Table 3 Cytotoxicity against Vero cells LC₅₀ (μg/ml) and Selectivity index of the nine selected acetone crude extracts. Selectivity index values more than 1 are non-toxic extracts with a relatively good safe margin and promising antibacterial agents

E. erythrophylla

250 ± 0.06

0.78

12.55

3.14

2.35

1.57

0.78

3.53

E. natalitia

38 ± 0.01

0.48

0.48

0.24

0.24

0.48

0.24

0.36

E. woodii

202 ± 0.001

0.32

1.29

2.59

1.29

1.29

2.59

1.56

E. umtamvunensis

820 ± 0.05

5.27

21.07

10.54

2.63

5.27

2.63

7.90

E. zeyheri

1140 ± 0.17

0.91

14.53

14.53

8.72

3.63

7.27

8.27

S. legatii

140 ± 0.05

1.74

4.18

1.74

1.74

1.74

3.48

2.44

S. masukuense

70 ± 0.01

1.87

0.94

0.47

0.94

0.94

0.94

1.02

S. species A

61 ± 0.004

1.57

0.39

1.57

0.79

0.79

1.57

1.11

S. gerrardii

200 ± 0.03

5.11

1.28

2.56

0.64

1.28

5.11

2.66

Doxorubicin

12.07 ± 0.41

ND

ND

ND

ND

ND

ND

ND