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The efficient concentration at different times EC50,t (mg extract mg-1 DPPH•) is the amount of the extracts in relation to the amount of initial DPPH•, which calculated using the following equation:

where IC50,t is the inhibitory concentration at different times, defined as the concentration of extract (mg mL-1) required to scavenge 50 % of DPPH• and t=0 is the initial concentration of DPPH• (mg mL-1).

The efficient concentration at different times EC50,t (mg extract mg-1 DPPH•) is the amount of the extracts in relation to the amount of initial DPPH•, which calculated using the following equation:

where IC50,t is the inhibitory concentration at different times, defined as the concentration of extract (mg mL-1) required to scavenge 50 % of DPPH• and t=0 is the initial concentration of DPPH• (mg mL-1).

IC 50 is half maximal inhibitory concentration and its a measure of the effectiveness of a substance in inhibiting a specific biological or biochemical function by half (e.g. inhibition of enzymes, affinity to cell receptors). In pharmaceutical research, it is a frequently used unit to specify the in vitro potency of a drug. For competition binding assays and functional antagonist assays IC50 is the most common summary measure of the dose-response curve

EC50 is when the half of ts maximal effect is observed. The EC50 of a quantal dose response curve represents the concentration of a compound .

The concepts of IC50 and EC50 are fundamental to pharmacology. The EC50 is the concentration of a drug that gives half-maximal response. The IC50 is the concentration of an inhibitor where the response (or binding) is reduced by half.

Seems simple enough. But when you actually go to fit data to determine these values, there are several complexities and ambiguities.

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The rest of this article is about IC50 (I for inhibition, for downward sloping dose-response curves). All the ideas can be applied to stimulatory curves and EC50 (E for effective) as well.

Can IC50 and EC50 be same of the drug? Suppose if we plot the dose response curve using % cytotoxicity by MTT assay in case of death caused by virus, which is inhibited at various concentrations of drug? X axis involves virus alone and virus in combination with various concentration of drug and Y axis has % cytotoxicity. How to calculate IC50 and EC50 from this graph?

in order to evaluate the antioxidant activity in my plant extract i did the DPPH essay. i want to express my result but i’m confused because the effective concentration at which the DPPH radical was scavenged by 50% is mentioned as EC50 in some articles and IC50 in others.

What is the meaning of IC 50 value in case of DPPH free radical scavenging method and how it is related with the antioxidant activity???

I prepared Trolox working solution at different concentration – 0, 200, 500..800 uM in 10 ml abs MeOH. DPPH was used as antioxidant assay.

For antioxidant activity procedure, 0.15 ml of each Trolox working solution was added to 2.85 ml DPPH assay. Absorbance (515 nm) vs Trolox conc. gave linear correlation (R2=0.96776).

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Working solution of sample was prepared by dissolving 20 mg dried sample in 10 ml abs MeOH, then 0.15 ml of it was mixed with 2.85 DPPH assay. Let say I got a certain absorbance value corresponding to 200 uM Trolox, how could I convert it to Trolox equivalent / (g-dry mass)? I confused whether to multiply the denominator with 10 ml or 0.15 ml. Thank you.

I am testing antioxidants with the use of DPPH. Can anyone explain to me whether to use methanol/ethanol, how much of each concentrations I should use or how to work it out and what would be the best intervals etc.?

I am a little confused as all literature varies in different ranges, so basically an easy protocol to follow would be of great help. Also, what else should I test for to validate antioxidant activity to go alongside the DPPH?

What is the significance of IC50 value when the drug is exogenously administered to an animal tissue?

I have data for antioxidant activity on Excel sheet and I draw scatter chart with the equation: y = 1.3534 x + 0.58, and R² = 0.9927. I want to calculate the IC50 for inhibition %. Someone can help me to figure out how to calculate IC50 value?

In addition, some of my colleagues use a function called “Growth” in Excel to calculate IC50 by just by selection inhibition data column and then choose Growth from Insert Function (fx = ) and obtaining the result. Is it a correct way?

i have completed DPPH assay with Trolox as a standard. How do i express my results in Trolox equivalent/g dry weight?

Effects of Solvents on the In-vitro Antioxidant Activity of Dennettia tripetala G. Baker and Milicia excelsa (Welw.) C. Berg Root Extracts

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