Multivariable optimization of ultrasound-assisted extraction for the determination of phenolic and antioxidants compounds from arrayan (Luma apiculata (DC.) Burret) leaves by microplate-based methods and mass spectrometry

The present study reports a multivariable optimization of ultrasound-assisted extraction of phenolic compounds from arrayan leaves. The parameters ethanol percentage in extraction solvent, temperature and extraction time, and mass to solvent ratio were optimized applying full factorial and central composite designs. According to the models, the optimal extraction conditions were: 42% of ethanol, extraction time of 27 min, extraction temper-ature of 50?& nbsp;and a mass to solvent ratio of 1:33.4 g mL(-1). Under these conditions, a total phenolic content (TPC) of 128.16 & nbsp;+/- 1.18 and 593.64 & nbsp;+/- 6.49 mg of gallic acid equivalent per g of dry weight (DW) were determined in raw extract (RE) and polyphenols-rich extract (PRE), which was obtained by semi-preparative chromatography on XAD-7 column. Antioxidant capacity determined via FRAP analysis showed values of 1349.53 +/-& nbsp;28.99 and 6175.47 +/-& nbsp;127.64 mu mol Trolox equivalent per g of DW for RE and PRE, and DPPH IC50 values of 831.40 +/-& nbsp;0.80 and 132.21 +/-& nbsp;2.51 mu g mL(-1), respectively. Polyphenols profile analyzed by liquid chromatography-mass spec-trometry showed the presence of quercetin 3-ss-D-glucoside, myricetin, quercetin, kaempferol 3-glucoside and gallic acid; the latter compounds are reported for the first time in arrayan leaves. Due to the presence of poly-phenols, antiviral activity was assayed over norovirus and hepatitis A showing a significant dose-dependent effect.