In vitro susceptibility of Mycobacterium tuberculosis to extracts of Eucalyptus camaldulensis and Eucalyptus torelliana and isolated compounds

Figures & data

Table 1.  Anti-Mtb activity of lyophilized crude extracts of Eucalyptus camaldulensis (Ec) and E. torelliana (Et) on Mtb H37RvATCC 27294.

Conc. (µg/mL)	% Inhibition									RMP
	hEcL	cEcL	mEcL	hEcS	cEcS	hEtL	cEtL	hEtS	cEtS	Conc. (µg/mL)	% Inhibition
128	99	99	98	100	95	100	100	98	98	8	100
64	98	99	98	100	93	100	99	96	98	4	100
32	98	97	76	100	83	100	95	93	97	2	100
16	73	69	59	99	54	97	61	72	86	1	100
8	58	65	55	94	37	90	39	40	70	0.5	97
4	55	54	54	90	25	69	34	13	61	0.25	90
2	52	52	52	79	0	69	14	11	56	0.125	73
1	50	50	50	56	0	61	0	0	43	0.0625	49
MIC (µg/mL)	24.2	26.8	52.2	4	50.8	8	28.2	29.9	18.8	0.25

c, chloroform; h, hexane; L, leaf; m, methanol; RMP, rifampicin; S, stem bark.

Table 2.  Anti-Mtb activity of pure compounds 1 and 2 against Mycobacterium tuberculosis H37RvATCC 27294.

Sample	MIC (µg/mL)	MBC (µg/mL)	IC50 (µg/mL)	SI*
Compound 1	49.5	62.5	>100	>2.02
Compound 2	46.9	62.5	38.21	0.81
Rifampicin	0.07	0.5	147.58	2108

*Selectivity index (SI = IC₅₀/MIC).

Table 3.  Proton NMR (¹H) of compound 1.

δ (^1H)ppm	Characteristics	^1H-^1H COSY	HSQC direct coupling	Remarks
0.919–0.96	Doublet	Couples with 0.893–0.908	–	C-14 protons
0.893–0.908	Doublet	–	32; 28; 22; 18; 16	Methyl protons of side chain
1.2		Couples with 0.893–0.908	37	C-13 protons
1.3–1.8	Multiplet	Couples with 0.919–0.96	37	C-5, C-6 protons & likely C-12 protons
2.147			41; 32
2.180			43
2.494	Multiplet	Couples with 1.3–1.8 multiplet	58	C-2 protons
2.755 3.21–3.25	Multiplet	Couples with 0.919–0.96; also with 2.18, 2.147
3.558	Singlet, weak, broad
3.671	Singlet			CH3 linked to the ester
3.86, 3.90				C-3 protons
5.9	Singlet, weak, broad			Hydroxyl proton

Table 4.  Proton NMR (¹H) of compound 2.

δ (^1H)ppm	Characteristics	^1H-^1H COSY	HSQC direct coupling	Remarks
0.84	Triplet	Couples with 0.89	Carbon 42.124 & 42.182
0.89	Multiplet	Couples with 0.84	Carbon 42.128 & 42.182	Equitorial in rings B, C, D
1.23	Multiplet	Couples with 2.13 & 2.41	Carbon centred on 42	Axial Protons in ring B, C, D
2.13	Singlet			Ring A; adjacent to C=O
2.41	Singlet			CH=CH2
3.27	Singlet
3.62	Singlet			CH3

Figure 1.  Compound 1 (3-hydroxymyristic acid methyl ester).

Figure 2.  Compound 2 (substituted pyrenyl ester).