On the production of isochlorogenic acid in sweet potato [Ipomoea batters, Convolvulaceae]

In this investigation, some factors which affect the synthesis of isochlorogenic acid in disks of Ipomoea batatas were studied. These factors included: sucrose, some salts, quinic and shikimic acids, ethionine, chloramphenicol and light. Isochlorogenic acid formation has been shown to occur in disks of lpomoea tuber which are initially almost devoid of this compound. Both sucrose and quinic acid stimulated the synthesis of isochlorogenic acid markedly, whereas shikimic acid appeared to have no effect other than a salt stimulation. Salts such as calcium chloride and nitrate strimulated the synthesis of isochlorogenic acid to a lesser extent. The small effect of ammonium nitrate may be due to the oxidation of some of the isochlorogenic acid synthesized to the brown pigments. Light stimulated the synthesis of isochlorogenic acid. The synthesis was doubled when the disks were briefly exposed to light of relatively low intensity. Further stimulation was by much exposures to light of relatively high intensity. In disks cultured under illumination, the rate of isochlorogenic acid accumulation increased continuously attaining the highest level observed. Isochlorogenic acid synthesis was inhibited by high concentrations of ethionine and chloramphenicol. Concentrations of chloramphenicol as high as those required for ethionine inhibition were necessary to demonstrate an inhibitory effect on production

influence of light on the accumulation of phenylic acids, [-] -epicatechin and tannis during germination of Ricinus communis L

The changes in phenolic acids. [-]-epicatechin and tannins during germina ion of Ricinus communis L. under various light treatments were studied. Under the light/dark photoperiod, phenolic acids, [-]-epicatechin and tannins were first detected only towards the last stages of germination. Continuous illumination with white or fluorescent light promoted the production of phenolic acids and tannins by Ricinus seedlings. On the other hand, previous exposure of the seedlings to red light enhanced the formation of phenolic acids and tannins, whereas blue light inhibited their biosynthesis. During the different stages of germination under all light treatments, roots contained no or only trace amounts;henolic acids and tannins

Studies on the anthocyanin-flavonoid complex in coleus blumei infested by the mealy bug icerya aegyptiaca

Leaves and inflorescences of Coleus blumei from healthy, and from plants infested with Icerya aegyptiaca were analysed to study the changes in flavonoid and anthocyanin complexes associated with the visible changes in the infested leaves, for 6 weeks following infestation. Anthocyanins and flavonoids remained unchanged or increased slightly following infestation compared to healthy leaves. The aglycones of some anthocyanins and flavonoids were detected after the 3rd and 4th week of infestation and increased slightly thereafter. Anthocyanins and flavonoids in the inflorescence were somewhat those in the leaves of healthy plants, and did not change following infestation. The biosynthetic and transport pathways causing changes in anthocyanin-flavonoid complex during infestation of the investigated plant are discussed