Standardization of DPPH, ABTS and FRAP assays with six reference compounds for estimating antioxidant capacity of the tomato extracts using an ultrasound assisted extraction

Comparative calibrating of the antioxidant power of standard compounds, including gallic acid, catechin, Trolox, α-tocopherol, ascorbic acid and BHT were assessed by DPPH, ABTS and FRAP assays to determine total antioxidant activity of ten varieties of tomato extracts using ultrasound assisted extraction. Similar trends in their scavenging activities were found, resulted in the following rank; gallic acid > catechin > trolox > α-tocopherol > ascorbic acid > BHT. Both lipophilic and hydrophilic parts of the extracts were given in these assays in association with using hexane and 50% (v/v) methanol as their efficient extraction solvents, respectively. Their averaged values of the ascorbic acid equivalent antioxidant capacities (AEAC, µmol ascorbic acid/100g DW) were relatively confined in the same ranges of 1341.8-1834.5, 1334.2-2194.8 and 930.7-1734.7 for DPPH, ABTS and FRAP, respectively. In addition, both contents of total phenolics and ascorbic acid known as major deals of antioxidants were also determined, indicating highly existing constituents of the natural antioxidants.

Standardization of DPPH, ABTS and FRAP assays with six reference compounds for estimating antioxidant capacity of the tomato extracts using an ultrasound assisted extraction

Comparative calibrating of the antioxidant power of standard compounds, including gallic acid, catechin, Trolox, α-tocopherol, ascorbic acid and BHT were assessed by DPPH, ABTS and FRAP assays to determine total antioxidant activity of ten varieties of tomato extracts using ultrasound assisted extraction. Similar trends in their scavenging activities were found, resulted in the following rank; gallic acid > catechin > trolox > α-tocopherol > ascorbic acid > BHT. Both lipophilic and hydrophilic parts of the extracts were given in these assays in association with using hexane and 50% (v/v) methanol as their efficient extraction solvents, respectively. Their averaged values of the ascorbic acid equivalent antioxidant capacities (AEAC, µmol ascorbic acid/100g DW) were relatively confined in the same ranges of 1341.8-1834.5, 1334.2-2194.8 and 930.7-1734.7 for DPPH, ABTS and FRAP, respectively. In addition, both contents of total phenolics and ascorbic acid known as major deals of antioxidants were also determined, indicating highly existing constituents of the natural antioxidants.

Determination of Capsaicin and Dihydrocapsaicin in Some Chilli Varieties using Accelerated Solvent Extraction Associated with Solid-Phase Extraction Methods and RP-HPLC-Fluorescence

Reversed phase-HPLC with fluorescence detection of two major capsaicinoids was described. Isocratic elution using a ratio of methanol and deionized water (66:34, v/v) as mobile phase was used at a flow rate of 0.9 mL/min with well achieved separation within 6 min. Under optimum conditions, their analytical figures of merit for the HPLC method were validated. The linearity was in the range of 1.0-25.0 μg/mL with multiple determination coefficients of higher than 0.995. The limit of detection was ranged of 0.008-0.01 μg/mL. The repeatability and reproducibility of the retention time and peak area for these compounds were in good precision with their relative standard deviations (RSDs) lower than 1% and 5%, respectively. Both capsaicin and dihydrocapsaicin were extracted using an accelerated solvent extraction (ASE) of methanol as an extraction solvent for 5 min static time with 3 cycles. The methanolic extracts were subjected to clean up with C18 solid-phase extraction (SPE) with its recoveries ranking of 90.2-98.0%. The method recoveries of real samples were found to be 60.7-98.6%. The optimized extraction method were applied for the determination of the two capsaicinoids in ten vareities of hot chilli pepper samples. Total contents of capsaicinoids were found in the range of 2,307.0-9047.3 μg/g DW with their corresponding Scoville heat unit (SHU) of 34,600-135,700. Additionally, the contents of capsaicinoids using external calibration method comparing with those of standard addition were not significantly different, indicating accuracy of the method. Mostly, the contents of capsaicin found in these real samples were rather higher than those of dihydrocapsaicin