Wicher Barbara, Pyta Krystian, Przybylski Piotr, Tykarska Ewa, Gdaniec Maria
Faculty of Chemistry, Adam Mickiewicz University, 60-780 Poznań, Poland.
Acta Crystallogr C. 2012 May;68(Pt 5):o209-12. doi: 10.1107/S0108270112015296. Epub 2012 Apr 27.
Rifampicin belongs to the family of naphthalenic ansamycin antibiotics. The first crystal structure of rifampicin in the form of the pentahydrate was reported in 1975 [Gadret, Goursolle, Leger & Colleter (1975). Acta Cryst. B 31, 1454-1462] with the rifampicin molecule assumed to be neutral. Redetermination of this crystal structure now shows that one of the phenol -OH groups is deprotonated, with the proton transferred to a piperazine N atom, confirming earlier spectroscopic results that indicated a zwitterionic form for the molecule, namely (2S,12Z,14E,16S,17S,18R,19R,20R,21S,22R,23S,24E)-21-acetyloxy-6,9,17,19-tetrahydroxy-23-methoxy-2,4,12,16,18,20,22-heptamethyl-8-[(E)-N-(4-methylpiperazin-4-ium-1-yl)formimidoyl]-1,11-dioxo-1,2-dihydro-2,7-(epoxypentadeca[1,11,13]trienimino)naphtho[2,1-b]furan-5-olate pentahydrate, C(43)H(58)N(4)O(12)·5H(2)O. The molecular structure of this antibiotic is stabilized by a system of four intramolecular O-H···O and N-H···N hydrogen bonds. Four of the symmetry-independent water molecules are arranged via hydrogen bonds into helical chains extending along [100], whereas the fifth water molecule forms only one hydrogen bond, to the amide group O atom. The rifampicin molecules interact via O-H···O hydrogen bonds, generating chains along [001]. Rifampicin pentahydrate is isostructural with recently reported rifampicin trihydrate methanol disolvate.
利福平属于萘并安莎霉素类抗生素。1975年报道了五水合物形式的利福平的首个晶体结构[加德雷、古尔索勒、勒热和科莱特（1975年）。《晶体学报》B辑31卷，1454 - 1462页]，当时假定利福平分子呈中性。现在对该晶体结构的重新测定表明，其中一个酚 -OH基团发生了去质子化，质子转移至哌嗪的一个氮原子上，这证实了早期光谱学结果，即该分子呈两性离子形式，即（2S，12Z，14E，16S，17S，18R，19R，20R，21S，22R，23S，24E）-21 - 乙酰氧基 - 6,9,17,19 - 四羟基 - 23 - 甲氧基 - 2,4,12,16,18,20,22 - 七甲基 - 8 - [（E） - N - （4 - 甲基哌嗪 - 4 - 鎓 - 1 - 基）甲脒基] - 1,11 - 二氧代 - 1,2 - 二氢 - 2,7 - （环氧十五碳[1,11,13]三烯亚氨基）萘并[2,1 - b]呋喃 - 5 - 醇五水合物，C(43)H(58)N(4)O(12)·5H(2)O。该抗生素的分子结构通过四个分子内O - H···O和N - H···N氢键体系得以稳定。四个对称独立的水分子通过氢键排列成沿[100]方向延伸的螺旋链，而第五个水分子仅与酰胺基团的氧原子形成一个氢键。利福平分子通过O - H···O氢键相互作用，沿[001]方向生成链。利福平五水合物与最近报道的利福平三水合物甲醇溶剂化物同构。
