Phytotoxic triterpene saponis from Bellis longifolia, an endemic plant of Crete

Authors: STAVROPOULOU, MARIA - University Of Athens; ANGELIS, APOSTOLIS - University Of Athens; ALIGIANNIS, NEKTARIOUS - University Of Athens; KALPOUTZAKIS, ELEFTHERIOUS - University Of Athens; MITAKOU, SOFIA - University Of Athens; Duke, Stephen; FOKIALAKIS, NIKOLAS - University Of Athens

Submitted to: Phytochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/29/2017
Publication Date: 9/8/2017
Citation: Stavropoulou, M.I., Angelis, A., Aligiannis, N., Kalpoutzakis, E., Mitakou, S., Duke, S.O., Fokialakis, N. 2017. Phytotoxic triterpene saponis from Bellis longifolia, an endemic plant of Crete. Phytochemistry. 144:71-77. doi:10.1016/j.phytochem.2017.08.019.

Interpretive Summary: In a study of natural compounds that might be potential bioherbicides from Greek plants, three new triterpene saponins were isolated and identified from Bellis longifolia, a member of the Asteraceae family. These compounds had herbicidal activities similar to those of some commercial herbicides in a duckweed bioassay. Unfortunately, the compounds would be too expensive to commercialize as herbicides.

Technical Abstract: In continuation of our research on discovery of bioactive compounds from plants we have screened extracts of 65 plant species of the Cretan flora for their phytotoxic activity. All plants were extracted successively with CH2Cl2, MeOH and H2O. Phytotoxicity evaluation of the 249 generated extracts was performed against Lactuca sativa L. (Asteraceae) and Agrostis stolonifera L. (Graminae). Among the extracts, the MeOH extract of Bellis longifolia, which is an endemic plant of Crete, was the most potent. Bioassay guided fractionation revealed that a fraction consisting mainly of saponins proved to be the most effective, thus it was selected for further investigation. The separation of the saponins was performed using initially step-gradient Centrifugal Partition Chromatography (CPC). The phytochemical investigation of the active fraction led to the isolation and structure elucidation of three new triterpenic saponins, 3-O-ß-D-fucopyranosyl polygalacic acid (8), 28-O-a-L-rhamnopyranosyl-(1->2)-ß-D-fucopyranosyl polygalacic acid (9) and 3-O-ß-D-fucopyranosyl-2a,3ß,23-trihydroxyolean-12-en-28-oic acid (10) which were present as the main phytoxic compounds of the methanol extract. Moreover, three kaempferol glucoside (1-4), chlorogenic acid (5) and two triterpenes, bellisonic acid (6) and polygalacic acid (7) were isolated from the same fraction. The isolated compounds were identified by spectroscopic techniques. Compounds 8 and 9 had phytotoxic activity similar to some commercial herbicides (IC50 values of ca. 25 µM) against duckweed (Lemna paucicostata).