Specific blockade of muscle acetylcholine receptor by α-conotoxin MIA and MIB / 药学学报

The α-conotoxins are peptide toxins that are identified from the venom of marine cone snails and they hold outstanding potency on various subtypes of nicotinic acetylcholine receptors (nAChRs). nAChRs have an important role in regulating transmitter release, cell excitability, and neuronal integration, so nAChR dysfunctions have been involved in a variety of severe pathologies. Four types of α-3/5 conotoxins MI, MIA, MIB and MIC have been found from Conus magus. Among them, the activity and selectivity of MIA and MIB have not been well studied. In this study, four α-3/5 conotoxins MI, MIA, MIB and MIC were synthesized by solid peptide synthesis method, and the bioactivities of them were screened by double electrode voltage clamp electrophysiology. The results showed that MIA and MIB selectively inhibited muscle type acetylcholine receptors with IC50 values of 14.45 and 72.78 nmol·L-1, respectively, which are slightly weaker than MI and MIC. Molecular docking results have shown MIA and MIB interact with muscle-type nAChRs with similar mechanism. The reasons for activity differences may relate to the size of the N-terminal amino acids. Together, the conotoxins MIA and MIB may have the potential to develop as a tool for detect the function of muscle type nAChRs, as well as the diagnosis or treat of related diseases.

Study on combined effects of chemical components for different flowers blossoming degree of yellow medicinal Chrysanthemum morifolium from Zhejiang / 中国中药杂志

The ingredients of five kinds of Zhejiang's yellow Chrysanthemum morifolium with different flower blossoming stages were comparatively analyzed. Polysaccharides, total flavonoids, volatile oil, alcohol extract, water extract, chlorogenic acid, luteolin, 3,5-O-dicaffeoyl quinic acid and fingerprint of the ingredient were determined as indicators. During flower blossoming stages, the ingredients of Ch. morifolium showed a big difference with a certain variation. At the early opening stage, the contents of flavonoids and volatile oil were higher, the content of chlorogenic acid, luteolin, 3,5-O-dicaffeoyl quinic acid were higher in the middle of the flowers 50% -80% fowers blossoming degree is the optimal time for harvest.