Three Novel Compounds from the Flowers of Bombax malabaricum

Two unusual 9′‐norneolignans, bombasin ( 1 ) and bombasin 4‐ O ‐ β ‐glucoside ( 2 ), and a novel D ‐gulono‐ γ ‐lactone derivative, bombalin ( 3 ), were isolated from the flowers of Bombax malabaricum , together with the three known compounds dihydrodehydrodiconiferyl alcohol 4‐ O ‐ β ‐ D ‐glucopyranoside ( 4 ), trans ‐3‐( p ‐coumaroyl)quinic acid ( 5 ), and neochlorogenic acid ( 6 ). Their structures were elucidated by extensive spectroscopic methods as well as chemical transformation. Compounds 1 – 3 were evaluated against the HGC‐27 gastrointestinal and Hela cervical human cancer cell lines, but all were inactive in both lines ( IC 50 >50 μ M ).