Elution with CHCl3-MeOH (50:3) gave a crystalline compound, m.p. 190-191.5°C (MeOH), which was identified as siderin, 4,7-dimethoxy-5methylcoumarin (reported [2,3] m.p. 194–195°C) by UV, IR, NMR, MS and comparison with an authentic sample prepared by synthesis [4]. Siderin, a biogenetically novel coumarin [2], has previously been isolated only from the two Sideritus species (Labiatae), S. romana L. [2], and S. canadensis Ait [3]. The chipped stem and bark (24 kg) of Bruguiera cylindrica (L.) BL. (Rhizophoraceae) from Klang, Malaya was extracted with CHCl3 at 50-60°C. The extract was concentrated to give a dark brown solid, which was chromatographed on a silica gel column firstly with CHCl3 and then with MeOH-Me2CO-C6H6 (2:1:1) as solvents. The eluted fraction was rechromatographed on an aluminium oxide (Al2O3) column with Me2CO-C6H6 (1:1), yielding brugine, (+)-tropine 1,2-dithiolane-3-carboxylate (50 mg). Brugine has the molecular formula C12H19NO2S2, [α]D2.5 -23 (c, 3.5 in CHCl3), m/e 273 (with isotopic ion peaks at M + 1 and M + 2), vmax (CHCl3) 1727 (-CO-O-), λmax (EtOH) 278 nm (ε 360) and 324.3 nm (sh), and δppm data (4.93 (t, 1H (-CH2)=CH-O-), 4.17 (dd, 1H, J 7.7 -S-(-CO)-CH-CH2), 3.8–2.5 (m, 6H), 2.27 (s, 3H, -N-Me), 1.55-2.02 (m, 8H)) consistent with published data [1,2]. Hydrolysis of brugine overnight at room temperature in 0.05 N NaOH in 50% EtOH gave, after extraction with CHCl3, tropine (mp 62°C) which was identical to an authentic sample in NMR, IR and MS.