Synthesis and antidiabetic activity of 5,7-dihydroxyflavonoids and analogs.

In a study to evaluate the structural elements essential for the antidiabetic activity of flavonoids, we synthesized two series of flavonoids, 5,7-dihydroxyflavanones and 5,7-dihydroxyflavones. In a screening for potential antidiabetic activity, most of the flavonoids showed a remarkable in vitro activity, and compounds 1f, 2d, and 3c were significantly more effective than the positive control, metformin. The biological activity was mainly affected by structural modification at the ring B moiety of the flavonoid skeleton. The results suggest that 5,7-dihydroxyflavonoids can be considered as promising candidates in the development of new antidiabetic lead compounds.

(S,E)-N-Methyl-4-[(S)2,6,6-trimethyl-4-oxocyclo-hex-2-en-yl]but-3-en-2-aminium chloride.

The title compound, C(14)H(24)NO(+)·Cl(-), crystallizes with four independent mol-ecules in the asymmetric unit. It was isolated from plant Pachysandra terminalis Siebold & Zucc. The six-membered ring has a conformation close to an envelope. In the crystal, N-H⋯Cl hydrogen-bonding inter-actions exist between secondary ammonium groups and free chloride anions, resulting in a one-dimensional supra-molecular structure oriented along [100]. The crystal studied was found to be a two-component non-merohedral twin with twin law [[Formula: see text]00/0[Formula: see text]0/101], the fractional contribution of the minor component being approximately 33%.

(E)-1-[2-Hy-droxy-4,6-bis-(meth-oxy-meth-oxy)phen-yl]-3-[3-meth-oxy-4-(meth-oxy-meth-oxy)phen-yl]prop-2-en-1-one.

The title compound, C(22)H(26)O(9), crystallizes with two independent mol-ecules in the asymmetric unit in which the dihedral angles between the two benzene rings are 21.4 (2) and 5.1 (2)°. An intra-molecular O-H⋯O hydrogen bond occurs in each mol-ecule. Inter-molecular C-H⋯O hydrogen bonds stabilize the crystal structure.