Two innovative 20-S-camptothecin (
CPT) formulations, previously found suitable to achieve therapeutically relevant
CPT concentrations, were assessed for their in vitro cytotoxic potential as compared to an aqueous
CPT solution, using the MTT assay. The formulations, cationic
CPT-containing
liposomes (
CPT-Lip),
hydroxypropyl-beta-cyclodextrin (
HP-beta-CD) complexed
CPT (
CPT-CD) and a saturated aqueous
CPT solution (
CPT-
Sol), were diluted in culture medium to appropriate
CPT concentrations (4.7-300 ng/ml), and incubated with HT-29 and SW-480 human colon
carcinoma cell lines. IC50 values were calculated after 48 and 72 h incubation for the HT-29 and SW-480 cell lines, respectively, and were found to be of the same magnitude for all formulations, with only a slight difference (
CPT-
Sol<
CPT-CD<
CPT-lip). The cells obtained apoptotic morphology after 36 h incubation with
CPT-CD and were demonstrated to be active
caspase-3 immuno-positive. Both formulations investigated,
CPT-CD and
CPT-Lip, showed significant cytotoxicity in vitro relative to
CPT-
Sol and warrant investigation for future therapeutic application.