Uv visible spectrophotometer

The reagents and chemicals used for the spectrophotometer quantification were: sodium borate decahydrate (Carlo Erba), sodium hydroxide (Carlo Erba), sodium acetate (Carlo Erba) and acetic acid (Chem Lab). For the preparation of acetate buffer, 3.49 g of sodium acetate was diluted in 800 mL of purified water with 0.4 mL of acetic acid then added and taken to a final volume of 1000 mL with purified water. The optimal pH value was 5.5 ± 0.1. The substrate solution was composed of 105 mg of 4-nitrophenyl-α D galacto-pyranoside (Sigma Aldrich) dissolved into 50 mL of acetate buffer solution. The last solution needed for the enzymatic activity was borate solution composed of 23.8 g of sodium borate decahydrate in 1000 mL of purified water, where the pH was corrected at 9.7 ± 0.1.
The UV–Visible spectrophotometer (JASCO) employed for analysis was initially qualified and calibrated in accordance with cGMP before this activity was conducted.

The %ɳ of curcumin inside the three formulations of MPs was measured dissolving 10 mg of MPs in 1 mL of DMSO for 30 min, at room temperature. The solution was then analyzed by UV–vis (UV–Visible-V-730 UV–Visible Spectrophotometer, Jasco, (Cremella, (LC), Italy) following the signal at 426 nm. The quantity of curcumin-loaded was obtained through the Beer–Lambert law using 58,547 dm³·mol⁻¹·cm⁻¹ as the molar extinction coefficient of curcumin in DMSO [41 (link)]. All experiments were performed in triplicate.

According to the previous description, NIPAAm and HMAAm were copolymerized. Briefly, 80 mol% NIPAAm was dissolved in 20 ml of DMF, followed by 20 mol% HMAAm and 0.01 mol% AIBN. In total, the monomers possessed a molar concentration of 50 mmol. For the copolymerization, 62°C was maintained for 20 h before four freeze-thaw cycles degassed it completely. After polymerization, AIBN, unreacted monomers, impurities, and solvent were removed by dialysis against ethanol (FUJIFILM Wako Pure Chemical Corporation, Osaka, Japan) and distilled water for 7 days. It takes 3 days for the dialyzed solutions to be lyophilized after they have been dialyzed. The chemical structure of the copolymer was verified by NMR (JEOL, Tokyo, Japan). The average molecular weight (Mn) and polydispersity index (PDI) of the copolymer was determined by gel permeation chromatography (GPC, JASCO International, Tokyo, Japan) using DMF with lithium bromide (LiBr, 10 mm) (Tosho Corporation, Tokyo, Japan) as an eluent sample. A UV-Visible spectrophotometer (JASCO Corporation, Tokyo, Japan) with a heating rate of 1.0 C/min was used to measure temperature-dependent changes in the transmittance of the copolymer in phosphate-buffered saline (PBS) (pH = 7.4, 0.1% w/v). We defined the lower critical solution temperature of the copolymer as the temperature at which 50% of the transmission was achieved.

Total flavonoid contents of Caralluma edulis were calculated by the modified aluminum chloride colorimetric method [19 ]. The mixture containing 0.5 mL of AlCl₃ (5%), 0.5 mL of potassium acetate solution (1 M), and 2 mL of each sample extract was incubated at 25 °C for 15 min. The control sample contained absolute ethanol. UV–visible spectrophotometer (Jasco, Portland, OR, USA) was set at 415 nm to measure the absorbance of all samples. The reference standard for flavonoid estimation was quercetin. The result was determined as mg of quercetin equivalent (QE) per gram of extract (dry weight). The calibration curve equation was y = 0.0265x + 0.154, where R² = 0.996.

The concentration of some important phytochemicals (campesterol, β-sitosterol, (E)-stilbene, gallic acid, pentadecanoic acid) were measured by UV–visible spectrophotometer (Jasco, Portland, OR, USA) at different wavelengths. These compounds have demonstrated antioxidant, anti-inflammatory, and antidiabetic properties in recent studies [22 (link),23 (link),24 (link)].

Total alkaloids were estimated by the colorimetric method [20 (link)]. In total, 1 mL of sample extract was taken, and its pH was adjusted to neutral by the consecutive washing of 10 mL of chloroform. The plant extract was then mixed with 5 mL of bromocresol green solution. A total of 5 mL of phosphate buffer was added. The resultant solution was vigorously shaken with chloroform in a flask. UV–visible spectrophotometer (Jasco, Portland, OR, USA) was set at 470 nm to measure the absorbance of all samples. Atropine was used as a reference. The result was expressed as mg of atropine equivalent (AE) per gram of extract (dry weight). The calibration curve equation was y = 0.0032x + 0.027, where R² = 0.994.