A Comprehensive Metabolite Profile of Green and White Asparagus (Asparagus officinalis L.) and Their Antioxidant Properties in Differing Cultivation Conditions

Abstract

Asparagus ( Asparagus officinalis L.) is a food crop with a variety of pharmacological effects that can be classified as green or white, depending on cultivation methods. However, no research has been conducted on the profiles of primary and secondary metabolites in green and white asparagus. Hence, the aim of this study was to comprehensively analyze and understand the metabolic variations associated with the color differences in asparagus under different cultivation conditions. Through extensive profiling of primary and secondary metabolites, we identified 48 hydrophilic compounds, nine policosanols, seven terpenoids, six flavonoids, and one phenolic acid. Multivariate and metabolic pathway analyses revealed notable distinctions between green and white asparagus. Green asparagus contained high levels of flavonoids, policosanols, and primary metabolites (organic and amino acids). In contrast, white asparagus contained high levels of sugars, proline, and terpenoids (tocopherols, phytosterols, and protodioscin). These results suggest that green asparagus has higher energy and amino acid synthesis metabolism for plant development and growth through photosynthesis under light cultivation conditions than white asparagus. In contrast, white asparagus accumulated stress-related metabolites, such as sucrose, proline, and phenylalanine, under dark cultivation conditions. In addition, flavonoid metabolism was activated under light conditions, whereas terpenoid biosynthesis was activated under dark conditions. The DPPH and ABTS scavenging activities of green asparagus were at least twice as high as those of white asparagus. Overall, green asparagus is a good source of nutrients and contains more antioxidants than white asparagus. These findings might be the first report of comprehensive metabolome in asparagus, and they will significantly contribute to understanding the effects of different cultivation conditions on the asparagus metabolome.