Acta Farnz. Borlaerense 18 (4): 271-5 (1999) Recibido el 10 de julio de 1998 Aceptado el 19 de julio de 1999 Trabajos originales Two New Macrocyclic Alkaloids from Albizia inopinata t Telmice Sirnoes de ASSIS l, Reinaldo Nóbrega de ALMEIDA l, Emídio V.L. da-CUNHA ' Isac A. de MEDEIROS l, Micheline de A. LIMA l, Maria de Fátima Vanderlei de SOUZA l. Marcelo Sobra1 da SILVA l, Raimundo BRAZ-FILHO and José Maria BARBOSA-FILHO l* l Laboratório de Tecnologia Farmac2utica, Universidade Federal da Paraíba, Caixa Postal 5009,58051-970, Joáo Pessoa, Paralba, Brazil. Setor de Química de Produtos Naturais - LCQUI-CCT - Universidade Estadual do Norte Fluminense, 28015-620, Campos, Rio de Janeiro, Brazil SUMMARY. Two new macrocyclic spermine alkaloids were isolated as a mixture from the leaves of Albizia inopinatu. These alkaloids are being reported here for the first time and were given the trivial names felipealbizine A and felipealbizine B. They were identified ,on the basis of spectroscopic techniques, including 2D NMR experiments, as well as by comparison with related compounds from previous reports. Preliminary studies indicated that the compounds shown a posible pharmacological depresor activity on the central nervous system. RESUMEN. "Dos nuevos alcaloides macrocíclicos de Albizia inopinata". De las hojas de Albizia inopinafa fue aislada una mezcla de dos nuevos alcaloides macrocíclicos del tipo espermina, denominados felipealbizina A y felipealbizina B. Los nuevos alcaloides fueron identificados en base a técnicas espectroscópicas, incluyendo RMN 2D y comparación con compuestos anteriormente publicados. Estudios farmacológicos preliminares indi- caron que estos compuestos muestran una posible actividad depresora en el sistema nervioso central. INTRODUCTION The family Leguniiriosae is widely distributed around the world, mainly in tropical, subtropical and temperate zones, where it is represented by trees of small to niedium size. The family is formed by severcil genera, including Albizia. There are aproximately 150 species of this genus, yet to be chernically studied. In Brazil, the species A. inopinata is found sparsely dis- tributed around tlie country, and is especially abundant in the Northeast. Its use in folk medicine is not known, but it is very used as or- namental tree in streets and squares 1. There are references to the use oí' the bark of Albizia juli6~issi~t for the treatnient of insoinnia 2 ancl the bark of Albizia Iebbek for the treatment of asthnia in India 3. Tliere is also a report of the use of Albizin zjgia ori psychiatric disordeis i ~ i Nigeria '. Studies with seeds of Albizia a/??a,n 5 suggested that this genus is rich in severa1 class- es of natural products such as saponins, lignans, steroids, triterpenes, and in some species, ma- crocyclic-type alkaloids. The absence of any ref- erence to Albizia inopinata on Chemical Abs- tracts and on the NAPRALERT database led us to investigate the occurrence of similar alkaloids in this species, as well as the biological activity of these constituents. MATERIAL AND METHODS Piant Materiul The leayes of Albizia inopinata (Harms) G.P. Lewis were collected near the city of Santa Rita, Paraíba, Brazil, in April 1997 and were identified by the botariist Maria de Fátima Agra. A voucher specimen (Agra e Gois 3599) is kept at the her- barium Prof. Lauro Pires Xavier, Joiio Pessoa, Paraíba, Brazil. KEY WORDS: Albiziri inopinotn, Leguiniiiosae, Macrocyclic alkaloid, Felipealbizine A, Felipealbizine B. PALABRAS CLAVE: Albiíici inopinntn. Leguiiiiiiosae, Alcaloide iiiacrocíclico, Felipealbizina A, Felipealbizina B * Autlior to whoiii conespoiideiice sliould be addressed. t Pan of this work was subiiiitted to the Universidade Federal da Paraíba, Joáo Pessoa, PB, Brasil, in partial fulfilment of an M.Sc. in Plianuacology iind Cheniistry of Natural Products.