¹Department of Pharmaceutical Technology, Faculty of Pharmacy, Yeditepe University, Istanbul, Turkey DOI : 10.29228/jrp.107 The potential antimicrobial and antioxidant benefit of high levels of ursolic, rosmarinic acids and carvacrol in oregano extract has been limited until now by poor bioavailability arising from the low aqueous-phase solubility and slow dissolution behavior of the freeze-dried extract. To address this issue, microencapsulation technique had been used to solve above mentioned problems and to protect active substances from deteriorating due to environmental conditions, such as moisture, oxidation. The experimental settings were performed by statistical mixture experimental design. Moreover, microcapsules and freeze-dried extract were compared to ascertain the merit of microcapsules as a carriers for these poorly aqueous-soluble compounds. When the wall material solution contained 1.43 g of maltodextrin, 4.17 g of gum arabic, 14.39 g of modified starch, and 20 g of ethanol oregano extract, the yield of oregano’s active compounds, ursolic, rosmarinic acids and carvacrol, were 0.98 mg/g, 3.38 mg/g and 3.38 mg/g respectively. In particular, the release profile of ursolic, rosmarinic acids and carvacrol had levelled off after 15 minutes, depicting an impressive 2.7- 3.0 fold increase compared to the freeze-dried control extract. The results imply that all actives can be conveniently delivered via oral and mucosal routes by first internalizing oregano extracts into appropriately engineered microcapsules. Keywords : Microencapsulation; spray-drying; freeze-drying; Oregano; in vitro dissolution data