Sphenoclea zeylanica

Several secondary metabolites are dithiolanes, as for instance the allelochem-icals found in the tropical weed, Sphenoclea zeylanica. Zeylanoxide A is present in two stereoisomeric forms depending on whether the chirality at sulfur is (R) or (5) the latter form is 44 (Scheme 15). Zeylanoxides B are similar but in these cases the oxide function is on the sulfur at the 2 position. These molecules inhibited root growth in rice seedlings as well as the germination of letuce seeds.95... 

Little is known of the chemistry of the family (Raffauf and Higu-rashi, 1988). Sphenoclea zeylanica gave one positive test for alkaloids during the testing of five samples. 

In seeded paddy rice, fentrazamide mixture with propanil (Lecspro ) is used as an early post-emergence herbicide for controlling ECHSS, CYPDI, Cyperus iria, Fimbristylis mUiacea, Leptochloa chinensis and Sphenoclea zeylanica [35]. 

Four novel isomeric cyclic thiosulfinates, the zeylanoxides, have been isolated from the tropical weed Sphenoclea zeylanica. The structures and absolute stereochemistry of these compounds, which are plant growth inhibitors, have been determined by synthesis from the enantiomers of glucose. Use of L-glucose as outlined in Scheme 35 gave a mixture, separable by HPLC, of zeylanoxide A (187, a-sulfoxide), epi-zeylanoxide A (187, p-sulfoxide), zeylanoxide B (188, a-sulfoxide), and epi-zeylanoxide B (188, p-sulfoxide), with optical rotations in good agreement with those of the natural products. ... 

To date, there is only a single report on unique cyclic thiosulfmates, named zeylanoxides, and known secoiridoid glucosides, both groups discovered as constituents of the tropical weed Sphenoclea zeylanica Gaertn. (Sphenocleaceae), one of the most serious weeds of rice. All these metaboUtes are assumed to be potent allelochemicals since they completely inhibited the root growth of rice seedlings at 3.0mM (Hirai et al. 2(XX)). 

Heywood VH (ed) (1978) Flowering plants of the world. Elsevier, Oxford, UK Hirai N, Sakashita S, Sano T, Inoue T, Ohigashi H, Premasthira C, Asakawa Y, Harada J, Fuji Y (2000) AUelochemicals of the tropical weed Sphenoclea zeylanica. Phytochemistry 55 131-140 Hosaka K, Ogihara Y, Matsubayashi M, Tsunewaki K (1984) Phylogenetic relationship between tuberous Solanum species as revealed by restriction endonuclease analysis of chloroplast DNA. Jap J Genet 59 349-369... 

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