Nine plant growth inhibitors were isolated from the tropical weed Sphenoclea zeylanica, which shows allelopathic properties. Those compounds hitherto not reported from any plant source were the isomers of cyclic thiosulfinate, (1S,3R,4R)-(+)- and (1R,3R,4R)-(+)-4-hydroxy-3-hydroxymethyl-1,2-dithiolane-1-oxides, and (2R,3R,4R)-(-)- and (2S,3R,4R)-(+)-4-hydroxy-3-hydroxymethyl-1,2-dithiolane-2-oxides. These were named zeylanoxide A, epi-zeylanoxide A, zeylanoxide B and epi-zeylanoxide B, respectively. The absolute configurations at C-3 and C-4 were elucidated by chemical synthesis of both enantiomers from L- and D-glucose. Two of the inhibitors were secologanic acid and secologanoside. and three other inhibitors were by known secoiridoid glucosides formed as artifacts during extraction with methanol. The cyclic thiosulfinates and secoiridoid glucosides completely inhibit the root growth of rice seedlings at 3.0 mM. While the specific activity of the inhibitors was not high, since they accumulated to circa 0.61% S. zelanica by dry weight, this suggests that the inhibitors are nervertheless potent allelochemicals in this weed.
allelopathy, plant growth inhibitor, secoiridoid glucoside, Sphenoclea zeylanica, Sphenocleaceae, gooseweed, thiosulfonate, 4-hydroxy-3-hydroxymethyl-1, 2-dithiolane-1-oxide, 2-dithiolane-2-oxide
NCBI PubMed ID: 11065289Publication DOI: 10.1016/s0031-9422(00)00264-8Journal NLM ID: 0151434Publisher: Elsevier
Correspondence: hirai@kais.kyoto- u.ac.jp
Institutions: Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan, National Weed Science Research Institute, Bangkok, Thailand, National Institute of Agro-environmental Sciences, Tsukuba, Japan
Methods: 13C NMR, 1H NMR, EI-MS, NMR-2D, IR, FAB-MS, biological assays, HPLC, UV, extraction, optical rotation measurement, acetylation, CC, isotopic labeling, melting point determination, antibacterial assay, derivatization, evaporation, antifungal activity test, germination assay
Found