Search

Phytochemical investigation on the aerial parts of Tabernaemontana bufalina Lour. (Apocynaceae) led to the identification of four undescribed monoterpenoid indole alkaloids named taberbufamines A−D, an undescribed natural product, and fourteen known indole alkaloids. The structures of the undescribed alkaloids were established by spectroscopic and computational methods, and their absolute configurations were further determined by quantum chemical TDDFT calculations and the experimental ECD spectra. Taberbufamines A and B possessed an uncommon skeleton incorporating an indolizidino [8,7- b ]indole motif with a 2-hydroxymethyl-butyl group attached at the pyrrolidine ring. Biosynthetically, Taberbufamines A and B might be derived from iboga-type alkaloid through rearrangement. Vobatensine C showed significant bioactivity against A-549, Bel-7402, and HCT-116 cells with IC 50 values of 2.61, 1.19, and 1.74 μM, respectively. Ervahanine A showed antimicrobial activity against Bacillus subtilis , Mycobacterium smegmatis , and Helicobacter pylori with MIC values of 4, 8, and 16 μg/mL, respectively. 19(S)-hydroxyibogamine was shown as butyrylcholinesterase inhibitor (IC 50 of 20.06 μM) and α-glycosidase inhibitor (IC 50 of 17.18 μM), while tabernamine, ervahanine B, and ervadivaricatine B only showed α-glycosidase inhibitory activities with IC 50 values in the range of 0.95–4.61 μM. Taberbufamines A and B possessed an uncommon skeleton incorporating an indolizidino [8,7-b]indole motif with a 2-hydroxymethyl-butyl group attached at the pyrrolidine ring. [Display omitted] • Taberbufamines A and B had a skeleton with an indolizidino [8,7-b]indole motif. • Some alkaloids showed cytotoxicity, antimicrobial and BChE inhibitory activities. • The mechanisms against BChE were tested by Lineweaver-Burk plot analysis. • A plausible biogenetic pathway for taberbufamines A and B was proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] In this present study, a series of novel (E)-2-benzylidene- N -(3-cyano-4,5,6,7-tetrahydrobenzo[ b ]thiophen-2-yl)hydrazine-1-carboxamide derivatives against α-glucosidase were designed and synthesized, and their biological activities were evaluated in vitro and in vivo. Most of the designed analogues exhibited better inhibitory activity than the marketed acarbose, especially the most potent compound 7 with an IC 50 value of 9.26 ± 1.84 μM. The direct binding of 7 and 8 with α-glucosidase was confirmed by fluorescence quenching experiments, and the kinetic and molecular docking studies revealed that 7 and 8 inhibited α-glucosidase in a non-competitive manner. Cytotoxicity bioassay indicated compounds 7 and 8 were non-toxic towards LO2 and HepG2 at 100 μM. Furthermore, both compounds were demonstrated to have in vivo hypoglycemic activity by reducing the blood glucose levels in sucrose-treated rats. [ABSTRACT FROM AUTHOR]