2.8. Lipase Assay

The inhibitory activity of S. horneri extracts on lipase was determined as previously described [28] with some modification. In brief, lipase (type II, from porcine pancreas, 400 units/mg protein; Sigma-Aldrich Corp., Saint Louis, MO, USA) was dissolved in distilled water at 5 mg/mL and then centrifuged (1000× g, 5 min), and the supernatant was used as the enzyme source. Next, 4-Nitrophenyl butyrate (4-NPB; Sigma-Aldrich Corp., Saint Louis, MO, USA) was dissolved in dimethylsulfoxide. The reaction mixture contained 100 μL of enzyme solution and 100 μL of S. horneri extract in 4 mL of 20 mM Tris-HCl buffer pH 8.5. The mixture was pre-incubated at 37 °C for 10 min. The reaction was started by the addition of 100 μL of 5 mM 4-NPB solution and then incubated for 30 min at 37 °C. The absorbance was measured at 400 nm.