Structure-Activity Relationships of 3,3′-Phenylmethylene-bis-4-hydroxycoumarins: Selective and Potent Inhibitors of Gram-Positive Bacteria

Table 1

Reaction yield and antibacterial properties of dicoumarols.

CID	R1	R2	R3	R4	R5	% yield	Inhibition zone (mm)^a
							S. aureus	E. coli	B. subtilis	Klebsiella sp.
1						85	28	nz	32	nz
2	Cl	H	Cl	H	H	72	26	nz	32	nz
3	H	Cl	Cl	H	H	76	23	nz	28	nz
4	Cl	H	H	H	H	78	24	nz	29	nz
5	H	Cl	H	H	H	80	26	nz	28	nz
6	H	H	Cl	H	H	78	25	nz	29	nz
7	H	H	Br	H	H	75	24	nz	28	nz
8	H	H	H	H	H	71	23	nz	29	nz
9	H	H	Me	H	H	82	23	nz	25	nz
10	H	H	tBu	H	H	85	20	nz	20	nz
11	H	H	OH	H	H	74	20	nz	26	nz
12	H	NO2	H	H	H	87	24	nz	25	nz
13	H	OH	H	H	H	84	19	nz	38	nz
14	H	OMe	OH	H	H	83	22	nz	22	nz
15	H	OMe	OH	OMe	H	87	23	nz	22	nz
16	H	OMe	OMe	OMe	H	88	16	nz	23	nz
17	H	OMe	OMe	H	H	83	18	nz	22	nz
18	H	H	OMe	H	H	81	19	nz	27	nz
19	OMe	H	H	H	H	81	21	nz	31	nz
20	OMe	H	OMe	H	H	89	19	nz	28	nz
21	Positive control^b						40	nz	35	nz
22	DMSO						nz	nz	nz	nz

Note: ^athe antibiotic tests were undertaken twice. Average values are reported. nz: no inhibition zone; nf: not found. ^bPositive control is penicillin G for S. aureus and E. coli, while chloramphenicol was used for B.  subtilis and Klebsiella sp.