Antibacterial Properties of Plants — Bushnell, et al. 
181 
TABLE 6 
Action of Certain Plant Extracts upon Five Enteric Pathogens* 
ACTION 
NAME OF PLANT 
PART 
OF PLANT 
pH 
OF EX- 
TRACT 
Salmonella 
typhosa N 
Z 
Salmonella q 
montevideo ^ 
2 
x 
Salmonella g 
schottmuelleri 3 
0 
z 
Shigella p- 
paradys. BH Z 
2 
S 
Shigella ^ 
paradys. III-Z 
VERY 
Punica Granatum 
whole fruit 
3.5 
20 
18 
27 
17 
12 
EFFECTIVE 
Eugenia malaccensis 
bark 
5.9 
0 
0 
0 
20 
20 
leaves 
5.4 
0 
0 
0 
30 
35 
MODERATELY 
Psidium Guajava 
fruit 
3.5 
20 
19 
18 
22 
30 
EFFECTIVE 
Morinda citrifolia 
ripe fruit 
4.4 
23 
10 
12 
22 
20 
young fruit 
5.2 
10 
0 
0 
15 
15 
Momordica Charantia 
leaves 
7.3 
8 
0 
0 
12 
12 
Bidens pilosa 
whole plant 
5.8 
17 
8 
8 
8 
8 
SLIGHTLY 
Pittosporum Tobira 
bark 
6.2 
10 
8 
0 
8 
8 
EFFECTIVE 
leaves 
6.1 
8 
8 
0 
8 
8 
Solanum nodiflorum 
ripe fruit 
6.2 
8 
8 
8 
8 
8 
Plantago major 
whole fruit 
7.0 
8 
7 
9 
8 
8 
*The following extracts were found to be ineffective against the enteric pathogens: Colocasia escu- 
lenta (corm, 7.0); Commelina diffusa (whole plant, 5.4); Dioscorea alata (tuber, 5.7); Musa paradisi- 
aca ssp. sapientum var. (stems, 5.7; leaves. 6.2; flower bud, 5.0); Pelea sp. (leaves, 5.7); Schinus 
terehinthifolius (leaves, 4.7; berries, 5.2); Dodonaea visc.osa (leaves, 5.5); Psidium Guajava (leaves and 
flowers, ?); Ipomoea congesta (whole plant, 5.5); Morinda citrifolia (leaves and stems, 5.1). 
ported it (Neal, 1948: 555). (It could not 
have come too soon for the dying Hawaiian 
race, for by this time the bloody fluxes, intro- 
duced by almost every vessel calling at Ha- 
waii, had long since begun to take their toll 
of native lives, and the surviving Hawaiians 
must have been seeking desperately for rem- 
edies against them.) 
It is possible that many of the other plants 
which were not tested for their action upon 
these enteric pathogens will possess proper- 
ties antagonistic to them. A minor but inter- 
esting phenomenon is the apparent selective 
action of some of these plant extracts upon 
some of the intestinal pathogens: the action 
of Eugenia malaccensis, for example, is di- 
rected against the two Shigella strains only; 
and the young fruit of the noni, Morinda citri- 
folia, also exhibits its peculiar selectivity for 
the two Shigella strains and the typhoid 
bacillus. 
Most of the plant extracts listed on page 
179, far from inhibiting the test bacteria, 
markedly stimulated their growth. Many of 
the plant extracts which showed some degree 
of effectiveness against the test bacteria also 
stimulated the growth of the bacteria in those 
areas around and beyond the periphery of the 
zones of inhibition. This action probably can 
be attributed to the presence of foodstuffs and 
of growth-promoting factors in the extracts, 
even in those extracts which also possess 
agents which are antagonistic to the bacteria. 
It is also possible that, as is known to be the 
case with many substances, the same agent 
in a plant extract may be inhibitory, or even 
bactericidal, in high concentrations and stim- 
ulating in low concentrations. 
It must be remembered, too, that the effi- 
cacy of these extracts is dependent to a con- 
siderable extent upon the diff usability of 
their component parts. It is, therefore, highly 
probable that other results might be obtained 
if other methods of assay were employed, or 
that many more of the plants might be shown 
to have a greater degree of effectiveness 
