Weak C—H...X(X= O, N) hydrogen bonds in the crystal structure of dihydroberberine

Abstract

Dihydroberberine (systematic name: 9,10-dimethoxy-6,8-dihydro-5H-1,3-dioxolo[4,5-g]isoquinolino[3,2-a]isoquinoline), C20H19NO4, a reduced form of pharmacologically important berberine, crystallizes from ethanol without interstitial solvent. The molecule shows a dihedral angle of 27.94 (5)° between the two arene rings at the ends of the molecule, owing to the partial saturation of the inner quinolizine ring system. Although lacking classical O—H or N—H donors, the packing in the crystalline state is clearly governed by C—H···N and C—H···O hydrogen bonds involving the two acetal-type C—H bonds of the 1,3-dioxole ring. Each dihydroberberine molecule is engaged in four hydrogen bonds with neighbouring molecules, twice as donor and twice as acceptor, thus forming a two-dimensional sheet network that lies parallel to the (100) plane.

Polymorphism of bis(1,3-benzothiazol-2-yl) trithiocarbonate

“…Those contacts are identified as two C-HÁ Á ÁN hydrogen bonds (Table 1) between N1 and C6 and N2 and C15 with lengths of 3.467 (2) and 3.552 (2) Å , respectively. This is in the range of other C-HÁ Á ÁN hydrogen bonds reported previously (Mambanda et al 2007;Pingali et al, 2014). The fifth contact is a symmetric SÁ Á ÁS interaction between S3 and its adjacent symmetry-equivalent clone, with a distance of 3.509 (1) Å .…”

Comparative pharmacokinetics and safety assessment of transdermal berberine and dihydroberberine

“…DHB was synthesized according to a published method with slight modifications [ 29 ]. Briefly, a sodium borohydride (0.5 g) solution in 5% aqueous sodium hydroxide was added dropwise to a stirring solution of berberine chloride hydrate (5.0 g) and potassium carbonate (6.5 g) in methanol (100 mL) under nitrogen.…”

Tetrahydroberberine, a pharmacologically active naturally occurring alkaloid

“…The dihedral angle between the C 6 arene groups at the two ends of the molecule is 24.72 (5) , which is the simplest way to quantify its departure from planarity. The corresponding value in dihydroberberine was observed to be modestly larger at 27.94 (5) (Pingali et al, 2014).…”

“…In earlier work (Pingali et al, 2014), we described the structure of dihydroberberine in the crystalline state and noted that it shows a capacity to engage in CH 2 Á Á ÁX (X = O, N) hydrogen bonding that could have pertinence to the nature of interactions with in vivo systems. As noted in that report, dihydroberberine and derivatives of it show manifold pharmacological effects that may have use in the treatment of human disease.…”