R 200 rotary evaporator

Two extractions were performed using different parts of the berries: fresh berry pulp (FBP) and dried berry seeds. The fresh pulp (skin included) was separated from the seed and crushed, the fresh seeds were dried at 40 °C for 24 h and ground. The samples were extracted immediately, in a ratio of 1:20 (w/v) with methanol, for 1 h, at room temperature, in a magnetic stirrer. Upon centrifugation at 1018× g for 10 min, the supernatant was filtered and evaporated under vacuum (in an R-200 rotary evaporator, Buchi, Switzerland). The FBP extract was freeze-dried and stored at room temperature (extraction yield of 8.2 g/100 g fresh pulp). The evaporation of the seed extract yielded two fractions, a residue (BSR) and an oil (BSO), which were separated by decantation. The BSR extract was freeze-dried and stored at room temperature, while the BSO was stored at 4 °C (extraction yields of 2.7 g/100 g and 1.8 mL/100 g dried seeds, respectively). Stock solutions were prepared and stored at 4 °C prior to the determination of chemical composition and evaluation of antioxidant potential. The FBP and BSO extracts were solubilized in ethanol at a concentration of 5 mg/mL, while for BSR, methanol was used, allowing to reach a concentration of 4 mg/mL.

Phenolic compounds were extracted from ground seeds using 80% (v/v) methanol at a solids to solvent ratio of 1:10 (w/v) for 15 min at 50 °C [23 (link)]. The extraction was repeated twice, the supernatants were filtered and combined, and methanol was evaporated under vacuum in a R-200 rotary evaporator (Büchi Labortechnik AG, Flawil, Switzerland). The remaining aqueous solution was lyophilized.

Senna occidentalis was identified by Mr. Jonathan Ayayo, a taxonomist of the National Museums of Kenya (NMK), and a voucher specimen (38/81) was deposited at the East African Herbarium, NMK for future reference. The plant roots were collected from Migori County (0.9366^o S, 34.4198^o E), western Kenya, in the month of September in accordance with the WHO Guidelines on Good Agriculture and Collection Practices (GACP) for medicinal plants [32 ]. Air-dried roots were ground into powder, and absolute methanol was used to prepare the extract by maceration at room temperature for 48 h. The filtrate (Whatman No. 1 filter paper) was concentrated by rotary vaporization at 50°C and reduced pressure (BÜCHI R-200 rotary evaporator), and the extract (paste) was stored in sealed sample bottles at 4°C until needed.