The dichloromethane extract of Callicarpa longissima rich in diterpenoid phenols exerts anti-inflammatory effect via inhibiting the TLR4/NF-κB signaling pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Callicarpa longissima is a typical Yao ethnomedicine that has been used to treat arthritis in China. Our previous study found that the dichloromethane extract (DCME) of C. longissima showed anti-inflammatory activity in vitro. However, the anti-inflammatory mechanism and detailed chemical composition of DCME remain unclear, which lead to the original interest of this study. AIM OF THE STUDY: The study aimed to evaluate the anti-inflammatory properties of the DCME from C. longissima and further explore the accurate chemical components responsible for this active extract. MATERIALS AND METHODS: The anti-inflammatory activity of DCME in vivo was tested with carrageenan-induced mice paw edema model. Its anti-inflammatory mechanism was explored with LPS-stimulated RAW264.7 macrophages model. The compounds in DCME were isolated by repeated column chromatography and their structures were identified on the basis of nuclear magnetic resonance spectroscopy. The anti-inflammatory activities of the isolates in vitro were also tested by suppressing releases of inflammatory mediators (NO, IL-6 and TNF-α) in RAW264.7 macrophages model. In addition, the molecular docking analysis, which evaluated the potential interaction between the compounds and Toll-like receptor 4 (TLR4) and nuclear factor κB (NF-κB), was performed. RESULTS: DCME effectively alleviated the mice paw edema induced by carrageenan. In LPS-stimulated RAW264.7 cells, DCME significantly decreased the production of interleukin (IL)-6 and tumor necrosis factor α (TNF-α) via inhibiting their mRNA transcription, down-regulated the expression of TLR4 and myeloid differentiation factor 88, inhibited the phosphorylation of alpha inhibitor of NF-κB (IκBα), NF-κB p65, and degradation of IκBα. Twelve diterpenoid phenols were identified from DCME, and they not only showed different inhibitory effects on the production of NO, IL-6 and TNF-α in LPS-stimulated RAW264.7 cells, but also could bind to TLR4 and NF-κB as analyzed by molecular docking. CONCLUSIONS: Taken together, DCME from C. longissima could inhibit inflammatory response both in vitro and in vivo, which is mainly attributed to the synergistic effect of abundant diterpenoid phenols through inhibiting the TLR4/NF-κB signaling pathway, and might be a promising agent for the treatment of inflammatory diseases.

Preparative Isolation of Piceatannol Derivatives from Passion Fruit (Passiflora edulis) Seeds by High-Speed Countercurrent Chromatography Combined with High-Performance Liquid Chromatography and Screening for α-Glucosidase Inhibitory Activities.

Passiflora edulis Sims (passion fruit) seeds are often discarded as byproducts during juice processing. In fact, the seeds are of considerable commercial value in the food and cosmetics industry because of their rich polyphenols, especially piceatannol. In this study, high-speed countercurrent chromatography (HSCCC) was applied for the separation of stilbene polyphenols from passion fruit seeds. The n-hexane-ethyl acetate-methanol-water (1:2:1:2.8, v/v) was found to be the optimum two-phase solvent for the preparation of two major stilbenes, scirpusin B (8) and piceatannol (9) with purities of 90.2% and 94.8%, respectively. In addition, a continuous semipreparative HPLC was applied to further purify the HSCCC fractions containing minor stilbenes and obtain four new piceatannol derivatives (1-4) along with three known ones (5-7). The structures of these new compounds were determined using spectroscopic methods, including NMR, high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), and circular dichroism (CD). The isolated compounds were evaluated for α-glucosidase inhibitory activities in vitro. The result suggested that all of them exhibited more significant activity than acarbose, and passiflorinol B (2) had the strongest activity, with a IC50 value of 1.7 µM.