Cosmetic actives from rice husk

Abstract

In this work, rice husks from five strains of rice cultivar Chai-nat 1 (CN), Look Daeng Pattani (LD), Leb Nok Pattani (LN), Go Ko 1 (GK) and Jasmine (JM), were extracted and screened for biological activities including anti-tyrosinase, antioxidant and UV screening activity. The dichlormethane and ethylacetate crude extracts of CN possess potent radical scavenging effect, moderate inhibition effect toward tyrosinase, and some UV (290-400 nm) absorption property. The active compounds in CN crude extract were isolated by chromatographic techniques and identified as dipentyl phthalate (0.16% w/w yield) and 4-hydroxy-3-methoxycinnamaldehyde (0.22% w/w yield) by [superscript1]H and [superscript13]C NMR, IR and mass spectroscopy. Dipentyl phthalate showed inhibitory effect toward typrosinase while 4-hydroxy-3-methoxycinnamaldehyde exhibited strong antioxidant activity and UV screening activity. Anti-tyrosinase activity of dipentyl phthalate at concentration of 750 mug/ml was equivalent to that of reference kojic acid at concentration of 30 mug/ml. A 4-hydroxy-3methoxycinnamaldehyde possessed similar 2,2-diphenyl-l-picrylhydrazyl (DPPH) radical scavenging activity to that of the reference butylated hydroxytoluene (BHT). The IC[subscript50] values were 69.49 and 42.3 ug/ml for 4-hydroxy-3methoxycinnamaldehyde and BHT respectively. In addition, 4-hydroxy-3-methoxycinnamaldehyde possessed UVA absorption property with 339 nm and the molar absorptivity of 32,000 cm[superscript-1]M[superscript-1]. Furthermore, alkene and anthracene were also found in CN extract.