4-Amino-2-methyl-1-naphthol is a
menadioneanalog. Its water-soluble
hydrochloride (HCl) salt is often called vitamin K5. The HCl salt has been used as a medicine for
vitamin K deficiency under tradenames such as Synkamin,[1][2] which was sold by
Parke-Davis, but has since been discontinued.[3]
Vitamin K function of the compound was first noted in 1940.[4][5]
Oral
lethal dose for the HCl salt in rats is 0.7 g/kg.[5]
Uses
4-Amino-2-methyl-1-naphthol HCl salt is a vitamin K and prevents bleeding caused by vitamin K deficiency when given via
intravenous or
intramuscular injections at doses of about 1–3 mg. HCl salt is water-soluble and its
parenteral administration requires no
emulsifiers[6][7] unlike fat-soluble
phylloquinone for example, which is often in formulations with
lecithin or
glycocholic acid.[8] Parenterally given 1 mg/ml aqueous solutions and orally taken 4 mg tablets of the HCl salt have been available commercially.[1]
Chemistry
4-Amino-2-methyl-1-naphthol HCl salt has a mass of 209.57 g/mol.[1] It darkens at 262 °C and decays without melting at 280–282 °C.[2]
HCl salt breaks down in aqueous solutions via oxidation which is quite fast at neutral
pH. First a pink and later a purple precipitant forms. The colored precipitant is (4-oxy-2-methylnaphtylimine)-2-methyl-1,4-naphthoquinone, which is a
condensation reaction product of 4-amino-2-methyl-1-naphthol and
menadione. Latter is formed via oxidation and
deamination of 4-amino-2-methyl-1-naphthol.[9]
4-Amino-2-methyl-1-naphthol HCl salt prevents the growth of different
molds and
bacteria. Thus it has been studied as potential food preservative.[10][9]
HCl salt has been studied as a potential treatment for cancer as it prevents
glycolysis in cancer cells, which provides them energy for growth.[11]
^
abVeldestra H, Wiardi PW (1943). "Water soluble antihemorrhagic substances I: synthesis of 2-methyl-4-aminonaphthol-1 hydrochloride and of 2-methyl-1,4-diaminonaphthalene dihydrochloride, the water soluble synthetic vitamins K5 and K6". Recueil des Travaux Chimiques des Pays-Bas. 62 (2): 75–84.
doi:
10.1002/recl.19430620203.
ISSN0165-0513.
^Seed L, et al. (1940). "Parenteral administration of a watersoluble compound with vitamin K activity: 4-amino-2-methyl-1-naphthol hydrochloride". Archives of Surgery. 41 (5): 1244–1250.
doi:
10.1001/archsurg.1940.01210050204012.
ISSN0272-5533.