Comparative metabolomics reveals distinct metabolic profiles and in vitro activities of fermented noni juice from Samoa and China's Hainan.

Noni (Morinda citrifolia L.) is a tropical fruit with significant bioactive potential, yet quality variations between geographical origins remain poorly understood. This study employed UPLC-ESI-MS/MS and GC-MS metabolomics to characterize Samoan (WSM-FNJ) and Hainan, China (HN-FNJ) fermented noni juices. A total of 2047 soluble and 283 volatile metabolites were identified, with 726 and 81 differentially accumulated ones, respectively. While both juices exhibited potent antioxidant capacities, WSM-FNJ exhibited superior antimicrobial activity with inhibition zones of 14.67 ± 0.45 mm and 14.97 ± 0.75 mm against Escherichia coli and Staphylococcus aureus, respectively (significantly higher than those of HN-FNJ, P < 0.01). Furthermore, WSM-FNJ more effectively suppressed pneumonia-related pro-inflammatory genes (IL-6, IL-8) in vitro. These differences may be associated with the higher abundance of specific phenolic acids (e.g., 3-(3-hydroxyphenyl)propionic acid) and iridoids in WSM-FNJ. This work provides preliminary data for the screening of origin-associated biomarkers and the targeted functional development of noni-based products.