QUINOA SEED STORAGE PROTEINS & BETANIN INTERACTIONS FOR NANOCARRIERS DESIGN

JIMENA HEBE MARTINEZ; FRANCISCO VELAZQUEZ DUARTE; HERNAN PABLO BURRIEZA; MARTÍNEZ, KARINA D.; ANA PAULA DOMÍNGUEZ RUBIO; MARÍA DEL PILAR BUERA; PÉREZ, OSCAR E.

Los Cocos, Córdoba

Simposio; XII Simposio Argentino de Polímeros; 2017

Quinoa seeds are rich in proteins and 11S globulin, one of its storage proteins is eligible for control delivery of bioactives upon nanoencapsulation [1]. In the other hand, betanin is a strong natural antioxidant that has not yet been utilized in pharmaceutical preparations due to poor stability and lack of scientific reports highlighting their value alongside their bioavailability [2]. The aim of this work was to construct 11S nanocarriers for betanin. In the present study we obtain purified 11S globulin which was used as encapsulating material of betanin. Quinoa flour was obtained by grinding whole seeds in a mill, sieved (3660 m) and defatted. The protein content (17% w/w) was determined by the micro-Kjeldhal method. Afterwards 11S was extracted with high salt buffer, an enriched fraction was achieved by selectively precipitation at pH=5 and subjected to gel filtration chromatography using a high-resolution separation of 11S according its size in a FLPC. Fractions were analyzed by SDS-PAGE (10%). A highly enriched 11S fraction was obtained (basic and acidic monomers, 17 y 30 KDa respectively) displaying the characteristic band pattern. 11S-betanine complexes were induced by mixing purified 11S protein solutions with different amount of betanin. Intrinsic Tryptophan fluorescence quenching analysis of mixtures using Stein-Volmer model produce a quenching rate constant of ~1013 M-1s-1; this kq is higher than maximal dynamic constant, suggesting static quenching (11S-betanin) [3].These complexes of 11S and betanin were characterized at pH=8 by DLS (10.9 ± 2.7 11S vs 10.08 ± 3.77 11S- betanin) nm and Z potential (-16.7 ± 1.3 11S vs -17.4± 0.3 11S-betanin) mV.These results suggest that betanin binds 11S through non electrostatic interactions, which is reflected by fluorescence and the lack of changes in the superficial charges. This approach allows us to report a putative nanocarriers that possibly protects betanin bioactivity.