Diterpenoids properties

The benzannulation reaction of ethynylferrocene 120 with the diterpenoid chromium alkoxycarbene 119 leads to novel diterpenoid ferrocenyl quinones 121 which, due to their electron-transfer properties, are regarded as potential candidates for non-linear optical materials [71] (Scheme 52). 

Januario AH, Simone LS, Silvana M, et al. Neo-clerodane diterpenoid, a new metallo-protease snake venom inhibitor from Baccharis trimera (Asteraceae) anti-proteolytic and anti-hemorrhagic properties. Chem Biol Interact 2002 150 243-251. 

Barriault developed a new pericyclic domino process for the synthesis of the bioactive diterpenoid vinigrol (4-262), which was isolated from Vtrgaria nigra [92]. The natural product possesses antihypertensive and anti-platelet-aggregating properties. 4-262 contains a unique tricyclo [4.4.4.04a8a]tetradecane framework, which could be obtained by a combination of an oxy-Cope, a Claisen and an ene reaction... 

The most important manoyl oxide derivative is forskolin (9), Fig. (7), (7p-acetoxy-8, 13-epoxy-la, 6p, 9a-trihydroxylabd-14-en-ll-one) [151-153]. It belongs to the labdane series of diterpenes and was isolated from the Indian herb Coleus forskohlii (Willd.) Briq. (Labiatae). Since ancient times it has been used in Hindu and Ayurvedic traditional medicine [154]. The plant Coleus forskohlii (Willd.) Briq. has been extensively studied, and from its extracted roots a group of diterpenoids, with the basic skeleton of 11-oxo-manoyl oxide, have been isolated. The main compound, forskolin, presented remarkable chemical and biological properties [155]. Analogues of forskolin were then prepared by semisynthesis [156] or obtained by microbial transformations [157]. New analogues, more soluble than forskolin have shown activities comparable to and even higher than forskolin [158]. 

From the marine alga Stypopodium flabelliforme, several diterpenoids with interesting biological properties were isolated. The diterpenoid epitaondiol exhibited a potent anti-inflammatory activity related to inhibition of human PLA2 activity and leukocyte accumulation [64], Additionally, epitaondiol has been shown as a potent calcium antagonist in... 

Numerous UCNMR investigations on alkaloids have been reported in the literature [598, 599]. In Table 5.13 the 13C chemical shifts and structures of representative alkaloids of different types are collected Pyrrolidine, piperidine and pyridine [600-602], tropane [600, 603-605], izidine [606-612], indole [600, 603, 613-633], isoquinoline [599, 630, 634-647], quinolinic [648-656], imidazole [657], yuzurimine alkaloids [658], alkaloids with exocyclic nitrogen [659, 660], diterpenoid [661-663], steroid [664-666] and peptide alkaloids [667-671], The complete signal assignment for the alkaloids given in Table 5.13 was achieved using the correlations between 13C NMR spectral parameters and structural properties and the 13C chemical shift values of model compounds described in Chapters 3 and 4 of this monograph. 

The diterpenoid alkaloids, isolated mainly from Aconitum and Delphinium species (Ranunculaceae), have been of great interest since the early 1800s because of their pharmacological properties. Extracts of Aconitum species were used in ancient times for treatment of gout, hypertension, neuralgia, rheumatism, and even toothache. Extracts have also been used as arrow poisons. Some Delphinium species are extremely toxic and constitute a serious threat to livestock in the western United States and Canada. Delphinium extracts also manifest insecticidal properties. In the last 30 to 40 years, interest in the diterpenoid alkaloids has increased because of the complex structures and interesting chemistry involved. 

Included in this chapter is a catalog of all known C20-diterpenoid alkaloids showing the correct structures, physical properties, plant sources, and key references. Previously published books (19 21) and recent reviews (15-16) have reported incorrect structures for several well-known C20-diterpenoid alkaloids. This catalog should be very useful for it presents in a single place important structural information on the C20-diterpenoid alkaloids that has been scattered through hundreds of papers and dozens of review articles. 

The literature of Cnidara includes 2444 articles comprised of 3744 chemical structures.27 Included within this impressive list is the commercially available diterpenoid glycosides, the pseudopterosins,369,370 with remarkable antiinflammatory and analgesic properties, eleutherobin and the sarcodyctins. Figure 6.6 shows that study within Cnidaria has focused on two orders, that of the soft corals, the Alcyonacea and the Gorgonacea. 

Diterpenoids are the most important compounds responsible of the biological activities found in numerous Salvia species. Antituberculous effects have been established for S. blepharochlyna [5], S. multicaulis also reported for it s antifungic effect [6] and S. prionitis which possess antiphlogistic and antibacterial properties [7,8] beside its antituberculous activity. 

Chapter 2 by Giovanni Appendino provides a fascinating treatment of Taxine, a collective name referring to a mixture of diterpenoid alkaloids from the yew tree (genus Taxus). Taxine is responsible for the toxic properties of the yew tree that has been documented in historical and fictional literature, from Julius Caesar to Shakespeare, and from Agatha Christie to T. S. Eliot. The chapter treats the history, isolation techniques, structure elucidation, chemistry, and pharmacology of Taxine. 

A number of bicyclic diterpenoids have insect anti-feedant properties and consequently the synthesis of intermediates such as (93) in this series has attracted... 

In the following table an attempt has been made to list all diterpenoid alkaloids isolated since 1977. The references relate in most cases to their isolation, purification, and structure determination. For work on known alkaloids, especially structural revision, the review sources listed at the beginning of the chapter should be consulted. Blank spaces in the table signify that the appropriate properties have not been recorded. Only alkaloids for which a reasonably substantiated structure has been advanced are included. Entries marked with an asterisk may be artefacts. The literature has been covered up to the end of 1985, and some 1986 references have been included. The alkaloids have been arranged in order of natural source. 

Diterpenoids have, by definition, 20 carbon atoms in their structure. This means that very few are sufficiently volatile to possess an odour. One diterpenoid is used in perfumery because it and the derivatives concerned are odourless. That is, they are used as solvents. In view of their hydrophobicity and low volatility, these solvents also have fixative properties. Abietic acid is a major component of tall oil, the residue from distillation of turpentine. Esterification and hydrogenation produces two solvents as shown in Figure 4.43. 

---