StatusThe thesis was presented on the 4 April, 2019
Approved by NCAA on the 9 July, 2019
Abstract– 0.80 Mb / in romanian
3.30 Mb /
Dissertation consists of an introduction compartment, three chapters containing theoretical concepts and personal contributions including experimental results, general conclusions and recommendations, references with 231 titles, 100 pages of basic text, 5 tables and 72 figures. The obtained results were published in 13 scientific papers.
The field of study: 143.04 - Bioorganic chemistry, chemistry of natural and physiologically active compounds.
Aim of the study. The isolation of biologically active ent-kauranic and ent-trachylobanic diterpenoids from sunflower waste, and their subsequent utilization as precursors in the production of other natural bioactive diterpenoids and potentially bioactive synthetic compounds.
Objectives of the study: identifying the optimal solvent for the extraction of ent-trachylobanic and ent-kauranic diterpenoids from sunflower waste; study of the superacid isomerization reaction of ent-kaur-16-en-19-oic and ent-trachiloban-19-oic acids; oxidative functionalization of ent-kaur-16-en-19-oic acid at C-15, C-16, and C-17 positions; polyfunctionalization of ent-kaur-16-en-19-oic and ent-trachyloban-19-oic acids with Ph(OAc)2 – LiBr and/or NaIO4-LiBr systems.
Originality and scientific novelty, theoretical value: For the first time, a new concept of retro-biomimetic synthesis was proposed. Based on this concept, the structural diversification of compounds was performed and the convergence of ent-trachilobanic and ent-kauranic skeletons into biogenetically related compounds was demonstrated. The isomerisation of ent-trachyloban-19-oic acid with Ph(OAc)2-LiBr system was achieved as well, and the new highly functionalized ent-kaurane and ent-atisane derivatives were obtained. The oxidative functionalization of natural ent-kaur-16-en-19-oic acid at C-15, C-16 and C-17 positions was performed producing natural and new synthetic ent-kauranoic derivatives.
The solved scientific problem consists of the identification of the new interesting synthesis pathways towards some biologically active natural diterpenoid compounds with low content in natural sources, as well as obtaining the new synthetic derivatives with potential biological activity.
Applicative value of the work. Into the spirit of green chemistry, an important aspect of this work is the use of sunflower waste in order to obtain practically useful substances for the economy of country. Also, the functionalization of ent-kaurenoic and ent-rachilobanoic derivatives isolated from sunflower has a particular practical interest, as it represents an effective way of the accumulation of bioactive natural compounds, in particular, ent-antisane derivatives.
Implementation of scientific results. The optimized extraction process of sunflower waste is widely used in the laboratory of Chemistry of Natural and Biological Active Compounds, Institute of Chemistry. The diterpenic acids obtained by this method serve as a raw material in various synthetic routes. Also, the material presented in the current thesis is part of a teaching cycle, the master's degree level at the Faculty of Chemistry and Chemical Technology of Moldova State University.