Table 1.

The method used to validate results of HPLC quantification of dimethoxycurcumin (DMC) in plasma and tissue samples

Samples	Linearity (0.05–50 μg/mL)	Precision (%)		Accuracy (%)	Recovery (%)
		Intra-day	Inter-day
Plasma	y=0.5020x, R2=0.99	4.89	6.24	100.6	88.75
Heart	y=0.3407x, R2=0.99	6.84	7.13	101.4	90.32
Liver	y=0.6916x, R2=0.99	5.48	7.31	98.78	88.62
Spleen	y=0.2601x, R2=0.99	6.91	7.22	99.56	90.72
Lung	y=0.2614x, R2=0.99	5.33	6.71	100.4	87.56
Kidney	y=0.7298x, R2=0.99	5.92	6.88	99.78	79.45
Brain	y=0.2829x, R2=0.99	6.13	7.41	100.5	80.73
Tumor	y=0.4827x, R2=0.99	5.96	7.26	101.3	93.41

Notes: The concentrations of DMC in plasma and tissue samples were determined by reverse-phase HPLC with UV detection. Plasma or tissue samples were mixed with 10 μL of bis-demethoxycurcumin (100 μg/mL), 50 μL of HCl (1 mol/L) and 3 mL of ethyl acetate. The mixtures were vortexed, ultrasonic extracted, and were then centrifuged at 8,000 rpm for 10 minutes. After that, the organic layer was transferred to a clean Eppendorf tube and was evaporated to dryness under pressure by using a gas-blowing concentrator at 40°C. The extraction residue was reconstituted in 100 μL of mobile phase, and 20 μL aliquots were injected into the HPLC system. According to the US FDA guidelines for the validation of bioanalytical methods, the method was fully validated in terms of selectivity, linearity, accuracy, precision, stability, and recovery.⁴¹

Abbreviations: HPLC, high-performance liquid chromatography; UV, ultraviolet; US FDA, US Food and Drug Administration.