Miscellaneous Diterpenoids

Full papers have appeared on the structures149 and absolute configuration150 of the decipiene diterpenoids. The structure (86) was assigned151 to a new member of this series on the basis of X-ray evidence. 

The defensive secretions of termites have afforded an unusual group of diterpenoids. Spectral and 26-ray crystallographic evidence has been presented for the structure (87) assigned to a secotrinervitane which was obtained152 from Nasu-titermes princeps. X-Ray crystallographic studies have also led to the structures of 

Cleomeolide (91) is an unusual bicyclic diterpenoid obtained156 from Cleome viscosa (Capparaceae). The Basidiomycetes contain a number of unusual terpenoid metabolites such as the cyathins. These have now been thoroughly reviewed.157 

Some aspects of the chemistry of lauren-l-ene, including the remote functionalization of other rings based on the I2-Pb(OAc)4 oxidation of laurenan-2-ols, have been described.158 X-Ray crystallographic evidence has been presented for the structure (92) of cinncassiol D, a pentacyclic diterpenoid from the dried bark of Cinnamomum cassia possessing anti-complement activity.159 

Tursch, Bull. Soc. chim. beiges, 1976,85, 801. 

A group of guaiane diterpenoids including dictyol B acetate (149) and dictyotadiol 

Sacculatal (155) and its C-9 epimer, isosacculatal, are two diterpenoid dialdehydes which contribute to the pungent odour of the liverwort, Trichocoleopsis sacculata. Their structures bear a resemblance to the sesquiterpenoid drimanes. A diterpenoid analogue of the cadinene group is found in the structure of dihy-droxyserrulatic acid (156), from Eremophila serrulata (Myoporaceae). 

Ptilosarcone (157) is a toxin which was isolated from the sea pen, Ptilosarcus gurneyi. Its structure was assigned by comparison of its n.m.r. spectrum with that of 

Danise, L. Minale, R. Riccio, V. Amico, G. Oriente, M. Piattelli, C. Tringali, E. Fattorusso, S. 

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Dil29 enl -13-epi -8,13-Epoxy-2-oxa-3- oxolabd-14-ene-W -carboxylic acid methyl ester Miscellaneous Diterpenoid E. agallocha EBV [124]... 

Tables 2-5 list monoterpenoids (Mo), sesquiterpenoids (Sq), diterpenoids (Di), and retinoids (Re), sesterterpenoids (St), meroterpenoids and miscellaneous terpenoids (Me), respectively, discussed in this review. The bioassay systems in which the compounds exhibited inhibitory effects, together with the major sources of the compounds, are included in the Tables. Most of these terpenoids are isolated from natural sources, and their structures are shown in Figs. (2)-(5). Some terpenoids which exhibit significant and/or a broad range of chemopreventive and anti-inflammatory activities are discussed below.

Cassane and Miscellaneous Tricyclic Diterpenoids The Chemistry of Ring A The Chemistry of Ring b The Chemistry of Ring c... 

Over the last seventy years over sixty species of Aristolochia have been exploited for chemical examination by research groups throughout the world and a variety of compounds have been isolated. The spectrum of physiologically-active metabolites from Aristolochia species covers 14 major groups based on structure aristolochic acid derivatives, aporphines, amides, benzylisoquinolines, isoquinolones, chlorophylls, terpenoids, lignans, biphenyl ethers, flavonoids, tetralones, benzenoids, steroids, and miscellaneous. The aristolochic acid derivatives, host of phenanthrene derived metabolites were further classified into aristolochic acids, sodium salts of aristolochic acids, aristolochic acid alkyl esters, sesqui- and diterpenoid esters of aristolochic acids, aristolactams, denitroaristolochic acids, and aristolactones. The terpenoids can further be subdivided into 4 groups mono-, sesqui-, di- and tetraterpenoids. 

Cassane and Miscellaneous Tricyclic Diterpenoids.—A group of furanoid diterpenoids, related to the caesalpins, has been isolated from Pterodon emargina-and P. pubescens. They include compounds (39—42). Some further diterpene alkaloids of the cassaic acid class have been isolated from Erythro-phleum ivorense. 

Miscellaneous Types of Sesquiterpenoid Alkaloids Diterpenoid Alkaloids... 

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