The extracts UV spectrum had a single maximum of absorption at 280 nm and this aspect allowed us to treat the extracts as a single component. The EE was calculated using the following formula (Shi et al., 2014 (link)):
Where drug means the phenolic compounds under study (EF1, EF2 and Ole). Each preparation was filtered using the syringe filters with a porosity equal to 0.2 μm (Millipore, Italy). 100 μL of filtrate are taken and brought to a final volume of 5 mL with distilled water. The amount of free and total drug was calculated by using the V-530 spectrophotometer (JASCO) at 280 nm (Mazzotta et al., 2020 (link)).
Where drug means the phenolic compounds under study (EF1, EF2 and Ole). Each preparation was filtered using the syringe filters with a porosity equal to 0.2 μm (Millipore, Italy). 100 μL of filtrate are taken and brought to a final volume of 5 mL with distilled water. The amount of free and total drug was calculated by using the V-530 spectrophotometer (JASCO) at 280 nm (Mazzotta et al., 2020 (link)).
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