Evaluation of Metabolites and Biological Activities of Areca Nut (Areca catechu L.) Under Different pH: Untargeted Mass Spectrometry–Based Metabolomics Approach

Abstract

Chewing areca nuts (ANs) produces a mild sense of excitement and happiness, particularly under alkaline conditions. To identify the substances responsible for these effects, we conducted a nontargeted metabolomics analysis comparing AN metabolites at different pH levels. Subsequently, AN’s active components were determined, and the in vitro antioxidant activities were evaluated. The results showed that pH affected the expression of flavonoid and isoflavonoid biosynthesis pathways, leading to changes in flavonoid, alkaloid, and organic acid levels. Alkaline conditions facilitated the hydrolysis of arecoline and guvacoline to arecaidine and guvacine, respectively. Twenty-eight alkaloids were identified as AN metabolites, of which 22 are reported for the first time. Among these, arecoline, arecaidine, scopolamine, and theobromine may be responsible for the excitatory effects of AN. The active component content and antioxidant activity of AN were significantly influenced by pH. The antioxidant activity of AN was highest at pH 12, which might be another reason AN consumer products require alkaline conditions. The excitatory effects of AN under alkaline conditions are likely owing to the combined effects of various active ingredients. In conclusion, we clarified the effect of pH on the composition and activity of AN and determined the biochemical basis of the excitatory effect of AN. These findings provide theoretical guidance for further development and utilization of active AN functions.