What phase do plant alkaloids primarily work in during the cell cycle?

Plant alkaloids primarily target the late G2 and S phases of the cell cycle. During the S phase, the DNA is actively being synthesized, and plant alkaloids interfere with the process by disrupting the microtubule formation necessary for proper cell division. They achieve this by binding to tubulin, which ultimately prevents the formation of the mitotic spindle required for separating chromosomes during mitosis.

As the cell progresses from G2 into mitosis, continued action of plant alkaloids in the late G2 phase ensures that the cell cannot transition effectively, leading to cell cycle arrest. This is significant in cancer treatment, as many tumor cells may be highly proliferative, making them particularly susceptible to agents that disrupt normal cell cycle functions. Therefore, the effectiveness of plant alkaloids is characterized by their action during these specific phases, underscoring their role in halting the growth of rapidly dividing cells.