Clinopodium serpyllifolium is a perennial medicinal plant generally used as herbal tea in folk medicine. Leaves of C. serpyllifolium from the representative exemplars in the Newe Ya’ar living germplasm collection were analyzed for their polyphenolic and volatiles composition, and tested for their antioxidant activity. The oxygenated monoterpenes pulegone (10.4–50.6%), piperitenone oxide (3.2–28.6%), piperitenone (0.9–14.6%), trans-piperitone oxide (0.3–11.2%), iso-menthol (0.3–8.8%) and sesquiterpene β-caryophyllene (7.4–13.7%) were found to be the major constituents from the solvent extraction of C. serpyllifolium analyzed by gc-ms. The representative exemplars were grouped into two chemotypes: one rich in pulegone and the second rich in piperitenone oxide and piperitenone. The total polyphenolics content, determined range from 26.6 to 62.9 mg gallic acid equivalents/g dry weight (dw). The antioxidant activity ranged from (42.8–77.1 mg chlorogenic acid equivalents/g dw). hplc analysis revealed the rosmarinic acid content also showed remarkable differences in C. serpyllifolium (0.3–1.8 dry weight %). The results indicate that there is chemical diversity and also difference in the content of polyphenols of the representative exemplars. Antioxidant activity was in correlation with phenolic components.
