Falcarinol (also known as carotatoxin or panaxynol) is a natural pesticide and

fatty alcohol Fatty alcohols (or long-chain alcohols) are usually high-molecular-weight, straight-chain primary alcohols, but can also range from as few as 4–6 carbons to as many as 22–26, derived from natural fats and oils. The precise chain length varies ...

found in

carrot The carrot ('' Daucus carota'' subsp. ''sativus'') is a root vegetable, typically orange in color, though purple, black, red, white, and yellow cultivars exist, all of which are domesticated forms of the wild carrot, ''Daucus carota'', nat ...

s (''

Daucus carota ''Daucus carota'', whose common names include wild carrot, European wild carrot, bird's nest, bishop's lace, and Queen Anne's lace (North America), is a flowering plant in the family Apiaceae. It is native to temperate regions of the Old Wor ...

''), red

ginseng Ginseng () is the root of plants in the genus ''Panax'', such as Korean ginseng ('' P. ginseng''), South China ginseng ('' P. notoginseng''), and American ginseng ('' P. quinquefolius''), typically characterized by the presence of ginsenosides an ...

(''Panax ginseng'') and

ivy ''Hedera'', commonly called ivy (plural ivies), is a genus of 12–15 species of evergreen climbing or ground-creeping woody plants in the family Araliaceae, native to western, central and southern Europe, Macaronesia, northwestern Africa and ...

. In carrots, it occurs in a concentration of approximately 2 mg/kg. As a

toxin A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849– ...

, it protects

root In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the sur ...

s from fungal diseases, such as liquorice rot that causes black spots on the roots during storage. The compound requires the freezing condition to maintain well because it is sensitive to light and heat. Falcarinol was also credited for helping to prevent colon cancer.

Chemistry

Falcarinol is a

polyyne In organic chemistry, a polyyne () is any organic compound with alternating single and triple bonds; that is, a series of consecutive alkynes, with ''n'' greater than 1. These compounds are also called polyacetylenes, especially in the natural p ...

with two carbon-carbon triple bonds and two double bonds. The double bond at the carbon 9 position has ''cis'' stereochemistry was introduced by the desaturation, which requires oxygen and NADPH (or NADH) cofactors, creates a bend in the molecule that prevent fatty acid from solidifying in oils and cellular membranes. It is structurally related to the

oenanthotoxin Oenanthotoxin is a toxin extracted from hemlock water-dropwort (''Oenanthe crocata'') and other plants of the genus '' Oenanthe''. It is a central nervous system poison, and acts as a noncompetitive antagonist of the neurotransmitter gamma-aminob ...

and

cicutoxin Cicutoxin is a naturally-occurring poisonous chemical compound produced by several plants from the family Apiaceae including water hemlock (''Cicuta'' species) and water dropwort (''Oenanthe crocata''). The compound contains polyene, polyyne ...

Biological effects

Falcarinol is an irritant that can cause

allergic reaction Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derma ...

s and

contact dermatitis Contact dermatitis is a type of acute or chronic inflammation of the skin caused by exposure to chemical or physical agents. Symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, or swelling. These rashes are ...

. It was shown that falcarinol acts as a covalent

cannabinoid receptor type 1 Cannabinoid receptor type 1 (CB1), also known as cannabinoid receptor 1, is a G protein-coupled cannabinoid receptor that in humans is encoded by the ''CNR1'' gene. The human CB1 receptor is expressed in the peripheral nervous system and central ...

inverse agonist In pharmacology, an inverse agonist is a drug that binds to the same receptor as an agonist but induces a pharmacological response opposite to that of the agonist. A neutral antagonist has no activity in the absence of an agonist or inverse agon ...

and blocks the effect of

anandamide Anandamide (ANA), also known as ''N''-arachidonoylethanolamine (AEA), is a fatty acid neurotransmitter. Anandamide was the first endocannabinoid to be discovered: it participates in the body's endocannabinoid system by binding to cannabinoid rec ...

keratinocyte Keratinocytes are the primary type of Cell (biology), cell found in the epidermis (skin), epidermis, the outermost layer of the skin. In humans, they constitute 90% of epidermal skin cells. Basal cells in the stratum basale, basal layer (''str ...

s, leading to pro-allergic effects in human skin. Normal consumption of carrots has no toxic effect in humans.

Biosynthesis

Starting with oleic acid (1), which possesses a cis double bond at the carbon 9 position from desaturation and a bound of phospholipids (-PL), a bifunctional desaturase/acetylnase system occurred with oxygen (a) to introduce the second cis double bond at the carbon 12 position to form linoleic acid (2). This step was then repeated to turn the cis double bond at the carbon 12 position into a triple bond (also called acetylenic bond) to form crepenynic acid (3). Crepenynic acid was reacted with oxygen (b) to form a second cis double bond at the carbon 14 position (conjugated position) leading to the formation of dehydrocrepenynic acid (4). Allylic isomerization (c) was responsible for the changes from the cis double bond at the carbon 14 position into the triple bond (5) and formation of the more favored trans (E) double bond at the carbon 17 position (6). Finally, after forming the intermediate (7) by decarboxylation (d), falcarinol (8) was produced by hydroxylation (e) at the carbon 16 position that introduced the R conformation to the system. Falcarinol - Natural Product copy

References

{{Cannabinoidergics Plant toxins Fungicides Neurotoxins Alkene derivatives Secondary alcohols Conjugated diynes

Chemistry

Biological effects

Biosynthesis

See also

References