Biosynthesis and synthetic biology of psychoactive natural products

Synthetic Biology in Natural Product Biosynthesis

Synthetic biology has played an important role in the renaissance of natural products research during the post-genomics era. The development and integration of new tools have transformed the workflow of natural product discovery and engineering, generating multidisciplinary interest in the field. In this review, we summarize recent developments in natural product biosynthesis from three different aspects. First, advances in bioinformatics, experimental, and analytical tools to identify natural products associated with predicted biosynthetic gene clusters (BGCs) will be covered. This will be followed by an extensive review on the heterologous expression of natural products in bacterial, fungal and plant organisms. The native host-independent paradigm to natural product identification, pathway characterization, and enzyme discovery is where synthetic biology has played the most prominent role. Lastly, strategies to engineer biosynthetic pathways for structural diversification and complexity generation will be discussed, including recent advances in assembly-line megasynthase engineering, precursor-directed structural modification, and combinatorial biosynthesis.

Microbe Engineering to Provide Drimane-Type Building Blocks for Chiral Pool Synthesis of Meroterpenoids

Drimane-type merosesquiterpenoids (DMT) are a class of natural products with diverse structures and broad biological activity. Classical DMT synthesis relies on atom-inefficient plant-derived chiral pool building blocks, while alternative drimane-type building blocks such as drimenol and albicanol offer more direct routes but face production challenges. In this study, we engineered a microbial platform for efficient production of these building blocks. By optimizing the PhoN-IPK system through rational engineering and incorporating a Nudix hydrolase, we achieved a drimenol production of 398 mg/L and high albicanol titers of 1805 mg/L in shake flasks and 3.5 g/L in a bioreactor. Structural analysis and molecular dynamics simulations of the engineered PhoN provided insights into its improved catalytic efficiency. We demonstrated the utility of this platform by synthesizing several DMT using albicanol as the starting material, reducing the number of synthetic steps and improving overall efficiency as compared to classical approaches.

Immobilized Nucleoside 2'-Deoxyribosyltransferases from Extremophiles for Nucleoside Biocatalysis

The synthesis of nucleosides is crucial for pharmaceutical and biotechnological applications, acting as drugs and as essential building blocks for numerous therapeutic agents. However, most enzymes employed in nucleoside biocatalysis are not recycled, possess limited stability, and have strict substrate selection for ribonucleosides or 2'deoxyribonucleosides. We employed 2'-deoxyribonucleoside transferase (NDT) enzymes from thermophilic and psychrophilic bacteria to demonstrate they can be immobilized to enhance specific activity, stability, and recyclability. NDT enzymes from Chroococcidiopsis thermalis (CtNDT), and Bacillus psychrosaccharolyticus (BpNDT) were immobilized by covalent attachment to chitosan beads. A double mutant of CtNDT, capable of generating 3'deoxyribonucleosides, showed remarkable and increased stability after immobilization compared to the same enzyme in the solution. Furthermore, we demonstrated the recyclability of immobilized biocatalysts, with a 10-fold improvement in reaction yield over 20 consecutive cycles, highlighting the practicality and sustainability of the developed immobilization method. We used our strategy to produce a pharmaceutically relevant 3'deoxyribonucleoside (2-fluoro-3'-deoxyadenosine). This highlights the importance of efficient immobilization techniques to enhance the catalytic properties of NDT enzymes, expanding their utility in biocatalysis.

Unveiling the Psychedelic Journey: An Appraisal of Psilocybin as a Profound Antidepressant Therapy

Depression, a global health concern with significant implications for suicide rates, remains challenging to treat effectively with conventional pharmacological options. The existing pharmaceutical interventions for these illnesses need daily dosing, are accompanied by various adverse effects, and may exhibit limited efficacy in certain cases. However, hope emerges from an unlikely source-Psilocybin, a natural hallucinogen found in certain mushrooms. Recently, this enigmatic compound has garnered attention for its potential therapeutic benefits in addressing various mental health issues, including depression. Psilocybin alters mood, cognition, and perception by acting on a particular subtype of serotonin receptors in the brain. It's feasible that these shifts in consciousness will promote healing development, offering a novel approach to depression management. This comprehensive review explores psilocybin, derived from specific mushrooms, and its implications in the treatment of depression. The study examines new perspectives and therapeutic possibilities surrounding psilocybin, addressing existing gaps in academic literature. It delves into its biosynthesis, unique mechanisms of action, therapeutic applications, and anti-depressive effects. By uncovering the potential of this mind-altering substance, the review aims to advance psychiatric care, offering hope to those globally affected by depression.

Asymmetric Synthesis of 2-Arylethylamines: A Metal-Free Review of the New Millennium

2-Arylethylamines are presented in several natural bioactive compounds, as well as in nitrogen-containing drugs. Their ability to surpass the blood-brain barrier makes this family of compounds of especial interest in medicinal chemistry. Asymmetric methodologies towards the synthesis of 2-arylethylamine motives are of great interest due to the challenges they may present. Thus, a concise metal-free review presenting recent advances in the asymmetric synthesis of 2-arylethylamines is presented, covering last-millennium studies, considering different methodologies towards the aforementioned motif, including chiral induction, organocatalysis, organophotocatalysis and enzymatic catalysis.

Deciphering substrate promiscuity and specificity of indolethylamine N-methyltransferase family enzymes from amphibian toads

N-methylation is a crucial post-modification process in natural product biosynthesis and also contributes to the metabolism of various physiological substances, such as neurotransmitter, hormone, and trace elements. In this study, we identified seven indolethylamine N-methyltransferase (INMT) family enzymes from the amphibian toad Bufo gargarizan with distinct catalytic properties. Among these enzymes, BNMT 1, BNMT 5, BNMT 6 and BNMT 7 exhibited notable promiscuity, demonstrating the ability to methylate multiple derivatives of indolethylamine, phenylethylamine, phenylethanolamine, and nicotinamide. Conversely, BNMT 3 and BNMT 4 exhibited more specific substrate preferences, targeting particular phenylethylamine, phenylethanolamine, and nicotinamide-type substrates. Additionally, one enzyme, BNMT 11, exhibiting high specificity towards phenylethanolamines. By employing molecular docking and mutating key amino acids, we provided a rational explanation for the promiscuity and specificity mechanisms exhibited by these enzymes. This research offers valuable insights into the catalytic mechanisms of INMT family enzymes in B. gargarizans, as well as other organisms. Moreover, the identification of these broadly substrate-specific enzymes holds promise for leveraging synthetic biology in the production of a wide variety of naturally occurring N-methylated compounds.

Evolution of the biochemistry underpinning purine alkaloid metabolism in plants

Purine alkaloids are naturally occurring nitrogenous methylated derivatives of purine nucleotide degradation products, having essential roles in medicine, food and various other aspects of our daily lives. They are generated through convergent evolution in different plant species. The pivotal reaction steps within the purine alkaloid metabolic pathways have been largely elucidated, and the convergent evolution of purine alkaloids has been substantiated through bioinformatic, biochemical and other research perspectives within S-adenosyl-ʟ-methionine-dependent N-methyltransferases. Currently, the biological and ecological roles of purine alkaloids, further refinement of the purine alkaloid metabolic pathways and the investigation of purine alkaloid adaptive evolutionary mechanisms continue to attract widespread research interest. The exploration of the purine alkaloid metabolic pathways also enhances our comprehension of the biochemical mechanism, providing insights into inter-species interactions and adaptive evolution and offering potential value in drug development and agricultural applications. Here, we review the progress of research in the distribution, metabolic pathway elucidation and regulation, evolutionary mechanism and ecological roles of purine alkaloids in plants. The opportunities and challenges involved in elucidating the biochemical basis and evolutionary mechanisms of the purine alkaloid metabolic pathways, as well as other research aspects, are also discussed. This article is part of the theme issue 'The evolution of plant meta-bolism'.

The protective effect of natural medicines in rheumatoid arthritis via inhibit angiogenesis

Rheumatoid arthritis is a chronic immunological disease leading to the progressive bone and joint destruction. Angiogenesis, accompanied by synovial hyperplasia and inflammation underlies joint destruction. Delaying or even blocking synovial angiogenesis has emerged as an important target of RA treatment. Natural medicines has a long history of treating RA, and numerous reports have suggested that natural medicines have a strong inhibitory activity on synovial angiogenesis, thereby improving the progression of RA. Natural medicines could regulate the following signaling pathways: HIF/VEGF/ANG, PI3K/Akt pathway, MAPKs pathway, NF-κB pathway, PPARγ pathway, JAK2/STAT3 pathway, etc., thereby inhibiting angiogenesis. Tripterygium wilfordii Hook. f. (TwHF), sinomenine, and total glucoside of Paeonia lactiflora Pall. Are currently the most representative of all natural products worthy of development and utilization. In this paper, the main factors affecting angiogenesis were discussed and different types of natural medicines that inhibit angiogenesis were systematically summarized. Their specific anti-angiogenesis mechanisms are also reviewed which aiming to provide new perspective and options for the management of RA by targeting angiogenesis.

Polyphenolic Platform Ameliorated Sanshool for Skin Photoprotection

Natural evolution has nurtured a series of active molecules that play vital roles in physiological systems, but their further applications have been severely limited by rapid deactivation, short cycle time, and potential toxicity after isolation. For instance, the instability of structures and properties has greatly descended when sanshool is derived from Zanthoxylum xanthoxylum. Herein, natural polyphenols are employed to boost the key properties of sanshool by fabricating a series of nanoparticles (NPs). The intracellular evaluation and in vivo animal model are conducted to demonstrate the decreased photodamage score and skin-fold thickness of prepared NPs, which can be attributed to the better biocompatibility, improved free radical scavenging, down-regulated apoptosis ratios, and reduced DNA double-strand breaks compared to naked sanshool. This work proposes a novel strategy to boost the key properties of naturally occurring active molecules with the assistance of natural polyphenol-based platforms.

Effects of hallucinogenic drugs on the human heart

Hallucinogenic drugs are used because they have effects on the central nervous system. Their hallucinogenic effects probably occur via stimulation of serotonin receptors, namely, 5-HT2A-serotonin receptors in the brain. However, a close study reveals that they also act on the heart, possibly increasing the force of contraction and beating rate and may lead to arrhythmias. Here, we will review the inotropic and chronotropic actions of bufotenin, psilocin, psilocybin, lysergic acid diethylamide (LSD), ergotamine, ergometrine, N,N-dimethyltryptamine, and 5-methoxy-N,N-dimethyltryptamine in the human heart.

Aconitine and its derivatives: bioactivities, structure-activity relationships and preliminary molecular mechanisms

Aconitine (AC), which is the primary bioactive diterpene alkaloid derived from Aconitum L plants, have attracted considerable interest due to its unique structural feature. Additionally, AC demonstrates a range of biological activities, such as its ability to enhance cardiac function, inhibit tumor growth, reduce inflammation, and provide analgesic effects. However, the structure-activity relationships of AC are remain unclear. A clear understanding of these relationships is indeed critical in developing effective biomedical applications with AC. In line with these challenges, this paper summarized the structural characteristics of AC and relevant functional and bioactive properties and the structure-activity relationships presented in biomedical applications. The primary temporal scope of this review was established as the period spanning from 2010 to 2023. Subsequently, the objective of this review was to provide a comprehensive understanding of the specific action mechanism of AC, while also exploring potential novel applications of AC derivatives in the biomedical field, drawing upon their structural characteristics. In conclusion, this review has provided a comprehensive analysis of the challenges and prospects associated with AC in the elucidation of structure-bioactivity relationships. Furthermore, the importance of exploring modern biotechnology approaches to enhance the potential biomedical applications of AC has been emphasized.

A journey with psychedelic mushrooms: From historical relevance to biology, cultivation, medicinal uses, biotechnology, and beyond

Psychedelic mushrooms containing psilocybin and related tryptamines have long been used for ethnomycological purposes, but emerging evidence points to the potential therapeutic value of these mushrooms to address modern neurological, psychiatric health, and related disorders. As a result, psilocybin containing mushrooms represent a re-emerging frontier for mycological, biochemical, neuroscience, and pharmacology research. This work presents crucial information related to traditional use of psychedelic mushrooms, as well as research trends and knowledge gaps related to their diversity and distribution, technologies for quantification of tryptamines and other tryptophan-derived metabolites, as well as biosynthetic mechanisms for their production within mushrooms. In addition, we explore the current state of knowledge for how psilocybin and related tryptamines are metabolized in humans and their pharmacological effects, including beneficial and hazardous human health implications. Finally, we describe opportunities and challenges for investigating the production of psychedelic mushrooms and metabolic engineering approaches to alter secondary metabolite profiles using biotechnology integrated with machine learning. Ultimately, this critical review of all aspects related to psychedelic mushrooms represents a roadmap for future research efforts that will pave the way to new applications and refined protocols.

A mechanistic insight for the biosynthesis of N,N-dimethyltryptamine: An ONIOM theoretical approach

Psychoactive natural products are potent serotonergic agonists capable of modulating brain functions such as memory and cognition. These substances have shown therapeutic potential for treating various mental disorders. The fact that N,N-dimethyltryptamine (DMT) is produced endogenously in several plants and animals, including humans, makes it particularly attractive. As an amino acid-derived alkaloid, the DMT biosynthetic pathway is part of the L-tryptophan biochemical cascade and can be divided into the decarboxylation by an aromatic L-amino acid decarboxylase (AADC) for tryptamine formation and the subsequent double-methylation by the indolethylamine-N-methyltransferase (INMT) through the cofactor S-adenosyl-L-methionine (SAM), a methyl donor. Unlike the decarboxylation mechanism of L-tryptophan, the molecular details of the double methylation of tryptamine have not been elucidated. Therefore, we propose an in silico model using molecular dynamics (MD), non-covalent interaction index (NCI) and density functional theory (DFT) calculations with the ONIOM QM:MM B3LYP/6-31+G(d,p):MM/UFF level of theory. Based on the obtained energetic data, the potential energy surface (PES) indicates an SN2 mechanism profile, with the second methylation energy barrier being the rate-limiting step with δG‡=60kJ∙mol-1 larger than the previous methylation, following the NCI analysis showing more repulsive interactions for the second transition state. In addition, the hybridization information of each reaction step provides geometric details about the double-methylation.

Chemistry and biology of ent-morphinan alkaloids

Morphinan alkaloids have attracted constant attention since the isolation of morphine by Sertürner in 1805. However, a group of 45 compounds possessing a complete ent-morphinan backbone can also be found in the literature. These compounds are related to the morphinandienone subgroup and display a substitution pattern which is different from the morphinans. In particular, these alkaloids could be substituted at position C-2 and C-8 either by a hydroxy function or a methoxy moiety. Four groups of ent-morphinan alkaloids can be proposed, the salutaridine, pallidine, cephasugine and erromangine series. Interestingly, the botanical distribution of the ent-morphinans is more widespread than for the morphinans and includes the Annonaceae, Berberidaceae, Euphorbiaceae, Fumariaceae, Hernandiaceae, Lauraceae, Menispermaceae, Monimiaceae, Papaveraceae, and Ranunculaceae families. To date, their exact mode of production remains elusive and their interplay with the biosynthetic pathway of other classes of benzyltetrahydroisoquinoline alkaloids, in particular aporphines, should be confirmed. Exploration of the biological and therapeutic potential of these compounds is limited to some areas, namely central nervous system (CNS), inflammation, cancer, malaria and viruses. Further studies should be conducted to identify the cellular/molecular targets in view of promoting these compounds as new scaffolds in medicinal chemistry.

Examination of Secondary Metabolite Biosynthesis in Apicomplexa

Natural product discovery has traditionally relied on the isolation of small molecules from producing species, but genome-sequencing technology and advances in molecular biology techniques have expanded efforts to a wider array of organisms. Protists represent an underexplored kingdom for specialized metabolite searches despite bioinformatic analysis that suggests they harbor distinct biologically active small molecules. Specifically, pathogenic apicomplexan parasites, responsible for billions of global infections, have been found to possess multiple biosynthetic gene clusters, which hints at their capacity to produce polyketide metabolites. Biochemical studies have revealed unique features of apicomplexan polyketide synthases, but to date, the identity and function of the polyketides synthesized by these megaenzymes remains unknown. Herein, we discuss the potential for specialized metabolite production in protists and the possible evolution of polyketide biosynthetic gene clusters in apicomplexan parasites. We then focus on a polyketide synthase from the apicomplexan Toxoplasma gondii to discuss the unique domain architecture and properties of these proteins when compared to previously characterized systems, and further speculate on the possible functions for polyketides in these pathogenic parasites.

Total Synthesis and Structural Plasticity of Kratom Pseudoindoxyl Metabolites

Mitragynine pseudoindoxyl, a kratom metabolite, has attracted increasing attention due to its favorable side effect profile as compared to conventional opioids. Herein, we describe the first enantioselective and scalable total synthesis of this natural product and its epimeric congener, speciogynine pseudoindoxyl. The characteristic spiro-5-5-6-tricyclic system of these alkaloids was formed through a protecting-group-free cascade relay process in which oxidized tryptamine and secologanin analogues were used. Furthermore, we discovered that mitragynine pseudoindoxyl acts not as a single molecular entity but as a dynamic ensemble of stereoisomers in protic environments; thus, it exhibits structural plasticity in biological systems. Accordingly, these synthetic, structural, and biological studies provide a basis for the planned design of mitragynine pseudoindoxyl analogues, which can guide the development of next-generation analgesics.

Investigation of Small-Molecule Constituents in Voacanga africana Seeds and Mapping of Their Spatial Distributions Using Laser Ablation Direct Analysis in Real-Time Imaging-Mass Spectrometry (LADI-MS)

Plant seeds are a renewable resource that can furnish access to medicinal natural products that can only otherwise be isolated from aerial or root parts, the harvest of which may be destructive to the plant or threaten its viability. However, optimization of the isolation of such compounds from seeds would be greatly assisted if the spatial distribution of the molecules of interest within the plant tissue were known. For example, iboga alkaloids that hold promise for the treatment of opioid use disorder are typically isolated from the leaves, bark, or roots of Tabernanthe or Voacanga spp. trees, but it would be more environmentally sustainable to isolate such compounds from their seeds. Here, we leveraged the unique capabilities of the ambient mass spectral imaging technique termed laser ablation direct analysis in real-time imaging-mass spectrometry (LADI-MS) to reveal the spatial distributions of a range of molecules, including alkaloids within V. africana seeds. In addition to six compounds previously reported in these seeds, namely, tetradecanoic acid, n-hexadecanoic acid, (Z,Z)-9,12-octadecadienoic acid, (Z)-9-octadecenoic acid, octadecanoic acid, and Δ14-vincamine, an additional 31 compounds were newly identified in V. africana seeds. The compound classes included alkaloids, terpenes, and fatty acids. The ion images showed that the fatty acids were localized in the embryo of the seed. The alkaloids, which were mainly localized in the seed endosperm, included strictamine, akuammidine, polyneruidine, vobasine, and Δ14-vincamine. This information can be exploited to enhance the efficiency of secondary metabolite isolation from V. africana seeds while eliminating the destruction of other plant parts.

Bioactive Natural Product Discovery via Deuterium Adduct Bioactivity Screening

The discovery of bioactive natural products lies at the forefront of human medicine. The continued discovery of these molecules is imperative in the fight against infection and disease. While natural products have historically dominated the drug market, discovery in recent years has slowed significantly, partly due to limitations in current discovery methodologies. This work demonstrates a new workflow, deuterium adduct bioactivity screening (DABS), which pairs untargeted isotope labeling with whole cell binding assays for bioactive natural product discovery. DABS was validated and led to the discovery of a new isoprenyl guanidine alkaloid, zillamycin, which showed anti-cancer and anti-microbial activities. DABS thus represents a new workflow to accelerate discovery of natural products with a wide range of bioactive potentials.

Ergotamine Stimulates Human 5-HT4-Serotonin Receptors and Human H2-Histamine Receptors in the Heart

Ergotamine (2'-methyl-5'α-benzyl-12'-hydroxy-3',6',18-trioxoergotaman) is a tryptamine-related alkaloid from the fungus Claviceps purpurea. Ergotamine is used to treat migraine. Ergotamine can bind to and activate several types of 5-HT₁-serotonin receptors. Based on the structural formula of ergotamine, we hypothesized that ergotamine might stimulate 5-HT₄-serotonin receptors or H₂-histamine receptors in the human heart. We observed that ergotamine exerted concentration- and time-dependent positive inotropic effects in isolated left atrial preparations in H₂-TG (mouse which exhibits cardiac-specific overexpression of the human H₂-histamine receptor). Similarly, ergotamine increased force of contraction in left atrial preparations from 5-HT₄-TG (mouse which exhibits cardiac-specific overexpression of the human 5-HT₄-serotonin receptor). An amount of 10 µM ergotamine increased the left ventricular force of contraction in isolated retrogradely perfused spontaneously beating heart preparations of both 5-HT₄-TG and H₂-TG. In the presence of the phosphodiesterase inhibitor cilostamide (1 µM), ergotamine 10 µM exerted positive inotropic effects in isolated electrically stimulated human right atrial preparations, obtained during cardiac surgery, that were attenuated by 10 µM of the H₂-histamine receptor antagonist cimetidine, but not by 10 µM of the 5-HT₄-serotonin receptor antagonist tropisetron. These data suggest that ergotamine is in principle an agonist at human 5-HT₄-serotonin receptors as well at human H₂-histamine receptors. Ergotamine acts as an agonist on H₂-histamine receptors in the human atrium.

Using inorganic nanoparticles to fight fungal infections in the antimicrobial resistant era

Fungal infections pose a serious threat to human health and livelihoods. The number and variety of clinically approved antifungal drugs is very limited, and the emergence and rapid spread of resistance to these drugs means the impact of fungal infections will increase in the future unless alternatives are found. Despite the significance and major challenges associated with fungal infections, this topic receives significantly less attention than bacterial infections. A major challenge in the development of fungi-specific drugs is that both fungi and mammalian cells are eukaryotic and have significant overlap in their cellular machinery. This lack of fungi-specific drug targets makes human cells vulnerable to toxic side effects from many antifungal agents. Furthermore, antifungal drug resistance necessitates higher doses of the drugs, leading to significant human toxicity. There is an urgent need for new antifungal agents, specifically those that can limit the emergence of new resistant species. Non-drug nanomaterials have primarily been explored as antibacterial agents in recent years; however, they are also a promising source of new antifungal candidates. Thus, this article reviews current research on the use of inorganic nanoparticles as antifungal agents. We also highlight challenges facing antifungal nanoparticles and discuss possible future research opportunities in this field. STATEMENT OF SIGNIFICANCE: Fungal infections pose a growing threat to human health and livelihood. The rapid spread of resistance to current antifungal drugs has led to an urgent need to develop alternative antifungals. Nanoparticles have many properties that could make them useful antimycotic agents. To the authors' knowledge, there is no published review so far that has comprehensively summarized the current development status of antifungal inorganic nanomaterials, so we decided to fill this gap. In this review, we discussed the state-of-the-art research on antifungal inorganic nanoparticles including metal, metal oxide, transition-metal dichalcogenides, and inorganic non-metallic particle systems. Future directions for the design of inorganic nanoparticles with higher antifungal efficacy and lower toxicity are described as a guide for further development in this important area.

Diversity-Oriented Biosynthesis Yields l-Kynurenine Derivative-Based Neurological Drug Candidate Collection

Natural product libraries with a remarkable range of biological activities play pivotal roles in drug discoveries due to their extraordinary structural complexity and immense diversity. l-Kynurenine (l-Kyn)-based derivatives are privileged pharmacophores that exhibit diverse therapeutic implications in neurological disorders. However, the difficulty in obtaining l-Kyn analogues with different skeletal structures has recently led to a decline in its medicinal research. Herein, we report a two-step, one-pot protocol for diversity-oriented biosynthesis of a collection of previously intractable l-Kyn-like compounds. The success of these challenging transformations mainly depends on unlocking the new catalytic scope of tryptophan 2,3-dioxygenases, followed by rational site-directed mutagenesis to modify the substrate domains further. As a result, 18 kynurenine analogues with diverse molecular scaffolds can be rapidly assembled in a predictable manner with 20-83% isolated yields, which not only fill the voids of the catalytic profile of tryptophan 2,3-dioxygenases with an array of substituent groups (e.g., F, Cl, Br, I, CH₃, OCH₃, and NO₂) but also update the current understanding of its substrate spectrum. Our work highlights the great potential of existing enzymes in addressing long-standing synthetic challenges for facilitating the development or discovery of new drug candidates. Furthermore, our approach enables translating the reaction parameters from Eppendorf tubes to 1 L scale, affording l-4-Cl-Kyn and l-5-Cl-Kyn both on a gram scale with more than 80% isolated yields, and provides a promising alternative to further industrial applications.

Leveraging yeast to characterize plant biosynthetic gene clusters

Plant biosynthetic gene clusters (BGCs) contain multiple physically clustered non-homologous genes that encode enzymes catalyzing diverse reactions in one plant natural product biosynthetic pathway. A growing number of plant BGCs have emerged as an underlying resource for understanding plant specialized metabolism and evolution, but the characterization remains challenging. Recent studies have demonstrated that baker's yeast can serve as a versatile platform for the characterization of plant BGCs, from single-gene characterization to multiple genes and hitherto unknown putative BGC validation and elucidation. In this review, we will summarize the strategies and examples of the applications of yeast in plant BGC characterization and share our perspective on the development of a systematic pipeline to fully leverage yeast to advance the understanding of plant BGCs and plant natural product biomanufacturing.

Psychoactive Isoxazoles, Muscimol, and Isoxazole Derivatives from the Amanita (Agaricomycetes) Species: Review of New Trends in Synthesis, Dosage, and Biological Properties

Herbal products found in nature can serve as great systems of study for drug design. The Amanita muscaria mushroom is native to many parts of the Northern Hemisphere and has a very distinctive appearance with its red cap and white spotted warts. The mushroom comprises several pharmacologically active alkaloids, including muscazone, muscarine, ibotenic acid, and muscimol, the latter two compounds being potent GABA agonists. Muscimol has served as a backbone in the design of GABA agonists devoid of effects on the GABA-metabolizing enzyme, GABA transaminase, and GABA uptake systems. In this sense, several analogs of muscimol have been synthesized and studied including THIP, THPO, iso-THIP, iso-THAZ and 4-PIOL which all interact with the GABA receptors much differently. The growing pharmacological and toxicological interest based on many conflicting opinions on the use of the neuroprotective role of muscimol analogs against some neurodegenerative diseases, its potent role in the treatment of cerebral ischemia and other socially significant health conditions provided the basis for this review.

Discovery and Engineering of the Cocaine Biosynthetic Pathway

Cocaine, the archetypal tropane alkaloid from the plant genus Erythroxylum, has recently been used clinically as a topical anesthesia of the mucous membranes. Despite this, the key biosynthetic step of the requisite tropane skeleton (methylecgonone) from the identified intermediate 4-(1-methyl-2-pyrrolidinyl)-3-oxobutanoic acid (MPOA) has remained, until this point, unknown. Herein, we identify two missing enzymes (EnCYP81AN15 and EnMT4) necessary for the biosynthesis of the tropane skeleton in cocaine by transient expression of the candidate genes in Nicotiana benthamiana. Cytochrome P450 EnCYP81AN15 was observed to selectively mediate the oxidative cyclization of S-MPOA to yield the unstable intermediate ecgonone, which was then methylated to form optically active methylecgonone by methyltransferase EnMT4 in Erythroxylum novogranatense. The establishment of this pathway corrects the long-standing (but incorrect) biosynthetic hypothesis of MPOA methylation first and oxidative cyclization second. Notably, the de novo reconstruction of cocaine was realized in N. benthamiana with the two newly identified genes, as well as four already known ones. This study not only reports a near-complete biosynthetic pathway of cocaine and provides new insights into the metabolic networks of tropane alkaloids (cocaine and hyoscyamine) in plants but also enables the heterologous synthesis of tropane alkaloids in other (micro)organisms, entailing significant implications for pharmaceutical production.

Engineered Production of Strictosidine and Analogues in Yeast

Monoterpene indole alkaloids (MIAs) are an expansive class of plant natural products, many of which have been named on the World Health Organization's List of Essential Medicines. Low production from native plant hosts necessitates a more reliable source of these drugs to meet global demand. Here, we report the development of a yeast-based platform for high-titer production of the universal MIA precursor, strictosidine. Our fed-batch platform produces ∼50 mg/L strictosidine, starting from the commodity chemicals geraniol and tryptamine. The microbially produced strictosidine was purified to homogeneity and characterized by NMR. Additionally, our approach enables the production of halogenated strictosidine analogues through the feeding of modified tryptamines. The MIA platform strain enables rapid access to strictosidine for reconstitution and production of downstream MIA natural products.

Biocatalysis making waves in organic chemistry

Biocatalysis has an enormous impact on chemical synthesis. The waves in which biocatalysis has developed, and in doing so changed our perception of what organic chemistry is, were reviewed 20 and 10 years ago. Here we review the consequences of these waves of development. Nowadays, hydrolases are widely used on an industrial scale for the benign synthesis of commodity and bulk chemicals and are fully developed. In addition, further enzyme classes are gaining ever increasing interest. Particularly, enzymes catalysing selective C-C-bond formation reactions and enzymes catalysing selective oxidation and reduction reactions are solving long-standing synthetic challenges in organic chemistry. Combined efforts from molecular biology, systems biology, organic chemistry and chemical engineering will establish a whole new toolbox for chemistry. Recent developments are critically reviewed.

Shortening Synthetic Routes to Small Molecule Active Pharmaceutical Ingredients Employing Biocatalytic Methods

Biocatalysis, using enzymes for organic synthesis, has emerged as powerful tool for the synthesis of active pharmaceutical ingredients (APIs). The first industrial biocatalytic processes launched in the first half of the last century exploited whole-cell microorganisms where the specific enzyme at work was not known. In the meantime, novel molecular biology methods, such as efficient gene sequencing and synthesis, triggered breakthroughs in directed evolution for the rapid development of process-stable enzymes with broad substrate scope and good selectivities tailored for specific substrates. To date, enzymes are employed to enable shorter, more efficient, and more sustainable alternative routes toward (established) small molecule APIs, and are additionally used to perform standard reactions in API synthesis more efficiently. Herein, large-scale synthetic routes containing biocatalytic key steps toward >130 APIs of approved drugs and drug candidates are compared with the corresponding chemical protocols (if available) regarding the steps, reaction conditions, and scale. The review is structured according to the functional group formed in the reaction.

Recent Advancements in Microbial Polysaccharides: Synthesis and Applications

Polysaccharide materials are widely applied in different applications including food, food packaging, drug delivery, tissue engineering, wound dressing, wastewater treatment, and bioremediation sectors. They were used in these domains due to their efficient, cost-effective, non-toxicity, biocompatibility, and biodegradability. As is known, polysaccharides can be synthesized by different simple, facile, and effective methods. Of these polysaccharides are cellulose, Arabic gum, sodium alginate, chitosan, chitin, curdlan, dextran, pectin, xanthan, pullulan, and so on. In this current article review, we focused on discussing the synthesis and potential applications of microbial polysaccharides. The biosynthesis of polysaccharides from microbial sources has been considered. Moreover, the utilization of molecular biology tools to modify the structure of polysaccharides has been covered. Such polysaccharides provide potential characteristics to transfer toxic compounds and decrease their resilience to the soil. Genetically modified microorganisms not only improve yield of polysaccharides, but also allow economically efficient production. With the rapid advancement of science and medicine, biosynthesis of polysaccharides research has become increasingly important. Synthetic biology approaches can play a critical role in developing polysaccharides in simple and facile ways. In addition, potential applications of microbial polysaccharides in different fields with a particular focus on food applications have been assessed.