Pergamon 0031-9422(95)00912-4 Phytochemistry, Vol. 42, No. 1, pp. 129-133, 1996 Copyright © 1996 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0031-9422/96 $15.00 + 0.00 PODACYCLINE A AND B, TWO CYCLIC PEPTIDES IN THE LATEX OF JATROPHA PODAGRICA ALBERT J. J. VAN DEN BERG,* STEPHANF. A. J. HORSTEN,J. JANTINA KETrENES-VAN DEN BOSCH,t CEES J. BEUKELMAN, BURT H. KROES, BAS R. LEEFLANG:~ and RUDI P. LABADIE Department of Pharmacognosy and tDepartment of Pharmaceutical Analysis, Faculty of Pharmacy, Universiteit Utrecht, P.O. Box 80082, 3508 TB Utrecht, The Netherlands; :~Departmentof NMR Spectroscopy, Bijvoet Centre, Faculty of Chemistry, Universiteit Utrecht, Utrecht, The Netherlands (Received 19 September 1995) Key Word Index--Jatropha podagrica; Euphorbiaceae; cyclic peptides; podacycline A; podacycline B. Abstract--Two novel cyclic peptides were isolated from the latex of Jatropha podagrica, which we named podacycline A and B. Podacycline A is a cyclic nonapeptide with the sequence Glyl-Leu2-Leu3-Gly4-Ala5-Val6- Trp7-Ala8-Gly9-Glyl. The sequence of podacycline B, a cyclic heptapeptide, was determined to be Phel-Ala2- Gly-3-Thr4-Ile5-Phe6-Gly7-Phel. The amino acid residues of both compounds were found to have the L- configuration. INTRODUCTION In our search for immunomodulating plant constituents, a cyclic decapeptide and a cyclic nonapeptide were isolated from the latex of Jatropha multifida by an activity-guided fractionation procedure; both com- pounds inhibit classical pathway activity of human complement [1]. This led us to investigate also other Jatropha species for the presence of such peptides. As a result, several cyclic peptides were obtained, e.g. curcacycline A, a cyclic octapeptide, and cyclogossine A, a cyclic heptapeptide, isolated from the latices of J. curcas and J. gossypifolia, respectively [2, 3]. This paper deals with the isolation of two novel cyclic peptides from the latex of J. podagrica, which we named podacycline A and B, and the determination of their primary structures by a combination of amino acid analysis, FAB-mass spectrometry, and two-dimensional ~H NMR spectroscopy (HOHAHA and ROESY). The absolute configurations of the amino acid residues were also determined. RESULTS AND DISCUSSION Podacycline A and B were isolated from the latex of J. podagrica Hook. Both compounds showed a positive reaction with chlorine/o-tolidine reagent, which indi- cates the presence of amide groups [4]. By amino acid analysis, the acid hydrolysate of podacycline A was *Author to whom correspondence should be addressed. found to contain (molar ratio in parenthesis): Gly (glycine; 33.9), Ala (alanine; 27.8), Val (valine; 16.1), Leu (leucine; 32.2) and Trp (tryptophan; 11.9); im- monium ions (R---CH=NH~) in the FAB-mass spectrum indicated the presence of Gly (m/z 30), Ala (m/z 44), Val (m/z 72), Leu/Ile(isoleucine) (m/z 86), and Trp (m/z 130 and 159). The results of the amino acid analysis suggested that podacycline A contained two Gly, two Ala, one Val, two Leu, and one Trp, corre- sponding with a M r of 785. The FAB-mass spectrum, however, showed a [M + H] + at mlz 825, whereas in the HOHAHA spectrum [5] of podacycline A three spin systems characteristic of glycine could be assigned. Although (repeated) amino acid analysis resulted in rather low molar ratio values for glycine, it was concluded that podacycline A is a nonapeptide consist- ing of three (and not two) Gly, two Ala, one Val, two Leu, and one Trp, for which linear structure a M r of 842 is calculated. The actual M r of 824, however, indicates a loss of one H20; in addition, no sequence ions were observed in the FAB-mass spectrum. There- fore, it was concluded that podacycline A is a cyclic nonapeptide, containing three Gly, two Ala, one Val, two Leu, and one Trp. In the 'H NMR spectrum of podacycline A (and also B) three clusters of resonances could be observed characteristic of peptides, i.e. downfield amide and aromatic protons (8 9-7), aH protons (8 5-3), and upfield side-chain protons (8 2-0). In agreement with the results from amino acid analysis and FAB-mass spectrometry, the tH NMR spectrum of podacycline A showed resonances of 10 protons which could be 129