Merremia spp

This metabolite was discovered in Datura stramonium (Solanaceae) and represents an isomer of methylecgonine (2B-carbomethoxytropan-3P-ol), the precursor of cocaine in Erythroxylum spp. (Inythroxylaceae). Methylpseudoecgonine could be detected in Bonamia spectabilis, Merremia aegyptia, and M. gemella. 

Almost all species which contained the corresponding 3a isomers (T5-type) turned out to be also TlO-positive. These esters were the only 36-acyloxytropanes of Bommia brevifolia, four Convolvulus spp., and Merremia gemella. 

Benzoic acid was detected, e.g., in the leaves of Merremia vitifolia (Jenett-Siems 1996) as well as in the roots of Ipomoea purpurea, two Jacquemontia spp., and Merremia aegyptia (Henrici 1996). p-Hydroxybenzoic acid could be proven, e.g., in 14 out of 29 convolvulaceous species (Nair et al. 1986). Salieylie aeid was detectable, e.g., in eight out of 10 speeies (genera Hewittia, Ipomoea, Jacquemontia, Merremia, Operculina) (Henrici 1996). 

However, to date reports on structural elucidations of resin glycosides are confined to 34 species belonging to six genera, altogether listed in Table 8.2 together with the respective authorities for the species and the phytochemical references Ipomoea (23 spp.), Merremia (3), Convolvulus (3), Operculina (2) Cuscuta (2), Calystegia (1). The vast majority of these plants are of tropical origin. 

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