Monolactone macrolides

Only three macrolides have been isolated from lichens (Table VII). On the other hand, plants produce about 700 macrolides (Table VIII), but most of them are macrodiolides or macrotriolides such as tannins and alkaloids (e.g., pyrroliz-idines). Their biosynthetic pathways are quite different from polyketide macrolides. A small group of monolactone macrolides has up to 19-membered ring lactones. Some of them have a musky odor. 

Fig. 30. Structures of monolactone macrolides and macrodiolides produced by invertebrates.

Section 3 deals with the polycyclic macrolides such as cytochalasin B and hybridalactone. These compounds also exhibit profound biological activity. Since they are substantially more complicated than the other monolactones, we felt a separate section was warranted. 

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