Synthesis and Antimycobacterial and Photosynthesis-Inhibiting Evaluation of 2-[(E)-2-Substituted-ethenyl]-1,3-benzoxazoles

Table 1

Structure of 2-substituted benzoxazoles 1–12, experimentally determined values of lipophilicity and predicted parameters of individual substituents: distributive parameters , molar volume MV [cm⁻³], and in vitro antimycobacterial activities [MIC (μmol/L)] in comparison with standard isoniazid (INH) and IC₅₀ [μmol/L] values related to PET inhibition in spinach chloroplasts in comparison with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) standard.

Comp.	R			MV^a [cm^−3]	[μmol/L]
					MIC			PET; IC50
					MTB	MA	MK
					14d	14d	14d
					21d	21d	21d
1		0.9409	1.76	80.88	125; 125	62.5; 125	125; 125	148.8
2		0.9325	1.42	103.61	125; 125	62.5; 125	125; 125	76.3
3		0.9382	1.57	103.61	62.5; 62.5	32; 62.5	62.5; 125	216.1
4		1.1225	2.24	111.37	62.5; 125	62.5; 62.5	62.5; 62.5	199.3
5		1.1226	2.22	97.11	250; 250	125; 250	250; 500	102.0
6		1.1271	2.33	92.25	250; 250	250; 500	500; 500	516.6
7		1.1317	2.73	113.57	125; 250	125; 250	250; 500	b
8		0.9397	1.58	100.92	62.5; 62.5	32; 32	62.5; 250	131.4
9		0.7503	0.95	62.74	62.5; 125	62.5; 125	125; 125	224.1
10		1.0702	1.94	95.74	250; 250	250; 250	62.5; 250	122.3
11		1.1411	2.61	99.65	125; 250	250; 500	500; 500	777.5
12		1.1394	2.56	123.65	125; 250	125; 125	125; 250	351.0
INH	—	—		—	0.5; 0.5	>250; >250	>250; >250	—
DCMU	—	—		—	—	—	—	1.9

^acalculated for the uncharged molecules using ACD/Percepta (Advanced Chemistry Development, Inc., Toronto, ON, Canada, 2012); ^bprecipitation during experiment; MTB: Mycobacterium tuberculosis My 331/88; MA: M. avium My 330/88; and MK: M. kansasii My 235/80.