Methanol Extracts from Cirsium japonicum DC. var. australe Kitam. and Their Active Components Reduce Intracellular Oxidative Stress in Caenorhabditis elegans.

Cirsium japonicum DC. var. australe Kitam. has been used as an herbal remedy and often involves using the whole plant or roots. However, the bioactivities of different parts of the plant have been far less explored. This study aimed to evaluate the antioxidative ability of methanol extracts from the flowers, leaves, stems, and roots of the Cirsium plant and their possible active components against juglone-induced oxidative stress in the nematode Caenorhabditis elegans. The results showed that the highest dry weight (12.3 g per plant) was observed in leaves, which was followed by stems (8.0 g). The methanol extract yields from the flowers, leaves, and roots were all similar (13.0-13.8%), while the yield from stems was the lowest (8.6%). The analysis of the silymarin contents in the extracts indicated that the flowers, leaves, stems, and roots contained silychristin and taxifolin; however, silydianin was only found in the leaves, stems, and roots. The flower, leaf, and stem extracts, at a concentration of 10 mg/L, significantly reduced juglone-induced oxidative stress in C. elegans, which was potentially due to the presence of silychristin and taxifolin. Overall, C. japonicum DC. var. australe Kitam. contains a significant amount of silymarin and exhibits in vivo antioxidative activity, suggesting that the prospects for the plant in terms of health supplements or as a source of silymarin are promising.

Lucidone, a novel melanin inhibitor from the fruit of Lindera erythrocarpa Makino.

The effects of lucidone on tyrosinase and antimelanogenic activity were investigated. Initially, we found that lucidone strongly inhibits the activity of mushroom tyrosinase. The effects of lucidone on tyrosinase were further examined in alpha-MSH-induced B16 melanoma cells. Lucidone significantly inhibits tyrosinase activity and leads to decreased melanin content in cultured B16 melanoma cells. Lucidone also attenuates the expression of tyrosinase and MITF (Microphthalmia-associated Transcription Factor) protein in a concentration-dependent manner, as shown by western blot. Quantitative real-time reverse-transcription polymerase chain reaction (RT-PCR) confirmed that lucidone inhibits the expression of tyrosinase mRNA. Accordingly, the effects of lucidone on the ERK signaling pathway were also investigated, but lucidone was not found to play major role in the induction of ERK activation. Our data indicate that the antimelanogenic activity of lucidone is probably due to its inhibition of tyrosinase activity and the suppression of tyrosinase and MITF expression.