Synthesis and Plant Growth Regulatory Activity of 6α,7β-Dihydroxyvouacapan-17β-oic Acid Derivatives.

Abstract

Five new derivatives of 6α,7β-dihydroxyvouacapan-17β-oic acid were prepared. The effect of these new furan diterpenes on the radicle growth of Sorghum bicolor L. and Cucumis sativus L. was evaluated. All compounds, at a concentration of 100 ppm, showed an inhibitory effect (40–63%) on the radicle growth of S. bicolor L. and a small stimulatory growth effect (3–15%) on the radicle of C. sativus L. None of the compounds had any effect on the germination rate of both plants.

Preparation, X-ray structural studies and plant growth regulatory activity of methyl 6alpha,7beta-thiocarbonyldioxyvouacapan-17 beta-oate

“…3 The infrared spectrum of compound 5 showed all the expected signals, specially a sharp band at 1296 cm -1 due to the C=S bond stretching. The 13 C NMR spectrum of 5 showed six signals with no correlation in the HMQC contour map assigned to carbons 12 and 13 of the furan ring, the quaternary carbons 4 and 10, the ester carbonyl and the thiocarbonyl.…”

“…8 The effects of compounds 1 and 4 on the radicle growth of C. sativus L. and S. bicolor L. were previously reported. 3 As compound 5 was obtained in a relatively good yield, being another sulphur derivative of the natural product 1 and presenting a new ring fused to the vouacapane skeleton, we decided to evaluate its influence in plant radicle growth. The same preliminary test conditions previously described 3 were applied to compound 5.…”

“…4,5 The bisxanthate 4, was unexpectedly obtained from the lactone 3 (Scheme 1) upon reaction with NaH, imidazole, CS 2 and MeI. 3 As compound 4 showed an inhibitory effect on the radicle growth of Sorgum bicolor L. (-50%), and a stimulatory effect (+10%) on the radicle growth of Cucumis sativus L., 3 a variation of this methodology 6 was applied directly onto the natural product 2, as an attempt of preparing larger amounts of the bis-xanthate 4 to further investigate the biological activity detected. Using the conditions showed in the Scheme 2, compound 4 was obtained as a secondary product and a new derivative containing a five membered ring fused to the vouacapane skeleton was isolated and characterized as the methyl 6α,7β-thiocarbonyldioxyvouacapan-17β-oate (5).…”

“…Using the conditions showed in the Scheme 2, compound 4 was obtained as a secondary product and a new derivative containing a five membered ring fused to the vouacapane skeleton was isolated and characterized as the methyl 6α,7β-thiocarbonyldioxyvouacapan-17β-oate (5). We undertook crystallization and structure elucidation by X-ray diffraction of compound 5 and the effects of this compound on the radicle growth of C. sativus L. and S. bicolor L. were determined by the method described by Demuner et al 3 and compared to the results obtained for compounds 1 and 4.…”

“…1 These diterpenes have shown a variety of interesting biological activities, 2 being potent analgesic and anti-inflammatory agents. It was recently discovered that compound 1, at a concentration of 100 ppm, possess an inhibitory effect (41%) on the radicle growth of Sorgum bicolor L. and a small stimulatory growth effect (4%) on the radicle of Cucumis sativus L.. 3 Due to the possibility of application of these diterpenes as medicines or as agrochemicals, a series of derivatives for biological evaluation has been synthesized. 4,5 The bisxanthate 4, was unexpectedly obtained from the lactone 3 (Scheme 1) upon reaction with NaH, imidazole, CS 2 and MeI.…”