THE GRIESS ASSAY - SUITABLE FOR A BIO-GUIDED FRACTIONATION OF ANTIINFLAMMATORY PLANT-EXTRACTS

In the field of inflammation research the inducible nitric oxide synth ase (iNOS) became an important pharmacological target, since overprodu ction of nitric oxide (NO) after induction of this enzyme seems to be associated with numerous pathological conditions. NO released from cel ls can be detected and quantified photometrically as its stable produc t nitrite by a simple colorimetric reaction (Griess reaction). The aim of our study was to investigate whether this method might be suitable for the bio-guided fractionation of anti-inflammatory plant extracts. For this purpose we assayed extracts as well as fractions of the root s of Curcuma zanthorrhiza Roxb. which contain the known iNOS inhibitor curcumin, and compared the obtained activity with their curcumin cont ent. Furthermore, leaf extracts of Betula pendula Roth, to which defin ed amounts of curcumin were added, were examined to clarify the questi on whether chlorophyll might interfere with the test system. The prese nted results suggest that the Griess assay is indeed suitable to guide fractionation of plant extracts in order to isolate highly active com pounds. Factors, however, which might restrict the broad application o f this assay are the limited selection of solvents which do not interf ere with the system and high contents of chlorophyll in plant extracts .