Tizoxanide pyridine monosolvate

Zheng, H.; Deng, H.; Chen, Y.; Li, D.

doi:10.1107/S1600536812016133

organic compounds

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ISSN: 2056-9890

Volume 68| Part 5| May 2012| Pages o1453-o1454

doi:10.1107/S1600536812016133

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Tizoxanide pyridine monosolvate

Huaqin Zheng,^a Hui Deng,^a Yunyun Chen ^a and Ding Li ^a ^*

^aSchool of Pharmaceutical Science, Sun Yat-sen University, Guangzhou, 510006, People's Republic of China
^*Correspondence e-mail: liding@mail.sysu.edu.cn

(Received 6 April 2012; accepted 13 April 2012; online 21 April 2012)

In the title compound [systematic name: 2-hydroxy-N-(5-nitro-1,3-thiazol-2-yl)benzamide pyridine monosolvate], C₁₀H₇N₃O₄S·C₅H₅N, the dihedral angle between the pyridine and benzamide rings is 80.55 (7)°. An intamolecular O—H⋯N hydrogen bond occurs in the tizoxanide. In the crystal, the components are linked by an O–H⋯N hydrogen bond, forming a zigzag chain along the c axis. Aromatic π–π interactions between inversion-related pyridine rings [centroid–centroid distance = 3.803 (6) Å] are also observed.

Related literature

For the biological activity of tizoxanide, see: Rao et al. (2009 ); Gargala et al. (2000 ); Dubreuil et al. (1996 ); Ashton et al. (2010 ); Korba, Elazar et al. (2008 ); Zhao et al. (2010 ). For related structures and background to the bioactivity of tizoxanide, see: Pankuch & Appelbaum (2006 ); Stettler et al. (2003 ); Broekhuysen et al. (2000 ). For details on experimental methods used to obtain this form and analogues, see: Navarrete-Vazquez et al. (2011 ). For a pyridine-solvated forms, see: Dong et al. (2011 ). For additional literature on related tizoxanide thiazolide compounds, see: Megraud et al. (1998 ); Chan-Bacab et al. (2009 ); Korba, Montero et al. (2008 ); Stachulski et al. (2011a b ). For the biological activity of the anti-parasitic agent nitazoxanide {systematic name: [2-[(5-nitro-1,3-thiazol-2-yl)carbamoyl]phenyl]ethanoate}, see: Hemphill et al. (2006 ); Rossignol et al. (2006 ). For the structure of nitazoxanide, see: Bruno et al. (2010 ). For the effect of crystallization from different solvents on drug properties, see: Trask et al. (2004 ).

Experimental

Crystal data

C₁₀H₇N₃O₄S·C₅H₅N
M_r = 344.35
Triclinic, $[P \overline 1]$
a = 6.9826 (3) Å
b = 10.0462 (5) Å
c = 11.8387 (7) Å
α = 102.998 (5)°
β = 99.037 (5)°
γ = 104.367 (4)°
V = 763.69 (7) Å³
Z = 2
Cu Kα radiation
μ = 2.16 mm⁻¹
T = 293 K
0.20 × 0.15 × 0.10 mm

Data collection

Agilent Xcalibur Onyx Nova diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2011 ) T_min = 0.712, T_max = 0.806
4493 measured reflections
2481 independent reflections
2349 reflections with I > 2σ(I)
R_int = 0.016

Refinement

R[F² > 2σ(F²)] = 0.028
wR(F²) = 0.075
S = 1.08
2481 reflections
265 parameters
All H-atom parameters refined
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.25 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N7—H7⋯O1	0.85 (2)	1.95 (2)	2.6248 (16)	135.9 (18)
O1—H25⋯N8	0.94 (2)	1.64 (2)	2.5671 (16)	175 (3)

Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009 ); software used to prepare material for publication: OLEX2.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536812016133/qm2062sup1.cif

Supporting information file. DOI: 10.1107/S1600536812016133/qm2062Isup2.mol

Structure factors: contains datablock I. DOI: 10.1107/S1600536812016133/qm2062Isup3.hkl

Supporting information file. DOI: 10.1107/S1600536812016133/qm2062Isup4.cml

checkCIF report

Comment top

Nitazoxanide was first developed as an anti-parasitic agent, and marketed in the USA since 2002 (Stachulski et al., 2011a). In humans, once orally administered, nitazoxanide is hydrolyzed in plasma to its active metabolite tizoxanide (TIZ), which is 99% protein bound (Broekhuysen et al., 2000; Ashton et al., 2010). Nitazoxanide exhibits a broad spectrum of activities against intracellular and extracellular protozoa, helminthes, aerobic and anaerobic bacteria, and viruses infecting humans and animals (Hemphill et al., 2006; Rossignol et al., 2006; Korba, Montero et al., 2008; Zhao et al., 2010; Stachulski et al., 2011b).

In the present study, tizoxanide was prepared via deacetylation of nitazoxanide in pyridine and it crystallized as a 1:1 ratio complex with pyridine as crystals. Thermogravimetric analysis was performed to study the thermal stability of the title complex, which indicated a one-step molecular weight loss of 22.43% corresponding to one pyridine molecule in the temperature range of 333–373 K, confirming a 1:1 ratio complex of tizoxanide-pyridine (theoretical weight loss 22.97%).

The tizoxanide and pyridine are linked through hydrogen bond O1–H···N8 (bond distance = 2.567 Å). A stable crystal was formed through intramolecular O1—H···N7 (bond distance = 2.625 Å) and intermolecular O1—H···N8 hydrogen-bonding interactions involving the benzamide group and the pyridine molecule. It is arresting that π–π interactions play an important role in the molecular packing. Inversion-related pyridine molecules are linked by π-π interactions [centroid-centroid distance = 3.803 (6) Å], which stabilize the crystal. By comparison with X-ray of prodrug nitazoxanide (Bruno et al., 2010), tizoxanide has stronger intramolecular hydrogen bonds. These hydrogen bonds may be useful for pharmaceutical preparation of tizoxanide. The molecular and crystal structures are stabilized by intra- (O1—H···N7) and intermolecular (O1—H···N8, π-stacking) interactions respectively, which give a great stability to the crystal building.

When the drug crystallized from different solvents, the crystal form may be changed and then altering a drug's properties, such as melting point and solubility (Trask et al., 2004). We speculated that the replacement of a weak alkaline solvent or solid compound containing the pyridine ring may form the corresponding crystals made of different formulations of active drugs for tizoxanide. Obviously, crystal form of the title compound is different from prodrug nitazoxanide, which suggests that changing solvent or pyridine derivatives may form new crystals and new dosage forms of drugs. This is our future work.

Related literature top

For the biological activity of tizoxanide, see: Rao et al. (2009); Gargala et al. (2000); Dubreuil et al. (1996); Ashton et al. (2010); Korba, Elazar et al. (2008); Zhao et al. (2010). For related structures and background to the bioactivity of tizoxanide, see: Pankuch & Appelbaum (2006); Stettler et al. (2003); Broekhuysen et al. (2000). For details on experimental methods used to obtain this form and analogues, see: Navarrete-Vazquez et al. (2011). For a pyridine-solvated forms, see: Dong et al. (2011). For additional literature on related tizoxanide thiazolide compounds, see: Megraud et al. (1998); Chan-Bacab et al. (2009); Korba, Montero et al. (2008); Stachulski et al. (2011a,b). For the biological activity of the anti-parasitic agent nitazoxanide {systematic name: [2-[(5-nitro-1,3-thiazol-2-yl)carbamoyl]phenyl]ethanoate}, see: Hemphill et al. (2006); Rossignol et al. (2006). For the structure of nitazoxanide, see: Bruno et al. (2010). For the effect of crystallization from different solvents on the properties of drugs, see: Trask et al. (2004).

Experimental top

A solution of 80 mg of nitazoxanide in 250 ul of pyridine was stirred for 15 min at 333 K and left to crystallize at 293 K overnight. A size suitable flaxen needle was attained for X-ray analysis.

Thermogravimetric analysis for the title complex was performed using a NETZSCH STA409 instrument with sample. The sample was placed in an aluminium cell, heated at 5 °C min^-1 and purged with nitrogen gas flowing at 20 cm³ min^-1.

Computing details top

Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO (Agilent, 2011); data reduction: CrysAlis PRO (Agilent, 2011); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Figures top

	Fig. 1. A view of the molecular structure of the title compound (I). The displacement ellipsoids are at the 50% probability level.
	Fig. 2. The two-dimensional plane formed by the hydrogen bonds of the molecules; dashed lines represent hydrogen bonds and some of the H atoms have been omitted for reasons of clarity.
	Fig. 3. The thermogravimetric analysis of the title compound showing a one-step molecular weight loss of 22.43% corresponding to one pyridine molecule.

2-Hydroxy-N-(5-nitro-1,3-thiazol-2-yl)benzamide pyridine monosolvate top

Crystal data top

C₁₀H₇N₃O₄S·C₅H₅N	Z = 2
M_r = 344.35	F(000) = 356
Triclinic, P1	D_x = 1.497 Mg m⁻³
a = 6.9826 (3) Å	Cu Kα radiation, λ = 1.5418 Å
b = 10.0462 (5) Å	Cell parameters from 3840 reflections
c = 11.8387 (7) Å	θ = 3.9–65.7°
α = 102.998 (5)°	µ = 2.16 mm⁻¹
β = 99.037 (5)°	T = 293 K
γ = 104.367 (4)°	Rod, colorless
V = 763.69 (7) Å³	0.20 × 0.15 × 0.10 mm

Data collection top

Agilent Xcalibur Onyx Nova diffractometer	2481 independent reflections
Radiation source: Nova (Cu) X-ray Source	2349 reflections with I > 2σ(I)
Mirror monochromator	R_int = 0.016
Detector resolution: 8.2417 pixels mm^-1	θ_max = 64.0°, θ_min = 3.9°
ω scans	h = −4→8
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2011)	k = −11→11
T_min = 0.712, T_max = 0.806	l = −13→13
4493 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.075	All H-atom parameters refined
S = 1.08	w = 1/[σ²(F_o²) + (0.0385P)² + 0.2467P] where P = (F_o² + 2F_c²)/3
2481 reflections	(Δ/σ)_max = 0.001
265 parameters	Δρ_max = 0.20 e Å⁻³
0 restraints	Δρ_min = −0.25 e Å⁻³

Crystal data top

C₁₀H₇N₃O₄S·C₅H₅N	γ = 104.367 (4)°
M_r = 344.35	V = 763.69 (7) Å³
Triclinic, P1	Z = 2
a = 6.9826 (3) Å	Cu Kα radiation
b = 10.0462 (5) Å	µ = 2.16 mm⁻¹
c = 11.8387 (7) Å	T = 293 K
α = 102.998 (5)°	0.20 × 0.15 × 0.10 mm
β = 99.037 (5)°

Data collection top

Agilent Xcalibur Onyx Nova diffractometer	2481 independent reflections
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2011)	2349 reflections with I > 2σ(I)
T_min = 0.712, T_max = 0.806	R_int = 0.016
4493 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.028	0 restraints
wR(F²) = 0.075	All H-atom parameters refined
S = 1.08	Δρ_max = 0.20 e Å⁻³
2481 reflections	Δρ_min = −0.25 e Å⁻³
265 parameters

Special details top

Experimental. Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
S1	0.13956 (5)	0.44049 (4)	−0.18461 (3)	0.02193 (13)
O2	0.38793 (16)	0.69194 (12)	−0.07942 (9)	0.0287 (3)
O4	−0.09371 (17)	0.24233 (13)	−0.40776 (9)	0.0379 (3)
O5	−0.23353 (17)	0.06550 (12)	−0.34113 (10)	0.0375 (3)
N6	−0.12170 (18)	0.18630 (14)	−0.32633 (11)	0.0274 (3)
N7	0.31757 (17)	0.56377 (13)	0.04990 (11)	0.0200 (3)
N8	0.59845 (19)	0.69146 (13)	0.49121 (11)	0.0275 (3)
C9	0.5749 (2)	0.80811 (15)	0.24522 (13)	0.0208 (3)
C10	0.5468 (2)	0.80762 (15)	0.12457 (12)	0.0201 (3)
N11	0.09847 (18)	0.33048 (13)	−0.00698 (11)	0.0225 (3)
C12	0.4136 (2)	0.68695 (15)	0.02405 (12)	0.0208 (3)
C13	−0.0197 (2)	0.22865 (17)	−0.10729 (14)	0.0241 (3)
C14	−0.0158 (2)	0.26888 (16)	−0.20893 (13)	0.0230 (3)
C15	0.8152 (2)	1.04417 (17)	0.29859 (14)	0.0290 (4)
C16	0.1899 (2)	0.44557 (15)	−0.03509 (12)	0.0196 (3)
C17	0.7287 (2)	0.61931 (18)	0.51622 (16)	0.0344 (4)
C18	0.5727 (3)	0.7465 (2)	0.69334 (16)	0.0470 (5)
C19	0.6541 (2)	0.92756 (16)	0.09458 (14)	0.0252 (3)
C20	0.7871 (2)	1.04502 (17)	0.17969 (15)	0.0296 (4)
C21	0.5227 (3)	0.75377 (18)	0.57844 (15)	0.0354 (4)
C22	0.7067 (3)	0.6728 (2)	0.71945 (17)	0.0518 (6)
C23	0.7866 (3)	0.6082 (2)	0.6301 (2)	0.0489 (5)
C24	0.7100 (2)	0.92842 (16)	0.33129 (14)	0.0251 (3)
O1	0.47188 (15)	0.69476 (11)	0.27650 (9)	0.0237 (2)
H19	0.631 (3)	0.9235 (18)	0.0134 (17)	0.029 (4)*
H24	0.725 (3)	0.9313 (19)	0.4158 (17)	0.032 (4)*
H20	0.857 (3)	1.127 (2)	0.1564 (17)	0.040 (5)*
H13	−0.093 (3)	0.138 (2)	−0.1026 (15)	0.028 (4)*
H15	0.906 (3)	1.122 (2)	0.3591 (17)	0.035 (5)*
H7	0.332 (3)	0.561 (2)	0.1221 (18)	0.033 (5)*
H17	0.779 (3)	0.575 (2)	0.4501 (18)	0.040 (5)*
H21	0.427 (3)	0.805 (2)	0.5559 (19)	0.052 (6)*
H22	0.739 (4)	0.670 (3)	0.799 (2)	0.075 (7)*
H18	0.514 (4)	0.800 (3)	0.762 (2)	0.068 (7)*
H23	0.877 (3)	0.558 (2)	0.641 (2)	0.056 (6)*
H25	0.525 (4)	0.698 (3)	0.355 (2)	0.073 (8)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.0230 (2)	0.0258 (2)	0.01336 (19)	0.00558 (15)	0.00094 (14)	0.00226 (14)
O2	0.0343 (6)	0.0325 (6)	0.0151 (5)	0.0044 (5)	0.0018 (4)	0.0073 (4)
O4	0.0353 (6)	0.0502 (7)	0.0181 (6)	0.0042 (5)	0.0012 (5)	0.0023 (5)
O5	0.0310 (6)	0.0309 (6)	0.0347 (7)	−0.0005 (5)	−0.0007 (5)	−0.0057 (5)
N6	0.0209 (6)	0.0329 (8)	0.0206 (7)	0.0062 (6)	0.0005 (5)	−0.0030 (6)
N7	0.0223 (6)	0.0237 (6)	0.0121 (6)	0.0062 (5)	0.0014 (5)	0.0033 (5)
N8	0.0310 (7)	0.0258 (7)	0.0186 (6)	−0.0012 (5)	0.0002 (5)	0.0063 (5)
C9	0.0200 (7)	0.0237 (7)	0.0195 (7)	0.0088 (6)	0.0045 (6)	0.0049 (6)
C10	0.0200 (7)	0.0232 (7)	0.0176 (7)	0.0096 (6)	0.0037 (6)	0.0035 (6)
N11	0.0227 (6)	0.0238 (6)	0.0200 (6)	0.0071 (5)	0.0034 (5)	0.0044 (5)
C12	0.0194 (7)	0.0249 (8)	0.0186 (7)	0.0086 (6)	0.0038 (6)	0.0051 (6)
C13	0.0208 (7)	0.0237 (8)	0.0249 (8)	0.0062 (6)	0.0032 (6)	0.0027 (6)
C14	0.0192 (7)	0.0255 (8)	0.0197 (7)	0.0064 (6)	0.0010 (6)	−0.0006 (6)
C15	0.0291 (8)	0.0231 (8)	0.0263 (8)	0.0031 (7)	0.0008 (7)	−0.0009 (7)
C16	0.0186 (7)	0.0247 (7)	0.0158 (7)	0.0097 (6)	0.0031 (5)	0.0030 (6)
C17	0.0292 (8)	0.0318 (9)	0.0379 (10)	0.0005 (7)	0.0043 (7)	0.0128 (8)
C18	0.0652 (13)	0.0402 (10)	0.0225 (9)	−0.0032 (9)	0.0079 (9)	0.0052 (8)
C19	0.0273 (8)	0.0267 (8)	0.0220 (8)	0.0086 (6)	0.0044 (6)	0.0078 (6)
C20	0.0320 (8)	0.0247 (8)	0.0300 (9)	0.0047 (7)	0.0058 (7)	0.0084 (7)
C21	0.0433 (10)	0.0320 (9)	0.0248 (9)	0.0046 (8)	0.0050 (7)	0.0047 (7)
C22	0.0655 (13)	0.0449 (11)	0.0231 (10)	−0.0172 (10)	−0.0096 (9)	0.0168 (9)
C23	0.0374 (10)	0.0422 (11)	0.0595 (14)	−0.0019 (9)	−0.0110 (9)	0.0292 (10)
C24	0.0268 (8)	0.0264 (8)	0.0187 (8)	0.0074 (6)	0.0022 (6)	0.0018 (6)
O1	0.0269 (5)	0.0253 (6)	0.0146 (5)	0.0025 (4)	0.0018 (4)	0.0048 (4)

Geometric parameters (Å, º) top

S1—C14	1.7269 (15)	C13—H13	0.944 (18)
S1—C16	1.7363 (14)	C15—C20	1.393 (2)
O2—C12	1.2240 (18)	C15—C24	1.382 (2)
O4—N6	1.2381 (17)	C15—H15	0.94 (2)
O5—N6	1.2265 (18)	C17—C23	1.383 (3)
N6—C14	1.4217 (19)	C17—H17	0.97 (2)
N7—C12	1.3775 (19)	C18—C21	1.373 (3)
N7—C16	1.3684 (19)	C18—C22	1.369 (3)
N7—H7	0.85 (2)	C18—H18	1.06 (2)
N8—C17	1.334 (2)	C19—C20	1.377 (2)
N8—C21	1.335 (2)	C19—H19	0.939 (18)
C9—C10	1.410 (2)	C20—H20	0.97 (2)
C9—C24	1.403 (2)	C21—H21	0.98 (2)
C9—O1	1.3483 (18)	C22—C23	1.381 (3)
C10—C12	1.481 (2)	C22—H22	0.94 (3)
C10—C19	1.403 (2)	C23—H23	0.92 (2)
N11—C13	1.365 (2)	C24—H24	0.983 (19)
N11—C16	1.3148 (19)	O1—H25	0.93 (3)
C13—C14	1.355 (2)

C14—S1—C16	86.32 (7)	N11—C16—S1	116.83 (11)
O4—N6—C14	116.98 (13)	N11—C16—N7	121.36 (13)
O5—N6—O4	124.16 (13)	N8—C17—C23	121.43 (18)
O5—N6—C14	118.86 (13)	N8—C17—H17	116.3 (11)
C12—N7—H7	119.5 (13)	C23—C17—H17	122.3 (11)
C16—N7—C12	123.00 (12)	C21—C18—H18	121.1 (13)
C16—N7—H7	117.4 (13)	C22—C18—C21	118.52 (19)
C17—N8—C21	118.94 (14)	C22—C18—H18	120.4 (13)
C24—C9—C10	118.84 (13)	C10—C19—H19	116.6 (11)
O1—C9—C10	120.13 (13)	C20—C19—C10	121.77 (14)
O1—C9—C24	121.02 (13)	C20—C19—H19	121.6 (11)
C9—C10—C12	124.80 (13)	C15—C20—H20	121.2 (11)
C19—C10—C9	118.97 (13)	C19—C20—C15	118.89 (15)
C19—C10—C12	116.22 (13)	C19—C20—H20	119.8 (11)
C16—N11—C13	109.77 (12)	N8—C21—C18	122.73 (18)
O2—C12—N7	119.41 (13)	N8—C21—H21	116.0 (13)
O2—C12—C10	123.02 (13)	C18—C21—H21	121.2 (13)
N7—C12—C10	117.56 (12)	C18—C22—C23	119.32 (17)
N11—C13—H13	120.4 (11)	C18—C22—H22	116.7 (16)
C14—C13—N11	114.35 (14)	C23—C22—H22	124.0 (16)
C14—C13—H13	125.2 (11)	C17—C23—H23	116.4 (15)
N6—C14—S1	120.07 (11)	C22—C23—C17	119.06 (19)
C13—C14—S1	112.72 (11)	C22—C23—H23	124.5 (15)
C13—C14—N6	127.21 (14)	C9—C24—H24	119.1 (11)
C20—C15—H15	121.3 (11)	C15—C24—C9	120.72 (14)
C24—C15—C20	120.79 (15)	C15—C24—H24	120.1 (11)
C24—C15—H15	117.9 (11)	C9—O1—H25	111.8 (16)
N7—C16—S1	121.81 (11)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N7—H7···O1	0.85 (2)	1.95 (2)	2.6248 (16)	135.9 (18)
O1—H25···N8	0.94 (2)	1.64 (2)	2.5671 (16)	175 (3)

Experimental details

Crystal data
Chemical formula	C₁₀H₇N₃O₄S·C₅H₅N
M_r	344.35
Crystal system, space group	Triclinic, P1
Temperature (K)	293
a, b, c (Å)	6.9826 (3), 10.0462 (5), 11.8387 (7)
α, β, γ (°)	102.998 (5), 99.037 (5), 104.367 (4)
V (Å³)	763.69 (7)
Z	2
Radiation type	Cu Kα
µ (mm⁻¹)	2.16
Crystal size (mm)	0.20 × 0.15 × 0.10

Data collection
Diffractometer	Agilent Xcalibur Onyx Nova diffractometer
Absorption correction	Multi-scan (CrysAlis PRO; Agilent, 2011)
T_min, T_max	0.712, 0.806
No. of measured, independent and observed [I > 2σ(I)] reflections	4493, 2481, 2349
R_int	0.016
(sin θ/λ)_max (Å⁻¹)	0.583

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.028, 0.075, 1.08
No. of reflections	2481
No. of parameters	265
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.20, −0.25

Computer programs: CrysAlis PRO (Agilent, 2011), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), OLEX2 (Dolomanov et al., 2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N7—H7···O1	0.85 (2)	1.95 (2)	2.6248 (16)	135.9 (18)
O1—H25···N8	0.94 (2)	1.64 (2)	2.5671 (16)	175 (3)

Acknowledgements

We thank Sun Yat-sen University for financial support of this work. We also thank Professor Xiaopeng Hu for the data collection.

References

Agilent (2011). CrysAlis PRO. Agilent Technologies, Yarnton, England. Google Scholar
Ashton, L. V., Callan, R. L., Rao, S. & Landolt, G. A. (2010). Vet Med Int. pii: 891010. Google Scholar
Broekhuysen, J., Stockis, A., Lins, R. L., De Graeve, J. & Rossignol, J. F. (2000). Int. J. Clin. Pharmacol. Ther. 38, 387–394. Web of Science CrossRef PubMed CAS Google Scholar
Bruno, F. P., Caira, M. R., Monti, G. A., Kassuha, D. E. & Sperandeo, N. R. (2010). J. Mol. Struct. 984, 51–57. Web of Science CSD CrossRef CAS Google Scholar
Chan-Bacab, M. J., Hernandez-Nunez, E. & Navarrete-Vazquez, G. (2009). J. Antimicrob. Chemother. 63, 1292–1293. Web of Science PubMed CAS Google Scholar
Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341. Web of Science CrossRef CAS IUCr Journals Google Scholar
Dong, F.-Y., Wu, J., Tian, H.-Y., Ye, Q.-M. & Jiang, R.-W. (2011). Acta Cryst. E67, o3096. Web of Science CSD CrossRef IUCr Journals Google Scholar
Dubreuil, L., Houcke, I., Mouton, Y. & Rossignol, J. F. (1996). Antimicrob. Agents Chemother. 40, 2266–2270. CAS PubMed Web of Science Google Scholar
Gargala, G., Delaunay, A., Li, X., Brasseur, P., Favennec, L. & Ballet, J. J. (2000). J. Antimicrob. Chemother. 46, 57–60. Web of Science CrossRef PubMed CAS Google Scholar
Hemphill, A., Mueller, J. & Esposito, M. (2006). Expert Opin. Pharmacother. 7, 953–964. Web of Science CrossRef PubMed CAS Google Scholar
Korba, B. E., Elazar, M., Lui, P., Rossignol, J. F. & Glenn, J. S. (2008). Antimicrob. Agents Chemother. 52, 4069–4071. Web of Science CrossRef PubMed CAS Google Scholar
Korba, B. E., Montero, A. B., Farrar, K., Gaye, K., Mukerjee, S., Ayers, M. S. & Rossignol, J. F. (2008). Antiviral Res. 77, 56–63. Web of Science CrossRef PubMed CAS Google Scholar
Megraud, F., Occhialini, A. & Rossignol, J. F. (1998). Antimicrob. Agents Chemother. 42, 2836–2840. Web of Science CAS PubMed Google Scholar
Navarrete-Vazquez, G., Chavez-Silva, F., Argotte-Ramos, R., Rodriguez-Gutierrez, M. C., Chan-Bacab, M. J., Cedillo-Rivera, R., Moo-Puc, R. & Hernandez-Nunez, E. (2011). Bioorg. Med. Chem. Lett. 21, 3168–3171. Web of Science CAS PubMed Google Scholar
Pankuch, G. A. & Appelbaum, P. C. (2006). Antimicrob. Agents Chemother. 50, 1112–1117. Web of Science CrossRef PubMed CAS Google Scholar
Rao, R. U., Huang, Y., Fischer, K., Fischer, P. U. & Weil, G. J. (2009). Exp. Parasitol. 121, 38–45. Web of Science CrossRef PubMed CAS Google Scholar
Rossignol, J. F., Abu-Zekry, M., Hussein, A. & Santoro, M. G. (2006). Lancet, 368, 124–129. Web of Science CrossRef PubMed CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Stachulski, A. V., Pidathala, C., Row, E. C., Sharma, R., Berry, N. G., Iqbal, M., Bentley, J., Allman, S. A., Edwards, G., Helm, A., Hellier, J., Korba, B. E., Semple, J. E. & Rossignol, J. F. (2011a). J. Med. Chem. 54, 4119–4132. Web of Science CrossRef CAS PubMed Google Scholar
Stachulski, A. V., Pidathala, C., Row, E. C., Sharma, R., Berry, N. G., Lawrenson, A. S., Moores, S. L., Iqbal, M., Bentley, J., Allman, S. A., Edwards, G., Helm, A., Hellier, J., Korba, B. E., Semple, J. E. & Rossignol, J. F. (2011b). J. Med. Chem. 54, 8670–8680. Web of Science CrossRef PubMed Google Scholar
Stettler, M., Fink, R., Walker, M., Gottstein, B., Geary, T. G., Rossignol, J. F. & Hemphill, A. (2003). Antimicrob. Agents Chemother. 47, 467–474. Web of Science CrossRef PubMed CAS Google Scholar
Trask, A. V., Motherwell, W. D. & Jones, W. (2004). Chem. Commun. pp. 890–891. Web of Science CSD CrossRef Google Scholar
Zhao, Z., Xue, F., Zhang, L., Zhang, K., Fei, C., Zheng, W., Wang, X., Wang, M., Zhao, Z. & Meng, X. (2010). J. Vet. Pharmacol. Ther. 33, 147–153. Web of Science CrossRef PubMed Google Scholar