Electrochemical investigation of redox reactions of herbal drug-shikonin and its determination in pharmaceutical preparations

Author: Zhou Hongbi   Wang Jiying   Yea Baoxian  

Publisher: MAIK Nauka/Interperiodica

ISSN: 1061-9348

Source: Journal of Analytical Chemistry, Vol.65, Iss.7, 2010-07, pp. : 749-754

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Abstract

The electrochemical behaviour of the anticancer herbal drug shikonin was investigated at glassy carbon electrode in 0.16 M HAc-NaAc (20% ethanol, pH 3.98) buffer solution using cyclic voltammetry, square-wave voltammetry and chronocoulometry. Shikonin gives a pair of quasi-reversible redox peaks at potentials of E pc = 0.698 V and E pa =0.632 V by absorption-controlled process at a scan rate of 100 mV/s. The electrode process dynamics parameters (saturated adsorptive amount Γ, charge transfer coefficient α, and apparent rate constant K s) and reaction mechanism were also investigated with result of two electrons and two hydrogen ions participating in electrode reaction. The experimental conditions were optimized for the determination of shikonin and the square-wave anodic peak currents were linearly related to the shikonin concentrations in the range from 2.08 × 10−8 to 1.82 × 10−6 M with correlation coefficient of 0.998 and detection limit of 7.8 × 10−9 M. Using the established method without pretreatment and pre-separation, shikonin in herbal drug Gromwell Root was determined with satisfactory result.

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