This study aimed at investigating the anticancer activity of tagalsins A, B, C, D, E, F and G isolated from the roots of Ceriops tagal. Their structures were established based on the IR, MS and NMR spectral data. Anticancer activity was evaluated using caspase-3 colourimetric assays and the minimum activation concentrations were established. The study revealed that tagalsin A, B, C, D, E, F and G induces apoptosis through the activation of caspase-3 enzyme. Tagalsin A was the most active (MAC value of 0.12 μg/mL) followed by tagalsin B (MAC of 0.15 μg/mL) and and tagalsin E was the least active (MAC value of 1.16 μg/mL). Structure activity relationship revealed that epoxide rings and oxygenation enhanced the activity of tagalsins in inducing caspase-3 activation of apoptotic pathway, thus, providing an avenue for the development of anticancer agents with novel mechanism of actions.Keywords: Ceriops tagal, dolaboranes, tagalsins, caspase-3