Abstract
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•The flowers of Citharexylum spinosum were studied for their phytotoxic activity.•The ethyl acetate extract was the most inhibitory compound on the growth of lettuce seedling at 6000ppm.•The ethyl acetate extract was subjected to bio-guided chromatographic separation yielding a new iridoid glucoside, designed as spinoside (1) and its known analogue durantoside-I (2).•The most allelochemical compound was identified to be the durantoside-I tetraacetylated.
The aim of this study was to assess the phytotoxic potential of flowers of Citharexylum spinosum, as well as to isolate the main bioactive compounds. Results showed that the ethyl acetate extract induced the highest reduction, showing 100% inhibition of lettuce growth at 6000ppm. This bioactive ethyl acetate extract was subjected to bio-guided chromatographic separation yielding the acetylated form of a new iridoid glucoside, designated as spinoside (1) together with two acetylated forms (2a) and (2b) of its known analogue durantoside-I (2). Their structures were established via their acetylated derivatives by means of spectroscopic and chemical data. The most inhibitory compound on the growth of lettuce seedling was identified to be the durantoside-I tetraacetylated (2b).