Secondary Metabolomic Analysis and In Vitro Bioactivity Evaluation of Stems Provide a Comprehensive Comparison between Dendrobium chrysotoxum and Dendrobium thyrsiflorum.

The stems of Dendrobium chrysotoxum (DC) are commonly used as health-promoting foods due to their excellent biological activities. However, the stems of D. thyrsiflorum (DT) are often used to meet the scarcity of DC in production because of their highly similar morphology. However, the related metabolomic and bioactive information on the stems of DC and DT are largely deficient. Here, secondary metabolites of DC and DT stems were identified using an ultra-performance liquid chromatography-electrospray ionization-mass spectrometry, and their health-promoting functions were evaluated using several in vitro arrays. A total of 490 metabolites were identified in two stems, and 274 were significantly different. We screened out 10 key metabolites to discriminate the two species, and 36 metabolites were determined as health-promoting constituents. In summary, DT stems with higher extract yield, higher total phenolics and flavonoids, and stronger in vitro antioxidant activities demonstrated considerable potential in food and health fields.

Blow-up analysis for a periodic two-component µ-Hunter-Saxton system.

The two-component µ-Hunter-Saxton system is considered in the spatially periodic setting. Firstly, two wave-breaking criteria are derived by employing the transport equation theory and the localization analysis method. Secondly, a sufficient condition of the blow-up solutions is established by using the classic method. The results obtained in this paper are new and different from those in previous works.