Diterpene derivatives

Makinoa crispata (Steph.) Miyake from Japan was shown by Hashimoto et al. (1989) to contain diterpene derivatives of the sort illustrated as [466-469] (see Fig. 5.7 for stractures). More recently, Liu and Wu (1997) reported the presence of the rearranged abietane-type diterpenoid derivative makanin [470] from plant material of M. crispata collected on Taiwan. Of note was the apparent absence of any of these compounds in the Japanese plants. 

Biologically active secondary metabolites from fungi. 12. Oidiolactones A-F, labdane diterpene derivatives isolated from Oidiodendron truncata. John, M. Krohn, K. Florke, U. Aust, H-J. Draeger, S. Schulz, B. J. Nat. Prod. 1999, 62, 1218-1221. 

The marine isothiocyanates, with more than 80 compounds isolated so far, form the largest group of naturally occurring isothiocyanates. This well-established group of marine natural products is constituted mainly by terpene metabolites present as sesquiterpene and diterpene derivatives. The non-terpene isothiocyanate compounds include two cylindricine alkaloids and a series of long-chain aliphatic metabolites. Marine sponges constitute the main source of these compounds, although they are also found in nudibranches and tunicates. 

The diterpene derivative 1 was treated with BF3-OEt2 and AC2O in an attempt to induce a "pinacol-type rearrangement leading to a ring B-homo derivative. No such reaction was observed. Instead, the only product which could be isolated (33%) was shown to be 2, formed by "a profound backbone rearrangement" of 1. 

Aconites, commonly called wolfsbane or monkshood, are species of Aconitum (Ranunculaceae), valued ornamental herbaceous plants, grown for their showy blue or purple flowers, which are shaped like a monk s cowl. Their alkaloid content, mainly in the roots, makes them some of the most toxic plants commonly encountered. The dried roots of Aconitum napellus were once used, mainly externally for relief of pain, e.g. in rheumatism. The toxic alkaloids (0.3-1.5%) are complex diterpene-derived esters. Aconitine (Figure 6.124) is the principal component (about 30%) and is a diester of aconine with acetic and benzoic acids. Hydrolysis products benzoylaconine and aconine are also present in dried plant material. These alkaloids appear to behave as neurotoxins by acting on sodium channels. All species of Aconitum and Delphinium are potentially toxic to man and animals and must be treated with caution. 

The rosin component of tall oil is mostly made up of resin acids, which are diterpene derivatives. The major compounds (figures indicate averages) are as follow ... 

Taxane and its derivatives have not been included in this chapter, since none of the Taxus constituents recently isolated contains nitrogen. These are properly regarded as diterpene derivatives, and are reviewed as such by Dr. J. Hanson in the Specialist Periodical Report on Terpenes and Steroids (Senior Reporter Dr. K. Overton).—J.E.S. 

To date more than 100 species from the large genus Baccharis have been investigated chemically. The most widespread compounds are clerodane diterpene derivatives, but labdane derivatives have also been isolated. Furthermore, typical acetylenic compounds, baccharis oxide, a unique triterpene, and derivatives of hydroxyacetophenone are present, although it is mainly other biologically active constituents, e.g. flavonoids, sesquiterpenes and essential oils that have been reported in the last years. The constituents of Baccharis species compiled from different sources are presented below. 

Approximately 5 000 naturally abundant acyclic and cyclic diterpenes derived from the parent hydrocarbon phytane are known The (3i ,7i ,ll )-enantiomer of phy-tane has been found in meteorites, oil slate, other sediments and, last but not least, in human liver. Oil slate additionally eontains (-)-(3if,7if,llif)-phytanoic acid which has also been isolated from butter. 1,3(20)-Phytadiene is one among many constituents of tobacco Nicotiana tabacum (Solanaceae) -1,3-phytadiene and its (%)-isomer are found in zooplankton. Chlorophyll in the chloroplasts of plant cells exemplifies an ester of +)-(lE,lR, l/ )-2-phyten-l-ol usually referred to as phytol. 2,6,10,14-Phytatetraene-l,19-diol, better known as plaunotol, is the ehief constituent of the leaves of flie Thai medicinal plant Croton sublyratus (Euphorbiaceae) used as "plau noi" or "kelnac" as an antiulcerative. 

Mono- and Bicyclic Diterpenes derived from Phytane... 

APPLICATION TO SOME DITERPENE DERIVATIVES WITH OCTAHYDROPHENANTHRENE STRUCTURE... 

Fig. 12 CD-curves of 3 diterpene derivatives (16,17,18) with only one additional substituent on the benzene chromophore.

Diterpenes Derived from Monocyclic Precursors Cembrene Taxanes... 

Fig. 22.6. Diterpenes derived from a monocyclic precursor (modified from Adolf and Hecker, 1977 used with permission of the copyright owner. Laser Pages Publishing, Ltd., Israel).

Back in 1958, Demole and Lederer [43] reported the separation of 4 diterpene derivatives. They chromatographed with n-hexane-ethyl acetate (85 + 15) on silica gel layers which had been prepared according to Reitsema [209]. The following hi /-values serve as rough guides phytol 35, isophytol 50, geranyl-linalool 44, phytyl acetate 66. 

Phillipson JD, Wright CW, Kirby GC, Wrhurst DC (1995) Structure and biological activity of sesquiterpene and diterpene derivatives horn medicinal plants. In Hostettmann K, Marston A, Maillard M, Hamburger M (eds) Phytochemistry of the plants used in traditional... 

These result from the condensation of two (monoterpenes), three (sesquiterpenes), four (diterpenes), six (triterpenes), or eight (tetraterpenes) isoprene residues. The lower terpenes are widely distributed in the essential oils of many plants. Phytol, ah imsaturated alcohol present in the chlorophyll molecule, is a diterpene derivative. 

The chlorophylls are methylphytol esters of the chlorophyllines, which are the corresponding acids. These are neutral substances containing magnesium in a non-ionic form. A hydrolase, called for this reason chloro-phyllase, splits off from chlorophylls a C-20 (with one double bond) aliphatic alcohol which is a diterpene derivative named phytol (see p. 31). 

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