A promising camptothecin derivative: Semisynthesis, antitumor activity and intestinal permeability.

Oral administration of camptothecin (CPT) derivatives and other antitumoral agents is being actively developed in order to improve the quality of life of patients with cancer. Though several lipophilic derivatives of CPT have shown interesting oral bioavailability in preclinical and clinical studies, only Topotecan has been approved for this route of administration. Semisynthesis, antitumor activity, biological inhibition mechanism, and in situ intestinal permeability of 9, 10-[1,3]-Dioxinocamptothecin (CDiox), an unexplored CPT derivative, have been studied in this paper.

Semisynthesis, cytotoxic activity, and oral availability of new lipophilic 9-substituted camptothecin derivatives.

Despite that 9-substituted camptothecins are promising candidates in cancer therapy, the limited accessibility to this position has reduced the studies of these derivatives to a few standard modifications. We report herein a novel semisynthetic route based on the Tscherniac-Einhorn reaction to synthesize new lipophilic camptothecin derivatives with amidomethyl and imidomethyl substitutions in position 9. Compounds were evaluated for their antiproliferative activity, topoisomerase I inhibition, and oral availability.

Synthesis, characterization, and framework heteroatom localization in ITQ-21.

ITQ-21 has been synthesized in a wide range of compositions. By rationally modifying the synthesis variables and zeolite composition, it is possible to fine-tune the crystallite size from nanocrystals (<80 nm) up to microns and to avoid the competition of other phases such as CIT-5, SSZ-24, or a laminar phase that can also be synthesized with the same organic structure directing agent. By means of XRD and (19)F MAS NMR, Ge and Si have been localized among the different crystallographic positions, and it is shown that Ge preferentially occupies T1 positions at the D4R cages, avoiding formation of Ge-O-Ge pairs.

ITQ-15: the first ultralarge pore zeolite with a bi-directional pore system formed by intersecting 14- and 12-ring channels, and its catalytic implications.

The pore topology of ITQ-15 zeolite consists of an ultra-large 14-ring channel that is intersected perpendicularly by a 12-ring pore; acid sites have been introduced in its framework and this unique structure shows advantages over unidirectional ultralarge pore zeolites for diffusing and reacting large molecules.

Incommensurate modulation in the microporous silica SSZ-24.

A detailed investigation of the structure of microporous silica, SSZ-24, is presented. It is shown by X-ray powder diffraction and (29)Si MAS NMR experiments that the structure deviates from the previously proposed AlPO(4)-5-type structure. At room temperature, electron diffraction (ED) patterns exhibit extra diffraction spots, which can be attributed to an incommensurate structural modulation along the c axis.

SSZ-23: An Odd Zeolite with Pore Openings of Seven and Nine Tetrahedral Atoms.

Single-crystal X-ray diffraction with synchrotron radiation enabled the structure of microcrystalline SSZ-23 (see drawing on the right), the first zeolite with channels bounded by seven- and nine-membered rings, to be solved.