Browsing by Author "Bilalov, Elchin"
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- Fractionation of olive leaf extracts with molecularly imprinted adsorbents working in continuous processes at the preparative scalePublication . Bilalov, Elchin; Dias, RolandoOlive leaves present high content of bioactive compounds. Despite this, they are discarded away without repurposing. These compounds are useful in a variety of industries such as food, cosmetics and pharmaceuticals. The present research proposes a continuous process of adsorption-desorption that relies on molecularly imprinting polymers (MIPs) as adsorbents, to purify the bioactive compounds. The first part of this work involves the design and synthesis of MIPs targeting quercetin, oleanolic acid, and oleuropein, which are representative compounds from the families of flavonoids, triterpenoids, and secoiridoids, respectively. Subsequently, these synthesized MIPs were assessed using solid-phase extraction to determine their retention capacities and selectivity towards bioactive compounds from the aforementioned families. This step permitted to select the materials that were suitable for continuous processes of adsorption-desorption. The criteria of this selection were based on the morphology of the materials (size, swelling etc.) and their retention capacity as well as their selectivity. For the continuous system, different-sized columns were utilized (up to 25 g of adsorbent was packed). The selected MIP was saturated with the extract and operated in recycle closed loop system, followed by desorption using various solvent fractions. Additionally, isotherm studies helped design the conditions for separating different families of bioactive compounds. The desorbed fractions were analysed using high-performance liquid chromatography (HPLC). The results show that the different desorbed fractions isolated contain specific types of bioactive compounds. It was also found that a second purification step could be considered to further increase the purity of the compounds.
- Separation of Bioactive Compounds in Olive Leaf with a Pyridyl-Functionalized Adsorbent and Hydroalcoholic SolventsPublication . Bilalov, Elchin; Martins, Cláudia Filipa; Costa, Mário Rui; Dias, RolandoThe separation of different types of bioactive compounds in olive leaf is demonstrated with a tailored adsorbent functionalized with pyridyl moieties and sorption−desorption processes developed to use only hydroalcoholic solvents. The competitive binding isotherms of mixtures of vanillic acid, oleuropein, quercetin, maslinic, and oleanolic acids in water/ethanol solvents, with the composition ranging from 50/50 up to 100% ethanol, prove the feasibility of the separation of such different classes of molecules. The bioactive compounds in two industrial olive leaf extracts with different crude compositions were separated with the pyridyl-based polymer particles in packed columns, employing multicycle sorption/desorption processes. A polyphenol-rich extract was subjected to separation, resulting in the isolation of fractions containing varying concentrations of specific compounds. For example, a fraction enriched with oleuropein exhibited a concentration of approximately 80% (an enrichment factor of ∼4 in comparison with the crude extract), while glycosylated flavonoids were present at a concentration of around 60% in another fraction (an enrichment factor of ∼12). Additionally, aglycone flavonoids were present in fractions at a concentration of approximately 83% (an enrichment factor of ∼49). On the other hand, the separation of polyphenols and triterpene acids in an olive leaf extract with a high triterpene content was also demonstrated, with a ratio of flavonoids to triterpenoids of approximately 23 in isolated fractions, as compared to approximately 1 observed in the crude extract. The developed approach yielded luteolin with an enrichment factor of approximately 7. These novel achievements are intended to contribute to sustainability and a circular bioeconomy through the efficient industrial valorization of agricultural by products.