A critical examination of the DPPH method: Mistakes and inconsistencies in stoichiometry and IC50 determination by UV–Vis spectroscopy

Menezes, Bryan Brummelhaus de; Frescura, Lucas Mironuk; Duarte, Rafael Mendonça; Villetti, Marcos A.; Rosa, Marcelo Barcellos da

doi:10.1016/j.aca.2021.338398

Cited by 55 publications

(38 citation statements)

References 59 publications

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“…The reaction of the stable radical DPPH· with various antioxidant compounds from the papaya extracts is presented in Figure 2 . Antioxidant compounds such as ascorbic acid, ferulic acid, and myricetin react with DPPH· in order to generate the neutral compound DPPH-H (2,2-diphenyl-1-pycrylhydrazine) and other radical intermediates, which are further transformed in neutral degradation compounds [ 41 , 42 ]. Only DPPH· radical has significant absorbance at 517 nm, while the neutral compounds do not absorb in this region.…”

Section: Resultsmentioning

confidence: 99%

“…Only DPPH· radical has significant absorbance at 517 nm, while the neutral compounds do not absorb in this region. The maximum absorbance of DPPH· is shifted to a much lower value after these reactions (<450 nm [ 41 , 42 ]). On the other hand, papaya extracts do not have significant absorbance at 517 nm (e.g., ascorbic acid has a maximum absorbance in the UV region at 243 nm, ferulic acid at 291 and 321 nm, while myricetin has a maximum absorbance at 328 nm [ 43 , 44 , 45 ]).…”

Section: Resultsmentioning

confidence: 99%

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A DPPH· Kinetic Approach on the Antioxidant Activity of Various Parts and Ripening Levels of Papaya (Carica papaya L.) Ethanolic Extracts

Iordănescu

Bala

Gligor

et al. 2021

Plants

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Papaya fruits (Carica papaya L.) are valuable both as food, including concentrates and mixed beverages and in traditional medicine. The goal of the study was to evaluate the antioxidant activity of various parts of unripe and ripe papaya fruit from the DPPH· kinetics point of view. Peel, pulp, seed, and seed-pulp of unripe and ripe papaya fruits (¼ and >¾ level of ripening) were extracted with ethanol and monitored at 517 nm in the presence of DPPH·. The radical scavenging capacity (RSC) at various time ranges and DPPH· reaction rates for specific time intervals were determined. The highest RSC values were obtained for papaya pulp extracts, consistently higher for the ripe samples in comparison with the unripe ones (86.4% and 41.3%). The DPPH· rates significantly differ for the unripe and ripe papaya extracts, especially for the first time range. They are more than double for the ripe papaya. These values were 2.70, 4.00, 3.25, 2.75 μM/s for the peel, pulp, seed, seed-pulp extracts from the ripe papaya and only 1.00, 1.65, 1.40, 1.80 μM/s for the unripe samples. DPPH· kinetic approach can be useful for a fast and simple evaluation of the overall antioxidant properties of fruit extracts.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

A DPPH· Kinetic Approach on the Antioxidant Activity of Various Parts and Ripening Levels of Papaya (Carica papaya L.) Ethanolic Extracts

Iordănescu

Bala

Gligor

et al. 2021

Plants

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“…Antioxidant activity quantification can be deduced from the half-maximal inhibitory capacity when challenged by DPPH radicals. The IC50 value is inversely proportional to the sample's scavenging free radicals [42,43]. Regardless of the variability and its consistency, sun drying is still the most popular method cost-wise.…”

Section: Antioxidant Activitymentioning

confidence: 99%

Determination of Moisture, Ash, Protein, Polyphenolic, Flavonoids, and Amino Acid Contents and Antioxidant Capacity of Dried Mekai (Pycnarrhena tumefacta Miers) Leaf as Potential Herbal Flavor Enhancers

Rohmah¹,

Saragih²,

Amaliah³

et al. 2022

Advances in Biological Sciences Research

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Mekai leaf (Pycnarrhena tumefacta Miers) is used by the Dayaks tribe as a glutamic acid substitute to enhance the umami flavor of traditional foods. A dried mekai leaf is applied directly to the pan during cooking. Mekai contains glutamate, but its amino acids and other properties such as antioxidant capacity and phenolic-related substances have not been quantified. This study aims to determine the moisture, ash, protein, polyphenolic, flavonoids, amino acid content, and the antioxidant capacity of Mekai, leaves were dried in the sun, gas, and electric ovens at various temperatures and times. The moisture content of dried Mekai leaves was 6.95-9.30% (w/w). The ash and protein contents of dried Mekai leaves were 4.22-5.47 % and 15.7-20.6 % (w/w), respectively. The optimal moisture and ash content conditions were obtained after 3.5 hours of electric oven drying at 60 °C. Different drying methods had no discernible effect on protein content; excepted for electric oven drying at 60 °C for 3.5 hours, which results in protein content of 16.90.0 percent (w/w). Sundried Mekai had the lowest TPC value, whereas samples dried in an electric oven had a higher TPC value than samples dried in a gas oven. Both electric and gas oven drying at 60 °C for 2.5 hours resulted in significantly higher levels of flavonoids and antioxidant activity than other drying conditions in the same group. Mekai leaves were identified by the presence of arginine, glutamate, aspartic acids, and leucine. After sun drying, arginine, leucine, and isoleucine concentrations increased more than other amino acids.

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“…As the color changes from purple to yellow, the stable free radical DPPH displays an electrical absorption band limit at 517 nm. When the odd electron of the DPPH radical is combined with hydrogen from a free radical scavenging antioxidant to form reduced DPPH, the absorption band narrows [26]. A 0.3mM DPPH solution was produced in DMSO and applied to the ligand in 1mL at different concentrations (0, 25, 50, 100, 200, and 400 µg/mL).…”

Section: Dpph Radical Scavenging Assaymentioning

confidence: 99%

Synthesis, spectral characterization, lethal dose (LD50) and acute toxicity studies of 1,4-Bis(imidazolylazo)benzene (BIAB)

Kyhoiesh

Al-Hussainawy

Waheeb

et al. 2021

Heliyon

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A critical examination of the DPPH method: Mistakes and inconsistencies in stoichiometry and IC50 determination by UV–Vis spectroscopy

Cited by 55 publications

References 59 publications

A DPPH· Kinetic Approach on the Antioxidant Activity of Various Parts and Ripening Levels of Papaya (Carica papaya L.) Ethanolic Extracts

A DPPH· Kinetic Approach on the Antioxidant Activity of Various Parts and Ripening Levels of Papaya (Carica papaya L.) Ethanolic Extracts

Determination of Moisture, Ash, Protein, Polyphenolic, Flavonoids, and Amino Acid Contents and Antioxidant Capacity of Dried Mekai (Pycnarrhena tumefacta Miers) Leaf as Potential Herbal Flavor Enhancers

Synthesis, spectral characterization, lethal dose (LD50) and acute toxicity studies of 1,4-Bis(imidazolylazo)benzene (BIAB)

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