Direct-Injection Electron Ionization-Mass Spectrometry Metabolomics Method for Analyzing Blueberry Leaf Metabolites That Inhibit Adult T-cell Leukemia Proliferation.

ABSTRACT

Metabolic profiling is often used to identify possible correlations between a compound's metabolic profile and biological activity. Direct-injection electron ionization-mass spectrometry "fingerprinting" is useful for characterizing biological materials. We demonstrate the utility of direct-injection electron ionization-mass spectrometry for metabolic profiling using 100 different extracts of leaves from 20 blueberry cultivars collected at 5 time points from April to December 2008. A qualitative direct-injection electron ionization-mass spectrometry method was used to profile the major and/or minor constituents in the blueberry leaf extracts. Blueberry leaf extracts could be distinguished by principal component analysis based on the absolute intensity of characteristic fragment ions. Twenty cultivars were categorized into four species, and the most appropriate discriminative marker m/z value for identifying each cultivar was selected statistically. Correlated m/z values indicating the collection month were determined in the same analysis, and air temperature variance factors were extracted from score plots by principal component analysis. We previously reported that blueberry extracts inhibit the proliferation of adult T-cell leukemia cells. Leaves of Vaccinium virgatum collected in December of 2008 exhibited significantly greater inhibition of adult T-cell leukemia cell proliferation than other species. Highly bioactive cultivars or species were identified by direct-injection electron ionization-mass spectrometry metabolomics analysis of blueberry leaf extracts. The components extracted based on our direct-injection electron ionization-mass spectrometry analyses could be used to construct a model to predict anti-adult T-cell leukemia bioactivity. This is the first study to report a relationship between seasonal variation and bioactivity of natural products using a direct-injection electron ionization-mass spectrometry metabolomics method.