Antimicrobial activity and comparative metabolomic analysis of Priestia megaterium strains derived from potato and dendrobium.

The growth of endophytic bacteria is influenced by the host plants and their secondary metabolites and activities. In this study, P. megaterium P-NA14 and P. megaterium D-HT207 were isolated from potato tuber and dendrobium stem respectively. They were both identified as Priestia megaterium. The antimicrobial activities and metabolites of both strains were explored. For antimicrobial activities, results showed that P. megaterium P-NA14 exhibited a stronger inhibition effect on the pathogen of dendrobium, while P. megaterium D-HT207 exhibited a stronger inhibition effect on the pathogen of potato. The supernatant of P. megaterium P-NA14 showed an inhibition effect only on Staphylococcus aureus, while the sediment of P. megaterium D-HT207 showed an inhibition effect only on Escherichia coli. For metabolomic analysis, the content of L-phenylalanine in P. megaterium P-NA14 was higher than that of P. megaterium D-HT207, and several key downstream metabolites of L-phenylalanine were associated with inhibition of S. aureus including tyrosine, capsaicin, etc. Therefore, we speculated that the different antimicrobial activities between P. megaterium P-NA14 and P. megaterium D-HT207 were possibly related to the content of L-phenylalanine and its metabolites. This study preliminarily explored why the same strains isolated from different hosts exhibit different activities from the perspective of metabolomics.

Combined metabolomics and proteomics to reveal beneficial mechanisms of Dendrobium fimbriatum against gastric mucosal injury.

As a dietary and medicinal plant, Dendrobium fimbriatum (DF) is widely utilized in China for improving stomach disease for centuries. However, the underlying mechanisms against gastric mucosal injury have not been fully disclosed. Here, metabolomics and proteomics were integrated to clarify the in-depth molecular mechanisms using cyclophosphamide-induced gastric mucosal injury model in mice. As a result, three metabolic pathways, such as creatine metabolism, arginine and proline metabolism, and pyrimidine metabolism were hit contributing to DF protective benefits. Additionally, γ-L-glutamyl-putrescine, cytosine, and thymine might be the eligible biomarkers to reflect gastric mucosal injury tatus, and DF anti-gastric mucosal injury effects were mediated by the so-called target proteins such as Ckm, Arg1, Ctps2, Pycr3, and Cmpk2. This finding provided meaningful information for the molecular mechanisms of DF and also offered a promising strategy to clarify the therapeutic mechanisms of functional foods.

[Identification of active components of Dendrobium inhibit growth of gastric cancer cells based on component-activity relationship].

Three cancer cell lines including gastric cancer SGC-7901, HGC-27, and MGC-803 cells were employed to evaluate the bioactivity of seven Dendrobium species. Simultaneously, these Dendrobium species were assessed with UPLC-Q-TOF-MS, and 504 common peaks were found. Based on the hypothesis that biological effects varied with differences in components, multivariate relevance analysis for chemical component-activity relationship of Dendrobium, including grey relation(GRA) and partial least squares(PLS) analysis were performed to evaluate the contribution of each identified component. The target peaks were identified by standards toge-ther with databases of Dendrobium, Nature Chemistry, MassBank, etc. Finally, four active components, including 3,5,9-trihydroxy-23-methylergosta-7,22-dien-6-one, diacylglycerol(14∶1/22∶6/0∶0), pipercitine, and 22-tricosenoic acid, might have negative effect on the growth of gastric cancer cells.