Optimization of the extraction and distillation process of bioactive compounds from the mastic tree leaf (Pistacia lentiscus L.)

U ovom radu istraživan je utjecaj konvencionalne ekstrakcije (CE) te ekstrakcije potpomognute mikrovalovima (MAE) na sastav i udio fenolnih spojeva (ukupni fenoli, flavonoidi, flavonoli i hidorksicimetne kiseline) lista tršlje sa lokacija Barbariga, Lun, Hvar i Vela Luka ubranog tijekom tri fenološke faze (cvatnja; rani plod i zreli plod) u ovisnosti o vrsti i polarnosti otapala (voda, 100% i 80% metanol i etanol) i vremenu ekstrakcije (30 - 210 minuta) kod CE, te temperature (50-70 °C), snage mikrovalova (200-500 W) i vremena (4-12 min) kod MAE. Optimalni uvjeti ekstrakcije definirani su na temelju masenih udjela fenolnih spojeva. Najbolji ekstrakcijski kapacitet kod CE i MAE postignut je upotrebom 80 %-tne vodene otopine metanola kao otapala i to kod CE tijekom 90 min, a kod MAE u vremenu od 12 min, temperaturi od 69 °C i snazi mikrovalova od 500 W. U ekstraktima lista tršlje dobivenim pri optimalnim uvjetima pomoću HPLC-DAD i LC-MS/MS provedena je kvalitativna i kvantitativna analiza pojedinčanih fenolnih spojeva te se pokazalo da je najzastupljenija fenolna kiselina je 5-O-galoilkina kiselina, dok je miricetin ramnozid određen kao dominantni flavonol glikozid. Istraživan je i utjecaj tlaka na prinos eteričnih ulja dobivenih iz uzoraka lista tršlje, te njihov antimikrobni učinak prema gram-negativnim bakterijama Escherichia coli soj AB1157 i Erwinia amylovora soj EaED pomoću disk difuzijske metode. GC-MS analizom identificirano i kvantificirano 56 sastavnica od kojih su α-pinen, β-pinen i limonen određene kao dominantne. Sva eterična ulja su pokazala umjereni antimikrobni učinak prema navedenim gram-negativnim bakterijama u usporedbi sa antimikrobnim učinkom antibiotika kloramfenikol. Antimikrobno djelovanje eteričnih ulja tršlje pripisuje se sinergističkom djelovanju svih sastavnica.This study researched the influence of conventional (CE) and microwave assisted extraction (MAE) on the composition and mass fractions of phenolic compounds (total phenols, flavonoids, flavonols and hydroxycinnamic acids) in mastic tree leaves harvested at locations Barbariga, Lun, Hvar and Vela Luka during three phenological stages (flowering, early and late fruiting) depending on the solvent type and polarity (100% water, 100% and 80% methanol or ethanol), extraction time (30-210 minutes) concerning CE as well as temperature (50-70°C), microwave power (200-500W) and time (4-12 min) regarding MAE. Optimal extraction conditions for CE and MAE were obtained by using 80% methanol as a solvent during 90 minutes regarding CE and 12 minutes concerning MAE at temperature of 69 °C and microwave power of 500 W. In mastic tree leaves extracts obtained by optimal extraction conditions, phenolic profile was determined using HPLC-DAD and UPLC-MS/MS methods by which the dominant fenolic acid determined was 5-O-galloylquinic acid, while myricetin rhamnoside was deterimined as a dominant flavonol gylcoside. Furthermore, the influence of pressure on the mastic leaf essential oil yield was researched as well as their antimicrobial activity against gram-negative bacteria Escherichia coli strain AB1157 and Erwinia amylovora strain EaED by disc-diffusion method. Using GC-MS analysis, 56 components of the obtained essential oil were identified and quanitified among which α-pinene, β-pinene and limonene were determined as dominant. All essential oil samples exhibited moderate antimicrobial activity against mentioned gram-negative bacteria, in comparison to antibiotic chloramphenicol, due to the synergictic activity of all essential oil compounds