Figure 3.

Classification scheme of indole alkaloids from Order Stigonematales. The previously described indole alkaloids are classified here as nine proposed groups; given are group number (as defined here), and corresponding chemical name of each group (based on previously named carbon skeletons). Note that stereochemistry is illustrated only for those sub-classes for which either a very limited number of variants have been identified (i.e., Groups 3, 6 and 8), and/or no variability in stereodisposition (e.g., 12-epimers, C-10/11/15) has been yet reported (i.e., Group 5 and 9). For more detailed explanation of variation within the subclasses, see Figure 4, Figure 5, Figure 6, Figure 7, Figure 8, Figure 9, Figure 10 and Figure 11.