Mini Reviews in Medicinal Chemistry - Volume 17, Issue 13, 2017

Background: In plants, vesicle transport occurs in the secretory pathway in the cytosol, between the membranes of different compartments. Several protein components have been identified to be involved in the process and their functions were characterized. Both cargos and other molecules (such as hormones) have been shown to use vesicle transport, although the major constituents of vesicles are lipids which are transferred from donor to acceptor membranes. In humans, malfunction of the cytosolic vesicle transport system leads to different diseases. Method: To better understand and ultimately cure these human diseases, studying other model systems such as yeast can be beneficial. Plants with their cytosolic vesicle transport system could serve as another model system. However, this review focuses on plant vesicles not present in the cytosol but in the chloroplasts, where lipids produced in the surrounding envelope are transported through the aqueous stroma to the thylakoid membranes. Although chloroplast vesicles have found both biochemical and ultrastructural support, only two proteins have been characterized as components of the pathway. However, using bioinformatics a number of other proteins have been suggested as homologs to the cytosolic system. Results & Conclusion: Based on these findings vesicles of chloroplasts are likely most similar to the vesicles trafficking from ER to Golgi, or may even be unique, but important experimental support is yet lacking. In this review, proposed vesicle transport components in chloroplasts are presented, and their possible future implementation for human medicine is discussed.

Background: Since the industrial revolution, the consumption of processed food increased dramatically. During processing, food material loses many of its natural properties. Objective: The simple restoration of the original properties of the processed food as well as fortification require food supplementation with compounds prepared chemically or of natural origin. The observations that natural food additives are safer and better accepted by consumers than synthetic ones have strongly increased the demand for natural compounds. Because some of them have only a low abundance or are even rare, their market price can be very high. This is the case for most carotenoids of natural origin to which this review is dedicated. The increasing demand for food additives of natural origin contributes to an accelerated depletion of traditional natural resources already threatened by intensive agriculture and pollution. To overcome these difficulties and satisfy the demand, alternative sources for natural carotenoids have to be found. In this context, photosynthetic microalgae present a very high potential because they contain carotenoids and are able to produce particular carotenoids under stress. Their potential also resides in the fact that only ten thousands of microalgal strains have been described while hundred thousands of species are predicted to exist. Carotenoids have been known for ages for their antioxidant and coloring properties, and a large body of evidence has been accumulated about their health potential. Conclusion: This review summarizes both the medicinal and food industry applications of microalgae with emphasis on the former. In addition, traditional and alternative microalgal sources used for industrial carotenoid extraction, the chemical and physical properties, the biosynthesis and the localization of carotenoids in algae are also briefly discussed.

Background: Open tetrapyrroles termed phycobilins represent the major photosynthetic accessory pigments of several cyanobacteria and some eukaryotic algae such as the Glaucophyta, Cryptophyta and Rhodophyta. These pigments are covalently bound to so-called phycobiliproteins which are in general organized into phycobilisomes on the thylakoid membranes. Objectives: In this work we first briefly describe the physico-chemical properties, biosynthesis, occurrence, in vivo localization and roles of the phycobilin pigments and the phycobiliproteins. Then the potential applications and uses of these pigments, pigment-protein complexes and related products by the food industry (e.g., as LinaBlue® or the so-called spirulina extract used as coloring food), by the health industry or as fluorescent dyes are critically reviewed. In addition to the stability, bioavailability and safety issues of purified phycobilins and phycobiliproteins, literature data about their antioxidant, anticancer, anti-inflammatory, immunomodulatory, hepatoprotective, nephroprotective and neuroprotective effects, and their potential use in photodynamic therapy (PDT) are also discussed.

Background: Thylakoids and chloroplasts harbor several vital metabolic processes, but are most importantly associated with photosynthesis. The undisturbed functioning of this process necessitates the ceaseless synthesis of photosynthetic pigments, including closed tetrapyrroles such as chlorophylls (Chls). Chls probably represent the most abundant natural pigment molecules which are via photosynthesis not only crucial for the autotrophic production of food sources for heterotrophic organisms but have also contributed to oxygen production essential for aerobic metabolism. Objectives: This review first briefly discusses the physico-chemical properties, biosynthesis, occurrence, in vivo localization and roles of the different Chl pigments. Then we provide a detailed overview of their potential applications in the food industry and medicine. These include the use of Chls and their derivatives (different chlorophyllins) as food colorants (identified as E140 and E141 in the European Union). Different sources used for industrial extraction as well as different factors influencing pigment stability during processing are also critically reviewed. The problems surrounding the nomenclature, the production and the composition of different chlorophyllin mixtures are also discussed. Finally, a comprehensive overview of the health benefits and potential medicinal applications of these pigments and the future directions of research in these fields are provided.

Background & Objective: Cannabis is one of the earliest cultivated plants. Cannabis of industrial utility and culinary value is generally termed as hemp. Conversely, cannabis that is bred for medical, spiritual and recreational purposes is called marijuana. The female marijuana plant produces a significant quantity of bio- and psychoactive phytocannabinoids, which regained the spotlight with the discovery of the endocannabinoid system of the animals in the early 90's. Nevertheless, marijuana is surrounded by controversies, debates and misconceptions related to its taxonomic classification, forensic identification, medical potential, legalization and its long-term health consequences. Method: In the first part, we provide an in-depth review of the botany and taxonomy of Cannabis. We then overview the biosynthesis of phytocannabinoids within the glandular trichomes with emphasis on the role of peculiar plastids in the production of the secreted material. We also compile the analytical methods used to determine the phytocannabinoid composition of glandular trichomes. In the second part, we revisit the psychobiology and molecular medicine of marijuana. Results & Conclusion: We summarize our current knowledge on the recreational use of cannabis with respect to the modes of consumption, short-term effects, chronic health consequences and cannabis use disorder. Next, we overview the molecular targets of a dozen major and minor bioactive cannabinoids in the body. This helps us introduce the endocannabinoid system in an unprecedented detail: its up-todate molecular biology, pharmacology, physiology and medical significance, and beyond. In conclusion, we offer an unbiased survey about cannabis to help better weigh its medical value versus the associated risks.78

Background: Vaccines produced in plants have opened up new opportunities in vaccination. Objective: Among the various categories of vaccines, the recombinant vaccine is generally regarded as the most economical and safest type because it cannot cause disease and does not require large-scale cultivation of pathogens. Due to the low cost of their cultivation, plants may represent viable alternative platforms for producing subunit vaccines. Genetic engineering of plastids is the innovation of the last three decades and has numerous benefits when compared to nuclear transformation. Due to the high level of expression, oral vaccines produced in transplastomic plants do not have to be purified as they can be consumed raw, which, therefore, reduces the cost of preparation, transportation and handling of the vaccines. Oral vaccination also excludes the risk of other infections or contaminations, while compartmentation of the plant cell provides an excellent encapsulation to the antigen within the plastid. Results & Conclusion: Herein we review the main biotechnological and immunological aspects of the progress achieved in the field of plastid derived edible vaccines during the last decade. As there is a public debate against genetically modified crops, the advantages and limitations of oral vaccines are also discussed.

Background: Higher plants have been used in medicine throughout human history. Method: While traditional medicinal uses relied on compounds produced naturally by plants, recent advances have enabled the use of plant-based factories to produce diverse agents including pharmaceuticals, antibiotics, and vaccines. The genes responsible for the production of these substances can be either transiently expressed in plants or integrated into their nuclear genome or plastid genome (plastome) by genetic transformation. This review focuses on the application of plastid transformation of higher plants to produce biopharmaceuticals for human applications that are neither antibiotics nor vaccines. Plastid transformation has several advantages over nuclear transformation and represents a minimal risk of transgene contamination to the environment via pollen grains because plastid genes are in most species normally maternally inherited and thus absent from pollen. Other advantages of sitedirected plastid insertion via homologous recombination include strong gene expression due to the plastid genome's high copy number and resistance to silencing, and the ability to achieve multi-gene expression with a single insertion step. Results: Compared to bacterial systems, plant-based bioreactors offer lower production costs, lower risks of human pathogen contamination, and the possibility of exploiting post-translational modification. Conclusion: Consequently, sustainable plant systems based on different species, plastids, and tissues could become an important source of added value in pharmaceutical production.