H E R A C L E N I N FROM THE SEEDS OF P R A N G O S P A B U L A R I A Kh. S. Mukhamedova, S. T. Akramov, and S. Yu. Yunusov Khimiya Prirodnykh Soedinenii, Vol. 3, No. 1, p. 70, 1967 We have previously reported the isolation from a petroleum ether extract of the seeds of P. pabutaria Lindl. of an optically active furocoumarin derivative of the composition CzsI-I~40~, mp 105-106°C, [a] D + 26" (c 1.2; pyridine) [1]. When the seeds were extracted with ether, the yield of this substance amounted to 1.7% of the weight of the dry raw materialso L

By hydrating this furocoumarin with oxalic acid we obtained its hydrate C1d-t!GO6, mp 114-115°C (alcohol), and by isomerizing it with 10% sulfuric acid we obtained a substance of the composition Ctd-t1405, mp 132-184 ° C. All the properties of the substance with mp 105--106 ° C and of the products of its hydration and isomerization agreed with the properties of heraclenin, heraclenin hydrate (heraclenol) and isoheraclenin [2-4]. REFERENCES lo 2. 3. 4.

Kh. S. Mukhamedova, S. T. Akramov, and S. Yu. Yunusov, DAN UzSSR, no. 2, 39, 1968. Y. N. Sharma, A. Zaman, and A. R. Kidwai, Tetrah., 20, 87, 1964. B. K. Gupta et al. Ind. J. Chem., 2, 464, 1964. S. Sh. Kerimov, ZhPKh, 39, no. 3, 660, 1966.

21 October 1966

Institute of the Chemistry of Plant Substances, AS UzSSR

R E A C T I O N OF B E N Z O Y L - D , L - A R G I N I N E - p - N I T R O A N I L I D E 1-FLUORO-2, 4-DINITROBENZENE

WITH

I. A. Surova and V. M. Stepanov Khimiya Prirodnyk.h Soedinenii, Vol. 3, No. 1, pp. 70-71, 1967 tn studying the primary structure of proteins, the method of splitting them with trypsin is widely used. The latter hydrolyzes the peptide bonds of arginine and lysine. In some cases, it is necessary to modify the lysine residues in order to limit the action of the trypsin to the hydrolysis of the arginine bonds. Several methods have been proposed for blocking the e-amino group of lysine, for example, treatment with fluorodinitrobenzene (FDNB), which, as is generally assumed, reacts with the amino groups of proteins but does not attack the guanido groups of arginine [1]. It is known, however, that some acylating agents can react with the guanido group. In particular, there is information on the acylation of guanido groups in proteins with azlactones [2]. We have obtained results indicating that FDNB can also modify the guanido groups of arginine under certain conditions. Benzoyl-DL-arginine p-nitroanilide (BANA) was treated with a large excess of FDNB in water at pH 9.8 and 37 ° C. Paper electrophoresis at pH 8.0 and 1000 V showed that the reaction mixture contained not only dinitrophenol and unchanged BANA but also a neutral reaction product. This compound, which was an intense orange yellow, possessed a characteristic absorption spectrum in the UV with a maximum at 380 my (the absorption maximum of BANA is at 330 my). After the substance had been hydrolyzed with 6 N hydrochloric acid (24 hr, 110 ° C), paper electrophoresis showed the presence of arginine. The substance is unstable and decomposes into BANA and dinitrophenol even on standing in the light. The combination of properties suggests that FDNB reacts with the guanido group of BANA. Thus, the possibility of the modification of the arginine residues must be taken into account when FDNB is used for the specific blocking of the s - a m i n o groups of lysine. REFERENCES 1. Ro Pc Redfield and Ch. B. Anfinsen, J. Biol. Chem., 221, 385, 1956. 2. T. Baranowski, M. Kochman, K. Nowak, and I. Siemion, Bull. Acad. Polon. Sci., t l , No. 3, 107, 1963. 8 October 1966

Institute of the Chemistry of Natural Compounds, AS USSR 59