Frontiers in Natural Product Chemistry

Comparative analysis of archaeal, bacterial, and eukaryotic genomes indicates the occurrence of horizontal gene transfer (HGT) in many genomes. Although widely studied in prokaryotic systems, eukaryotes, which were thought to evolve principally through reproduction and mutation (vertical gene transfer), also acquire novel genes and pathways through the acquisition of sequences from distantly related species. HGT is a notable phenomenon that allows the sharing of genetic information among members of most or all kingdoms. HGT leads to extremely dynamic genomes, which have the potential to effectively change the type and presence of secondary metabolites in an organism. HGT is documented in fungi, bacteria, animals, and plants - when viral mechanisms are included, all organisms likely are subject to HGT. The quantities of genetic material that are horizontally transferred range from small gene fragments to groups of genes, including whole operons that encode complex biochemical pathways. Examples of HGT that contribute to novel or expanded ranges of secondary metabolite products include filamentous and unicellular fungi, actinomycetes and other bacteria, and plants. In this chapter we will discuss several examples of secondary metabolite production that occur as a consequence of HGT, the study of natural products acquired through HGT processes and the ramifications of HGT for biosynthesis and exploitation of natural products that arise from horizontallytransferred pathways. We have focused primarily on the literature published from 2000 to 2015.

Over the past two decades, biotechnologies have provided a motor for innovation and sustainability in many economies all around the world by developing new processes and products in a bio-economy approach. Besides food and feed, increasing interest on biomass derived fuels, chemicals and materials, sustainably sourced and produced, has raised, providing an alternative to heavy reliance on finite fossil fuel resources. One of the most innovative and promising sectors of the bioeconomy is related to bio-based products, obtained in part or entirely from organic biomass, which account for about 16% of world production of bio-economy’s products. Plant biomass is rich in high added value compounds; mainly antioxidants and fibres, which once extracted can serve as green fine chemicals or can be used in food supplements and/or nutraceutical sector.

A great deal of evidence has established that the secondary compounds of higher plants (i.e. polyphenols) inhibit and/or quench free radicals and reactive oxygen species (ROS) thus protecting against oxidative damage. These compounds can therefore be exploited as additives in a large number of different commodities, such as plastics and nanomaterials.

This chapter gives an insight into the relevant research results regarding the valorization of polyphenol fractions extracted from agricultural wastes, focusing on those derived from fruit production and transformation. Structure-activity relationships will be discussed in view of their use in the field of innovative materials.

Tropical diseases are largely prevalent in the tropics and they are a significant cause of morbidity and mortality. Tropical diseases refer to infectious diseases such as malaria, leishmaniasis, lymphatic filariasis, American trypanosomiasis (Chagas disease), African trypanosomiasis, and dengue that thrive in relatively hot and humid conditions. This chapter presents an overview of recent developments on the use of various natural products active against malaria, leishmaniasis, lymphatic filariasis, American trypanosomiasis (Chagas disease) and African trypanosomiasis.

Vitamin B12 is synthesized by only certain bacteria but not by plants. Thus, foods derived from animals, namely meat, milk, fish, and shellfish, are major dietary sources of vitamin B12. Intestinal bacteria have the ability to synthesize various corrinoid compounds carrying different base moieties in the lower ligand. Thus, animal manures and human feces contain substantial amounts of various cobamides with different bases. When food corrinoids were purified and characterized, certain food items unexpectedly contained pseudovitamin B12, in which adenine replaces 5,6- dimethylbenzimidazole as the base. Cyanobacteria used as human health supplements provide substantial amounts of pseudovitamin B12, which functions as a cofactor for cobalamin-dependent methionine synthase in these organisms. Oral administration of pseudovitamin B12 to mammals suggests that this cobamide does not act as a vitamin B12 antagonist in the gastrointestinal absorption of vitamin B12 and cobalamindependent enzyme systems. Furthermore, vitamin B12 is converted into an inactive analogue vitamin B12[c-lactone] by the treatment with chloramine-T, which is used as a disinfectant. The unnatural vitamin B12 analogue was found in certain dried mushroom fruiting bodies.

Bioactive compounds are extra nutritional constituents occurring naturally in plant foods in small amounts, however in quantities enough to produce bioactive effects. Among bioactive compounds the phenolic compounds are a very large set of molecules, which include several groups such as for example flavonoids, phenolic acids or tannins. Small fruits and berries include a wide diversity of fruits, like grapes, strawberries, blackberries, blueberries, raspberries, cherries, hardy kiwi, gooseberries, cranberries, currants (black, white, red), physalis, crowberries, açaí, elderberries, dates or goji berries, and these have frequently been reported as having particularly high concentrations of phenolic compounds with antioxidant activity. Hence, the objective of this chapter is to review the literature about the type and content of different phenolic compounds present in small fruits and berries, as well as their bioactive properties, including antioxidant capacity. All the fruits and berries investigated in this chapter were particularly rich in bioactive compounds, including phenolic compounds that provide the fruits with high antioxidant properties. The most relevant health promoting effects include anti-cancer, anti-inflamatory, neuro protective, cardio protective or anti-diabetes, thus indicating that these foods are a valuable resource to prevent and treat diseases.

European elder plant, Sambucus nigra L., has been used since ancient times in folk medicine, and more recently in nutraceutical formulations, being considered the medicine “chest” from the days of Hippocratic medicine. This chapter aims at giving a general perspective of S. nigra L. berries and flowers potential as sources of healthpromoting compounds, covering first aspects ranging from its taxonomic classification and geographic distribution, current applications from food products to traditional medicine. Then, a detailed overview of berries and flowers chemical composition, specially focused on sterols, terpenic and phenolic components, and important factors that have impact on their biosynthesis and preservation are presented. Finally, the main findings regarding the potential health benefits of S. nigra-based preparations, namely antimicrobial, anti-viral, antioxidant, anti-inflammatory, anti-cancer, and antidiabetic are also described, and special focus is devoted to diabetes mellitus and related complications, as it is a disease of a major threat to human health due to its alarming incidence growth.

Flavonoids are polyphenolic secondary metabolites with various in vivo and in vitro structure-related benefits that are ubiquitously found in plants. In addition to their role in many physiological activities, flavonoids play major roles as phytoalexins and phytoanticipins in protecting plants from potent pathogens. Since the first discovery of such defense roles, their routes of biosynthesis induced upon pathogen infection and mechanisms of action have attracted the attention of researchers in various fields. The ultimate goal of the study of plant-pathogen interactions is to develop biotechnological applications that enhance crop production in an environmentally friendly manner, with the outcome of engineering highly pathogen-resistant genotypes. Steady progress has been made previously in this regard. Inoculation of potential pathogens in plant tissues, followed by the systematic analysis of various targeted biochemical changes, including investigations into flavonoid variations, has become an appealing methodological approach. In this chapter, the role of flavonoids as defense mechanisms in plant-pathogen interactions is discussed with respect to the latest findings. In addition, we emphasize research trends observed in this regard. In light of the most recent studies, including those conducted by some of the authors of this chapter, key findings in flavonoid variations upon pathogen infection are highlighted comprehensively, focusing on fungal inoculation and liquid chromatography-tandem mass spectrometry analysis for reasons described in later sections.