Table 2 Antioxidant and NO production inhibitory activity and cell viability of extracts from six Rubiaceae species

Cephalanthus natalensis

50

1.26 ± 0.14

53.81

104.67

68.64 ± 0.20^a

PRU 120872

25

1.32 ± 0.09

51.39

100.84

12.5

1.80 ± 0.08

33.95

90.02

6.25

2.34 ± 0.06

14.10

76.19

Cremaspora triflora

50

1.97 ± 0.16

27.66

96.70

90.02 ± 0.10^b

114710

25

2.43 ± 0.13

10.70

105.20

12.5

2.48 ± 0.08

8.77

104.25

6.25

2.90 ± 0.06

6.73

118.31

Oxyanthus speciosus

50

1.63 ± 0.06

40.25

109.84

259.7 ± 0.23^c

PRU 120873

25

1.57 ± 0.07

42.19

97.04

12.5

1.77 ± 0.12

34.92

91.61

6.25

1.94 ± 0.15

28.63

88.82

Pavetta lanceolata

50

0.80 ± 0.16

70.77

101.73

138.94 ± 0.18^d

PRU 120874

25

1.26 ± 0.10

53.81

112.10

12.5

1.84 ± 0.13

32.50

116.49

6.25

2.52 ± 0.10

7.31

123.03

Psychotria capensis

50

0.37 ± 0.05

86.27

4.44

29.73 ± 0.22^e

PRU 120875

25

1.08 ± 0.77

60.11

28.31

12.5

2.97 ± 0.22

9.16

75.40

6.25

3.22 ± 0.23

18.36

115.71

Psychotria zombamontana

50

2.19 ± 0.10

19.42

114.53

1.77 ± 0.13^f

PRU 120867

25

2.02 ± 0.20

25.72

93.32

12.5

2.05 ± 0.14

24.75

91.92

6.25

2.40 ± 0.10

11.67

76.91

Quercetin

25

0.35 ± 0.10

95.54

49.33

nd

12.5

0.30 ± 0.05

96.14

60.69

6.25

0.69 ± 0.08

91.08

73.76

3.12

2.50 ± 0.48

73.76

73.10

Trolox

nd

nd

nd

nd

5.67 ± 0.24^f

nd

Ascorbic acid

nd

nd

nd

nd

4.66 ± 0.25^h

nd