Two New Alkylated Piperidine Alkaloids from Western Honey Mesquite: Prosopis glandulosa Torr. var. torreyana

Prosopis glandulosa Torr. var. torreyana (L. Benson) M.C. Johnston root bark, collected in Texas, yielded two new alkylated piperidine alkaloids, namely 3-isocassine (1) and N-methyl-3-isocassine (2), together with the previously reported N-methylcassine (3). In addition, the alkylated piperidinyl indolizidine alkaloid juliprosopine (4) was isolated from the leaves of the same plant. The structures and stereochemistry of compounds 1–4 were determined by 1D and 2D NMR data, including COSY, HMQC, HMBC and NOESY experiments, and ESI-HRMS. Juliprosopine (4) demonstrated antimicrobial activities against a panel of microorganisms, including potent antifungal activities against Aspergillus fumigatus. Acknowledgement: The authors sincerely thank Dr. Robert C. Reynolds, SRI, Frederick, MD, for Mtb assay, and Mr. John Hester, NCNPR, for database management and assistance in biological work. This work was supported in part by the USDA, Agricultural Research Service Specific Cooperative Agreement No. 58-6408-2-009 and NIH, NIAID, Division of AIDS, Grant No. AI 27094.