Development of Microemulsions Containing Carthamus tinctorius Extract for 5α-Reductase Inhibition

Abstract

The purpose of this study was to develop micromeulsion consisting of Carthamus tinctorius floret extract (CT) as an ingredient to inhibit 5α-reductase activity. CT was extracted using a simple maceration technique with ethanol and inhibition of 5α-reductase activities was determined. Solutions of 2% CT extract were loaded into four microemulsion (ME) formulas (F1, F2, F3 and F4) and investigated for their physical properties, skin permeation and stability. Results showed that crude CT extract had no toxic effects on DU145 cells at concentrations of 0.0001-1.0 mg/mL. For reduction of 5α-reductase activities, concentration of CT extract at 0.05 mg/mL exhibited highest 5-reductase type-1 inhibition activity on the DU-145 cell line at 89.96% of the control, higher than standard finasteride (31.39%) and dutasteride (38.58%). The results indicated that a thermodynamically stable microemulsion improved the stability and permeation rate of CT extract. Among the ME formula, F3 was most appropriate for ME formulation with highest permeation rate and good stability during 30 days of storage. Therefore, using nanotechnology for stable transdermal delivery systems of bioactive compounds from Thai medicinal plants is one approach to improve skin and hair follicle permeation.