Synergistic Antimycobacterial Actions of Knowltonia vesicatoria (L.f) Sims

Table 2

Antimycobacterial activity against M. tuberculosis and cytotoxicity on U937 cells of test samples.

Samples	MIC^a (μg/mL)	FIC^b	ΔGI4-3 ± SD^c	IC50 (μg/mL ± SD)^d
V2^e	—	—	22.0±2.94	—
INH (0.2 μg/mL)	0.20	—	−2.50±2.12	>200.0
Actinomycin D^f	NT^g	—	—	3.820±0.258 ×10^−3
K. vesicatoria EtOH	50.00^h	—	−6.00±0.58	41.25±0.205
F4^i	>100.0	—	275.5±45.3	64.77±1.812
F2^j	>100.0	—	288.5±65.1	NT
E. natalensis CHCl3	8.000	—	−3.50±0.88	12.22±0.025
P. sidoides EtOH	5000	—	20.00±1.85	43.54±0.465
Compound (1)	50.00	—	−9.00±1.41	16.41±0.135
Compound (2)	100.0^k	—	—	44.70±0.50
Isomer mixture (2) and (3)	>100.0	—	117.0±8.49	>200.0
C1	1.000/6.250/625.0/0.025^l	0.50	−5.50±3.53	100.3±2.450
C2	4.000/25.00/2500^m	1.50	17.00±5.65	108.6±0.89
C3	6.250/0.025^n	0.25	−1.5±0.707	121.7±2.079

^aMinimum inhibitory concentration.
^bFractional inhibitory concentration index.
^cΔGI value (mean ± standard deviation).
^dFifty percent inhibitory concentration.
^e10⁻² inoculum control.
^fCytotoxicity assay positive control.
^gNot tested.
^hMIC value for K. vesicatoria against both clinical drug-resistant M. tb strains: 4388 (resistant to INH and ETH; V2 ΔGI_4-3 ± SD = 32.5±4.95) and 5479 (resistant to INH, EMB, STR, RIF; V2 ΔGI_3-2 ± SD = 34.5±0.71) was found to be 50.00 μg/mL with ΔGI_4-3 = 2.0±4.24 and ΔGI_3-2 = 0.33±0.57, respectively.
ⁱFraction 4: tannin-free Knowltonia fraction.
^j Fraction 2: hexane Knowltonia fraction.
^kBACTEC MIC not determined, MIC determined via microplate assay.
^lEightfold reduction of respective MIC values for E. natalensis (CHCl₃) + K. vesicatoria (EtOH) + P. sidoides (EtOH) + INH.
^mTwofold reduction of respective MIC values for E. natalensis (CHCl₃) + K. vesicatoria (EtOH) + P. sidoides (EtOH).
ⁿEightfold reduction of respective MIC values for K. vesicatoria (EtOH) + INH.