Helicostylum piriforme

Secondary steroidal alcohols react in preference to primary allylic alcohols in biochemical oxidations usingJihizopus arrhizus and Helicostylum piriforme or Cunninghamella blakesleeana. However, the reaction is complicated by hydroxylations in positions 6 (with Rhizopus arrhizus) and 9 (with Helicostylum piriforme or Cunninghamella blakesleeana) [1059]. 

Nawa and co-workers (N-651) have described the 16/3-hydroxylation of digitoxi-genin to gitoxigenin by Helicostylum piriforme. Identification was by paper chromatography. This example cannot be accommodated within the Dodson-Mizuba proposal. 

A fermenter containing a sterile medium at pH 4.9 made from commercial dextrose and corn steep inoculated with Helicostylum piriforme Bain (A.T.G.G. 8992), after 24 hrs. of vigorous agitation and aeration at 28° 11, 21-dihydroxy-pregna-4,17(20)-dien-3-one in acetone added, and the fermentation continued for 2 days 9a,21-dihydroxypregna-4,l7(20)-diene-3,11-dione. Y 59.0%. A. R. 

Additional Dihydroxy- and Trihydroxy spirosolanes. Solasodine (I) has been hydroxylated by the fungus Helicostylum piriforme yielding as the main product (30-35%) 9a-hydroxysolasodine (XXIII) as well as... 

An analogous incubation of the saturated alkaloids tomatidine (XVII) and soladulcidine (XVIII) with Helicostylum piriforme yielded 7a, 1 la-dihydroxy- (XXXIII) (25-30%), 7a-hydroxy- (XIX) (about 5%), and 9a-hydroxytomatidine (XXII) (about 0.5%) (217, 218) as well as 7j8-hydroxy- (XXI) and 9a-hydroxysoladulcidine (XXIV) (220), the structures of which have been determined in a similar manner to that described above for the hydroxylated solasodines, but especially by degradation of the acetates to the corresponding pregnane derivatives. 

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