I. cristulata

One further congener in I. lobata, minalobine K, was also found in higher concentrations though only in the roots. Both alkaloids were only present in this species. Minalobine O (Fig. 3.31), absent in I. lobata, could be isolated as a major alkaloid of I. cristulata (beside only two minor minalobines) moreover, it was detected as a minor constituent of I. sloteri (beside only one further minor congener, minalobine E) which could not be detected in any other species. This was also true for minalobine Q and I. cristulata. The congeners L and M were identified in I. cristulata and I. lobata. The remaining 14 minalobines were only found as minor constituents in I. lobata. 

Two of these seven species, I. cristulata and /. sloteri, were also capable of producing minalobines in addition to ipangulines/isoipangulines whereas five species are confined to synthesize the latter type of alkaloids... 

The molecular data are mainly based on those published by Manos et al. (2001) and Miller et al. (1999, 2004) they have been only extended with regard to three additional species belonging to sect. Mina (/. cholulensis, I. cristulata, I. sloteri). 

I. neei turned out to be sister to the species of the miiialobiiie clade . The molecular topology allows the hypothesis that the ability to synthesize minalob-ines evolved only once within sect. Mina, in the putative ancestor of I. lobata, I. cristulata, I. sloteri (minalobine-positive species) and I. coccinea, but that in the latter the synthesis pathway was either lost again or only very small, undetectable amounts are synthesized. As I. coccinea is one of the parental species of the hybrid I. X multifida (Raf.) Skinners from which the aUotetraploid species /. sloteri arose (Eckenwalder 1986), the minalobine pathway must in principle be present in this species under this hypothesis, because the other parental species, I. quamoclit, is not part of this minalobine clade . 

In fact, I. cristulata and I. sloteri closely related to each other showed co-occurrence of minalobines and ipangulines whereas I. lobata, sister of the two former species, exclusively synthesized minalobines but no ipangulines (Stech et al. 2007). 

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