Naturally derived crop protection agents:ROTENONE

CHEM 185 SPECIAL TOPIC

Mangao, Arnoldus

Ramos, Ana

Naturally derived crop protection agents:ROTENONE

CHEM 185 SPECIAL TOPIC

Mangao, Arnoldus

Ramos, Ana

Naturally derived crop protection agents:ROTENONE

CHEM 185 SPECIAL TOPIC

Mangao, Arnoldus

Ramos, Ana

Naturally derived crop protection agents

– Naturally derivedingredients that have been derived from nature that are used to

artificially create a product

– Crop protection agents are herbicides, insecticides, and fungicides farmers used to protect crops from damage and to increase yields

Examples: natural products as botanical insecticides including piperamides, thiophenes, rotenone, and limonoids

ROTENONE

– odorless, colorless, crystalline isflavone used as broad spectrum insecticide, piscicide, acaricide and molluscicide

– occurs naturally in the roots, seeds and stems of several plants, such as the jimaca vine plant, and the roots of several members of Fabaceae

– member of a class of compounds of related molecular structure referred to as isoflavones

– First member of rotenoids ( cis-fused tetrahydrochromeno[3,4-b]chromene nucleus)

– used for centuries as a selective fish poison and more recently as a commercial insecticide

– sold in dispersible powder, emulsifiable concentrate, and wettable powder formulations

– Used as molluscicide as well

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(2R,6aS,12aS)-8,9-dimethoxy-2-(prop-1-en-2-yl)-1,2,12,12a-tetrahydrochromeno[3,4-b]furo[2,3-h]chromen-6(6aH)-one

Source

– Rotenone occurs naturally as constituents of the roots, stems and leaves of many leguminous species of the genera Derris

– is related to isoflavonoid compounds derived from the roots of Derris spp. Which is found primarily in Southeast Asia

Source

– Rotenone is one of the important bio-active compounds extracted from Derris elliptica and other important constituents of Derris root

– Derris plants like Derris elliptica and D. malaccensis contain approximately 4% (w/w) to 5% (w/w) of rotenone

Source

Use

Molluscicide

-studies shows promising results

Use: Molluscicide

Application rate

Piscicide

– ancient, as early explorers noted Peruvian natives using crude extracts of the Cubé plant to stun fish for eating.

– highly selective piscicide for the control or eradication of non-native fish in streams and lakes across the United Statesbotanical pesticide registered by EPA for piscicidal (fish kill) uses

Insecticide

200 kg of rotenone is used per year as an insecticide for organically grown lettuce and tomatoe

Mode of Action

Mode of Action

– Rotenone acts through uncoupling oxidative phosphorylation within cell mitochondria by blocking electron transport at complex I

– Complex I is unable to pass off its electron to CoQ, creating a back-up of electrons within the mitochondrial matrix. Cellular oxygen is reduced to the radical, creating a reactive oxygen species, which can damage DNA and other components of the mitochondria

– efficacy in interrupting mitochondrial electron transport which hinders the utilization of oxygen in respiratory organisms, leading to cell death and eventually to the death of the organism if the dose is high enough

Mode of Action

General toxicity

– Rotenone is classified as either EPA toxicity class I or III (highly toxic or slightlytoxic) depending on product formulation.

– Only certified pesticide applicators can apply rotenone

General toxicity

– Not highly toxic to humans, mammals, and birds if ingested orally

– poorly absorbed because they are decomposed to more excretable fragments by a variety of oxidases as well as by bacterial fauna that thrive in our gut

– another efficient route of excretion is by way of molecular conjugation to sugar molecules. The resulting conjugates are then readily excreted from the body

– biological half-life in humans is 8 hours

– compound is broken down to less toxic components before toxic quantities can enter the bloodstream

– BUT inhalation results in significantly higher toxicity, as there is a more direct pathway into the bloodstream

Environmental Persistence

– Rotenone does not persist in the environment so there is no long-term accumulation in water, soil, plants, or animals.

– Its low vapor pressure (6.9x10-10 torr) and Henry’s Law constant (1.1x10-13 atm-m3 mol-1) limit its volatility

– Rotenone breaks down naturally with exposure to light and high temperatures.

– Its environmental significance does not extend far beyond the treatment duration.

– Rotenone has low mobility in soil. Because rotenone degrades quickly and does not leach far, it does not impact groundwater supplies.

Ecological Effects

– Applications of rotenone in lakes and ponds to kill fish usually cause significant declines in zooplankton and may also affect some bottom fauna.

– Treatments in streams and rivers also cause significant loss of invertebrate fauna but effects are usually most noticeable close to rotenone application stations.

Metabolic Fate in Higher Animals (birds and mammals)

– Large oral doses (200 mg/kg in pigeons, 10 mg/kg in dogs) usually stimulate vomiting in animals (Haag 1931). The same is reportedly true for humans following suicidal ingestion of Derris root (Ray 1991).

– Once absorbed, rotenone is effectively broken down by the liver to produce less toxic excretable metabolites. Approximately 20% of the oral dose (and probably most of the absorbed dose) is excreted within 24 hours (Ray 1991); around 80% as water soluble products with the remainder as hydroxylated rotenoids (Fukami et al. 1969).

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