Kuwanon

Morus alba callus and cell suspension cultures specifically produce chalomoradn 5 and kuwanon J 6 from dnnamoylpolyketide intermediates. Administration of [2- C]cinnamic add AT-acetylcysteamine thioester to the M. alba cell cultures revealed the cinnamoyl CoA intermediate to be a significant precursor <99H(50)989>. For further biosynthetic investip-tions see <99H(51)231>. 

About seventy kinds of new phenolic compounds could be isolated from Japanese cultivated mulberry tree (Morus alba, M. bombycis, and M, Ihou) and Chinese crude drug Sang-Bai-Pi (the root bark of Chinese mulberry tree). Most of them are isoprenylated flavonoids. Among them, kuwanon G (1) was the first isolation of the active substance exhibiting the hypotensive effect from the Japanese Morus alba root bark [9]. Furthermore, kuwanon G (1) and its isoprenylated derivative kuwanon H (2) [10] are considered to be formed through an enzymatic Diels-Alder type reaction of a chalcone and a dehydrokuwanon C or its... 

The root bark of the cultivated mulberry tree was extracted successively with n-hexane, benzene, and methanol. The methanol extract, 1—20 mg, showed a dose-dependent decrease in arterial blood pressure in pentobarbital-anesthetized rabbit, Fig. (4). The extract was fractionated successively by silica gel column chromatography (C.C.), polyamide C.C., silica gel preparative (p.) TLC, and p. HPLC leading to isolated of kuwanons G (1,0.2% yield) [9] and H (2,0.13% yield) [10]. 

Fig. (5). Effects of kuwanon G (1) and kuwanon H (2) on blood pressure. Electrocardiogram (ECG), phrenic nerve discharge (PN), and electroencephalogram (EEG) in a gallamine-immobilized rabbit...

On the other hand, in Japan, Sang-Bai-Pi (the root bark of Chinese mulberry tree) imported from China has been used as an herbal medicine, hence a study of the components of this crude drug purchased in the Japanese market was undertaken. Its phenolic components are different from those of Japanese mulberry tree. For example, morusin (3) and kuwanon G (1) are the main phenolic components of Japanese mulberry tree, in the case of Sang-Bai-Pi , these components are minor ones, while sanggenons A (4) [16], C (5) [17], and D (33) [61] are the main components [24]. Sanggenons C (5) and D (33) showed the hypotensive effects as follows Sanggenon C (5) caused transient decrease in arterial blood pressure at the doses of 1 mg/kg in pentobarbital-anesthetized rabbit by 15 mm Hg, while at the doses of 5 mg/kg the compound (5) caused a transient decrease by 100 mm Hg, which continued for more... 

VI. BOMBESIN RECEPTOR ANTAGONISTS, KUWANONS G (1) AND H (2), ISOLATED FROM MORUS SPECIES... 

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