, fattiviracin A1, milbemycin and deoxyuridines. Streptomyces microflavus also produces the ionophore valinomycin. Streptomyces microflavus is also known to cause potato common scab disease in Korea.
Streptomyces milbemycinicus is a bacterium species from the genus of Streptomyces which has been isolated from soil. Streptomyces milbemycinicus produces milbemycin.
Ossamycin is a fermentation-derived natural product belonging to a family of 22- to 26-membered macrocyclic polyketides which is featured with a 6,6-spiroacetal (1,7-dioxaspiro[5,5]-undecanyl) moiety connected to one side of the macrocycle. Widely-studied 26-membered oligomycins/rutamycins, 24-membered dunaimycins, and 22-membered cytovaricin are also in this family.
Streptomyces lydicamycinicus is a bacterium species from the genus of Streptomyces. Streptomyces lydicamycinicus produces the antibiotic lydicamycin.
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