Abamectin

Chemical properties

Off-White to Yellow Crystalline Solid

Chemical properties

Abamectin is a colorless to yellowish crystalline powder. It is soluble in acetone, methanol, toluene, chloroform, and ethanol, but insoluble in water. It is stable, and incompatible with strong oxidizing agents. Abamectin is a mixture of Abamectins containing about 80% Abamectin B1a and 20% Abamectin B1b. These two components, B1a and B1b, have very similar biological and toxicological properties. The Abamectins are insecticidal/miticidal compounds derived from the soil bacterium Streptomyces avermitilis. Abamectin is used to control insect and mite pests of citrus, pear, and nut tree crops, and is used by homeown- ers to control fi re ants. It acts on the nervous system of insects, causing paralyzing effects. Abamectin is a general use pesticide (GUP). It is grouped as toxicity class IV, meaning practically non-toxic, requiring no precautionary statement on its label

Originator

Abamectin,Yellow River Enterprise Co. (a.k.a Yelori)

The Uses of Abamectin

Mixture of Abamectins, containing at least 80% of Abamectin B1a (C48H72O14) and not more than 20% of Abamectin B1b (C47H70O14). Used as acaricide, insecticide

The Uses of Abamectin

ectoparasiticide, CNS stimuant, mutagen

The Uses of Abamectin

Acaricide; insecticide.

What are the applications of Application

Abamectin is a macrocyclic lactone compound

Definition

Any of a group of broad spectrum antiparasitic antibiotics produced by the actinomycete, Streptomyces avermitilis.

Manufacturing Process

1. The contents of a lyophilized tube of Streptomyces avermitilis MA-4680 is transferred aseptically to a 250 ml Erlenmeyer flask containing 305 ml of Medium 1: Dextrose 20 g, Peptone 5 g, Meat Extract 5 g, Primary Yeast 3 g, NaCl 5 g, CaCO3 (after pH adjustment) 3 g, Distilled water 1000 ml, pH 7.0. The inoculated flask is incubated for 3 days at 28°C on a rotary shaking machine at a speed of 220 RPM in a 2 inch radius circular orbit. At the end of this time, a 250 ml Erlenmeyer flask containing 50 ml of Medium 2 [Tomato Paste 20 g, Modified Starch (CPC) 20 g, Primary Yeast 10 g, CoCl2·6H2O 0.005 g, Distilled water 1000 ml, pH 7.2-7.4] is inoculated with a 2 ml sample from the first flask. This flask is incubated for 3 days at 28°C on a rotary shaking machine at a speed of 220 RPM in a 2 inch diameter circular orbit. 50 Ml of the resulting fermentation broth containing C-076 is effective against an N.dubius infection in mice.
2. A lyophilized tube of Streptomyces avermitilis MA-4680 is opened aseptically and the contents suspended in 50 ml of Medium 1 in a 250 ml Erlenmeyer flask. This flask is shaken for 3 days at 28°C on a rotary shaking machine 220 RPM with a 2 inch diameter circular orbit. A 0.2 ml portion of this seed medium is used to inoculate a Slant of Medium 3: Dextrose 10.0 g , Bacto Asparagine 0.5 g, K2HPO4 40.5 g, Bacto Agar 15.0 g , Distilled water 1000 ml, pH 7.0. The inoculated slant medium is incubated at 28°C for 10 days and stored at 4°C until used to inoculate 4 more slants of Medium 3. These slants are incubated in the dark for 8 days. One of these slants is used to inoculate 3 baffled 250 ml Erlenmeyer flasks containing 50 ml of No. 4 Seed Medium: Soluble Starch 10.0 g, Ardamine 5.0 g, NZ Amine E 5.0 g, Beef Extract 3.0 g, MgSO4·7H2O 0.5 g, Cerelose 1.0 g, Na2HPO4 0.190 g, KH2PO4 182 g, CaCO3 0.5 g, Distilled water 1000 ml, pH 7.0-7.2. The seed flasks are shaken for 2 days at 27-28°C on a rotary shaking machine at 220 RPM with a 2 inch diameter circular orbit. The contents of these flasks are pooled and used to inoculate (5% inoculum) baffled 250 ml Erlenmeyer flasks containing 40 ml of various production media. Flasks containing media 2, 5 and 6 are incubated for 4 days at 28°C on a rotary shaking machine at 220 RPM with a 2 inch diameter circular orbit. The resulting broth containing C-076 is then harvested and tested for anthelmintic activity. In all cases 6.2 ml of whole broth and the solids obtained from centrifuging 25 ml of whole broth are fully active against N.dubius helminth infections in mice.
3. The one of the four slants of Medium 3 prepared as in Example 2 is used to inoculate a baffled 250 ml Erlenmeyer flask containing 50 ml of Seed Medium No. 4. The seed flask is shaken for 1 day at 27- 28°C on a rotary shaking machine at 220 RPM with a 2 inch diameter circular orbit. The seed flask is then stored stationary at 4°C until it is ready to be used. The contents of this flask are then used to inoculate (5% inoculum) 20 unbaffled 250 ml Erlenmeyer flasks containing 40 ml of Medium No. 2. After 4 days incubation at 28°C on a rotary shaking machine at 220 RPM with a 2 inch diameter circular orbit, 19 of the flasks are harvested and pooled. The combined fermentation broths containing C-076 are filtered affording 500 ml of filtrate and 84 g of mycelia. 78 G of mycelia are extracted with 150 ml of acetone for ? hour with stirring and the mixture filtered. The filter cake is washed with 50 ml of acetone and the filtrate and washings are combined and concentrated to 46.5 ml 30 Ml of the concentrate is adjusted to pH 4 with dilute hydrochloric acid and extracted 3 times with 30 ml portions of chloroform. The extracts are dried by filtering through dry Infusorial Earth (Super-Cel) combined and concentrated to dryness in vacuum. The oily residue of C-076 weighing 91.4 mg is dissolved in chloroform sufficient to make 3 ml of solution which represents 1% of broth volume. The C-076 (Abamectin) obtained in this recovery procedure is fully active against N.dubius infections in mice. In addition, the chloroform extraction achieved a 70 fold purification of C-076 from the whole broth.

brand name

(Merck)Avomec [Veterinary] (Merial); Bovitin [Veterinary] (Merial); Doratect [Veterinary] (Merial); Duomectin [Veterinary] (Merial); Duotin [Veterinary] (Merial); Endecto (Merck); Enzec (Merck); Enzek (Merck); Parafoil (Merck); Vertimil (Zectin (Merck).

Therapeutic Function

Antiparasitic

General Description

Odorless off-white to yellow crystals from methanol. Does not hydrolyze in water at pH 3, 5, 7. Used as an acaricide and insecticide.

Reactivity Profile

A lactone.

Hazard

A poison by ingestion. Moderately toxic by inhalation and skin contact.

Health Hazard

Abamectin is an insecticide and miticide. It is very toxic and causes adverse health effects if swallowed and/or inhaled. Emulsifi able concentrate formulations of Abamectin cause slight to moderate eye irritation and mild skin irritation. The symptoms of poisoning observed in laboratory animals include pupil dilation, vomiting, convulsions and/or trem- ors, and coma. Abamectin acts on insects by interfering with the nervous system. At very high doses, laboratory mammals develop symptoms of nervous system depression, inco- ordination, tremors, lethargy, excitation, and pupil dilation. Very high doses have caused death from respiratory failure in animals. Additionally, Abamectin has been reported to cause reproductive effects. Abamectin blocks the nerval conduct system in insects, caus- ing paralysis and death. Laboratory studies have indicated that abamectin may affect the nervous system in experimental animals. A 1-year study with dogs given oral doses of abamectin (0.5 and 1 mg/kg/day) caused adverse health effects, such as pupil dilation, weight loss, lethargy, tremors, and recumbency.

Agricultural Uses

Acaricide, Miticide, Insecticide, Anthelmentic: Used on fruit, vegetable and ornamental crops; pears, citrus fruits, and nut crops; to control mite and insect pests, and also to control household and lawn insects, including fire ants. Approved by the EPA for use in ash trees for control of emerald ash borer. A U.S. EPA restricted Use Pesticide (RUP).

Trade name

ABACIDE®; AFFIRM®; AVID®, AVID-EC®; AVOMEC®; DYNAMEC®; INJECT-A- CIDE AV®; MK 936®(B 1A ); BOVITIN®; DORATECT®; DUOMECTIN®; DUOTIN®; ENDECTO®; ENZEC®; L 676,863® (B 1A ); MK 0936®; MK 936®; PARAFOIL®; VERTIMEC®, VERTIMIL®; VIVID®; ZECTIN®; ZEPHEYR®; ZEPHYR®

Metabolic pathway

Abamectin contains the closely related avermectin B_1a and B_1b as the active ingredients. Avermectin B_1a contains a sec-butyl moiety whereas avermectin B_1b contains an isopropyl moiety. Chemical degradation and metabolism studies were conducted with avermectin B_1a radiolabelled with ³H or ¹⁴C at various positions of this large molecule. The overall fates of avermectin B_1a and B_1b are similar since transformations at the butyl or propyl moiety were not observed.
Avermectin B_1a is stable to hydrolytic degradation, but it is readily degraded to numerous products in aqueous solutions, soil, glass and plant foliage/fruit surfaces after light irradiation. Isomerisation and O-demethylation appear to the primary degradation reactions. In addition, hydroxylation is a major metabolic reaction in animals. Significant amounts of the residues in plants and animals were characterised as unidentified polar components.

Degradation

[³H]Avermectin B_1a(1) was stable at 25 °C in pH 5,7 and 9 solutions up to 28 days. Less than 5% degradation was observed (PSD, 1992).
[¹⁴C]Avermectin B_1a degraded rapidly in aqueous solution when exposed to sunlight with an observed DT₅₀ of 3.5-12 hours. The △^8,9 geometric isomer of avermectin B_1a (2) was tentatively identified in aqueous solution (containing 2% acetone as photosensitiser) after irradiation under artificial light. Crouch et al. (1991) reported the photodegradation of avermectin B_1a, as a thin film on glass surfaces under artificial light (>260 nm). At least 10 photodegradation products were characterised including the geometric isomers (2, 3), hydroxylated (4-7) and O-demethylated products (8) shown in Scheme 1.

Precautions

During use of Abamectin, occupational workers should use safety glasses, gloves, and protective clothing to prevent prolonged skin contact, and work in good ventilation.