Methods of monitoring safety of quercetin compositions

Abstract

Provided herein are methods to determine the safety of quercetin compositions regarding contaminants that can result from the degradation of quercetin, such as by storage of solid form quercetin compositions in an air atmosphere. The contaminants include protocatechuic acid, 2,4,6-trihydroxybenzoic acid, and 2-(3,4-dihydroxybenzoyloxy)-4,6-dihydroxybenzoic acid. Provided herein are also methods which reduce degradation of solid form quercetin compositions and reduce the formation of such toxic compounds. The provided methods increase the shelf life and patient safety of quercetin compositions.

1 - 28 . (canceled) 
     
     
         29 . A method for maintaining safe storage of a solid form quercetin composition comprising (1) purging air from an airtight container containing the solid form quercetin composition, (2) filling the container with an atmosphere consisting essentially of an inert gas or a combination of inert gases, (3) storing the container at 15-30° C. for a storage period of at least 3 months, and (4) assessing whether the solid form quercetin composition after the storage period is safe or unsafe. 
     
     
         30 . The method of  claim 29 , wherein the quercetin composition comprises a pharmaceutically acceptable composition. 
     
     
         31 . (canceled) 
     
     
         32 . The method of  claim 29 , wherein the solid form quercetin composition comprises freeze-dried quercetin. 
     
     
         33 . The method of  claim 29 , wherein the solid form quercetin composition is prepared by spray drying, rotoevaporation, or crystallization. 
     
     
         34 . The method of  claim 29 , wherein the quercetin composition further comprises a drug delivery formulation. 
     
     
         35 . The method of  claim 34 , wherein the drug delivery formulation is selected from the group consisting of: a lipid-based carrier, a polymer-based carrier, nanoparticles, inclusion complexes, micelles, and a conjugate-based capsulation. 
     
     
         36 . (canceled) 
     
     
         37 . The method of  claim 35 , wherein the drug delivery formulation comprises a polymer-based carrier and the polymer-based carrier comprises polyvinylpyrrolidone. 
     
     
         38 . The method of  claim 37 , wherein the quercetin composition comprises about 8:1, about 9:1, about 10:1, about 11:1, or about 12:1 polyvinylpyrrolidone:quercetin w/w. 
     
     
         39 . The method of  claim 37 , wherein the quercetin composition comprises 7-11% quercetin and 89-93% polyvinylpyrrolidone w/w. 
     
     
         40 . The method of  claim 59 , wherein determining the level of a contaminant in the quercetin composition comprises chromatography. 
     
     
         41 . The method of  claim 40 , wherein the chromatography is selected from the group consisting of: liquid chromatography, thin layer chromatography, gas chromatography, and electrophoresis. 
     
     
         42 - 58 . (canceled) 
     
     
         59 . The method of  claim 29 , wherein assessing whether the solid form quercetin composition is safe or unsafe comprises comparing the level of the toxic contaminant to a threshold level;
 wherein the quercetin composition is identified as unsafe if the level of the toxic contaminant is above the threshold level; and,   wherein the quercetin composition is identified as not unsafe if the level of the toxic contaminant is below the threshold level.   
     
     
         60 . The method of  claim 59 , wherein the toxic contaminant is protocatechuic acid, 2,4,6-trihydroxybenzoic acid, or 2-(3,4-dihydroxybenzoyloxy)-4,6-dihydroxybenzoic acid. 
     
     
         61 . The method of  claim 60 , wherein the toxic contaminant is protocatechuic acid and the threshold level is about 0.12±0.02% (w/w) of protocatechuic acid/quercetin. 
     
     
         62 . The method of  claim 60 , wherein the toxic contaminant is 2,4,6-trihydroxybenzoic acid and the threshold level is about 0.05±0.02% (w/w) of 2,4,6-trihydroxybenzoic acid/quercetin. 
     
     
         63 . The method of  claim 60 , wherein the toxic contaminant is 2-(3,4-dihydroxybenzoyloxy)-4,6-dihydroxybenzoic acid and the threshold level is about 0.51±0.03% (w/w) of 2-(3,4-dihydroxybenzoyloxy)-4,6-dihydroxybenzoic acid/quercetin. 
     
     
         64 . The method of  claim 60 , wherein assessing whether the solid form quercetin composition is safe or unsafe comprises comparing the level of the toxic contaminant to a threshold level for at least two toxic contaminants selected from the group consisting of: protocatechuic acid, 2,4,6-trihydroxybenzoic acid, and 2-(3,4-dihydroxybenzoyloxy)-4,6-dihydroxybenzoic acid;
 wherein the threshold level is 1 and calculated for the contaminants determined by the equation: (% (w/w) of protocatechuic acid/quercetin)/T1+(% (w/w) of 2,4,6-trihydroxybenzoic acid/quercetin)/T2+(% (w/w) of 2-(3,4-dihydroxybenzoyloxy)-4,6-dihydroxybenzoic acid/quercetin)/T3;   wherein T1 is the threshold level of protocatechuic acid, T2 is the threshold level of 2,4,6-trihydroxybenzoic acid, and T3 is the threshold level of 2-(3,4-dihydroxybenzoyloxy)-4,6-dihydroxybenzoic acid/quercetin; and,   wherein for a contaminant not selected to be determined, the contribution to the threshold level is zero.   
     
     
         65 . The method of  claim 64 , wherein T1=0.65, T2=0.33, and T3=2.6 
     
     
         66 . The method of  claim 29 , wherein the safety of the solid form quercetin composition is determined by a  Daphnia magna  mobility assay or a cytotoxicity assay. 
     
     
         67 . The method of  claim 29 , wherein the method comprises filling the container with an atmosphere consisting essentially of nitrogen.