Broussonetia

Rice paper is the widely used misnomer for two entirely different materials also made in the form of thin sheets Chinese kung-shu, which is not paper (see text below) and washi. Also known as Japanese rice paper, washi is paper made from the cellulose fibers derived from the bark and branches of mulberry trees (Broussonetia kajinoki) (Inaba and Sugisita 1988 Barrett 1988). 

M. Shibano, S. Kitagawa, and G. Kusano, Studies on the constituents of Broussonetia species. I. Two new pyrrolidine alkaloids, broussonetines C and D, as (l-galactosidasc and P-mannosidase inhibitors from Broussonetia kazinoki SIEB., Chem. Pharm. Bull., 45 (1997) 505-508. 

Fang, S.-C. et al., Isoprenylated flavonols of Formosan Broussonetia papyrifera. Phytochemistry, 38, 535, 1995. 

Chen, R.M. et al.. Natural PTPIB inhibitors form Broussonetia papyrifera, Bioorg. Med. Chem. Lett., 12, 3387,2002. 

Matsumoto, J. et al., Components of Broussonetia papyrifera. I. Structures of the two new isoprenylated flavonols and two chalcone derivatives, Chem. Pharm. Bull, 33, 3250, 1985. 

The genus Broussonetia L Her. ex Vent, of the Moraceae (mulberry family) is represented by lactiferous trees or shrubs. Broussonetia comprises about 30 species and is distributed throughout various regions of the world including Africa, East Asia, and North America [1,2]. Thus far, only three species of the genus Broussonetia have been studied for their secondary metabolites, namely, B. kazinoki, B. papyrifera, and B. zeylanica. 

Broussonetia kazinoki Siebold Zucc. is a deciduous tree growing to 4.5 m that flowers in August. It occurs in mainland China, Japan, and Korea [1]. The plant requires well-drained soil but can grow in... 

Broussonetia zeylanica (Thwait.) Comer is endemic to Sri Lanka and its tough bark-fibers were used to make string [15]. 

Several types of bioactive compounds have been reported from the genus Broussonetia including glycosidase inhibitory alkaloids and aromatase inhibitory or cytotoxic flavonoids. This chapter reviews the biologically active constituents from the genus Broussonetia reported by the end of 2001. 

The bioactive secondary metabolites reported from Broussonetia kazinoki can be classified into major two groups, alkaloids and flavonoids (Table 1), Fig. (1). The Kusano group at Osaka University of Pharmaceutical Sciences in Japan reported over 20 pyrrolidine alkaloids, broussonetines A-H, K-M, O-T, V-X, and Mi, and broussonetinines A and B, four pyrrolidinyl piperidine alkaloids, broussonetines I, J, Ji, and J2, two pyrroline alkaloids, broussonetines U and U, and one pyrrolizidine alkaloid, broussonetine N, from hot water extracts of B. kazinoki [16-24]. As shown in Table 1, some of these alkaloids exhibited strong... 

Table 1. Bioactive Compounds from Broussonetia kazinoki...

The major types of bioactive constituents reported from Broussonetia papyrifera are the prenylated flavonoids, which include compounds of the diphenylpropane, chalcone, flavan, flavanone, flavone, flavonol, and aurone classes (Table 2), Fig. (7). An early study on B. papyrifera resulted in the isolation of two diphenylpropanes, broussonins A (29) and B (30), and a coumarin, marmesin (52), with antifungal activity [39]. Also, a diprenylated diphenylpropane derivative, kazinol F (31) [40], was reported as an antioxidant and tyrosinase inhibitory constituent [34]. 

Antiproliferation activity shown by the inhibition of [3H]thymidine incorporation into DNA in the proliferation of rat vascular smooth muscle cells. The effect was expressed as % of control 45 0-7.8,46 0-0.4. kActivity found as a constituent of a plant other than a Broussonetia species. 

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