Chemical modification of the trans,trans-germacranolide stizolicin synthesis,molecular, and crystal structure of 6α-acetoxy-13-methoxy-1,10; 4,5-diepoxy-1,5,7α(H),8,11β(H)-E,E-germacr-8,12-olide

The results of the chemical modification of stizolicin, a sesquiterpene lactone of the trans,trans-germancrane type and, in particular, the epoxidation, saponification, and acetylation of its molecule are discussed. On the basis of the results of an x-ray structural experiment, for 6-acetoxy-13-methoxy-1,10-epoxystizolicin we propose the structure of 6α-acetoxy-13-methoxy-1,10: 4,5-diepoxy-1,5,7α(H),8,11β(H)-E,E-germacr-8,12-olide.     

Sesquiterpene lactones as stimulators of photodynamically active porphyrins

The photosensitizing properties of sesquiterpene lactones have been considered by means of a study of their influence on the pigmentary system of plants. An investigation of the action of germacranolides, eudesmanolides, guaianolides, and pseudoguaianolides on the fluorescence spectra of leaves in the presence of exogenous 5-aminolevulinic acid (5-ALA) has permitted the conclusion that these compounds are capable of inhibiting the transformation of 5-ALA in the chain of the biosynthesis of chlorophyll.Institute of Organic Synthesis and Coal Chemistry, Kazakhstan Academy of Sciences. Institute of Physiologically Active Compounds, Russian Academy of Sciences, Chernogolovka. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 637–640, November–December, 1992.     

Enthalpy of solution of tigogenin saponin in dioxane and the temperature dependence of its heat capacity

The heats of solution of tigogenin C₂₇H₄₄O₃ in dioxane at dilutions equal to 1: 9000, 1: 18 000, and 1: 36 000 (mol solute/mol solvent) have been studied by isothermal calorimetry. The standard enthalpy of C₂₇H₄₄O₃ solution in dioxane at infinite dilution was derived by the mathematical processing of the calorimetric data. Dynamic calorimetry over the range 173–423 K has been used to study the heat capacity of tigogenin. The C _p ^o ～ f(T) plot has a jump at 298.15. K. The standard enthalpies of formation and combustion and the heat of melting of tigogenin have been indirectly calculated.