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. 2017 May 4;22(5):732. doi: 10.3390/molecules22050732

Figure 2.

Figure 2

Brazilian green propolis (BGP) extract enhanced protoporphyrin IX (PpIX)-mediated photocytotoxicity in vitro. Combined effects of BGP extract and PpIX-mediated PDT (PpIX-PDT) in A431 and HeLa cells were tested by MTT according to the methods described above. (a) A431 cells were incubated with several PpIX concentrations (1.8, 2.7 and 4.0 μM) employing the BGP extract (62.5 and 75 μg/mL); (b) For HeLa cells, the concentrations of PpIX were 0.20, 0.30 and 0.45 μM employing the BGP extract (25 and 50 μg/mL). All groups were illuminated by laser. Results were expressed as viability relative to the control. The combination index (CI) corresponded with the data of viability. CI is a quantitative measure of the degree of drug interaction in terms of additive effect (CI = 1), synergism (CI < 1), or antagonism (CI > 1). Data were expressed as mean ± SEM of three independent experiments.