Responses to Herbal Compounds in Brain Cancer Cells: two Cell-Calcium Assays and a Molecular Docking Computation Study

Abstract

Herbal plant secondary metabolites such as curcumin, resveratrol, and capsaicin are becoming increasingly popular as natural remedies. These herbal compounds are also known to act on the calcium signaling pathways, and therefore cell calcium assays can be used to study the relative interactions of these compounds with cellular receptors pertaining to natural remedies. To investigate this, Fluo-4, a fluorophore that specifically binds to Ca2+, was used to detect the increase in calcium signaling in human glioblastoma cells treated with curcumin, resveratrol, and capsaicin. The human cells used are U87 MG cells which expresses TRPV1, a pain receptor on the cell membrane. The increases of the fluorescence intensity in the cells treated with the three herbal compounds were measured using a bulk microplate assay, which generates data in a high throughput, and a microfluidic single-cell assay, which allows for the observation of the cell calcium changes in real-time. It was found that all three compounds would increase the intracellular Ca2+ concentrations on the two assays, with curcumin generating the highest increase, which confirms the greatest responses elicited by this herbal compound from the cell. Furthermore, the data obtained by a molecular docking computation study, which has been used to determine the binding affinities of the three compounds with the TRPV1 receptor, corroborate with the experimental finding of the highest cellular response due to curcumin.