The root bark of Morus alba L. has been used as a blood pressure depressant in China and Japan from old times. The constituents of the root bark were well investigated by T. Nomura 1) and H. Hikino's 2) groups and many flavones and their derivatives were isolated as active principles. The leaves of this plant have also been used as a blood pressure depressant, but the constituents of the leaves have not yet been thoroughly investigated. We have investigated the pharmacological activities of the leaves of this plant and found that the butanol extracts of the leaves inhibit the increase of serum cholesterol and prevent atherosclerosis. 3a,b) In order to investigate the relationship of the constituents and the pharmacological activities of the leaves, we have studied the constituents of the butanol extracts of mulberry leaves. In this paper, we report the isolation and structural elucidation of two novel prenylflavanes (1, 2) and a glycoside (3) of 1 along with six known compounds, isoquercitrin (4), 4) astragalin (5), 5) scopolin (6), 6) skimmin (7), 7) roseoside II (8) 8) and benzyl D-glucopyranoside (9), 9) from the leaves of M. alba. The substitution pattern on the benzene rings was investigated by the analysis of heteronuclear multiple bond correlation spectroscopy (HMBC) spectrum of 1. As shown in (Fig. 2). The results of the NOE experiments and the spectral data mentioned above was satisfactorily explained by the structure (1) shown in Fig. 2. Results and DiscussionCompound 2 was obtained as an amorphous powder, [a] D Ϫ1.6°(cϭ1.0, MeOH). Its CI-MS spectrum showed the [MϩH] ϩ ion peak at m/z 341 corresponding to the molecular formula C 21 H 25 O 4 . Comparison of the 1 H-and 13 C-NMR spectra of 2 with those of 1 suggested that compound 2 is an isomer having the same framework as 1 and the structural difference should be the location of a methoxyl group. In the HMBC spectrum of 2, the methoxyl proton signal at d 3.74 showed a cross peak with the carbon signal at d 157.0 (C-7) which exhibited long range couplings with the proton signals at d 3.63-3.74 (H-1Љ) assignable to the methylene protons of a prenyl group. Furthermore, in the difference NOE experiments, irradiation of the methoxyl proton signal produced significant enhancement of the proton signal at d 6.57 due to February 2001 Chem. Pharm. Bull. 49(2) Two novel prenylflavanes (1, 2) and a glycoside (3) of 1 were isolated along with six known compounds, isoquercitrin (4), astragalin (5), scopolin (6), skimmin (7), roseoside II (8) and benzyl D-glucopyranoside (9), from the leaves of Morus alba. The inhibitory activities of compounds 1, 2 and 3 on the oxidation of human low density lipoprotein (LDL) were investigated.

Three of four natural compounds, which are caffeic acid, eupatilin and 4'-demethyleupatilin, isolated from Chinese plant, Artbmisia rubripes Nakai selectively inhibited 5lipoxygenase of cultured mastocytoma cells. Half-inhibition doses (1.50) for caffeic acid, eupatilin and 4' -demethyleupatilin were 3.7, 14 and 18 x 10e6 M, respectively. The inhibition by caffeic acid was non-competitive types. Prostaglandin synthase activities were little inhibited by eupatilin and 4'-demethyleupatilin, but rather stimulated by affeic acid. The formation of leukotriene C4 and D4 by mast tumor cells was almost completely suppressed by these compounds at 10m4 M. J-Lipoxygenase Inhibitor leukotriene Caffeic acid Prostaglandin synthease Lipoxygenase

Three new cytotoxic polyacetylenes, PQ-1 (1), PQ-2 (2) and PQ-3 (3), have been isolated from Panax quinquefolium. The structures of these acetylenes were determined by analyses of their 1H-1H and 1H-13C COSY spectra. All these compounds exhibited strong cytotoxic activities against leukemia cells (L 1210) in tissue culture.

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