ABSTRACT
Thirty-five tigliane diterpenoids and two ent-kaurane diterpenoids were isolated from the leaves of Croton damayeshu, and, among them, compounds 1-10 were characterized as new tigliane diterpenoids. The structures of compounds 1-10 were determined by analysis of their HRESIMS, NMR, and ECD data and by chemical methods. The isolates were assayed for their larvicidal, antifungal, and α-glucosidase inhibitory activities, and compounds 8-10 were found to possess larvicidal activities against Plutella xylostella with LC50 values of 0.19, 0.16, and 0.26 µM, respectively, comparable to the LC50 of 0.14 µM for the positive control, flubendiamide.
Subject(s)
Croton , Diterpenes, Kaurane , Diterpenes , Phorbols , Antifungal Agents/pharmacology , Croton/chemistry , Diterpenes/chemistry , Diterpenes, Kaurane/pharmacology , Molecular Structure , alpha-GlucosidasesABSTRACT
Four new triterpene glucosides (1-4) were isolated from the 90% ethanol extract of Salacia cochinchinensis, together with five known compounds (5-9). The structures of the new compounds were elucidated by comprehensive spectroscopic analysis including HRESIMS, IR, 1 D and 2 D NMR analysis. All isolates were assayed for their α-glucosidase inhibitory activity. Compound 9 showed remarkable α-glucosidase inhibitory activity with an IC50 value of 0.31 µM, and the triterpene glycosides (1-5) exhibited moderate α-glucosidase inhibitory activity.
Subject(s)
Salacia , Triterpenes , Glucosides/chemistry , Glycoside Hydrolase Inhibitors/chemistry , Glycoside Hydrolase Inhibitors/pharmacology , Molecular Structure , Salacia/chemistry , Triterpenes/chemistry , Triterpenes/pharmacology , alpha-GlucosidasesABSTRACT
Two mild and metal-free methods for the preparation of two kinds of important benzothiazole derivatives, 2-acylbenzothiazoles and dialkyl benzothiazol-2-ylphosphonates, respectively, were developed. The dialkyl H-phosphonate (RO)2P(O)H exists in equilibrium with its tautomer dialkyl phosphite (RO)2POH. TBHP triggered α-carbon-centered phosphite radical formation, whereas DTBP triggered phosphorus-centered phosphonate radical formation. The two types of radicals led respectively to two different reaction processes, the direct C2-acylation of benzothiazoles and C2-phosphonation of benzothiazoles.
Subject(s)
Benzothiazoles/chemical synthesis , Organophosphonates/chemistry , Peroxides/chemistry , Benzothiazoles/chemistry , Catalysis , Metals , Molecular StructureABSTRACT
A novel and efficient silver catalyzed decarboxylative direct C2-alkylation of benzothiazoles with carboxylic acids for the synthesis of 2-alkyl benzothiazoles was developed.