2.3.2. Maceration

The powder of black locust flowers (2.0 g) was extracted with 20 cm<sup>3</sup> of 60% (v/v) ethanol at 25 ◦C for 24 h. The extract was further treated and analyzed as in the case of UAE.

## 2.3.3. Soxhlet Extraction

The extraction was carried out using 5.0 g of black locust flowers powder and 500 cm<sup>3</sup> of 60% (v/v) ethanol at boiling temperature for 6 h. The extract was subjected to the treatment and analysis as in the previous cases.

#### *2.4. Total Phenolic Compounds*

The TPC was determined according to the Folin–Ciocalteu colorimetric method [29]. Briefly, 0.1 cm<sup>3</sup> of the extract was mixed with 1 cm<sup>3</sup> of the Folin–Ciocalteu reagen<sup>t</sup> previously diluted tenfold with distilled water and 1 cm<sup>3</sup> of sodium carbonate (7%, w/v). The TPC was expressed as gram of gallic acid equivalents (GAE) per 100 g dry plant material (d.p.m.). A series of methanolic solutions of gallic acid (0.005–0.300 mg cm<sup>−</sup>3) was prepared by diluting the stock solution (1 mg cm<sup>−</sup>3) to construct the calibration curve. Instead of sodium carbonate, an equivalent amount of distilled water was added to the blank solution. Absorbance of the samples was measured at 760 nm and room temperature after incubation of 90 min in relation to distilled water on the Varian Cary 100 spectrophotometer (Mulgrave, Victoria, Australia) in the quartz cuvettes (1 × 1 cm).
