Juhee Ahn

Enhancement of Whitening Effects of Lithospermum erythrorhizon Extracts by Ultra High Pressure

In this study, whitening activity of Lithospermum erythrorhizon extracts were investigated according to several extraction processes: water extraction at (WE100) and (WE60), 70% ethyl alcohol extraction (EE) and ultra high pressure extraction (HPE) at 500 MPa for 30 minutes at . The extracts from ultra high pressure extraction showed the highest tyrosinase inhibition and melanogenesis inhibition activities as 52% and 79.5%, respectively, in adding than others extraction processes. HPE extracts also showed the strong reducing power as 3.19 that absorbance at 450 mm. The contents of polyphenol in WE100, we measured as in adding . Extracts have a high total flavonoid contents by HPE as at . We can conclude that better whitening activity of extracts from high pressure extraction was due to high antioxidant activities which could be extracted by higher polyphenol and flavonoid contents in HPE than others.

RNAi: An emerging field of molecular research

RNA silencing, named as co-suppression or post transcriptional gene silencing (PTGS) was found in transgenic plants which was the result of cellular mRNA degradation and silencing of gene expression. RNA interference (RNAi) is a specific technique using only a few double stranded RNA (dsRNA) molecules to stop the expression which has made it one of the important areas in molecular biology. By introducing a gene into the host genome which is highly homologous to an endogenous gene, the RNA silencing is initiated. Double-stranded RNA (dsRNA) is cut by the enzyme “Dicer” producing small interfering RNAs (siRNAs) which combine with RNA-induced silencing complex (RISC). RISC, a protein complex, binds one strand of siRNA with mRNA of native target gene for destruction, resulting in gene silencing. The mechanism of RNAi offers a quick and easy way to determine the function of a gene. In this review, we discuss the history, components, mechanism and the application of RNA interference.