The isolation of maridomycins (I, II, III, IV, V, VI) and the structure of maridomycin II have been reported in the preceding paper. All of these components show similar physicochemical, chemical and biological properties. Alkali hydrolysis of maridomycin I (C₄₅H₇₁NO₁₆), III (C₄₁H₆₇NO₁₆), IV (C₄₀H₆₅NO₁₆), V (C₄₀H₆₅NO₁₆), VI (C₃₉H₆₃NO₁₆) gave 1 mole each of propionic acid and isovaleric acid, 2 moles of propionic acid, 1 mole each of acetic acid and propionic acid, 1 mole each of acetic acid and propionic acid, and 2 moles of acetic acid, respectively. Methanolysis of I afforded α- and β-methyl isovaleryl mycaroside. By the same treatment both III and IV gave α-methyl propionyl mycaroside ([α]ᴰ²² -145.2, c = 0.5 in CHCl₃) and its β-anomer ([α]ᴰ²¹ +18.2, c = 1.5 in CHCl₃), while V and VI yielded α and β-methyl acetyl mycaroside. On mild acid hydrolysis of 9-dehydromaridomycins, 2 kinds of demycarosyl derivatives were obtained; one from 9-dehydro compounds of I, III, V and the other from those of II, IV, VI. The difference between the 2 demycarosyl derivatives is assumed to come from the fatty acid moieties at carbon 3, and differences among components in each type come from fatty acid moieties at carbon 4. NMR and IR spectra revealed functional groups. On the basis of these findings, the structures of maridomycins were proposed. To confirm the structures, mass fragmentation patterns were inspected: maridomycin I shows a molecular peak at 857 (14 mass units greater than II), with aglycone moieties differing by 1 methylene, and the same acylsugar moiety as II. These mass patterns and the liberation of propionic acid from I with alkali hydrolysis suggested the propionyl group is at carbon 3, confirmed by NMR spin decoupling excluding carbon 9. Thus, it was concluded that I has a propionyl group at carbon 3 instead of the acetyl group at carbon 3 in II. The structures of other maridomycin components were established analogously.