Alkaloids: Chemistry and Biology最新文献

The results described in these studies proved that the successful in vitro bioproduction of galanthamine from L. aestivum shoot-clumps required mainly the selection of in vitro clones with a genetically determined high ability to produce the desired alkaloids, although the expression of this ability could be additionally influenced by diverse exterior factors, such as some components of the nutrient medium, or the cultivation conditions of the ambience. Tissue differentiation was also of great importance for the biosynthetic capacity of the cultures. The most suitable inocula for in vitro biosynthesis of galanthamine in liquid medium were the directly regenerated shoot-clumps, ensuring high alkaloid concentrations between 1 and 2 mg/g DW for the selected clones. We observed astonishing clone-specific dynamics of the biosynthetic activity of all of the studied in vitro clones. The dynamics were obviously related to the strong biological clock of the species, persisting even in several-year old cultures. These dynamics did not coincide with those usual for the plants growing in situ and under controlled field conditions. In our opinion, the clone specificity of the biosynthetic dynamics could be due to the disturbance of the plant regulation mechanism under the equal conditions of the ambience in the culture room. The sharp decrease of the alkaloid concentrations were transient, followed by an increase, so that cultures were retaining their biosynthetic capacity. The biosynthesis of the main alkaloids, galanthamine and lycorine, was influenced by diverse stimulants such as substances causing stress (JA), feeding with alkaloid precursors (the amino acids phenylalanine and tyrosine, and CH), and physical treatment (acoustic waves). However, the course of the biosynthetic dynamics during the period of the treatments was always the most important factor for the success of secondary metabolism stimulation. As far as scaling-up of the in vitro biosynthesis of valuable compounds, a stable and predictable yield is required, and additional investigations aimed at the annulment of the effect plant biological clock on alkaloid biosynthesis are needed. The elucidation of the relative influences of the diverse factors modulating alkaloid biosynthesis was of great importance. The high galanthamine concentrations of the selected in vitro clones are a promising basis for future studies.

The diterpenoid alkaloids, with an intriguing chemistry and numerous varied bioactivities, constitute the largest and most complicated group of terpenoid alkaloids. Among them, the C19-diterpenoid alkaloids have attracted extensive and lasting attention from researchers. This chapter with 1075 references systematically summarizes the past 30 years of studies on the C19-diterpenoid alkaloids, covering the classification and distribution, biogenesis and biosynthesis, applications in the phytochemotaxonomy of Chinese Aconitum L., spectral properties (1H and 13C NMR, MS), X-ray crystallographic analysis, chemical reactions and chemical conversions (as a continuation of Volume 42 of this treatise), and pharmacological activity of this important group of alkaloids. This review on the C19-diterpenoid alkaloids, in combination with two previous reviews in this treatise (C20-diterpenoid alkaloids, Volume 59, and C18-diterpenoid alkaloids, Volume 67), will present readers with a complete and updated profile of the diterpenoid alkaloids. The only exception is the description of the total syntheses of the diterpenoid alkaloids, which will be summarized in a subsequent individual chapter.

The chemistry of Erythrina and related alkaloids from 1996 through to mid-2009 has been reviewed, with a particular focus on the preparation of Erythrina alkaloids possessing an aromatic D ring. A number of synthetic approaches to alkaloids bearing an aromatic D ring have been reported, including some asymmetric routes. Recent studies have explored strategies toward Erythrina alkaloids possessing a nonaromatic D ring, although, as yet, few total syntheses have been published.