Research on obtaining enotannins from Moldovan grape seeds
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LUPASCU, Tudor, TIMBALIUC, Nina, LUPAŞCU, Lucian, SPINU, Oxana, POVAR, Igor. Research on obtaining enotannins from Moldovan grape seeds. In: New trends and strategies in the chemistry of advanced materials with relevance in biological systems, technique and environmental protection, 8-9 iunie 2017, Timișoara. Timişoara, România: Institute of Chemistry Timişoara of the Romanian Academy, 2017, Ediția a 10-a, p. 28.
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New trends and strategies in the chemistry of advanced materials with relevance in biological systems, technique and environmental protection
Ediția a 10-a, 2017
Conferința "New trends and strategies in the chemistry of advanced materials with relevance in biological systems, technique and environmental protection"
Timișoara, Romania, 8-9 iunie 2017

Research on obtaining enotannins from Moldovan grape seeds


Pag. 28-28

Lupascu Tudor, Timbaliuc Nina, Lupaşcu Lucian, Spinu Oxana, Povar Igor
 
Institute of Chemistry of the Academy of Sciences of Moldova
 
Proiecte:
 
Disponibil în IBN: 29 iulie 2020



Teza

Research concerning the development of biologically active substances, preferably of natural origin, useful for protecting human health, is dictated by increasing the harmful factors impact on human body. A proper raw material for obtaining this category of substances is the grape seeds, which are a rich resource of condensed tannins with polyphenolic structure, called enotannins. They represent a complex mixture of catechol and epicatechol oligomers. The grape seeds constitute the most appropriate source of tannins in the Republic of Moldova. The enotannins content in the grape seeds depends on the grape variety as well as the geographical zones of grape cultivation [1]. The content of enotannins in studied grape seeds lies between 3.1 and 14.1 %.
As a raw material for obtaining enotannins, the grape seeds of the Black Fraga variety were chosen, because our previous research showed that just these seeds were characterized by a high content of enotannins. Initially the grape seeds contained various vegetal impurities. By multiple washings with tap water and subsequent decantation until a complete removal of impurities, the pure seeds were obtained, which then were dried in an oven at the temperature of 50°C till constant weight. The extraction of enotannins from grape seeds was carried out using the Soxhlet apparatus. Water and ethyl alcohol of 96% were used as solvents. The experiments were carried out both with the integrated and shredded seeds as well the seeds, from which the oil was previously extracted by hexane. The solutions of enotannins in water and ethyl alcohol of 96% were concentrated in a vacuum rotator at 65-70oC until the solution became rather viscous. The aqueous content was placed in the Petri dish and dried to constant weight in an oven at the temperature of 60°C.
Our subsequent research showed that the content of enotannins in the grape seeds of the Black Fraga variety soluble in ethyl alcohol of 96% was about 14%, while in those soluble in water was 2.6%.
Our investigations on the quality of enotannins soluble in alcohol of 96%, obtained from non- degreased seeds, have demonstrated that they contain large amounts of oil, up to 25%. Therefore, the enotannins can be extracted by ethyl alcohol with a concentration of 96% just after degreasing the seeds.
In order to improve the physical-chemical properties of enotannins, a new procedure for their solubilization in water has been developed in the Laboratory of Ecological Chemistry of the Institute of Chemistry of the Academy of Sciences of Moldova [2]. The solubility of enotannins is changed by oxidation-reduction processes [3]. The obtained product, named Enoxil-A, has been tested on sugar beet seeds. Tests have shown that Enoxil-A increases the plant resistance toward various diseases caused by fungi and a number of bacteria.