Grass contains essential oil, which includes thymol, Corvalol, sesquiterpenes, tannins and flavonoid substances, fatty oil, ascorbic acid, bitterness, phytoncides.Oregano herb contains volatile oils, tannins, ascorbic acid. Oregano is usually thought of as a culinary herb, but it has been used medicinally for thousands of years. Oregano is a powerful antiseptic; it also has calming, diuretic, cholagogic properties.