Synthesis and Biological Activity of Arylspiroborate Salts Derived from Caffeic Acid Phenethyl Ester

Table 2

Antimicrobial activity (IC₅₀s and MICs in µM [mg/mL]) of boric acid and 3–5 against Candida albicans, Staphylococcus aureus, and methicillin resistant S. aureus.

Compounds	C. albicans		S. aureus		MRSA
	IC50; SEM^1	MIC^2	IC50; SEM	MIC	IC50; SEM	MIC
B(OH)3	Inactive^3	Inactive	Inactive	Inactive	Inactive	Inactive
CAPE (3)	132.43; 0.40	176	39.1; 1.10	86	12.3; 1.50	86
	37.65; 0.11	50	11.12; 0.32	25	3.5; 0.40	25
4	72.2; 0.70	125	19.93; 1.45	42	22.9; 1.50	84
	43.22; 0.40	75	11.93; 0.87	25	13.71; 0.88	50
5	146.10; 1.50	>245	Inactive	Inactive	11.35; 1.10	61
	119.50; 1.20	>200			9.28; 0.88	50

IC₅₀s estimated by probit analysis. ²MIC (minimum inhibitory concentration) is defined as the lowest concentration that showed over 90% inhibition. ³Less than 50% inhibition in initial screening (at 100 g/mL) is considered to be inactive.