Inhibition of chlorogenic acid-induced cytotoxicity by CoCl2.

Chlorogenic acid (CGA) induced apoptotic cell death in human oral squamous cell carcinoma (HSC-2) and salivary gland tumor (HSG) cell lines. CGA exhibited oxidation potential in the culture medium, as demonstrated by NO monitor. Both cytotoxic activity and oxidation potential were significantly reduced by the addition of CoCl 2 . ESR spectroscopy showed that CGA produced seven peaks of radicals under alkaline condition, while addition of CoCl 2 altered the spectral pattern and diminished the radical intensity of CGA. CoCl 2 accelerated the CGA-induced coloration of the culture medium and modified the difference spectrum at around 325 nm, an absorption maximum characteristic of CGA. These data suggest that CoCl 2 induced conformational changes in the CGA molecule.