Observations on the phytochemistry of the Aloë leaf-exudate compounds

Abstract

Exudates from the cut surfaces of Aloë leaves contain compounds, many of which can be recognized by their colour reaction with fast blue B salt after separation on thin-layer chromatograms. About 90 chromatographic zones were observed from c. 240 Aloë species. These included 24 orange-staining zones, 35 purple-staining zones and a variety of zones staining shades of grey, green, blue and brown. A few of these substances have been identified as known compounds. Each of the remaining compounds is given a code according to its colour reaction and each is referred to a standard plant source in which it is prominent. Thus a convenient basis for phytochemical discussions is provided. The distribution of the known compounds in the genus as recorded in the literature is compared with present findings. Chemical relationships often followed accepted taxonomic groupings. In particular, correlations were found among shrubby African species and a group of species from Somalia.