Metabolic Activation and Cytotoxicity of Gramine Mediated by CYP3A in Rats.

Gramine (GRM), which occurs in Gramineae plants, has been developed to be a biological insecticide. Exposure to GRM was reported to induce elevations of serum ALT and AST in rats, but the mechanisms of the observed hepatotoxicity have not been elucidated. The present study aimed to identify reactive metabolites that potentially participate in the toxicity. In rat liver microsomal incubations fortified with glutathione or N-acetylcysteine, one oxidative metabolite (M1), one glutathione conjugate (M2), and one N-acetylcysteine conjugate (M3) were detected after exposure to GRM. The corresponding conjugates were detected in the bile and urine of rats after GRM administration. CYP3A was the main enzyme mediating the metabolic activation of GRM. The detected GSH and NAC conjugates suggest that GRM was metabolized to a quinone imine intermediate. Both GRM and M1 showed significant toxicity to rat primary hepatocytes.

Metabolomics and transcriptomics reveal the mechanism of alkaloid synthesis in Corydalis yanhusuo bulbs.

Corydalis yanhusuo W.T. Wang is a traditional herb. Benzylisoquinoline alkaloids (BIAs) are the main pharmacological active ingredients that play an important role in sedation, relieving pain, promoting blood circulation, and inhibiting cancer cells. However, there are few studies on the biosynthetic pathway of benzylisoquinoline alkaloids in Corydalis yanhusuo, especially on some specific components, such as tetrahydropalmatine. We carried out widely targeted metabolome and transcriptomic analyses to construct the biosynthetic pathway of benzylisoquinoline alkaloids and identified candidate genes. In this study, 702 metabolites were detected, including 216 alkaloids. Protoberberine-type and aporphine-type alkaloids are the main chemical components in C. yanhusuo bulbs. Key genes for benzylisoquinoline alkaloids biosynthesis, including 6-OMT, CNMT, NMCH, BBE, SOMT1, CFS, SPS, STOX, MSH, TNMT and P6H, were successfully identified. There was no significant difference in the content of benzylisoquinoline alkaloids and the expression level of genes between the two suborgans (mother-bulb and son-bulb). The expression levels of BIA genes in the expansion stage (MB-A and SB-A) were significantly higher than those in the maturity stage (MB-C and SB-C), and the content of benzylisoquinoline alkaloids was consistent with the pattern of gene regulation. Five complete single genes were likely to encode the functional enzyme of CoOMT, which participated in tetrahydropalmatine biosynthesis in C. yanhusuo bulbs. These studies provide a strong theoretical basis for the subsequent development of metabolic engineering of benzylisoquinoline alkaloids (especially tetrahydropalmatine) of C. yanhusuo.

Non-Heme Iron Enzymes Catalyze Heterobicyclic and Spirocyclic Isoquinolone Core Formation in Piperazine Alkaloid Biosynthesis.

We report the discovery and biosynthesis of new piperazine alkaloids-arizonamides, and their derived compounds-arizolidines, featuring heterobicyclic and spirocyclic isoquinolone skeletons, respectively. Their biosynthetic pathway involves two crucial non-heme iron enzymes, ParF and ParG, for core skeleton construction. ParF has a dual function facilitating 2,3-alkene formation of helvamide, as a substrate for ParG, and oxidative cleavage of piperazine. Notably, ParG exhibits catalytic versatility in multiple oxidative reactions, including cyclization and ring reconstruction. A key amino acid residue Phe67 was characterized to control the formation of the constrained arizonamide B backbone by ParG.

Bioactivity and mechanism of action of sanguinarine and its derivatives in the past 10 years.

Sanguinarine is a quaternary ammonium benzophenanthine alkaloid found in traditional herbs such as Chelidonium, Corydalis, Sanguinarum, and Borovula. It has been proven to possess broad-spectrum biological activities, such as antitumor, anti-inflammatory, antiosteoporosis, neuroprotective, and antipathogenic microorganism activities. In this paper, recent progress on the biological activity and mechanism of action of sanguinarine and its derivatives over the past ten years is reviewed. The results showed that the biological activities of hematarginine and its derivatives are related mainly to the JAK/STAT, PI3K/Akt/mTOR, NF-κB, TGF-ß, MAPK and Wnt/ß-catenin signaling pathways. The limitations of using sanguinarine in clinical application are also discussed, and the research prospects of this subject are outlined. In general, sanguinarine, a natural medicine, has many pharmacological effects, but its toxicity and safety in clinical application still need to be further studied. This review provides useful information for the development of sanguinarine-based bioactive agents.

Oxymatrine protects articular chondrocytes from IL-1ß-induced damage through autophagy activation via AKT/mTOR signaling pathway inhibition.

BACKGROUND: Osteoarthritis (OA) is a common degenerative joint disease characterized by persistent articular cartilage degeneration and synovitis. Oxymatrine (OMT) is a quinzolazine alkaloid extracted from the traditional Chinese medicine, matrine, and possesses anti-inflammatory properties that may help regulate the pathogenesis of OA; however, its mechanism has not been elucidated. This study aimed to investigate the effects of OMT on interleukin-1ß (IL-1ß)-induced damage and the potential mechanisms of action. METHODS: Chondrocytes were isolated from Sprague-Dawley rats. Toluidine blue and Collagen II immunofluorescence staining were used to determine the purity of the chondrocytes. Thereafter, the chondrocytes were subjected to IL-1ß stimulation, both in the presence and absence of OMT, or the autophagy inhibitor 3-methyladenine (3-MA). Cell viability was assessed using the MTT assay and SYTOX Green staining. Additionally, flow cytometry was used to determine cell apoptosis rate and reactive oxygen species (ROS) levels. The protein levels of AKT, mTOR, LC3, P62, matrix metalloproteinase-13, and collagen II were quantitatively analyzed using western blotting. Immunofluorescence was used to assess LC3 expression. RESULTS: OMT alleviated IL-1ß-induced damage in chondrocytes, by increasing the survival rate, reducing the apoptosis rates of chondrocytes, and preventing the degradation of the cartilage matrix. In addition, OMT decreased the ROS levels and inhibited the AKT/mTOR signaling pathway while promoting autophagy in IL-1ß treated chondrocytes. However, the effectiveness of OMT in improving chondrocyte viability under IL-1ß treatment was limited when autophagy was inhibited by 3-MA. CONCLUSIONS: OMT decreases oxidative stress and inhibits the AKT/mTOR signaling pathway to enhance autophagy, thus inhibiting IL-1ß-induced damage. Therefore, OMT may be a novel and effective therapeutic agent for the clinical treatment of OA.

Alkaloid uptake pathways in renal tubular epithelial cells from different processed products of Phellodendri chinensis Cortex.

This study aimed to investigate the absorption of alkaloids from Phellodendri chinensis Cortex (PC) by human renal tubular epithelial cells (HK-2). Cellular uptake and affinity ultrafiltration assays were employed to determine the alkaloid uptake pathway in HK-2 cells. Stemming from the hypothesis that salt-water processed PC introduces these alkaloids into the kidney at a cellular level, this research focused on different processed products of PC that are tailored for renal targeting. Utilizing the UPLC-QqQ-MS method, we quantified variations in the uptake capacity of phellodendrine, magnoflorine, jatrorrhizine, berberrubine, and berberine from raw Phellodendri chinensis Cortex (RPC), salt-water processed Phellodendri chinensis Cortex (SPC), and wine processed Phellodendri chinensis Cortex (WPC) in HK-2 cells. This study also tracked the concentration changes of these five alkaloids in HK-2 cells during the administration phase. Further, we evaluated the influence of two inhibitors on the absorption of these five alkaloids from PC and its processed products into HK-2 cells: the organic anion transporters (OATs) inhibitor-probenecid (PRO), and the organic cationic transporters (OCTs) inhibitor-tetraethylammonium chloride (TEAC). A pivotal component of this research was an investigation into the effects of PC and its processed products on the expression levels of OCT2, OAT1, and OAT3 proteins in HK-2 cells, facilitated by Western blot analysis. Finally, we appraised the binding affinity of PC's alkaloids to OCT2, OAT1, and OAT3 proteins using an ultrafiltration centrifugation technique. The uptake of different processed products of PC by HK-2 cells showed the following trend: SPC group > RPC group > WPC group. When considering inhibitor uptake in HK-2 cells, the group treated with PRO (an OATs inhibitor) demonstrated a higher uptake than the group treated with TEAC (an OCTs inhibitor). It was observed that different processed products of PC elevated the expression of OCT2 and OAT1 proteins in HK-2 cells. Specifically, both the SPC and berberrubine groups displayed enhanced expression of these proteins, with a marked increase noted for OCT2. Through affinity ultrafiltration assays, it was determined that the binding affinity of alkaloids from different processed products of PC to OCT2 and OAT1 significantly exceeded that to OAT3. These results indicate that PC-derived alkaloids are absorbed by HK-2 cells, predominantly through transport mechanisms mediated by OCT2 and OAT1, with OCT2 serving as the dominant transporter. The higher intake of alkaloids in SPC group can likely be linked to the amplified activity of kidney uptake transporters.

Ruminant metabolism of zygacine, the major toxic alkaloid in foothill death camas (Zigadenuspaniculatus).

Death Camas (Zigadenus spp.) are common poisonous plants distributed throughout North America. The toxic alkaloids in foothill death camas are zygadenine and a series of zygadenine esters, with zygacine, the 3-acetyl ester of zygadenine, being the most abundant. Both cattle and sheep can be poisoned by grazing death camas, however, sheep consume death camas more readily and are most often poisoned. We hypothesized that the presence of enzymes, including esterases present in the rumen, liver, and blood of livestock would metabolize zygacine. The objective of this study was to investigate the metabolism of zygacine in sheep and cattle using in-vitro and in-vivo systems. Results from experiments where zygacine was incubated in rumen culture, plasma, liver S9 fractions, and liver microsomes and from the analysis of rumen and sera from sheep and cattle dosed death camas plant material demonstrated that zygacine is metabolized to zygadenine in the rumen, liver and blood of sheep and cattle. The results from this study indicate that diagnosticians should analyze for zygadenine, and not zygacine, in the rumen and sera for the diagnosis of livestock suspected to have been poisoned by foothill death camas.

Piperlongumine, a Piper longum-derived amide alkaloid, protects mice from ovariectomy-induced osteoporosis by inhibiting osteoclastogenesis via suppression of p38 and JNK signaling.

Postmenopausal osteoporosis (PMOP) is a metabolic bone disease that results from overproduction and hyperactivation of osteoclasts caused by insufficient estrogen in women after menopause. Current therapeutic strategies are mainly focused on treating PMOP patients who have already developed severe bone loss or even osteoporotic fractures. Obviously, a better strategy is to prevent PMOP from occurring in the first place. However, such reagents are largely lacking. Piperlongumine (PLM), an amide alkaloid extracted from long pepper Piper longum, exhibits the anti-osteoclastogenic effect in normal bone marrow macrophages (BMMs) and the protective effect against osteolysis induced by titanium particles in mice. This study examined the preventive effect of PLM on PMOP and explored the potential mechanism of this effect using both ovariectomized mice and their primary cells. The result showed that PLM (5 and 10 mg kg-1) administered daily for 6 weeks ameliorated ovariectomy-induced bone loss and osteoclast formation in mice. Further cell experiments showed that PLM directly suppressed osteoclast formation, F-actin ring formation, and osteoclastic resorption pit formation in BMMs derived from osteoporotic mice, but did not obviously affect osteogenic differentiation of bone marrow stromal cells (BMSCs) from these mice. Western blot analysis revealed that PLM attenuated maximal activation of p38 and JNK pathways by RANKL stimulation without affecting acute activation of NF-κB, AKT, and ERK signaling. Furthermore, PLM inhibited expression of key osteoclastogenic transcription factors NFATc1/c-Fos and their target genes (Dcstamp, Atp6v0d2, Acp5, and Oscar). Taken together, our findings suggest that PLM inhibits osteoclast formation and function by suppressing RANKL-induced activation of the p38/JNK-cFos/NFATc1 signaling cascade, thereby preventing ovariectomy-induced osteoporosis in mice. Thus, PLM can potentially be used as an anti-resorption drug or dietary supplement for the prevention of PMOP.

O- and N-Methyltransferases in benzylisoquinoline alkaloid producing plants.

BACKGROUND: Secondary metabolites such as benzylisoquinoline alkaloids (BIA) have attracted considerable attention because of their pharmacological properties and potential therapeutic applications. Methyltransferases (MTs) can add methyl groups to alkaloid molecules, altering their physicochemical properties and bioactivity, stability, solubility, and recognition by other cellular components. Five types of O-methyltransferases and two types of N-methyltransferases are involved in BIA biosynthesis. OBJECTIVE: Since MTs may be the source for the discovery and development of novel biomedical, agricultural, and industrial compounds, we performed extensive molecular and phylogenetic analyses of O- and N-methyltransferases in BIA-producing plants. METHODS: MTs involved in BIA biosynthesis were isolated from transcriptomes of Berberis koreana and Caulophyllum robustum. We also mined the methyltransferases of Coptis japonica, Papaver somniferum, and Nelumbo nucifera from the National Center for Biotechnology Information protein database. Then, we analyzed the functional motifs and phylogenetic analysis. RESULT: We mined 42 O-methyltransferases and 8 N-methyltransferases from the five BIA-producing plants. Functional motifs for S-adenosyl-L-methionine-dependent methyltransferases were retained in most methyltransferases, except for the three O-methyltransferases from N. nucifera. Phylogenetic analysis revealed that the methyltransferases were grouped into four clades, I, II, III and IV. The clustering patterns in the phylogenetic analysis suggested a monophyletic origin of methyltransferases and gene duplication within species. The coexistence of different O-methyltransferases in the deep branch subclade might support some cases of substrate promiscuity. CONCLUSIONS: Methyltransferases may be a source for the discovery and development of novel biomedical, agricultural, and industrial compounds. Our results contribute to further understanding of their structure and reaction mechanisms, which will require future functional studies.

Aporphine and amide alkaloids from Illigera parviflora.

Three undescribed alkaloids (+)-9-hydroxy-N-acetylnordicentrine (1), illigeparvinine (2), and deca-(2E,4Z)-2,4-dienoic acid 4-hydroxy-2-phenethyl amide (3), along with 19 known analogues (4-22), were isolated from the ethnic medicinal plant Illigera parviflora. Their structures were established using NMR, MS, and other spectroscopic analyses as well as X-ray diffraction. Moderate inhibition of human gastric carcinoma (MGC-803) and breast adenocarcinoma (T-47D) cell lines proliferation was observed for actinodaphnine (4) with IC50 values of 28.74 and 11.65 µM, respectively. These findings contribute new anticancer potential compounds and expand the chemical diversity known from the valuable traditional medicinal plant I. parviflora.

Corydalis saxicolaBunting total alkaloid eliminates Porphyromonas gingivalis strain 33277 internalized into macrophages by inhibition of TLR2.

OBJECTIVE: This study aimed to investigate the impact of Corydalis Saxicola Bunting Total Alkaloid (CSBTA) on Porphyromonas gingivalis internalization within macrophages and explore the potential role of Toll-Like Receptor 2 (TLR2) in this process. METHODS: We established a P. gingivalis internalization model in macrophages by treating P. gingivalis-infected macrophages (MOI=100:1) with 200 µg/mL metronidazole and 300 µg/mL gentamicin for 1 h. Subsequently, the model was exposed to CSBTA at concentrations of 0.02 g/L or 1 µg/mL Pam3CSK4. After a 6 h treatment, cell lysis was performed with sterile water to quantify bacterial colonies. The mRNA expressions of TLR2 and interleukin-8 (IL-8) in macrophages were analyzed using RT-qPCR, while their protein levels were assessed via Western blot and ELISA respectively. RESULTS: P. gingivalis could internalize into macrophages and enhance the expression of TLR2 and IL-8. Activation of TLR2 by Pam3CSK4 contributed to P. gingivalis survival within macrophages and increased TLR2 and IL-8 expression. Conversely, 0.02 g/L CSBTA effectively cleared intracellular P. gingivalis, achieving a 90 % clearance rate after 6 h. Moreover, it downregulated the expression of TLR2 and IL-8 induced by P. gingivalis. However, the inhibitory effect of CSBTA on the internalized P. gingivalis model was attenuated by Pam3CSK4. CONCLUSION: CSBTA exhibited the ability to reduce the presence of live intracellular P. gingivalis and lower IL-8 expression in macrophages, possibly by modulating TLR2 activity.

Simultaneous Measurement and Distribution Analysis of Urinary Nicotine, Cotinine, Trans-3'-Hydroxycotinine, Nornicotine, Anabasine, and Total Nicotine Equivalents in a Large Korean Population.

Measurement of multiple nicotine metabolites and total nicotine equivalents (TNE) might be a more reliable strategy for tobacco exposure verification than measuring single urinary cotinine alone. We simultaneously measured nicotine, cotinine, 3-OH cotinine, nornicotine, and anabasine using 19,874 urine samples collected from the Korean National Health and Nutrition Examination Survey. Of all samples, 18.6% were positive for cotinine, 17.4% for nicotine, 17.3% for nornicotine, 17.6% for 3-OH cotinine, and 13.2% for anabasine. Of the cotinine negative samples, less than 0.3% were positive for all nicotine metabolites, but not for anabasine (5.7%). The agreement of the classification of smoking status by cotinine combined with nicotine metabolites was 0.982-0.994 (Cohen's kappa). TNE3 (the molar sum of urinary nicotine, cotinine, and 3-OH cotinine) was most strongly correlated with cotinine compared to the other nicotine metabolites; however, anabasine was less strongly correlated with other biomarkers. Among anabasine-positive samples, 30% were negative for nicotine or its metabolites, and 25% were undetectable. Our study shows that the single measurement of urinary cotinine is simple and has a comparable classification of smoking status to differentiate between current smokers and non-smokers relative to the measurement of multiple nicotine metabolites. However, measurement of multiple nicotine metabolites and TNE3 could be useful for monitoring exposure to low-level or secondhand smoke exposure and for determining individual differences in nicotine metabolism. Geometric or cultural factors should be considered for the differentiation of tobacco use from patients with nicotine replacement therapy by anabasine.

The Integration of the Metabolome and Transcriptome for Dendrobium nobile Lindl. in Response to Methyl Jasmonate.

Dendrobium nobile Lindl., as an endangered medicinal plant within the genus Dendrobium, is widely distributed in southwestern China and has important ecological and economic value. There are a variety of metabolites with pharmacological activity in D. nobile. The alkaloids and polysaccharides contained within D. nobile are very important active components, which mainly have antiviral, anti-tumor, and immunity improvement effects. However, the changes in the compounds and functional genes of D. nobile induced by methyl jasmonate (MeJA) are not clearly understood. In this study, the metabolome and transcriptome of D. nobile were analyzed after exposure to MeJA. A total of 377 differential metabolites were obtained through data analysis, of which 15 were related to polysaccharide pathways and 35 were related to terpenoids and alkaloids pathways. Additionally, the transcriptome sequencing results identified 3256 differentially expressed genes that were discovered in 11 groups. Compared with the control group, 1346 unigenes were differentially expressed in the samples treated with MeJA for 14 days (TF14). Moreover, the expression levels of differentially expressed genes were also significant at different growth and development stages. According to GO and KEGG annotations, 189 and 99 candidate genes were identified as being involved in terpenoid biosynthesis and polysaccharide biosynthesis, respectively. In addition, the co-expression analysis indicated that 238 and 313 transcription factors (TFs) may contribute to the regulation of terpenoid and polysaccharide biosynthesis, respectively. Through a heat map analysis, fourteen terpenoid synthetase genes, twenty-three cytochrome P450 oxidase genes, eight methyltransferase genes, and six aminotransferase genes were identified that may be related to dendrobine biosynthesis. Among them, one sesquiterpene synthase gene was found to be highly expressed after the treatment with MeJA and was positively correlated with the content of dendrobine. This study provides important and valuable metabolomics and transcriptomic information for the further understanding of D. nobile at the metabolic and molecular levels and provides candidate genes and possible intermediate compounds for the dendrobine biosynthesis pathway, which lays a certain foundation for further research on and application of Dendrobium.

Epichloë fungal endophyte interactions in perennial ryegrass (Lolium perenne L.) modified to accumulate foliar lipids for increased energy density.

BACKGROUND: Commercial cultivars of perennial ryegrass infected with selected Epichloë fungal endophytes are highly desirable in certain pastures as the resulting mutualistic association has the capacity to confer agronomic benefits (such as invertebrate pest deterrence) largely due to fungal produced secondary metabolites (e.g., alkaloids). In this study, we investigated T2 segregating populations derived from two independent transformation events expressing diacylglycerol acyltransferase (DGAT) and cysteine oleosin (CO) genes designed to increase foliar lipid and biomass accumulation. These populations were either infected with Epichloë festucae var. lolii strain AR1 or Epichloë sp. LpTG-3 strain AR37 to examine relationships between the introduced trait and the endophytic association. Here we report on experiments designed to investigate if expression of the DGAT + CO trait in foliar tissues of perennial ryegrass could negatively impact the grass-endophyte association and vice versa. Both endophyte and plant characters were measured under controlled environment and field conditions. RESULTS: Expected relative increases in total fatty acids of 17-58% accrued as a result of DGAT + CO expression with no significant difference between the endophyte-infected and non-infected progeny. Hyphal growth in association with DGAT + CO expression appeared normal when compared to control plants in a growth chamber. There was no significant difference in mycelial biomass for both strains AR1 and AR37, however, Epichloë-derived alkaloid concentrations were significantly lower on some occasions in the DGAT + CO plants compared to the corresponding null-segregant progenies, although these remained within the reported range for bioactivity. CONCLUSIONS: These results suggest that the mutualistic association formed between perennial ryegrass and selected Epichloë strains does not influence expression of the host DGAT + CO technology, but that endophyte performance may be reduced under some circumstances. Further investigation will now be required to determine the preferred genetic backgrounds for introgression of the DGAT + CO trait in combination with selected endophyte strains, as grass host genetics is a major determinant to the success of the grass-endophyte association in this species.

Lupin as a Source of Bioactive Antioxidant Compounds for Food Products.

Four species of lupin (white lupin, yellow lupin, blue lupin and Andean lupin) are widely cropped thanks to the excellent nutritional composition of their seeds: high protein content (28-48 g/100 g); good lipid content (4.6-13.5 g/100 g, but up to 20.0 g/100 g in Andean lupin), especially unsaturated triacylglycerols; and richness in antioxidant compounds like carotenoids, tocols and phenolics. Particularly relevant is the amount of free phenolics, highly bioaccessible in the small intestine. However, the typical bitter and toxic alkaloids must be eliminated before lupin consumption, hindering its diffusion and affecting its nutritional value. This review summarises the results of recent research in lupin composition for the above-mentioned three classes of antioxidant compounds, both in non-debittered and debittered seeds. Additionally, the influence of technological processes to further increase their nutritional value as well as the effects of food manufacturing on antioxidant content were scrutinised. Lupin has been demonstrated to be an outstanding raw material source, superior to most crops and suitable for manufacturing foods with good antioxidant and nutritional properties. The bioaccessibility of lupin antioxidants after digestion of ready-to-eat products still emerges as a dearth in current research.

Quaternary Benzophenanthridine Alkaloids Act as Smac Mimetics and Overcome Resistance to Apoptosis.

Defects in cell death signaling pathways are one of the hallmarks of cancer and can lead to resistance to conventional therapy. Natural products are promising compounds that can overcome this resistance. In the present study we studied the effect of six quaternary benzophenanthridine alkaloids (QBAs), sanguinarine, chelerythrine, sanguirubine, chelirubine, sanguilutine, and chelilutine, on Jurkat leukemia cells, WT, and cell death deficient lines derived from them, CASP3/7/6-/- and FADD-/-, and on solid tumor, human malignant melanoma, A375 cells. We demonstrated the ability of QBAs to overcome the resistance of these deficient cells and identified a novel mechanism for their action. Sanguinarine and sanguirubine completely and chelerythrine, sanguilutine, and chelilutine partially overcame the resistance of CASP3/7/6-/- and FADD-/- cells. By detection of cPARP, a marker of apoptosis, and pMLKL, a marker of necroptosis, we proved the ability of QBAs to induce both these cell deaths (bimodal cell death) with apoptosis preceding necroptosis. We identified the new mechanism of the cell death induction by QBAs, the downregulation of the apoptosis inhibitors cIAP1 and cIAP2, i.e., an effect similar to that of Smac mimetics.

Unravelling the Secrets of α-Pyrones from Aspergillus Fungi: A Comprehensive Review of Their Natural Sources, Biosynthesis, and Biological Activities.

Aspergillus, one of the most product-rich and genetically robust genera, contains a diverse range of species with potential economic and ecological implications. Chemically, Aspergillus is one of the essential sources of polyketides, alkaloids, diphenyl ethers, diketopiperazines, and other miscellaneous compounds, displaying a variety of pharmacological activities. The α-pyrones are unsaturated six-membered lactones. Although α-pyrone has a small structure, it is responsible for the structural diversity of several natural and synthetic compounds and multiple biological activities. In this review, we have summarized approximately 178 α-pyrone containing metabolites derivatives identified/reported from terrestrial, marine, endophytic, and filamentous Aspergillus species, including their sources, biological properties, and biosynthetic pathways until mid-2023, for the first time. This review is the first to compile and analyze the available data on α-pyrone metabolites from Aspergillus, which could facilitate further research and innovation in this field. Additionally, it offers a valuable source of scaffolds for future bioactive drug development, as some of these metabolites have shown potent antimicrobial, anti-inflammatory, and anticancer effects. Therefore, this review has significant implications for the advancement of natural product chemistry, pharmacology, biotechnology, and medicine.

Microbial degradation of plant toxins.

Plants produce a variety of secondary metabolites in response to biotic and abiotic stresses. Although they have many functions, a subclass of toxic secondary metabolites mainly serve plants as deterring agents against herbivores, insects, or pathogens. Microorganisms present in divergent ecological niches, such as soil, water, or insect and rumen gut systems have been found capable of detoxifying these metabolites. As a result of detoxification, microbes gain growth nutrients and benefit their herbivory host via detoxifying symbiosis. Here, we review current knowledge on microbial degradation of toxic alkaloids, glucosinolates, terpenes, and polyphenols with an emphasis on the genes and enzymes involved in breakdown pathways. We highlight that the insect-associated microbes might find application in biotechnology and become targets for an alternative microbial pest control strategy.

Harmful and beneficial properties of cyanotoxins: Two sides of the same coin.

Cyanotoxins are by definition "harmful agents" produced by cyanobacteria. Their toxicity has been extensively studied and reviewed over the years. Cyanotoxins have been commonly classified, based on their poisonous effects on mammals, into three main classes, neurotoxins, hepatotoxins and dermatotoxins, and, considering their chemical features, mainly identified as peptides, alkaloids and lipopolysaccharides. Here we propose a broader subdivision of cyanotoxins into eight distinct classes, taking into account their molecular structures, biosynthesis and modes of action: alkaloids, non-ribosomal peptides, polyketides, non-protein amino acids, indole alkaloids, organophosphates, lipopeptides and lipoglycans. For each class, the structures and primary mechanisms of toxicity of the main representative cyanotoxins are reported. Despite their powerful biological activities, only recently scientists have considered the biotechnological potential of cyanotoxins, and their applications both in medical and in industrial settings, even if only a few of these have reached the biotech market. In this perspective, we discuss the potential uses of cyanotoxins as anticancer, antimicrobial, and biocidal agents, as common applications for cytotoxic compounds. Furthermore, taking into account their mechanisms of action, we describe peculiar potential bioactivities for several cyanotoxin classes, such as local anaesthetics, antithrombotics, neuroplasticity promoters, immunomodulating and antifouling agents. In this review, we aim to stimulate research on the potential beneficial roles of cyanotoxins, which require interdisciplinary cooperation to facilitate the discovery of innovative biotechnologies.

An improved Nicotiana benthamiana bioproduction chassis provides novel insights into nicotine biosynthesis.

The model plant Nicotiana benthamiana is an increasingly attractive organism for the production of high-value, biologically active molecules. However, N. benthamiana accumulates high levels of pyridine alkaloids, in particular nicotine, which complicates the downstream purification processes. Here, we report a new assembly of the N. benthamiana genome as well as the generation of low-nicotine lines by CRISPR/Cas9-based inactivation of berberine bridge enzyme-like proteins (BBLs). Triple as well as quintuple mutants accumulated three to four times less nicotine than the respective control lines. The availability of lines without functional BBLs allowed us to probe their catalytic role in nicotine biosynthesis, which has remained obscure. Notably, chiral analysis revealed that the enantiomeric purity of nicotine was fully lost in the quintuple mutants. In addition, precursor feeding experiments showed that these mutants cannot facilitate the specific loss of C6 hydrogen that characterizes natural nicotine biosynthesis. Our work delivers an improved N. benthamiana chassis for bioproduction and uncovers the crucial role of BBLs in the stereoselectivity of nicotine biosynthesis.