Background: The search for natural anticancer agents is a worthy scientific research goal, driven by 
the hope to lessen cancer's tremendous global burden. 
Objective: This study aimed at evaluating the cytotoxic activity of Gardenia latifolia Ait. (Rubiaceae) 
against lung (A549) and colon (HCT116) cancer cell lines. Cytotoxicity-guided isolation of the 
bioactive phytochemicals was conducted, followed by various mechanistic validations of the appealing 
cytotoxic metabolites. 
Methods: The cytotoxic effects were determined using MTT assay. The two most cytotoxic compounds 
were further evaluated for their effects on cell cycle progression and apoptotic capabilities using flow 
cytometry approach. Additionally, we conducted a molecular docking analysis to reveal their potential 
interactions with the human topoisomerase IIα. 
Results: The phytochemical investigation led to isolation of nine compounds including a new one, (-) 
1-acetyl 4,5-di-O-caffeoyl quinic acid. The latter compound was the most cytotoxic against the colon 
cancer cell line (IC50 1.9 µg/ml) with a remarkable tumor-selectivity (SI ≈ 15). Moreover, the isolated 
glycoside, 1-O-[6-O-(5-O-vanilloyl-β-ᴅ-apiofuranosyl)-β-ᴅ-glucopyranosyl]-3,4,5-trimethoxybenzene, 
showed selective cytotoxicity towards A549 and HCT116 cells (IC50 values of 3.8 and 3.3 µg/ml, 
respectively). Both compounds considerably affected the cell cycle distribution. They caused G2/M cell 
cycle arrest, showed apoptotic capabilities, and displayed significant in silico topoisomerase IIα 
inhibition.
Conclusion: Two cytotoxic and apoptotic compounds were reported from Gardenia latifolia. 
Subsequent in vivo studies and clinical trials should be conducted to substantiate their anticipated 
therapeutic values.