Cytotoxicity of the Bacillus thuringiensis Crystal Protein against Mammalian Cells

The crystal proteins produced by Bacillus thuringiensis subsp, israelensis (Bti) and subsp. coreanensis A1519 strain were examined for the cytotoxicity against MOLT-4 and HeLa cells by MTT assay and LDH assay, The A1519 crystal proteins processed by proteinase K exhibited the specific cell-killing activity toward MOLT-4 with little damage to the cell membrane, On the other hand, the Bti crystal proteins processed by proteinase K caused the substantial damage to the cell membrane of both MOLT-4 and HeLa, leading to the cell lysis. The non-digested crystal proteins of both strains exhibited no cytotoxicity, These data suggested that while the Bti crystal proteins caused the colloid-osmotic swelling and cell lysis of MOLT-4 and HeLa, the proteinase K-digested A1519 crystal proteins induced the specific cell death of MOLT-4 through a mechanism other than that of Bti

Quinolizidines. XVI. Chiral syntheses of 9-demethylcephaeline and 10-demethylcephaeline

In order to establish the structure of the Alangium alkaloid demethylcephaeline, chiral syntheses of the two possible alternative structures, (-)-9-demethylcephaeline (1) and (-)-10-demethylcephaeline (2), have been accomplished through a "cincholoipon-incorporating route." The synthesis of (-)-2 started with an initial condensation of the tricyclic acid (-)-12b, prepared from the ester (-)-11b by alkaline hydrolysis, with 3-benzyloxy-4-methoxyphenethylamine and proceeded through the intermediates (-)-13b, (+)-15b, and (-)-14b. The 1\u27-epimers (-)-18b and (-)-17 were also produced in this reaction sequence. A parallel sequence of conversions starting with (+)-15a afforded (-)-1 via the intermediate (-)-14a, together with the 1\u27-epimer (-)-16 via (-)-18a. Unfortunately, however, lack of a sufficient amount of natural (-)-demethylcephaeline for a detailed and direct comparison precluded identification of either (-)-1 or (-)-2 with this alkaloid, leaving its chemistry incomplete

Quinolizidines. XV. A Racemic Synthesis of 10-Demethyltubulosine, an Alkaloid from Alangium lamarckii

The racemic synthesis of the Alangium lamarckii alkaloid 10-demethyltubulosine (2) has been accomplished for the first time via a "lactim ether route, "which included the intermediates (±)-7,(±)-8,(±)-10,and (±)-9. The 1\u27α-H isomers (±)-12 and (±)-11 were also obtained through this synthetic route. The assignments of the configuration at C-1\u27of (±)-2,(±)-9,(±)-11,and (±)-12 were based on four criteria, namely, the ratio of products from the catalytic reduction of (±)-10,thin-layer chromatographic mobility, and ^1H and ^C nuclear magnetic resonance spectral features. The identity of synthetic (±)-2 with (-)-demethyltubulosine from A. lamarckii unequivocally established the structure of this alkaloid