Phlomic acid is an unsaturated
fatty acid
In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an ...
with an
allene
In organic chemistry, allenes are organic compounds in which one carbon atom has double bonds with each of its two adjacent carbon atoms (, where R is hydrogen, H or some organyl group). Allenes are classified as diene#Classes, cumulated dienes ...
group, which gives it
axial chirality
In chemistry, axial chirality is a special case of chirality (chemistry), chirality in which a molecule contains two pairs of chemical groups in a non-planar arrangement about an axis of chirality so that the molecule is not superposable on its mi ...
and makes it
optically active. Phlomic is related to
laballenic acid but has a shorter chain length.
Phlomic acid is composed of 20 carbon atoms, with two consecutive
double bonds (
allene
In organic chemistry, allenes are organic compounds in which one carbon atom has double bonds with each of its two adjacent carbon atoms (, where R is hydrogen, H or some organyl group). Allenes are classified as diene#Classes, cumulated dienes ...
) in the position 7=8=9. The acid has the structural formula CH
3-(CH
2)
10-CH=C=CH-(CH
2)
5-COOH. This is one of the rare allenic fatty acids found in nature, probably biosynthesized by elongation of laballenic acid.
Natural occurrence
Phlomisic acid is found in some plant species of the ''
Lamiaceae
The Lamiaceae ( )
or Labiatae are a family (biology), family of flowering plants commonly known as the mint, deadnettle, or sage family. Many of the plants are aromatic in all parts and include widely used culinary herbs like basil (herb), ba ...
'' family. For example, it is present at 2.9% in the seed oil of ''
Phlomoides tuberosa''.
Other species of the genera ''
Phlomis'', such as
deadnettle,
hedgenettle, and ''
Leonurus'' also contain the compound. Out many species of the genus ''
Leucas'' examined, 11 species contained small amounts of phlomisic acid. Only in two species was the content above 1%, and the highest measured content was 1.86%.
Synthesis
Starting from hex-5-yn-1-ol, phlomic acid can be synthesized by a
copper(II) bromide-catalyzed reaction with (''S'')-dimethylprolinol as a
chiral auxiliary.
Discovery
The common name of the acid comes from the genus ''
Phlomis''. Phlomic acid was initially isolated in 1997 by K. Aitzetmüller, N. and K. Tsevegsüren Vosmann in the seed oil of various ''
Lamiaceae
The Lamiaceae ( )
or Labiatae are a family (biology), family of flowering plants commonly known as the mint, deadnettle, or sage family. Many of the plants are aromatic in all parts and include widely used culinary herbs like basil (herb), ba ...
''.
Further analysis have found that phlomic acid almost always occurs in association with
laballenic acid and
gadoleic acid.
Uses
Plant derivatives with high content of allenic fatty acids have shown cytotoxic, anti-inflammatory, and antiviral activity.
References
{{Fatty acids
Alkenoic acids
Fatty acids
Cumulated dienes