Otto R. Gottlieb

Chemosystematics of the Lauraceae

Abstract The various chemical constituents of the Lauraceae are discussed in relation to the taxonomy of the family. Although there is a great paucity of data, the variation in the arylpropanoids, alkaloids, flavanoids and terpene constituents is in general in agreement with the subdivision of the family put forward by Kostermans.

13C NMR spectroscopy of neolignans

Abstract The 13 C NMR spectra of 15 neolignans of several structural types and two lignans were analyzed and their carbon shifts assigned. The shifts of pyrogallol ether and ethyl phenyl carbinyl ether models were used in this connection. The stereochemistry of a dimeric sideproduct in the preparation of the latter models was determined by 13 C NMR analysis.

Integration of ethnobotany and phytochemistry. dream or reality

The major challenge of this paper comprises an attempt to compare the wealth of folk-information based on traditional knowledge with the efficacy of a chemo-biological background based on scientific knowledge. Surprisingly, correlations between plant uses (as food and medicine) and evolutionary status according to morphology (as assigned by Sporne indices) and metabolism (as assigned by diversity of phytochemicals) obey strikingly uniform systematic and evolutionary trends. The resulting patterns suggest a dynamic chemical mechanism for the bioactivity in plants regulated by the antagonistic gallate/caffeate pair. This finding is an important step toward the construction of a coherent chemo-biological language by a dynamic holistic quantitative methodology, one of the most potent prospects for understanding the functioning of nature.

Phytochemicals: Differentiation and function

Abstract In order to elucidate the causes of phytochemical differentiation, the alternative expressions of general vs special metabolic divisions, herbaceous vs woody metabolic classes, subclasses and structural types, as well as the selection and orientation of protection devices of these types in the formation of natural products, were submitted to stepwise analysis. Internal factors were shown to dominate the biosynthetic driving forces at all these metabolic ranks. Environmental factors, such as herbivory, constitute additional driving forces at the highest rank, accentuating the expression of special metabolism, and at the lowest rank, where the regiospecific localization of protection devices on structural types directs compound diversity.

Burchellin: effects on Triatoma infestans and on Trypanosoma cruzi within this vector

Abstract. Supplementation of blood with the neolignan burchellin (50xa0µg/ml), a compound from the arboreous Lauraceae Aniba burchelli, affected the ingestion of blood and the course of excretion of fourth- and fifth-instar larvae of Triatoma infestans, the latter especially within the first 4xa0h after feeding. The total resultant weight loss of treated fourth instars within 24 and 48xa0h after feeding was only 24% and 28% vs 41% and 48%, respectively, in untreated bugs. In fifth instars, the total weight losses of untreated bugs within 24 and 48xa0h after feeding were 38% and 41% whereas the weight of treated bugs decreased by 28% and 34%, respectively. In a treatment of Trypanosoma cruzi-infected fourth instars, burchellin significantly reduced the population density of the established infection in the rectum at 5 and 10xa0days after feeding. This was especially due to a significant increase in the number of the main dividing stage, the epimastigote.

Biosynthetic interdependence of lignins and secondary metabolites in angiosperms

Abstract The morphology and metabolism of angiosperms are connected to lignin production. Morphology depends on the structure of genetically controlled cellulose templates for lignin deposition; metabolism is the consequence of lignin-requirement directed biosynthesis of secondary metabolites. Hence, it is possible to correlate morphological features (such as evolutionary replacement of woodiness by herbaceousness) with general chemical features (such as evolutionary replacement of aromatics by aliphatics) and with particular chemical features (such as oxidative diversification of biosynthetic categories of metabolites). The first correlation is useful for the systematic classification of plants at higher levels (e.g. orders). The last correlation is useful for the evolutionary assessment of plants at lower levels (e.g. families). These concepts allow the construction of an integrated system of angiosperm classification based on morphology for the circumscription of taxa and on chemistry for the evolutionary assessment of plant groups.

A suggested role of galloyl esters in the evolution of dicotyledons

Galloyl esters (galloand ellagitannins), which occur throughout the more primitive members of the Hamamelididae, Dilleniidae and Rosidae (the HDR complex), are important chemosystematic markers. Their significance is not limited to their strong protein-binding activity, as was formerly believed, or to their toxic properties, which have more recently been recognized. They also have powerful electron scavenging properties, thus inhibiting oxidation, a reaction that is fundamental in the synthesis of secondary metabolites. The HDR complex indeed is poor in shikimate-derived compounds; polyketide, mevalonate, and Krebs cycle-derived substances, which originate primarily by reactions such as condensation, esterification, and reduction, prevail but lack systematic continuity. The absence of coherent chemosystematic markers reflects the systematic isolation of the orders and superorders in the HDR complex, where phylogenetic relationships are less obvious than in the other dicotyledonous subclasses. Phytoalexins are mostly found in members of the HDR complex that are poor in galloyl esters. In view of their molecular properties (small, planar, highly conjugated molecules) it is suggested that they equally act as antioxidants. The superorders belonging to the subclasses Magnoliidae, Caryophyllidae, and Asteridae, which lack galloyl esters, are endowed with antioxidants of weak efficacy (proanthocyanidins and/or caffeic acid esters) and have a rich array of secondary metabolites, which permits the recognition of major evolutionary lines.

Steroids, taxonomic markers?

The use of steroids as taxonomic markers of the angiosperms was evaluated. To this end evolutionary advancement parameters, based on oxidation state and skeletal specialization of each steroid were calculated. The averages of these values for the steroids registered for a particular plant group were assumed to represent the evolutionary parameters of the plant group. Positive correlations of these chemical parameters and of morphological Sporne indices, as well as of herbacity indices, were observed to constitute a general trend. Furthermore, steroids are not uniformly distributed within a morphologically homogeneous plant group, but are replacement characters. Thus, in spite of their functional importance, steroids can be considered, analogously to many other classes of secondary metabolites, for chemosystematic purposes.

Evolution of Natural Products

The evolution of natural products on earth has fascinated scientists and laymen alike for many years. A vast literature has been accumulated concerning the hypothetical interface of the prebiotic (chemical) and the organismic (biochemical) phases (50, 60). Nevertheless the entire concept, including the validity of its experimental basis, has more recently been questioned. Indeed the concept introduces a problem of the hen-and-egg type. Which ones came first — the complex molecules with genetic and enzymatic potential or the molecules generated by such catalytic macromolecules? Cairns-Smith (10) gave the sole reasonable answer: genes and enzymes. According to this author the most central molecules of life are the same in all organisms on earth today. Hence all life has descended from a common ancestor in which the central biochemical system was already fixed. That it should have remained fixed for so long is surely because of the critical interdependence of all components of the central highly complex machinery. Hence the ancestor must be situated at a quite high position of the evolutionary tree, preceded by simpler forms in which chemical reactions were catalyzed initially by geochemical genetic material such as clay crystals and metal ions. In the resulting progressively more sophisticated system “genetic takeover” must have occurred, the inorganic material having been gradually replaced by an organic one, preferentially endowed with information-carrying capacity and catalytic activity. So far only one macromolecule is known to possess such a double capacity: RNA (12). However, direct synthesis of RNA is an improbable event. The enzyme catalyzing its in vitro formation is far too complex to have had a clay template analogue on primitive earth (10).

Trends of plant use by humans and nonhuman primates in Amazonia

Analyses of plant use in Amazonia by three species of nonhuman primates reveal a common trend: more primitive plant species are used as food. An identical situation prevails for three indigenous human societies which additionally selected more recently evolved plant species as medicine. One hypothesis to explain the observations is related to the presence of toxic constituents in the more advanced species, in contrast to astringent polyphenols in the more primitive ones. Thus a certain degree of astringency might indicate absence of harmful chemicals, and even stimulate ingestion.