Alangium longiflorum Merr. Leaf Extract Induces Apoptosis in A549 Lung Cancer Cells with Minimal NFκB Transcriptional Activation

The chemotherapy drug doxorubicin (DOX) is effective in treating many types of cancers. However, due to its pro-inflammatory and cardiotoxic side effects, other remedies have also been explored as alternative treatments. The plant Alangium longiflorum was reported to contain cytotoxic activity against cancer cells, but it is unclear whether this plant would also yield side effects similar to doxorubicin. Hence, this study investigated cytotoxic activity of A. longiflorum leaf extract against lung cancer cells and compared its pro-inflammatory and cardiotoxic side effects with those of DOX.

Methods: Cytotoxic activity of A. longiflorum in human lung (A549) and breast (MCF-7) cancer cells was initially assessed by MTT assay and then was compared with doxorubicin. Presence of secondary metabolites in the leaf extract was examined by phytochemical screening. The ability of the plant extract to induce apoptosis was determined by measuring caspase-3/7 activity and apoptosis-related gene expression. Pro-inflammatory response was assessed by quantifying NFκB transcriptional activity and nuclear translocation with dual luciferase reporter and immunofluorescence assays, respectively. Cardiotoxicity was measured using zebrafish as a model organism.

Results: A. longiflorum leaf extract displayed high cytotoxic activity against A549 versus MCF-7, which led this study to focus further on A549. Phytochemical screening showed that the extract contained terpenoids, alkaloids, phenols, cardiac glycosides, and tannins. The extract induced apoptosis through activation of caspase-3/7 and upregulation of pro-apoptotic genes without causing NFκB transcriptional activation and nuclear localization. The extract also did not significantly reduce heart function in zebrafish.

Conclusion: Overall, our data suggested that extract from leaves of A. longiflorum can have the potential to serve as apoptotic agent towards lung cancer without inducing significant cardiotoxicity.

Keywords: Alangiaceae; Cytotoxicity; cardiotoxicity; senescence; zebrafish.