Abyssinine

TriOH-3 -OMe 5 -Pr C21H22O6 370 Abyssinin II Erythrina abyssinica Leguminosae StemB 86... 

The fresh root bark (2 kg) of abyssinica was collected near Kakamega, Kenya, in 1981, and extracted with aqueous methanol. The Isolation scheme 1s depicted in Figure 1. The crude extract was concentrated, and the residue was extracted with hexane, methylene chloride, and ethyl acetate. The bioactive methylene chloride extract was chromatographed on silica gel. A CHCI3-CH3OH (20 1) elution gave crude abyssinin (200 mg). 

Further elution with CHCI3-CH3OH (10 1) gave a mixture of crude abyssinol A, B, and C (20 mg). This mixture was further separated by TLC (Si02, CHCI3-CH3OH 10 1) into the three fractions composed of crude abyssinol A, B, and C, respectively. Each of the crude fractions of abyssinin, abyssinol A, B, and C still showed two spots with a ca. 1 1 ratio on TLC. The H NMR spectra of these crude fractions indicated that each fraction contained two structurally similar compounds epimeric at C-17. 

Figure 4. Groups contained by abyssinin as shown by the spectral data.

Isolated allylic 8-H at 3.05 ppm (1.8 Hz), this oleflnic proton was placed at C-15 to replace the methoxy group found in abyssinin. The UV spectral data are consistent with this. 

As a result, we isolated only abyssinin as an insect growth inhibitor while monitoring by an artificial diet feeding assay. 

Thus, the growth Inhibitory activity of abyssinin (I) compared to abyssinols (II-IV) could be attributed to a potent antifeedant effect which can cause starvation. Accordingly, the antifeedant activities of the abyssinols (II-IV) appear not to be strong enough as to force starvation. 

Derivatives A/,A/-Dimethyl-dihydro-abyssinine-C = A/-Methyl-dihydro-abyssinlne-B (132) A/-Acetyl-abysslnine-C (132)... 

Scutianine-A, -B, -C, -D and -E (hydrochloride salts) (18), mauritine-A, -B, -C, -D and -E (hydrochloride salts) (42) and mucronine-F, -G and -H (hydrochloride salts) (132) inhibited development of Pythium debaryanum. Pubescine-A and abyssinine-C showed fungicidal effect against P. debaryanum and Trichoderma viride (20, 132). 

Mauritine-E (124) Mauritine-F (121) Mauritine-H (123) Melofoline (51) Melonovine-A (46) Melonovine-B (64) 4-Methoxy-abyssinine-A 4-Methoxy-abyssinine-C A Methyl-americine (68)... 

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