Figure 2. Phloretin is unable to induce differentiation of pleomorphic slender form cells to procyclic forms.

T. brucei AnTat 1.1 90:13 cells (8×10⁵/ml) were cultured in HMI-9 at 37°C before the addition of 6 mM cis-aconitate, 100 µM phloretin or the same volume of 70% ethanol as a solvent control. After culture for 48 hours at 37°C, the cells were harvested, washed in phloretin-free procyclic medium (SDM-79), then inoculated into P-79 and incubated a further 5 days at 27°C. A. Phloretin treatment caused growth arrest within 24 hours in the pleomorphic slender cell cultures, with no outgrowth of procyclic cells being detected after transfer to phloretin-free procyclic medium. Cis-aconitate treated cells differentiated and proliferated as procyclic forms under the same culture conditions. B. The expression of the procyclic specific marker EP procyclin was monitored by flow cytometry for each culture. Whereas most cis-aconitate induced pleomorphic slender cells efficiently differentiated to procyclic forms within 48 hours, and expressed high levels of EP procyclin, phloretin treated cultures remained procyclin negative.