Retinoic acid

Retinoic acid
Chemical name	3,7-dimethyl-9-(2,6,6-trimethyl- 1-cyclohexen-1-yl)-2,4,6,8- nonatetraenoic acid
Chemical formula	C20H28O2
Molecular mass	300.42 g/mol
CAS number	[302-79-4]
Density	? g/cm3
Melting point	180-182 °C
Boiling point	? °C
SMILES	CC1(C)C(/C=C/C(C)=C/C=C/ C(C)=C/C(O)=O)=C(C)CCC1
Disclaimer and references

Retinoic acid, a short for all-trans retinoic acid and also known as Tretinoin, Retin-A and vitamin A acid, is a carotenoid organic compound that is a component of visual pigments. Retinoic acid is formed by Retinaldehyde dehydrogenase (Raldh2). It is also a cause of cell differentiation, and plays a part in the growth and development of embryos. During development there is a concentration gradient of retinoic acid along the anterior-posterior (head-tail) axis. Cells in the embryo respond differently to retinoic acid depending on the amount present. For example, in vertebrates the hindbrain transiently forms eight rhombomers and each rhombomere has a specific pattern of genes being expressed. If retinoic acid is not present the last four rhombomeres do not develop. Instead rhombomeres 1-4 grow to cover the same amount of space as all eight would normally occupy. Retinoic acid has its effects by turning on a differential pattern of Hox genes which encode different homeodomain transcription factors which in turn can turn on cell type specific genes. Deletion of the Hox-1 gene from rhombomere 4 makes the neurons growing in that region behave like neurons from rhombomere 2. The retina is also patterned by retinoic acid, with a concentration gradient that is high on the ventral side of the retina and low on the dorsal side.

Medicinally, it is used in tretinoin creams for the treatment of acne and other skin disorders. It is also a component of many commercial products that are advertised as being able to slow skin aging or remove wrinkles. In addition, it is also used to treat at least one form of cancer (Acute Promyelocytic Leukemia, also called Acute Myeloid Leukemia) by causing the immature blood cells to differentiate (i.e. mature) and die. The pathology of the leukemia is due to the highly proliferative immature cells; retinoic acid drives these cells to develop into functional cells, which helps to alleviate the disease. However, retinoic acid is also a teratogen, and therefore can cause birth defects.

In 2002 experiments were performed on mice whereby large parts of their lungs were destroyed. Upon treatment with 13-cis-retinoic acid ( Accutane ) most of the lung tissues were restored. [1] In early 2006 clinical trials on human emphysema patients were completed. As of the time of this writing results have not been reported on the web .