New antitumor sesquiterpenoids from Santalum album of Indian origin

Abstract Three new campherenane-type ( 1 , 4 , 7 ) and three new santalane-type ( 9 , 11 , 12 ) sesquiterpenoids, and two aromatic glycosides ( 21 , 22 ) together with 12 known metabolites including α,β-santalols ( 14 , 18 ), ( E )-α,β-santalals ( 15 , 19 ), α,β-santaldiols ( 16 , 20 ), α-santalenoic acid ( 17 ), and vanillic acid 4- O -neohesperidoside were isolated from Santalum album chips of Indian origin. The structures of the new compounds, including absolute configurations, were elucidated by 1D- and 2D-NMR spectroscopic and chemical methods. The antitumor promoting activity of these isolates along with several neolignans previously isolated from the same source was evaluated for both in vitro Epstein–Barr virus early antigen (EBV-EA) activation and in vivo two-stage carcinogenesis assays. Among them, compound 1 exhibited a potent inhibitory effect on EBV-EA activation, and also strongly suppressed two-stage carcinogenesis on mouse skin.