Topicorte,Roussel,France,1968
ChEBI: Dexamethasone in which the hydroxy group at the 17alpha position is substituted by hydrogen. A synthetic corticosteroid with glucocorticoid activity, it is used as an anti-inflammatory and anti-pruritic in the treatment of various skin dis
rders, including skin allergies and psoriasis.
(a) Production of 16α-Methyl-4-Pregnene-11β,21-diol-3,20-Dione (= 16αMethylcorticosterone): A fermenter of stainless steel having a 50 liter capacity
is charged with 30 liters of a nutrient solution containing:
sterilized for ? hour at 120°C and after cooling, inoculated with a spore
suspension of Curvularia lunata which is obtained by rinsing a seven day corn
culture (15 grams corn) with approximately 100 cc of physiological sodium
chloride solution.
After two days of culturing at 25°C under stirring (220 revolutions per minute)
and ventilating (1.65 m3/hr), 18 liters of the obtained culture are removed
under sterile conditions and introduced into a fermenter of the same size
charged with 28.2 liters of a nutrient solution containing:
After 24 hours cultivation under stirring and ventilation as described above,
7.5 grams of 16α-methyldesoxycorticosterone, obtained by saponification of
the corresponding 21-acetate and melting at 102-104°C, in 200 cc of ethanol
are added and fermented under the same conditions for 28 hours.
The course of the fermentation is tested by removal of samples, which are
extracted with methyl isobutyl ketone. The extract is analyzed by paper
chromatography in a system of dioxane + toluene/propylene glycol.
After the end of the fermentation (28 hours) the culture broth is filtered off by
suction over a large suction filter. The mycel residue is washed with water
several times. The filtrate is extracted three times, each time with 10 liters of
methyl isobutyl ketone. The extract is concentrated under vacuum in a
circulating evaporator and in a round flask carefully dried under vacuum. The
residue is crystallized from acetone/isopropyl ether. The melting point is 157-
158°C (fermentation yield = 60%). The pure product yield obtained after a
second crystallization and chromatography of the mother liquor on silica gel
amounts to 53% of the theoretical.
(b) 16α-Methyl-9α-Fluoro-?4-Pregnene-11β,21-Diol-3,20-Dione: 7.5 grams of
16α-methyl-9α-fluoro-?4-pregnene-21-ol-3,20-dione-21-acetate, obtained
from Step (a) by acetylating with acetic anhydride in pyridine followed by
reaction with HF in pyridine at 0°C, are fermented for 36 hours with
Curvularia lunata (Mutant NRRL 2380), whereby the 21-acetate group is
simultaneously saponified, and then further worked up. The residue is
extracted with MIBK, subjected to chromatography on silica gel and there is
obtained from chloroform/ethyl acetate (2:1) an eluate containing the 11βhydroxy compound, which is further dehydrogenated as the crude product.
(c) 16α-Methyl-9α-Fluoro-?1,4-Pregnadiene-11β,21-Diol-3,20-Dione: 16αmethyl-9α-fluoro-β4-pregnene-11β,21-diol-3,20-dione obtained as the crude
product under Step (b) above, is fermented with Bacillus lentus for 30 hours
and further worked up. The residue is extracted with methyl isobutyl ketone
and there is obtained as the crude product 16α-methyl-9α-fluoro-?1,4-
pregnadiene-11β,21-diol-3,20-dione.
Desoximetasone, 9-fluoro-11β, 21-dihydroxy-16α-methylpregna-1,4-diene-3,20-dione, like clocortolone pivalate, lacks a C17α OH group inits structure.
