Results published in the Journal of Food Science indicate that the extracts could be obtained from the portions of asparagus normally discarded by processors and growers, such as the leaves, offering a cheap source of the bioactives.
“These results provide biochemical evidence of the method by which A. officinalis exerts its biological functions, including the alleviation of alcohol hangover and the protection of liver cells against toxic insults,” wrote the researchers, from Jeju National University.
Extracts from young shoots and leaves of asparagus were tested to discover if they could reduce liver toxicity in human liver cells exposed to hydrogen peroxide.
According to their data, the nutritional content, namely the amino acids and inorganic minerals, was greater in the leaves than the shoots.
When the leaf extract was tested in the liver cells, the Korean researchers measured the degree of reactive oxygen species (ROS) formation on exposure to hydrogen peroxide, and found a reduction of 70 per cent.
Furthermore, toxicity to the cells from hydrogen peroxide and ethanol “were also significantly alleviated [by] the extracts of A. officinalis leaves and shoots”, said the researchers.
The impact of the asparagus extracts on two key enzymes that metabolise alcohol (ethanol) was also studied. Both alcohol dehydrogenase and aldehyde dehydrogenase, were “upregulated by more than 2-fold in response to the leaf- and shoot extracts”, they said.
“Because excess ethanol generates ROS in its metabolic pathways, alcohol dehydrogenase-dependent elimination of ethanol is the principle involved in the protection of cells from oxidative stress,” noted the Jeju-based researchers.
“These results suggest that the extracts of A. officinalis exert a wide spectrum of activities including strong antioxidant activity and the ability to act as a potent catalytic factor to stimulate the enzymatic activities required to metabolise ethanol,” they added.
“Thus, the leaves of A. officinalis, which are normally discarded, have the potential for use in therapy designed to protect the liver from various harmful insults,” they concluded.
Asparagus is a popular vegetable in Europe and the US. The main growing countries are China, Peru, the US, Germany and Spain. The latter country produced some 50,000 tons of asparagus in 2005 – both the green and the white variants.
Source: Journal of Food Science
Published online ahead of print, doi: 10.1111/j.1750-3841.2009.01263.x
“Effects of Asparagus officinalis Extracts on Liver Cell Toxicity and Ethanol Metabolism”
Authors: B.-Y. Kim, Z.-G. Cui, S.-R. Lee, S.-J. Kim, H.-K. Kang, Y.-K. Lee, D.-B. Park