Penstemon whippleanus

Carbomethoxy-pedicularine (30) was proposed as the structure for an alkaloid of mass 235 amu from a NH3 chemical ionization gc/ms analysis of the alkaloid extract of the flowers of Penstemon whippleanus (Scrophula-riacaeae) (30). No molecular ion was observed in the electron impact mass spectrum, only an (M-45)+ ion at m/z 190. The further fragmentation of this ion (m/z 162,146, and 117) compared well with the mass spectrum of pedicularine (31) (1,82,83), so the alkaloid was tentatively suggested to be a carbomethoxypedicularine (30). Isomeric structures for this alkaloid cannot excluded, particularly given biogenetic considerations. The isolate may even be the methyl ester of pedicularine. 

Noractinidine (95) was tentatively identified (UV, MS) as being present in the flowers of Penstemon whippleanus (30), although other isomers could not be excluded. It was also detected in the leaves of Tecoma starts (89) and the aerial parts of Pedicularis macrochila (Scrophulariaceae) (41). 

McCoy, J. W. and F. R. Stermitz, Alkaloids from Castilleja mini-ata and Penstemon whippleanus, two host species for the plume moth, Ambryptilia (Platyptilia) pica, J. Nat. Prod., 46,902-907 (1983). 

Flowers of Penstemon whippleanus (Scrophulariaceae) serve as a host for the plume moth, Amblyptilia (Platyptilia) mica. These flowers contain (+ )-boschniakine (10) and other iridoid-monoterpene-derived alkaloids (McCoy and Stermitz, 1983). Another host of this moth, Castilleja rhexi-folia (Scrophulariaceae) contains rhexifoline (11), an iridoid monoterpene alkaloid, as the major alkaloid of the seeds and flowers. The moths and adults of the insect contain rhexifoline (Roby and Stermitz, 1984). Rhexifoline (11) also can arise in some instances from the presence of ammonia in workup from penstemonoside, but this possibility was specifically precluded in this study by use of bicarbonate in place of ammonia in the workup. 

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