A novel azo-type compound from Dendrolobium triangulare

Thirteen compounds from Dendrolobium triangulare (Retz.) Schindl. were isolated and purified by chromatography on silica gel, macroporous resin column and recrystallization method, and their structures were elucidated by chemical and spectral analyses as azo-2, 2′-bis Z-(2, 3-dihydroxy-4-methyl-5-methoxy) phenyl ethylene (1), β-sitosterol (2), N-(2′-hydroxy-tetracosanoyl)-2-amino-1, 3, 4-trihydroxyoctadec-8E-ene (3), lupeol (4), cycloeucalenol (5), daucosterol (6), butulinc acid (7), betulin (8), slyceryl hexaccsanoate (9), slyceryl 26-hydroxy hexaccsanoate (10), methyl phaeophorbide-a (11), acecetin-7-O-α-L-rhamnopyranosyl (1→6)-β-D- glucopyranoside (12) and robinin (13).  To our knowledge, all compounds are obtained from Dendrolobium  genus for the first time and compound 1 is a novel compound.  Moreover, it is understood that compound 1 has better protection against PC12 cell damnification deduced by glutamate, than that of Vitamin E in 2 μg·mL⁻¹ concentration.