A comparison of the alkaloids of the fasciated and non-fasciated stems in two species of Sophora

Abstract

Fasciations are flattened, ribbon shaped deformities of the stem tip or other parts of the plant which arise unpredictably and sporatically on higher plants. These growths which proliferate rapidly have been compared to cancers or monstrosities of the plant. The causes of fasciations are still under investigation and may involve a hormonal imbalance in the plant due to genetic, environmental, biological and chemical factors. At the present time, experimental methods have been developed to induce some forms of fasciations. The effects of fasciations on the secondary plant constituents are of pharmaceutical and medicinal interest since these growths may alter the chemical composition of the plants. These changes may produce novel drugs at the site of fasciation. Alternatively, fasciations may lead to higher yields of useful natural products from medicinal plants. Two plants from the same genus, Sophora secundiflora and S. tomentosa, were observed to possess a limited number of fasciated stems. Since pharmaceutically active alkaloids have been reported in the genus, this group of compounds was used in a chemical comparison to detect variability between the stem types. Classical (liquid, column, preparative and thin-layer chromatography techniques) and more recent (gas chromatography, high pressure liquid chromatography, combined gas chromatography-mass spectrometry) methods were developed to separate, isolate and purify eleven alkaloids present in both stem types. Structural characterization of these eleven alkaloids was accomplished utilizing chemical and physical tests, melting points and mass, ultra-violet, infrared and nuclear magnetic resonance spectral data. Compounds previously reported from S. secundiflora by several authors are epi-lupinine, sparteine, β-isosparteine, cytisine, N-methylcytisine, 11-allyl cytisine, lupanine, Δ5,6-dehydrolupanine, rhombifoline, anagyrine and thermopsine. In our analysis of the normal and fasciated stem of S. secundiflora all but three of these compounds were encountered: 11-allyl cytisine, β-isosparteine and thermopsine. Two quinolizidine alkaloids were detected in the stems which had not been reported previously in this plant, N-formyl cytisine and N-acetyl cytisine. Compounds previously reported from S. tomentosa are N-methylcytisine, matrine, matrine N-oxide, baptifoline, N-acetyl cytisine and anagyrine. In our analysis matrine, cytisine, N-acetyl cytisine, anagyrine and N-methylcytisine were detected by a combination of gc-ms and other techniques. Also detected by this method were epilupinine and N-formyl cytisine, two previously unreported alkaloids from this species of Sophora. The differences observed between the two stem types of the same species were of quantitative nature. Overall the amount of the major alkaloid, cytisine in S. secundiflora and matrine in S. tomentosa, was reduced in the fasciated stem when compared to the non-fasciated stem and an internal standard. Other alkaloid constituents were either increased, reduced or remained the same. Noteworthy of these alkaloids with higher concentrations in the fasciated stems were sparteine in S. secundiflora (considered to be a precursor to cytisine) and the cytisine group of compounds (considered to be a biogenetic branch from matrine) in S. tomentosa