Table 2.

Synergistic effects of the silibinin with ampicillin against oral bacteria.

Strains	Agent	MIC/MBC (μg/mL)		FIC	FICI2	Outcome
		Alone	Combination1
S. mutans ATCC 251753	Silibinin	0.2/0.4	0.05/0.1	0.25/0.25	0.5/0.5	Synergistic/synergistic
	Ampicillin	0.125/0.5	0.0312/0.125	0.25/0.25
S. sanguinis ATCC 10556	Silibinin	0.4/0.4	0.1/0.2	0.25/0.5	0.5/0.75	Synergistic/additive
	Ampicillin	0.5/1	0.125/0.25	0.25/0.25
S. sobrinus ATCC 27607	Silibinin	0.4/0.8	0.1/0.2	0.25/0.25	0.5/0.5	Synergistic/synergistic
	Ampicillin	0.5/1	0.125/0.25	0.25/0.25
S. ratti KCTC 32944	Silibinin	0.8/0.8	0.1/0.2	0.125/0.25	0.375/0.75	Synergistic/additive
	Ampicillin	0.5/1	0.125/0.5	0.25/0.5
S. criceti KCTC 3292	Silibinin	0.8/1.6	0.2/0.4	0.25/0.25	0.5/0.375	Synergistic/synergistic
	Ampicillin	1/2	0.25/0.25	0.25/0.125
S. anginosus ATCC 31412	Silibinin	0.8/1.6	0.2/0.4	0.25/0.25	0.5/0.5	Synergistic/synergistic
	Ampicillin	1/2	0.25/0.5	0.25/0.25
S. gordonii ATCC 10558	Silibinin	0.1/0.2	0.025/0.05	0.25/0.25	0.5/0.5	Synergistic/synergistic
	Ampicillin	0.5/1	0.125/0.25	0.25/0.25
A. actinomycetemcomitans ATCC 43717	Silibinin	1.6/3.2	0.2/0.8	0.125/0.25	0.25/0.5	Synergistic/synergistic
	Ampicillin	64/64	8/16	0.125/0.25
F. nucleatum ATCC 51190	Silibinin	3.2/6.4	0.4/1.6	0.125/0.25	0.375/0.5	Synergistic/synergistic
	Ampicillin	2/4	0.5/1	0.25/0.25
P. intermedia ATCC 49049	Silibinin	1.6/3.2	0.2/0.8	0.125/0.25	0.375/0.75	Synergistic/additive
	Ampicillin	4/8	1/4	0.25/0.5
P. gingivalis ATCC 33277	Silibinin	0.4/0.8	0.1/0.2	0.25/0.25	0.5/0.5	Synergistic/synergistic
	Ampicillin	0.5/1	0.125/0.25	0.25/0.25

¹The MIC and MBC of the silibinin with ampicillin.

²The fractional inhibitory concentration index (FIC index).

³American Type Culture Collection (ATCC).

⁴Korean collection for type cultures (KCTC).