Magnetic Aerogels for Room-Temperature Catalytic Production of Bis(indolyl)methane Derivatives

The potential of aerogels as catalysts for the synthesis of a relevant class of bis-heterocyclic compounds such as bis(indolyl)methanes was investigated. In particular, the studied catalyst was a nanocomposite aerogel based on nanocrystalline nickel ferrite (NiFe2O4) dispersed on amorphous porous silica aerogel obtained by two-step sol-gel synthesis followed by gel drying under supercritical conditions and calcination treatments. It was found that the NiFe2O4/SiO2 aerogel is an active catalyst for the selected reaction, enabling high conversions at room temperature, and it proved to be active for three repeated runs. The catalytic activity can be ascribed to both the textural and acidic features of the silica matrix and of the nanocrystalline ferrite. In addition, ferrite nanocrystals provide functionality for magnetic recovery of the catalyst from the crude mixture, enabling time-effective separation from the reaction environment. Evidence of the retention of species involved in the reaction into the catalyst is also pointed out, likely due to the porosity of the aerogel together with the affinity of some species towards the silica matrix. Our work contributes to the study of aerogels as catalysts for organic reactions by demonstrating their potential as well as limitations for the room-temperature synthesis of bis(indolyl)methanes.

Synthesis, cytostatic evaluation and structure activity relationships of novel bis-indolylmethanes and their corresponding tetrahydroindolocarbazoles

BIMs (bis-indolylmethanes) (1a-n) were synthesized using glacial acetic acid as a protic acid for promotion of the condensation reaction of indoles with aldehydes in high yields (86-98 %). Corresponding tetrahydroindolo[2,3-b]carbazoles (2a-m) were synthesized via condensation of BIMs with aldehydes. Ten synthesized compounds have been submitted to the national cancer institute in the USA where all the submitted samples have been selected for one dose screening. As a result of the one dose screening of BIMs (1e,f,h,i,n) and of the indolocarbazoles (2e,f,h,i,j) the average highest cytostatic effects was recorded here for the BIM 1h and the indolocarbazole (2e) that showed the lowest mean values of "47.39%" and of "21.63%" respectively. Both compounds (1h and 2e) were further tested in five dose screening with the tested substance (1h) being significantly more sensitive for several cancers cell line as corresponding to their GI50 values. Furthermore, the basically substituted derivative 2e showed the highest antipoliferative activity in a nanomolar scale towards the three selected cancers cell lines Non small lung cell NCI-H460 with GI50 "616 nM", Ovarian Cancer cell line OVCAR-4 with GI50 "562 nM" and Breast Cancer cell line MCF7 with GI50 "930 nM".