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Natural cyanamide (NH2CN) has recently been found in three Leguminosae plants: Vicia villosa subsp. varia, Vicia cracca and Robinia pseudo-acacia. As cyanamide has long been thought to be absent in nature, its physiological role and biosynthesis are totally unknown. In the present study, we demonstrated the incorporation of 15N from [15N]nitrate and [15N]ammonium into cyanamide using shoots of V. villosa subsp. varia, which ruled out the possibility that nodules are essential in cyanamide biosynthesis. We also applied [15N2]cyanamide to shoots of V. villosa subsp. varia to monitor its turnover, and detected [15N2]cyanamide in the leaves within 4 h; it was present without detectable degradation for more than 4 days. In contrast, maximum incorporation of 15N into cyanamide molecules was observed after 4 days of feeding the shoots with 15N-labeled inorganic ions andl-[amide-15N]-glutamine, indicating that these nitrogenous compounds are distant precursors of cyanamide. Although the guanidino group ofl-arginine (-NH-C(NH2)=NH) and urea (NH2C(=O)NH2) were candidate precursors of cyanamide on the basis of structural similarity, direct incorporation of the guanidino group ofl-[13C6,15N4]-arginine and [13C,15N2]urea into cyanamide was not observed. These results eliminated the possibility that cyanamide is biosynthesized by the addition of ammonia to an electrophilic carbon or by the conversion of the tested compounds that were structurally relevant to cyanamide. [ABSTRACT FROM AUTHOR]

The article presents a simple analytical method for the quantification of cyanamide in plants. It further analyzes the cyanamide contents of the leaves, stems, cotyledons and roots of young seedlings of V. villosa and of the leaves of other Vicia species, Lens culinaris and Robinia pseudoacacia. It reports three advantages of this method over traditional ones which include requirement of less plant material, stable mass chromatogram and reduced risk of enzymatic activity.

The article presents a study which investigated the distribution of cyanamide in the plant kingdom using a direct quantitative determination method to detect and measure cyanamide by stable isotope dilution gas chromatography-mass spectrometry. The method proved to be a robust way to quantify cyanamide contents in the extracts of 101 species of herbaceous plants.

Abstract: Cyanamide (NH2CN) has recently been proven to be a natural product, although it has been synthesized for over 100 years for agricultural and industrial purposes. The distribution of natural cyanamide appears to be limited, as indicated by our previous investigation of 101 weed species. In the present study, to investigate the distribution of natural cyanamide in Vicia species, we monitored the cyanamide contents in V. villosa subsp. varia, V. cracca, and V. amoena during their pre-flowering and flowering seasons. It was confirmed that V. cracca was superior to V. villosa subsp. varia in accumulating natural cyanamide, and that V. amoena was unable to biosynthesize this compound under laboratory condition examined. The localization of cyanamide in the leaves of V. villosa subsp. varia seedlings was also clarified. In a screening study to find cyanamide-biosynthesizing plants, only Robinia pseudo-acacia was found to contain cyanamide among 452 species of higher plants. We have investigated 553 species to date, but have so far found the ability to biosynthesize cyanamide in only three species, V. villosa subsp. varia, V. cracca and R. pseudo-acacia. [Copyright &y& Elsevier]