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MAURICE WELSCH
Such is the case for carbomycins A and Β (272i, CXIV), from S. halst edit, S. hygroscopicus, and S. albireticuli; the three related compounds
(CXV) methymycin, from S. eurocidicus, neomethymycin, from Streptomyces sp., and picromycin, from S. felleus; narbomycin (CXVI), from
S. narbonensis (273), oleandomycin (CXVII), from S. antibioticus, and
erythromycins (274a,b) A, B, and C (CXVIII), from S. erythreus.
(nonactic acid: R = H)
(homononactic acid: R = CH 3 )
Macrotetrolides
e
(CXIX)
Ο
Rifamycin Β
(CXIXb)
e In nonactin, each R = H.
In monoactin, dinactin, and trinactin, respectively, one, two, or three R's = CH 3 ,
the other(s) = H.