Chemistry for Sustainable Development 11 (2003) 697–703 697 INTRODUCTION The present review provides grouping of natural metabolites allied with each other (higher terpenes and steroids), with the me- tabolites which represent a kind of the frag- ments of larger molecules, including such widespread terpenoids and steroids as oxy- gen-containing heterocyclic fragments of the furan and pyran series. The review is a logical continuation of the series of papers dealing with halogenated terpenoid and acetogenin metabolites [1–5]. FURANONES OF SEAWEEDS AND INVERTEBRATES Halogenated furanones are a group of rare- ly occurring metabolites extracted from sea organisms. A brief description of them is pre- sented in [6, 7]. The red alga Delisea fimbriata living near the north-eastern coast of Austra- lia contains really rare set of halogenated fu- ranones (1)–(17) [8]. Uniqueness of this alga as a generating species is connected with its abil- ity to generate lactones the molecules of which comprise only one of three halogens (chlorine, bromine, iodine). It is typical that neither of Natural Halogenated Furanones, Higher Terpenes and Steroids VALERY M. DEMBITSKY 1 and GENRICH A. TOLSTIKOV 2 1 Department of Pharmaceutical Chemistry and Natural Products, School of Pharmacy, The Hebrew University of Jerusalem, P. O. Box 12065, Jerusalem 91120 (Israel) E-mail: dvalery@cc.huji.ac.il 2 Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, Pr. Akademika Lavrentyeva 9, Novosibirsk 630090 (Russia) E-mail: gtolstik@nioch.nsc.ru (Received March 18, 2002) Abstract Natural halogenated furanones, higher terpenes and steroids comprising three relatively small groups of natural compounds were isolated mainly from sea organisms, as well as from some plant species. The struc- tures of about 90 compounds are considered and the data on the biological activity of some of them are presented. Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 697 Furanones of seaweeds and invertebrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – Furanones in natural water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 699 Higher terpenes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 700 Steroids of plants and sea organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 701