Cytotoxic investigation and photophysical analysis of serum protein binding with beta-carboline alkaloids

The work focused on interaction of beta-carboline alkaloids, harmalol and harmine, with HSA by biophysical and biochemical assays. Serum protein in the form of FBS in the culture media negatively alters the cytotoxicity of the alkaloids. MTT assay indicates concentration dependent growth inhibitory effect of the alkaloids on A375, MDA-MB-231, HeLa and ACHN cell, having maximum cytotoxicity with minimum GI₅₀ value of 6.5 μM on ACHN by harmine in presence of 1% of FBS. Detail cytotoxic investigation on ACHN cell highlight the apoptotic induction ability of harmine.

The binding constant was found to be 2.5 × 10³ M^-1 and 4.3 × 10⁴ M^-1, respectively, for harmalol and harmine by UV spectroscopy, the trend was also supported by fluorescence spectroscopy with HSA. Site markers demonstrated warfarin binding sites of the alkaloids to the protein.

The results serve as data for the future development of serum protein based targeted drugs.