Of morusin

Fig. (7). Reaction mechanism of photo-oxidative cyclization of morusin (3).

Fig. (8). Effects of morusin (3) on specific binding of [3H]TPA to a mouse skin particulate fraction.

Various concentrations of morusin ( ) or TPA (o) were incubated with a particulate fraction of mouse skin in the presence of 4 nmol/L [3H]TPA for 2 h at 4°C, and the assay mixture was filtered on glass filter membrane with acetone cooled in a dry ice-ethanol bath. Non-specific bindings were measured in the presence of 500-fold excess of unlabelled TPA. 

The more detailed data for the above these biochemical tests of morusin (3) were as follows [73]. As shown in Fig. (8), morusin (3) caused dose-dependent inhibition of the specific binding [3H]TPA to a mouse skin particulate fraction. The concentration of morusin (3) for 50% inhibition (ED5o) was 57 pmol/L, whereas that of unlabelled TP A was 4 nmol/L. 

The assay mixture (0.25 mL) contained 20 pmol/L CaClj, 7.5 pg of phosphatidylserine, 2.3 pmol/L teleocidin, and various concentrations of morusin (3) with 0.05 units of partially purified enzyme. Enzyme activity was measured as the incorporation of 32P from [y-32P]ATP into histone type lll-S during incubation for 3 min. at 30 C. 

While the other biochemical tests and the inhibition of tumor promotion of teleocidin in a two-stage carcinogenesis experiment have not been carried out, due to limitation in their amounts available, some of isoprenylated flavonoids from the moraceous plants showed the similar inhibitory potencies to those of morusin (3) and the related compounds, Figs. (6) and (12), as shown in Table 3. 

In order to clarify these points, we studied the C-NMR spectra of morusin (24) and related flavonoids with isoprenoid substituents... 

Two isomers of morusin monomethyl ether, 2 -0-methylmorusin (24 e) and 4 -0-methylmorusin (24 f), are formed on methylation of 24 with ethereal diazomethane in isopropyl alcohol and could be distinguished from each other by the Gibbs test. When a solution of 24 e was irradiated, starting material was recovered unchanged, but irradiation of 24f, gave morusinhydroperoxide monomethyl ether (49a). The structure of 49 was established as follows. The UV spectrum (X- ax 280 and 335 nm) resembled that of compound A (31) rather than that... 

Table 11. Antimicrobial Spectra of Morusin, Kuwanons, and Sanggenons... 

Phenolic Compounds of the Mulberry Tree and Related Plants Table 13. Effect of Morusin (24) on Tumor Promotion with Teleocidin... 

Nomura, T., T. Fukai, S. Yamada, and M. Katayanagi Studies on the Constituents of the Cultivated Mulberry Tree II. Photooxidative Cyclization of Morusin. Chem. Pharm. Bull. (Japan) 26, 1431 (1978). 

Nomura, T., and T. Fukai The Photo-sensitized Oxidation of Morusin. Heterocycles 8, 443 (1977). 

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