TABLE 1.

Effects of naphthoquinone drugs on incorporation in vitro of radiolabeled p-hydroxybenzoate into P. carinii ubiquinone^a

Drug and concn (μM)	Radioactivity (dpm)b	Incorporation of PHBA into CoQ (pmol/mg of protein)c
Atovaquoned
0	5,221–5,684	151.8 ± 2.4
0.01	2,037–2,516	59.3 ± 2.0
0.02	3,263–3,453	92.8 ± 1.0
0.1	5,815–6,668	170.5 ± 4.3
0.2	5,205–6,105	155.3 ± 5.4
1.0	2,458–2,905	74.3 ± 2.1
Diospyrine
0	525–1,037	66.0 ± 4.3
0.01	468–1,105	58.1 ± 6.5
0.05	495–832	56.2 ± 3.3
0.1	389–974	56.7 ± 5.1
0.5	411–1,042	56.5 ± 8.0
1	468–1,168	65.5 ± 6.3
5	474–1,200	63.2 ± 7.8
10	498–1,168	66.5 ± 6.2
25	403–1,037	59.9 ± 6.0
50	394–921	58.6 ± 4.6
100	442–1,105	60.6 ± 6.5
Diospyrin dimethylethere
0	252–397	48.2 ± 3.7
0.01	205–242	45.9 ± 1.9
0.05	237–435	53.9 ± 5.6
0.1	232–446	46.2 ± 2.5
0.5	137–382	46.7 ± 7.7
1	177–347	43.9 ± 5.2
5	226–279	51.5 ± 2.6
10	247–421	49.3 ± 4.8
25	253–381	46.6 ± 4.9
50	242–392	45.8 ± 3.4
100	221–432	46.4 ± 4.6
Diospyrin dimethylether hydroquinonee
0	274–689	58.2 ± 10.9
0.01	523–679	79.6 ± 5.0
0.05	295–453	63.9 ± 9.1
0.1	342–568	56.2 ± 6.3
0.5	418–621	63.0 ± 7.4
1	379–584	53.2 ± 6.4
5	442–668	77.2 ± 7.5
10	368–768	62.4 ± 10.6
25	354–820	61.1 ± 12.0
50	361–558	56.4 ± 7.2
100	279–515	48.5 ± 5.4

^aPurified organisms were incubated for 2 days in 10 ml of serum-free RPMI 1640 medium containing [U-¹⁴C]p-hydroxybenzoate and various concentrations of a drug. Values are means ± standard errors of the means. 

^bValues are ranges of radioactivity in the ubiquinone band isolated by TLC. 

^cProtein content of organisms prior to incubation. 

^dOrganisms were incubated with 10 μCi of the substrate (n = 4). 

^eOrganisms were incubated with 5 μCi of the substrate (n = 6 except in the assays with 0.01 and 5 μM, in which n = 3).