Definition
ChEBI: A carbohydrazide that results from the formal condensation of the carboxy group of DL-serine with the primary amino group of 4-(hydrazinylmethyl)benzene-1,2,3-triol. An aromatic-L-amino-acid decarboxylase
nhibitor (DOPA decarboxylase inhibitor) that does not enter the central nervous system, it is used as its hydrochloride salt as an adjunct to levodopa in the treatment of parkinsonism. By preventing the conversion of levodopa to dopamine in the periphery,
t causes an increase in the amount of levodopa reaching the central nervous system and so reduces the required dose. Benserazide has no antiparkinson actions when given alone.
Manufacturing Process
35.5 grams of DL-seryl-hydrazide hydrochloride was dissolved in 350 ml of
water and 35 grams of pyrogallolaldehyde (2,3,4-trihydroxy-benzaldehyde)
added thereto at one time. In about 5-10 minutes a clear solution resulted,
whereupon slow crystallization occurred and the temperature rose to about
6°-7°C. The crystallization was permitted to continue overnight at 5°C, and
the very fine precipitate was then isolated by centrifugation and in the
centrifuge washed with water, ethanol, and ether, yielding the dihydrate of DLseryl-(
2,3,4-trihydroxy-benzylidene) hydrazide hydrochloride, which melted at
134°-136°C and was poorly soluble in cold water, but very readily dissolved in
hot water. The condensation was also effected in absolute ethanol yielding the
anhydrous form of the hydrazone, which melted at 225°-228°C.
33.5 grams of the hydrazone-dihydrate was suspended in 330 ml of methanol
and hydrogenated with 2.5 grams of palladium-carbon. After the absorption of
2.8 liters of hydrogen, the catalyst was filtered off and the solution evaporated
in vacuo to a weight of about 52-55 grams. It was then immediately mixed
with 160 ml of absolute ethanol and permitted to crystallize for 24 hours at
room temperature and then for a further 24 hours at 0°C. The product was
then filtered off with suction and washed with absolute ethanol and absolute
ether. The so-obtained DL-seryl-(2,3,4-trihydroxy-benzyl)-hydrazide
hydrochloride formed a white crystalline powder which was readily soluble in
water and which melted at 146°-148°C.
