Inhibitory Effects of Compounds Isolated from <i>Morinda citrifolia</i> L. (Noni) Seeds against Particulate Matter-Induced Injury

<i>Morinda citrifolia</i> L. (noni) is native to the tropical and semitropical areas and has been commercially available in health food stores and chain grocery stores specializing in natural foods, recently. Noni seeds are discarded as waste products through the industrial production of noni juice even though their bioactivity components might be a potential source of functional foods. Not many studies of phytochemistry and biological activity have been investigated on noni seeds until now. In this study, the phytochemical investigation of <i>M. citrifolia</i> seeds led to the isolation of eight compounds (1-8) including four lignans (5-8). Their chemical structures were elucidated based on extensive spectroscopic analysis as well as the comparison with those reported in the literature. The isolated lignans were then evaluated for their anti-inflammatory activity by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphynyltetrazolium bromide (MTT) assay in human bronchial epithelium BEAS-2B cells stimulated by 1-nitropyrene. As results, both four isolated lignans displayed high effects on the viability of BEAS-2B cells, indicating promising anti-inflammatory role in the airway disease.