Nummularine-C-Type Cyclopeptide Alkaloids

The fragmentation pattern of these alkaloids follows the lines of 5(13)-zizyphine-A type cyclopeptide alkaloids fragments a, b, r, s, t, v, w, X, y, z, n, o, p, q, r, and s are the same. Fragments c-e are absent. Fragments f-j, p, q and u are the same but the alkyl residue of the ring-bound amino acid is designated as R and the 0-substituent as R .  

The different ring structure, compared with other cyclopeptide alkaloids, of this group leads to a different fragmentation pattern (Fig. 18). Fragments a, a, a , b-e, k and 1 are the most abundant. 

Fragments f, g and h are encountered in the dihydro derivatives of this group (Fig. 19). 

In addition to the fragments shown in Fig. 19, fragments n and m (Fig. 20), which arise from the ring-bound amino acid and the intermediate amino acid respectively, are frequently observed. Because the latter is always an He, fragment m has a mh value of 86. These fragments are similar to fragment q of 4(14)-type cyclopeptide alkaloids. 

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See also in sourсe #XX -- [ , , , , , , , , , , ]

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