Biologically Active Aliphatic Acetogenins from Specialized Idioblast Oil Cells. Pp. 1249-1260.
Cesar
Rodriguez-Saona and J. T. Trumble
Botrytis Species: An Intriguing Source of Metabolites with a Wide Range of Biological Activities. Structure, Chemistry and Bioactivity of Metabolites Isolated from Botrytis Species. Pp. 1261-1286.
I. G.
Collado, J. Aleu, R. Hernández-Galán and R. Durán-Patrón
Southern African Hyacinthaceae: Chemistry,
Bioactivity and Ethnobotany. Pp.
1287-1324.
T.S. Pohl, N.R. Crouch and D.A. Mulholland
[Back to top] Diterpenes from Marine Opisthobranch Molluscs.
Marine opisthobranchs represent a very
interesting source of bioactive natural products, which exhibit an
extraordinary variety of chemical structures. Opisthobranchs are naked
molluscs, apparently unprotected by the physical constrain of a shell. In spite
of this, they appear to be free of predation. Their survival is assured by a
series of alternative defensive strategies which include the use of chemicals.
These bioactive compounds, which are often localized in selected parts
of body and in the defensive mucous secretion, can be derived from the diet or de
novo biosynthesized.
Terpenes represent the major group of
secondary metabolites isolated from opisthobranchs. Most of these compounds
show both interesting biological properties and unique chemical structures. In
particular, diterpenes include some of the most interesting examples of
bioactive molecules.
This review covers the
chemistry of diterpenes from marine opisthobranchs, until approximately 1999.
Isolation, synthesis and biosynthesis are separately discussed throughout the
paper. Relevant data regarding biological activities are also reported.
[Back to
top] Biologically Active
Aliphatic Acetogenins from Specialized Idioblast Oil Cells.
More than three decades ago, Kashman and
coworkers [1,2] reported for the first time a class of closely related
compounds from avocados (Lauraceae). This class of compounds contains several
highly oxygenated long-chain acetylenic and olefinic natural products derived
from fatty acids (e.g. possibly C-18 oleic, linoleic, linolenic, or stearic
acid as precursors). These products form part of a group of compounds known as
the “biologically active aliphatic acetogenins”, the distribution of which is
thought to be restricted to the Annonaceae and Lauraceae. Current studies
indicate that the Lauraceous acetogenins are synthesized during early plant
development from specialized idioblast oil cells and transported from the oil
cells to other parts of the plant.
While
idioblast oil cells are found throughout the plant kingdom, their function in
many plant families has been the focus of considerable speculation because
little is known about the chemistry or biological activity of the oil in the
cells. Until recently, the idioblast cells were generally viewed simply as
unusual storage organs. In avocados, increasing evidence indicates that the
cells, and the oil they contain, may play an important defensive role against
pathogens and insects. Several of the compounds produced in avocado oil cells,
reported to occur almost exclusively in the genus Persea, are now known to have antibacterial, antifungal, and
insecticidal activity. In the present paper we review the distribution,
synthesis, biological activity, and mode of action of the most studied
Lauraceous acetogenins: the diene persin, (12Z,
5Z)-1-acetoxy-2-hydroxy-4-oxo-heneicosa-12,15-diene, and the persin-derived
furans known as avocadofurans.
[Back to
top] Botrytis Species:
An Intriguing Source of Metabolites with a Wide Range of Biological Activities.
Structure, Chemistry and Bioactivity of Metabolites Isolated from Botrytis Species.
The
Botrytis species belong to the most
geographically widespread group of plant pathogens and saprophytes, and cause
serious losses to very many commercial crops. These phytopathogenus fungi are
the agents of the disease known as grey mould. They biosynthesise
characteristic metabolites that, in vitro,
produce the grey mould symptoms. The
recent discovery that oxidative forces are involved when B. cinerea infects plant and the relevance of toxins for
pathogenicity, have increased the interest for these compounds, in order to
determinate the potential links to the plant oxyradical metabolism and the
induction of oxidative stress. This review describes the metabolites isolated
from Botrytis species, the
spectroscopic data, grouping together by structural family, synthesis and
chemical transformation, specially those carried out on botryane skeleton. The
basic skeleton of botrydial is a bicyclic, non isoprenoid sesquiterpene system
which has provided the stimulus for many investigations into the biosynthetic
pathway to this skeleton. The biosynthetic studies carried out and the
approaches to the asymmetric synthesis on this skeleton are reported in this
paper. On the other hand, a detailed study on biological activity showed for
these metabolites and the structure-activity relationship of metabolites with
the botryanes skeleton is included.
[Back to top] Southern African Hyacinthaceae: Chemistry, Bioactivity and Ethnobotany.
Southern Africa is one of two world centres of diversity in the Hyacinthaceae, harbouring approximately half the world’s family representatives. Some 368 species in 27 genera are locally represented. Plants are well distributed throughout the region, with a predominance in the Western Cape of South Africa. Some 23 species in nine genera have been phytochemically investigated, revealing compounds belonging to a diverse range of chemical classes. The chemical constituents from plants of this family have been divided into four classes, namely, homoisoflavanones, steroidal compounds, bufadienolides and miscellaneous compounds. A single report on the occurrence of Amaryllidaceae alkaloids in Urginea altissima is questioned following a reinvestigation of this species. Plants are employed for traditional medicinal purposes ranging from the treatment of hangovers, rheumatic fever, sprains and syphilis to cancer. A number of species have been toxicologically assessed following human deaths and livestock losses after ingestion. The bioactivity and ethnobotany of southern African hyacinthacs is reviewed, as is the pharmacology of isolated constituents and crude extracts.