Plant phenolics: recent advances on their biosynthesis, genetics, and ecophysiology.

“Plant phenolics” and “polyphenols” are secondary natural metabolites arising biogenetically fromeitherthe shikimate/phenylpropanoid pathway,which directly provides phenylpropanoids, or the “polyketide” acetate/malonate pathway, which can produce simple phenols, or both, thus producing monomeric and polymeric phenols and polyphenols, which fulfill a very broad range of physiological roles in plants. Higher plants synthesize several thousand known different phenolic compounds. The ability to synthesize phenolic compounds has been selected throughout the course of evolution in different plant lineages, thus permitting plants to cope with the constantly changing environmental challenges over evolutionary time. Plant phenolics are considered to have a key role as defense compounds when environmental stresses, such as high light, low temperatures, pathogen infection, herbivores, and nutrient deficiency, can lead to an increased production of free radicals and other oxidative species in plants. Both biotic and abiotic stresses stimulate carbon fluxes from the primary to the secondary metabolic pathways,

Phenolic Compounds: Introduction

The 1,4-naphthoquinones (1,4-NQs) are a diverse group of natural products found in every kingdom of life. Plants, including many horticultural species, collectively synthesize hundreds of specialized 1,4-NQs with ecological roles in plant-plant (allelopathy), plant-insect and plant-microbe interactions. Numerous horticultural plants producing 1,4-NQs have also served as sources of traditional medicines for hundreds of years. As a result, horticultural species have been at the forefront of many basic studies conducted to understand the metabolism and function of specialized plant 1,4-NQs. Several 1,4-NQ natural products derived from horticultural plants have also emerged as promising scaffolds for developing new drugs. In this review, the current understanding of the core metabolic pathways leading to plant 1,4-NQs is provided with additional emphasis on downstream natural products originating from horticultural species. An overview on the biochemical mechanisms of action, both from an ecological and pharmacological perspective, of 1,4-NQs derived from horticultural plants is also provided. In addition, future directions for improving basic knowledge about plant 1,4-NQ metabolism are discussed.

Biosynthesis and molecular actions of specialized 1,4-naphthoquinone natural products produced by horticultural plants.

Shikonin derivatives for cancer prevention and therapy

Microbial oddities such as versatile pigments are gaining more attention in current research due to their widely perceived applications as natural food colorants, textiles, antimicrobial activities, and cytotoxic activities. This indicates that the future generation will depend on microbial pigments over synthetic colorants for sustainable livelihood. Although several reviews have detailed the comprehensive applications of microbial pigments extensively, knowledge on several aspects of pigmented microbes is apparently missing and not properly reviewed anywhere. Thus, this review has been made to provide overall knowledge on biodiversity, distribution, pathogenicity, and ecological and industrial applications of microbial pigments as well as their challenges and future directions for food, industrial, and biomedical applications. Meticulously, this compendious review treatise on the pigments from bacteria, fungi, yeasts, and microalgae includes reports from the 1970s to 2018. A total of 261 pigment compounds produced by about 500 different microbial species are included, and their bioactive nature is described.

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Multifaceted Applications of Microbial Pigments: Current Knowledge, Challenges and Future Directions for Public Health Implications.

Chemical investigation of many bacterial and fungal, as well as plant species has revealed the presence of in- teresting compounds derived from naphthalene - 1,4-naphthoquinones and rarely also 1,2-naphthoquinones. They were detected in many species of families Bignoniaceae, Droseraceae, Plumbaginace, Boraginaceae, Juglandaceae as well as in species of small families, such as Dioncophyllaceae or Acanthaceae. Naphthoquinones have very interesting spectrum of biological actions, including antibiotic, antiviral, anti-inflammatory, antipyretic, antiproliferative and cytotoxic effects. Because of these properties the plants containing them are used in folk medicines, mainly by natives in Asia, where espe- cially Chinese medicine uses aerial as well as subterranean parts of these plants for hundreds years, and South America. The utilizing of naphthoquinones for medicinal purposes and their occurrence in nature is reviewed and discussed. Moreover, we review analytical techniques using for their analysis.

Babula Petr

Papers

Noteworthy Secondary Metabolites Naphthoquinones – their Occurrence, Pharmacological Properties and Analysis