Synthesis and biological activities of novel pyrazolomatrine derivatives

In continuation of our program aimed at the development of new natural product-based pesticides, a series of novel pyrazolomatrine derivatives were prepared by structural modifications of matrine, isolated as a quinolizidine alkaloid from the roots of Sophora flave. Their structures were confirmed by 1H NMR, HRMS, etc. Moreover, the steric structures of three compounds were determined by single-crystal X-ray diffraction. Among all derivatives, 19-(naphthyl-2-oyl)pyrazolomatrine (5y) showed 3.13-fold more potent acaricidal activity than its precusor matrine against Tetranychus cinnabarinus; 19-(4-methylbenzoyl)pyrazolomatrine (5j) and 19-(3,5-dimethylbenzoyl)pyrazolomatrine (5k) displayed the promising aphicidal activity against Aphis citricola van der. Their structure-activity relationships were also observed.