Enzymatic spectrophotometric determination of soluble oxalate content in some multiherbal functional products reducing stress related health disorders

Abstract

The aim of the study was to determine, with a highly selective and specific enzyme-spectrophotometric procedure, the unknown and not recognized soluble oxalate (SO) content in the aqueous infusions prepared from the randomly chosen series of 15 multiherbal functional products (MFP) commercially available in Poland and recommended for treatment of depression, mood relief and reducing of chronic stress induced by gastric lesions, secondary hypertension or hypercholesterolemia. The mean content of soluble oxalate in the all set of 15 studied MFP products was 1.34 mg/100 mL of the freshly prepared infusion. However, the highest mean content of soluble oxalate (above 2.0 mg/100mL infusion) was determined only in the studied five MFP containing mainly green tea, rooibos, peppermint and ginger rhizome. This highest amount of SO was comparable with previously reported levels of this antinutrient substance determined in case of the commonly drunk green tea infusions. The results of principal components analysis (PCA) revealed a significant relation between unique herbal composition of analyzed dry MFP and the variables characterizing their fresh aqueous infusions as pH, total acidity and level of soluble oxalates.