Flavonoid dimers from the total phenolic extract of Chinese dragon's blood, the red resin of Dracaena cochinchinensis.

Eight new flavonoid dimers, named cochinchinenins I–M ( 1 – 5 ), including three pairs of enantiomers ( 1a / 1b – 3a / 3b ) and two optically pure flavonoid dimers ( 4 – 5 ), along with a known analogue ( 6 ), were isolated from total phenolic extract of the red resin of Dracaena cochinchinensis (Chinese dragon's blood). The planar structures of 1 – 5 were elucidated by extensive spectroscopic analysis including HRESIMS and 1D/2D NMR. Their absolute configurations were determined on the basis of experimental and calculated electronic circular dichroism (ECD) data. Compounds 4 and 5 exhibited significant inhibition of nitric oxide production in lipopolysaccharide-stimulated BV-2 microglial cells with IC 50 value of 4.9 ± 0.4 and 5.4 ± 0.6 μM, respectively. [ABSTRACT FROM AUTHOR]