Medicinal history of North American Veratrum

Concise Synthesis of (-)-Veratramine and (-)-20-iso-Veratramine via Aromative Diels-Alder Reaction

A concise and convergent synthesis of the isosteroidal alkaloids veratramine and 20-iso-veratramine has been accomplished. A Horner-Wadsworth-Emmons olefination joins two chiral building blocks of approximately equal complexity and a transition-metal catalyzed intramolecular Diels-Alder cycloaddition-aromatization cascade constructs the tetrasubstituted arene. Other key steps include a highly diastereoselective crotylation of an N-sulfonyl iminium ion and an Eschenmoser fragmentation. The chiral building blocks developed for this synthesis could be used to access a range of additional isosteroidal alkaloids using our diversifiable strategy. Our work shows that 20-iso-veratramine is not identical with a natural product proposed to have that structure. The single crystal X-ray structures of veratramine and 20-iso-veratramine are reported.

A developmental gradient reveals biosynthetic pathways to eukaryotic toxins in monocot geophytes

Numerous eukaryotic toxins that accumulate in geophytic plants are valuable in the clinic, yet their biosynthetic pathways have remained elusive. A notable example is the >150 Amaryllidaceae alkaloids (AmAs), including galantamine, an FDA-approved treatment for Alzheimer's disease. We show that while AmAs accumulate to high levels in many daffodil tissues, biosynthesis is localized to nascent, growing tissue at the leaf base. A similar trend is found in the production of steroidal alkaloids (e.g., cyclopamine) in corn lily. This model of active biosynthesis enabled the elucidation of a complete set of biosynthetic genes that can be used to produce AmAs. Taken together, our work sheds light on the developmental and enzymatic logic of diverse alkaloid biosynthesis in daffodils. More broadly, it suggests a paradigm for biosynthesis regulation in monocot geophytes, where plants are protected from herbivory through active charging of newly formed cells with eukaryotic toxins that persist as above-ground tissue develops.

Verazine biosynthesis from simple sugars in engineered Saccharomyces cerevisiae

Steroidal alkaloids are FDA-approved drugs (e.g., Zytiga) and promising drug candidates/leads (e.g., cyclopamine); yet many of the ≥697 known steroidal alkaloid natural products remain underutilized as drugs because it can be challenging to scale their biosynthesis in their producing organisms. Cyclopamine is a steroidal alkaloid produced by corn lily (Veratrum spp.) plants, and it is an inhibitor of the Hedgehog (Hh) signaling pathway. Therefore, cyclopamine is an important drug candidate/lead to treat human diseases that are associated with dysregulated Hh signaling, such as basal cell carcinoma and acute myeloid leukemia. Cyclopamine and its semi-synthetic derivatives have been studied in (pre)clinical trials as Hh inhibitor-based drugs. However, challenges in scaling the production of cyclopamine have slowed efforts to improve its efficacy and safety profile through (bio)synthetic derivatization, often limiting drug development to synthetic analogs of cyclopamine such as the FDA-approved drugs Odomzo, Daurismo, and Erivedge. If a platform for the scalable and sustainable production of cyclopamine were established, then its (bio)synthetic derivatization, clinical development, and, ultimately, widespread distribution could be accelerated. Ongoing efforts to achieve this goal include the biosynthesis of cyclopamine in Veratrum plant cell culture and the semi-/total chemical synthesis of cyclopamine. Herein, this work advances efforts towards a promising future approach: the biosynthesis of cyclopamine in engineered microorganisms. We completed the heterologous microbial production of verazine (biosynthetic precursor to cyclopamine) from simple sugars (i.e., glucose and galactose) in engineered Saccharomyces cerevisiae (S. cerevisiae) through the inducible upregulation of the native yeast mevalonate and lanosterol biosynthetic pathways, diversion of biosynthetic flux from ergosterol (i.e., native sterol in S. cerevisiae) to cholesterol (i.e., biosynthetic precursor to verazine), and expression of a refactored five-step verazine biosynthetic pathway. The engineered S. cerevisiae strain that produced verazine contains eight heterologous enzymes sourced from seven different species. Importantly, S. cerevisiae-produced verazine was indistinguishable via liquid chromatography-mass spectrometry from both a commercial standard (Veratrum spp. plant-produced) and Nicotiana benthamiana-produced verazine. To the best of our knowledge, this is the first report describing the heterologous production of a steroidal alkaloid in an engineered yeast. Verazine production was ultimately increased through design-build-test-learn cycles to a final titer of 83 ± 3 μg/L (4.1 ± 0.1 μg/g DCW). Together, this research lays the groundwork for future microbial biosynthesis of cyclopamine, (bio)synthetic derivatives of cyclopamine, and other steroidal alkaloid natural products.

Divergent and gram-scale syntheses of (-)-veratramine and (-)-cyclopamine

Veratramine and cyclopamine, two of the most representative members of the isosteroidal alkaloids, are valuable molecules in agricultural and medicinal chemistry. While plant extraction of these compounds suffers from uncertain supply, efficient chemical synthesis approaches are in high demand. Here, we present concise, divergent, and scalable syntheses of veratramine and cyclopamine with 11% and 6.2% overall yield, respectively, from inexpensive dehydro-epi-androsterone. Our synthesis readily provides gram quantities of both target natural products by utilizing a biomimetic rearrangement to form the C-nor-D-homo steroid core and a stereoselective reductive coupling/(bis-)cyclization sequence to establish the (E)/F-ring moiety.

Pharmacology of Veratrum californicum Alkaloids as Hedgehog Pathway Antagonists

Veratrum californicum contains steroidal alkaloids that function as inhibitors of hedgehog (Hh) signaling, a pathway involved in the growth and differentiation of cells and normal tissue development. This same Hh pathway is abnormally active for cell proliferation in more than 20 types of cancer. In this current study, alkaloids have been extracted from the root and rhizome of V. californicum, followed by their separation into five fractions using high performance liquid chromatography. Mass spectrometry was used to identify the presence of twenty-five alkaloids, nine more than are commonly cited in literature reports, and the Bruker Compass Data Analysis software was used to predict the molecular formula for every detected alkaloid. The Gli activity of the raw extract and each fraction were compared to 0.1 µM cyclopamine, and fractions 1, 2, and 4 showed increased bioactivity through suppression of the Hh signaling pathway. Fractions 2 and 4 had enhanced bioactivity, but fraction 1 was most effective in inhibiting Hh signaling. The composition of fraction 1 consisted of veratrosine, cycloposine, and potential isomers of each.

Asymmetric Synthesis of Cyclopamine, a Hedgehog (Hh) Signaling Pathway Inhibitor

Cyclopamine is a teratogenic steroidal alkaloid, which inhibits the Hedgehog (Hh) signaling pathway by targeting the Smoothened (Smo) receptor. Suppression of Hh signaling with synthetic small molecules has been pursued as a therapeutic approach for the treatment of cancer. We report herein the asymmetric synthesis of cyclopamine based on a two-stage relay strategy. Stage-I: total synthesis of veratramine through a convergent approach, wherein a crucial photoinduced excited-state Nazarov reaction was applied to construct the basic [6-6-5-6] skeleton of C-nor-D-homo-steroid. Stage-II: conversion of veratramine to cyclopamine was achieved through a sequence of chemo-selective redox manipulations.

Comparative transcriptome analysis of Veratrum maackii and Veratrum nigrum reveals multiple candidate genes involved in steroidal alkaloid biosynthesis

Veratrum (Melanthiaceae; Liliales) is a genus of perennial herbs known for the production of unique bioactive steroidal alkaloids. However, the biosynthesis of these compounds is incompletely understood because many of the downstream enzymatic steps have yet to be resolved. RNA-Seq is a powerful method that can be used to identify candidate genes involved in metabolic pathways by comparing the transcriptomes of metabolically active tissues to controls lacking the pathway of interest. The root and leaf transcriptomes of wild Veratrum maackii and Veratrum nigrum plants were sequenced and 437,820 clean reads were assembled into 203,912 unigenes, 47.67% of which were annotated. We identified 235 differentially expressed unigenes potentially involved in the synthesis of steroidal alkaloids. Twenty unigenes, including new candidate cytochrome P450 monooxygenases and transcription factors, were selected for validation by quantitative real-time PCR. Most candidate genes were expressed at higher levels in roots than leaves but showed a consistent profile across both species. Among the 20 unigenes putatively involved in the synthesis of steroidal alkaloids, 14 were already known. We identified three new CYP450 candidates (CYP76A2, CYP76B6 and CYP76AH1) and three new transcription factor candidates (ERF1A, bHLH13 and bHLH66). We propose that ERF1A, CYP90G1-1 and CYP76AH1 are specifically involved in the key steps of steroidal alkaloid biosynthesis in V. maackii roots. Our data represent the first cross-species analysis of steroidal alkaloid biosynthesis in the genus Veratrum and indicate that the metabolic properties of V. maackii and V. nigrum are broadly conserved despite their distinct alkaloid profiles.

A developmental gradient reveals biosynthetic pathways to eukaryotic toxins in monocot geophytes

Numerous eukaryotic toxins that accumulate in geophytic plants are valuable in the clinic, yet their biosynthetic pathways have remained elusive. A lead example is the >150 Amaryllidaceae alkaloids (AmAs) including galantamine, an FDA-approved treatment for Alzheimer's disease. We show that while AmAs accumulate to high levels in many tissues in daffodils, biosynthesis is localized to nascent, growing tissue at the base of leaves. A similar trend is found for the production of steroidal alkaloids (e.g. cyclopamine) in corn lily. This model of active biosynthesis enabled elucidation of a complete set of biosynthetic genes for the production of AmAs. Taken together, our work sheds light on the developmental and enzymatic logic of diverse alkaloid biosynthesis in daffodil. More broadly, it suggests a paradigm for biosynthesis regulation in monocot geophytes where plants are protected from herbivory through active charging of newly formed cells with eukaryotic toxins that persist as aboveground tissue develops.

Steroidal alkaloids from the roots of Veratrum stenophyllum

Three new steroidal alkaloids, veratrasines A - C (1-3), along with ten known analogues (4-13) were isolated from the roots of Veratrum stenophyllum. Their structures were elucidated by NMR and HRESIMS data and comparison with the reported data in the literatures. A plausible biosynthetic pathway for 1 and 2 were proposed. Compounds 1, 3, and 8 showed moderate cytotoxic activity against MHCC97H and H1299 cell lines.

Transcriptome and metabolome profiling of the medicinal plant Veratrum mengtzeanum reveal key components of the alkaloid biosynthesis

Veratrum mengtzeanum is the main ingredient for Chinese folk medicine known as "Pimacao" due to its unique alkaloids. A diverse class of plant-specific metabolites having key pharmacological activities. There are limited studies on alkaloid synthesis and its metabolic pathways in plants. To elucidate the alkaloid pathway and identify novel biosynthetic enzymes and compounds in V. mengtzeanum, transcriptome and metabolome profiling has been conducted in leaves and roots. The transcriptome of V. mengtzeanum leaves and roots yielded 190,161 unigenes, of which 33,942 genes expressed differentially (DEGs) in both tissues. Three enriched regulatory pathways (isoquinoline alkaloid biosynthesis, indole alkaloid biosynthesis and tropane, piperidine and pyridine alkaloid biosynthesis) and a considerable number of genes such as AED3-like, A4U43, 21 kDa protein-like, 3-O-glycotransferase 2-like, AtDIR19, MST4, CASP-like protein 1D1 were discovered in association with the biosynthesis of alkaloids in leaves and roots. Some transcription factor families, i.e., AP2/ERF, GRAS, NAC, bHLH, MYB-related, C3H, FARI, WRKY, HB-HD-ZIP, C2H2, and bZIP were also found to have a prominent role in regulating the synthesis of alkaloids and steroidal alkaloids in the leaves and roots of V. mengtzeanum. The metabolome analysis revealed 74 significantly accumulated metabolites, with 55 differentially accumulated in leaves compared to root tissues. Out of 74 metabolites, 18 alkaloids were highly accumulated in the roots. A novel alkaloid compound viz; 3-Vanilloylygadenine was discovered in root samples. Conjoint analysis of transcriptome and metabolome studies has also highlighted potential genes involved in regulation and transport of alkaloid compounds. Here, we have presented a comprehensive metabolic and transcriptome profiling of V. mengtzeanum tissues. In earlier reports, only the roots were reported as a rich source of alkaloid biosynthesis, but the current findings revealed both leaves and roots as significant manufacturing factories for alkaloid biosynthesis.

Veratrum parviflorum poisoning: identification of steroidal alkaloids in patient blood and breast milk

INTRODUCTION

The Veratrum genus is composed of plants containing a diverse set of steroidal alkaloids. Veratrum plant material has been utilized for centuries as herbal medicines, however the alkaloids have such a low therapeutic index that they are not used in modern medicine. Here we report an incident of inadvertent ingestion of V. parviflorum by hikers in Georgia that allowed detection, and in several instances identification of alkaloids from the plant, and correlated their presence within patient blood and breast milk specimens.

CASE HISTORY

Eight patients, three male and five female, presented in the spring of 2020 and 2021 with symptoms requiring emergent medical attention after ingestion of Veratrum parviflorum. All patients believed the plants to be a local native species of wild leek, Allium tricoccum, locally known as ramps. Plants were identified using photographs as well as fresh and cooked plant material provided by patients, in consultation with botanists at the University of Georgia Herbarium. Written consent was obtained from all patients for collection of blood and breast milk specimens for laboratory identification of Veratrum alkaloids.

METHODS

V. parviflorum plant material, and patient serum and breast milk were analyzed by high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-QTOF) to identify steroidal alkaloids.

RESULTS

The V. parviflorum extract was confirmed to contain cyclopamine, veratramine, jervine, and muldamine. Two out of the eight patients had detectable concentrations of Veratrum alkaloids. Of the alkaloids identified in the plant, cyclopamine and jervine were detected within patient serum, and cyclopamine and veratramine were observed to be present in breast milk.

DISCUSSION

Toxicity resulting from Veratrum steroidal alkaloids has primarily been reported from V. album and V. viride. This is the second report of V. parviflorum poisoning. The present work reports for the first time the presence of muldamine and jervine within V. parviflorum. This work provides the first instance of identification of Veratrum alkaloids in breast milk. Thus, the findings presented herein add to literature record causative agents contributing to the toxicity of V. parviflorum when ingested and potential for secondary poisoning through breastfeeding.

CONCLUSION

V. parviflorum toxicity was observed to cause nausea, vomiting, hypotension, bradycardia, abdominal pain, light-headedness, blurred vision, and tingling in the arms. Patients experiencing mild symptoms improved with supportive care, IV fluids, and antiemetics, but hemodynamically unstable patients required atropine and vasopressors. This study demonstrated that more lipophilic Veratrum alkaloids can be passed along in breast milk, which suggests additional precautions may be critical to limit further poisonings.

Veratramine ameliorates pain symptoms in rats with diabetic peripheral neuropathy by inhibiting activation of the SIGMAR1-NMDAR pathway

CONTEXT

Veratramine may have a potential therapeutic effect for diabetic peripheral neuropathy (DPN).

OBJECTIVE

To evaluate whether veratramine ameliorates neuropathic pain in a rat diabetic model.

MATERIALS AND METHODS

Sprague-Dawley rats were used for a diabetic model induced by a streptozotocin + high-fat diet. Two months after the induction of the diabetic model, the rats with DPN were screened according to the mechanical pain threshold. The rats with DPN were divided into a model group (n = 12) and a treated group (n = 12). Rats with diabetes, but without peripheral neuropathy, were used in the vehicle group (n = 9). The treatment group received 50 μg/kg veratramine via the tail vein once a day for 4 weeks. During modelling and treatment, rats in all three groups were fed a high-fat diet.

RESULTS

The mechanical withdrawal threshold increased from 7.5 ± 1.9 N to 17.9 ± 2.6 N in DPN rats treated with veratramine. The tolerance time of the treated group to hot and cold ectopic pain increased from 11.8 ± 4.2 s and 3.4 ± 0.8 s to 20.4 ± 4.1 s and 5.9 ± 1.7 s, respectively. Veratramine effectively alleviated L4-L5 spinal cord and sciatic nerve pathological injury. Veratramine inhibited the expression of SIGMAR1 and the phosphorylation of the N-methyl-d-aspartate receptor (NMDAR) Ser896 site in spinal cord tissue, as well as inhibited the formation of SIGMAR1-NMDAR and NMDAR-CaMKII complexes.

DISCUSSION AND CONCLUSIONS

Veratramine may alleviate the occurrence of pain symptoms in rats with DPN by inhibiting activation of the SIGMAR1-NMDAR pathway.

Veratrum parviflorum: An Underexplored Source for Bioactive Steroidal Alkaloids

Plants of the Veratrum genus have been used throughout history for their emetic properties, rheumatism, and for the treatment of high blood pressure. However, inadvertent consumption of these plants, which resemble wild ramps, induces life-threatening side effects attributable to an abundance of steroidal alkaloids. Several of the steroidal alkaloids from Veratrum spp. have been investigated for their ability to antagonize the Hedgehog (Hh) signaling pathway, a key pathway for embryonic development and cell proliferation. Uncontrolled activation of this pathway is linked to the development of various cancers; most notably, basal cell carcinoma and acute myeloid leukemia. Additional investigation of Veratrum spp. may lead to the identification of novel alkaloids with the potential to serve as chemotherapeutics. V. parviflorum is a relatively uncommon species of Veratrum that resides in the southeastern regions of North America. The phytochemical profile of this plant remains largely unexplored; however, bioactive steroidal alkaloids, including cyclopamine, veratramine, veratridine, and verazine were identified in its extract. The structural elucidation and bioactivity assessment of steroidal alkaloids in lesser abundance within the extract of V. parviflorum may yield potent Hh pathway inhibitors. This review seeks to consolidate the botanical and phytochemical information regarding V. parviflorum.

Identification of Veratrum Species in Pimacao Based on ITS2 Sequences and Steroidal Alkaloids by a Pseudo-Targeted Metabolomics Method

Pimacao is a traditional Chinese folk medicine and is the main component of the famous Chinese herbal remedy "Yunnan Baiyao" for its significant analgesic activity in the treatment of wounds. Due to increases in consumption, its wild population is now difficult to find, and adulterant from the same genus has occurred. However, this is challenging to distinguish the species of Veratrum in Pimacao using dried roots and rhizomes or medicinal powder. ITS2 sequences and steroidal alkaloids by the non-targeted and pseudo-targeted metabolomics methods were taken advantage of establishing an effective identification method. Based on the ITS2 sequence, metabolite profiling of steroidal alkaloids and morphological characteristics, the classification of two distinct subspecies in V. mengzeanum has been reinforced. In addition, the new subspecies V. mengzeanum subsp. phuwae was collected in China for the first time. The ITS2 sequence could be used in the identification of V. taliense, V. mengtzeanum, V. stenophyllum, and V. nigrum, but is insufficient for intraspecific identification. Simultaneously, 147 variables were labeled by non-targeted analysis accomplished utilizing an ultra-high-performance liquid chromatography electrospray ionization orbitrap tandem mass spectrometry (UPLC-ESI-QE-Orbitrap-MS) system consisting of an Orbitrap QE HF-X. Followed by a pseudo-targeted analysis method developed for the Qtrap 6500-plus mass spectrometry system coupled with an ESI source, 29 labeled steroidal alkaloids detected by the MRM mode could distinguish between four species. Notably, 25 labeled steroidal alkaloids could distinguish between three closely related species. These have the potential to be used as markers for identification. Furthermore, there were several variables with statistical differences between two subspecies of V. mengtzeanum and populations of V. taliense, V. mengtzeanum, and V. stenophyllum.

Comparative chloroplast genome analysis of medicinally important Veratrum (Melanthiaceae) in China: Insights into genomic characterization and phylogenetic relationships

Members of Veratrum are perennial herbs widely used in traditional Chinese medicine to induce vomiting, resolve blood stasis and relieve pain. However, the intrageneric classification and phylogenetic relationships within Veratrum have long been controversial due to the complexity of morphological variations and lack of high-resolution molecular markers. In this study, we reevaluated the infrageneric relationships with the genus Veratrum using complete chloroplast genome sequence data. Herein, the complete cp genomes of ten species of Veratrum were newly sequenced and characterized. The complete cp genomes of ten species of Veratrum had the typical quadripartite structure, ranging from 151,597 bp to 153,711 bp in size and comprising a total of 135 genes. The structure of Veratrum cp genomes (i.e., gene order, content, and genome components) was highly similar across species. The number of simple sequence repeats (SSRs) ranged from 63 to 78, and of long repeats ranged from 31 to 35. Eight highly divergent regions (ndhF, psbC-psbZ, psbK-psbI, rpoB-trnC_GCA, trnK_UUU-trnQ_UUG, trnS_GCU-trnG_UCC, trnT_UGU-trnL_UAA and ycf1) were identified and are potentially useful for the DNA barcoding of Veratrum. Phylogenetic analysis among 29 taxa based on cp genomes, total genes, protein-coding genes and intergenic regions strongly supported the monophyly of Veratrum. The circumscription and relationships of the infrageneric taxa of Veratrum were well-presented with great resolution. These results will facilitate the identification, taxonomy, and utilization of Veratrum plants as well as the evolutionary studies of Melanthiaceae.

Enantioselective Total Synthesis of (+)-Heilonine

Chemical transformations that rapidly and efficiently construct a high level of molecular complexity in a single step are perhaps the most valuable in total synthesis. Among such transformations is the transition metal catalyzed [2 + 2 + 2] cycloisomerization reaction, which forges three new C-C bonds and one or more rings in a single synthetic operation. We report here a strategy that leverages this transformation to open de novo access to the Veratrum family of alkaloids. The highly convergent approach described herein includes (i) the enantioselective synthesis of a diyne fragment containing the steroidal A/B rings, (ii) the asymmetric synthesis of a propargyl-substituted piperidinone (F ring) unit, (iii) the high-yielding union of the above fragments, and (iv) the intramolecular [2 + 2 + 2] cycloisomerization reaction of the resulting carbon framework to construct in a single step the remaining three rings (C/D/E) of the hexacyclic cevanine skeleton. Efficient late-stage maneuvers culminated in the first total synthesis of heilonine (1), achieved in 21 steps starting from ethyl vinyl ketone.

Review: Veratrum californicum Alkaloids

Veratrum spp. grow throughout the world and are especially prevalent in high mountain meadows of North America. All parts of Veratrum plants have been used for the treatment of ailments including injuries, hypertension, and rheumatic pain since as far back as the 1600s. Of the 17-45 Veratrum spp., Veratrum californicum alkaloids have been proven to possess favorable medicinal properties associated with inhibition of hedgehog (Hh) pathway signaling. Aberrant Hh signaling leads to proliferation of over 20 cancers, including basal cell carcinoma, prostate and colon among others. Six of the most well-studied V. californicum alkaloids are cyclopamine (1), veratramine (2), isorubijervine (3), muldamine (4), cycloposine (5), and veratrosine (6). Recent inspection of the ethanolic extract from V. californicum root and rhizome via liquid chromatography-mass spectrometry has detected up to five additional alkaloids that are proposed to be verazine (7), etioline (8), tetrahydrojervine (9), dihydrojervine (10), 22-keto-26-aminocholesterol (11). For each alkaloid identified or proposed in V. californicum, this review surveys literature precedents for extraction methods, isolation, identification, characterization and bioactivity to guide natural product drug discovery associated with this medicinal plant.

The complete chloroplast genome sequence of Veratrum oxysepalum and phylogenetic analysis

Veratrum oxysepalum Turcz. is a medicinal plant belonging to Melanthiaceae occurring in Northeast China. However, there are still limited genomic resources available for genus Veratrum. The complete chloroplast (cp) genome of V. oxysepalum was determined and analyzed in this study. The complete cp genome was 153,705 bp. That contains a large single copy (LSC) region of 83,384 bp, a small single copy (SSC) region of 17,607 bp, which were separated by a pair of 26,358 bp inverted repeat regions (IRs). A total of 135 genes were annotated, including 83 protein-coding genes, 38 tRNAs, and eight rRNAs. Phylogenetic analysis using total chloroplast genome sequence of 21 species revealed that V. oxysepalum was closely relates to V. patulum of Veratrum with 100% bootstrap value.

Diversity in Chemical Structures and Biological Properties of Plant Alkaloids

Phytochemicals belonging to the group of alkaloids are signature specialized metabolites endowed with countless biological activities. Plants are armored with these naturally produced nitrogenous compounds to combat numerous challenging environmental stress conditions. Traditional and modern healthcare systems have harnessed the potential of these organic compounds for the treatment of many ailments. Various chemical entities (functional groups) attached to the central moiety are responsible for their diverse range of biological properties. The development of the characterization of these plant metabolites and the enzymes involved in their biosynthesis is of an utmost priority to deliver enhanced advantages in terms of biological properties and productivity. Further, the incorporation of whole/partial metabolic pathways in the heterologous system and/or the overexpression of biosynthetic steps in homologous systems have both become alternative and lucrative methods over chemical synthesis in recent times. Moreover, in-depth research on alkaloid biosynthetic pathways has revealed numerous chemical modifications that occur during alkaloidal conversions. These chemical reactions involve glycosylation, acylation, reduction, oxidation, and methylation steps, and they are usually responsible for conferring the biological activities possessed by alkaloids. In this review, we aim to discuss the alkaloidal group of plant specialized metabolites and their brief classification covering major categories. We also emphasize the diversity in the basic structures of plant alkaloids arising through enzymatically catalyzed structural modifications in certain plant species, as well as their emerging diverse biological activities. The role of alkaloids in plant defense and their mechanisms of action are also briefly discussed. Moreover, the commercial utilization of plant alkaloids in the marketplace displaying various applications has been enumerated.

Exploring Sonic Hedgehog Cell Signaling in Neurogenesis: Its Potential Role in Depressive Behavior

Depression is the most prevalent form of neuropsychiatric disorder affecting all age groups globally. As per the estimation of the World Health Organization (WHO), depression will develop into the foremost reason for disability globally by the year 2030. The primary neurobiological mechanism implicated in depression remains ambiguous; however, dysregulation of molecular and signaling transductions results in depressive disorders. Several theories have been developed to explain the pathogenesis of depression, however, none of them completely explained all aspects of depressive-pathogenesis. In the current review, we aimed to explore the role of the sonic hedgehog (Shh) signaling pathway in the development of the depressive disorder and its potential as the therapeutic target. Shh signaling has a crucial function in neurogenesis and neural tube patterning during the development of the central nervous system (CNS). Shh signaling performs a basic function in embryogenesis and hippocampal neurogenesis. Moreover, antidepressants are also known to enhance neurogenesis in the hippocampus, which further suggests the potential of Shh signaling. Furthermore, there is decreased expression of a glioma-associated oncogene (Gli1) and Smoothened (Smo) in depression. Moreover, antidepressants also regulate brain-derived neurotrophic factor (BDNF) and wingless protein (Wnt) signaling, therefore, Shh may be implicated in the pathogenesis of the depressive disorder. Deregulation of Shh signaling in CNS results in neurological disorders such as depression.

Veratramine suppresses human HepG2 liver cancer cell growth in vitro and in vivo by inducing autophagic cell death

Liver cancer is the second leading cause of cancer‑related deaths. Traditional therapeutic strategies, such as chemotherapy, targeted therapy and interventional therapy, are inefficient and are accompanied by severe side effects for patients with advanced liver cancer. Therefore, it is crucial to develop a safer more effective drug to treat liver cancer. Veratramine, a known natural steroidal alkaloid derived from plants of the lily family, exerts anticancer activity in vitro. However, the underlying mechanism and whether it has an antitumor effect in vivo remain unknown. In the present study, the data revealed that veratramine significantly inhibited HepG2 cell proliferation, migration and invasion in vitro. Moreover, it was revealed that veratramine induced autophagy‑mediated apoptosis by inhibiting the PI3K/Akt/mTOR signaling pathway, which partly explained the underlying mechanism behind its antitumor activity. Notably, the results of in vivo experiments also revealed that veratramine treatment (2 mg/kg, 3 times a week for 4 weeks) significantly inhibited subcutaneous tumor growth of liver cancer cells, with a low systemic toxicity. Collectively, the results of the present study indicated that veratramine efficiently suppressed liver cancer HepG2 cell growth in vitro and in vivo by blocking the PI3K/Akt/mTOR signaling pathway to induce autophagic cell death. Veratramine could be a potential therapeutic agent for the treatment of liver cancer.

[Chemical-toxicological diagnosis of hellebore (veratrum) poisoning]

The problem of laboratory diagnosis of acute and fatal poisoning by hellebore, which is possible when used in traditional medicine, the erroneous use of hellebore preparations orally or use of various types of this plant for food, remains relevant. Currently, in the practice of chemical-toxicological laboratories and the bureau of forensic medical examination there is no single approach to the laboratory diagnosis of such poisoning. The diagnosis is most often based on anamnesis. In this regard, the development and validation of a legally significant methodology for the determination of hellebore alkaloids in various biological objects seems relevant. The physicochemical and toxic properties of alkaloids of various types of hellebore are characterized. It was shown that for the identification of hellebore alkaloids, it is advisable to use HPLC-MS/MS as the most sensitive and specific instrumental method corresponding to the characteristics of hellebore alkaloids (high molecular weight, high thermal lability, high polarity).

Representational Difference Analysis of Transcripts Involved in Jervine Biosynthesis

Veratrum-type steroidal alkaloids (VSA) are the major bioactive ingredients that strongly determine the pharmacological activities of Veratrum nigrum. Biosynthesis of VSA at the molecular and genetic levels is not well understood. Next-generation sequencing of representational difference analysis (RDA) products after elicitation and precursor feeding was applied to identify candidate genes involved in VSA biosynthesis. A total of 12,048 contigs with a median length of 280 bases were received in three RDA libraries obtained after application of methyl jasmonate, squalene and cholesterol. The comparative analysis of annotated sequences was effective in identifying candidate genes. GABAT2 transaminase and hydroxylases active at C-22, C-26, C-11, and C-16 positions in late stages of jervine biosynthesis were selected. Moreover, genes coding pyrroline-5-carboxylate reductase and enzymes from the short-chain dehydrogenases/reductases family (SDR) associated with the reduction reactions of the VSA biosynthesis process were proposed. The data collected contribute to better understanding of jervine biosynthesis and may accelerate implementation of biotechnological methods of VSA biosynthesis.

Turning Meadow Weeds Into Valuable Species for the Romanian Ethnomedicine While Complying With the Environmentally Friendly Farming Requirements of the European Union's Common Agricultural Policy

The cross-compliance mechanism of the European Union (EU)'s common agricultural policy (CAP) makes the approval of the direct payments to the European farmers subject to compliance with the requirement to maintain the land in good agricultural and environmental condition. One of the obligations of the Romanian land owners and farmers is to avoid the installation of unwanted vegetation on their land plots. This vegetation is represented by some species of herbaceous or woody plants, annual or perennial, that spontaneously invade the agricultural lands, diminishing the production capacity of the cultivated plants. Included in this category are 10 meadow weeds, without fodder value or even toxic to animals: Arctium lappa L., Carduus nutans L., Conium maculatum L., Eryngium campestre L., Euphorbia cyparissias L., Pteridium aquilinum (L.) Kuhn, Rumex acetosella L., Veratrum album L., Xanthium spinosum L., and Xanthium strumarium L. Various and multiple uses in traditional medicine of these meadow weed species have been reported for Romania and other nine neighboring East European countries, i.e. Bosnia and Herzegovina, Bulgaria, Czech Republic, Estonia, Kosovo, Russia, Turkey, Serbia, and Ukraine. For A. lappa were recorded the highest number of ethnomedicinal uses, in the largest number of East European countries, including Romania. C. maculatum and V. album are not recommended for human consumption but can be further investigated as potential sources of pharmaceutically active compounds. Once removed by landowners and farmers from their land, the raw plant material of these 10 species become readily and easily available to the Romanian local communities and the industry of herbal food supplements, while the biodiversity of the agro-ecosystems is maintained.

Seven new veratramine-type alkaloids with potent analgesic effect from Veratrum taliense

ETHNOPHARMACOLOGICAL RELEVANCE

Veratrum taliense is traditionally used TCMs in Yunnan province of China for pain and inflammation. Previous research and clinical applications have shown that V. taliense had significant analgesic activity. Jevine-type alkaloids were shown to be one of the anti-inflammatory and analgesic agents from V. taliense. However, other types of compounds from V. taliense related to its traditional use remains unknown.

AIM OF THE STUDY

To identify veratramine-type steroidal alkaloids with analgesic effects from the roots and rhizomes of V. taliense.

MATERIALS AND METHODS

Compounds were isolated from the roots and rhizomes of V. taliense by chromatographic separation. Their structures were elucidated based on UV, IR, NMR and MS spectra data. Analgesic activity was assessed with acetic acid-induced writhing in mice model.

RESULTS

Seven new veratramine-type alkaloids were isolated from the roots and rhizomes of V. taliense. They all exhibited significant analgesic activity, of which alkaloids 1 and 4 were more potent antalgic than the well-known analgesic drug, pethidine.

CONCLUSIONS

The veratramine-type alkaloids from V. taliense may serve as new leads for the discovery of analgesic drugs.

Steroidal alkaloid variation in Veratrum californicum as determined by modern methods of analytical analysis

Veratrum californicum is a rich source of steroidal alkaloids, many of which have proven to be antagonists of the Hedgehog (Hh) signaling pathway that becomes aberrant in over twenty types of cancer. These alkaloids first became known in the 1950's due to their teratogenic properties, which resulted in newborn and fetal lambs developing cyclopia as a result of pregnant ewes consuming Veratrum californicum. It was discovered that the alkaloids in V. californicum were concentrated in the root and rhizome of the plant with much lower amounts of the most active alkaloid, cyclopamine, present in the aerial plant, especially in the late growth season. Inspired by the limitations in analytical instrumentation and methods available to researchers at the time of the original investigation, we have used state-of-the-art instrumentation and modern analytical methods to quantitate four steroidal alkaloids based on study parameters including plant part, harvest location, and growth stage. The results of the current inquiry detail differences in alkaloid composition based on the study parameters, provide a detailed assessment for alkaloids that have been characterized previously (cyclopamine, veratramine, muldamine and isorubijervine), and identify at least six alkaloids that have not been previously characterized. This study provides insight into optimal harvest time, plant growth stage, harvest location, and plant part required to isolate, yet to be characterized, alkaloids of interest for exploration as Hh pathway antagonists with desirable medicinal properties.

State of the art of Smo antagonists for cancer therapy: advances in the target receptor and new ligand structures

Since the Hedgehog signaling pathway has been associated with cancer, it has emerged as a therapeutic target for cancer therapy. The main target among the key Hedgehog proteins is the GPCR-like Smo receptor. Therefore, some Smo antagonists that have entered clinical trials, including the US FDA-approved drugs vismodegib and sonidegib, to treat basal cell carcinoma and medulloblastoma. However, early resistance of these drugs has spawned the need to understand the molecular bases of this phenomena. We therefore reviewed details about Smo receptor structures and the best Smo antagonist chemical structures. In addition, we discussed strategies that should be considered to develop new, safer generations of Smo antagonists that avoid current clinical limitations.

Native V. californicum Alkaloid Combinations Induce Differential Inhibition of Sonic Hedgehog Signaling

Veratrum californicum is a rich source of steroidal alkaloids such as cyclopamine, a known inhibitor of the Hedgehog (Hh) signaling pathway. Here we provide a detailed analysis of the alkaloid composition of V. californicum by plant part through quantitative analysis of cyclopamine, veratramine, muldamine and isorubijervine in the leaf, stem and root/rhizome of the plant. To determine whether additional alkaloids in the extracts contribute to Hh signaling inhibition, the concentrations of these four alkaloids present in extracts were replicated using commercially available standards, followed by comparison of extracts to alkaloid standard mixtures for inhibition of Hh signaling using Shh-Light II cells. Alkaloid combinations enhanced Hh signaling pathway antagonism compared to cyclopamine alone, and significant differences were observed in the Hh pathway inhibition between the stem and root/rhizome extracts and their corresponding alkaloid standard mixtures, indicating that additional alkaloids present in these extracts are capable of inhibiting Hh signaling.

Hikers poisoned: Veratrum steroidal alkaloid toxicity following ingestion of foraged Veratrum parviflorum

INTRODUCTION

Steroidal alkaloids are found in plants of the genus Veratrum. Their toxicity manifests as gastrointestinal symptoms followed by a Bezold-Jarisch reflex: hypopnea, hypotension, and bradycardia. Some Veratrum steroidal alkaloids are also teratogens interfering with the hedgehog-2 signaling pathway, which causes cyclopsia and holoprosencephaly. We present a case of accidental poisoning from Veratrum parviflorum mistaken for the edible Allium tricoccum (ramps, wild leek).

CASE HISTORY

A 27-year-old man and his 25-year-old wife presented to the emergency department with nausea, vomiting, hypotension, and bradycardia after foraging and ingesting plants that they believed to be a local native species of wild leek.

METHODS

We collected and analyzed the implicated fresh plant material and both patients' serum/plasma. We used liquid chromatography-mass spectroscopy and high-resolution electrospray ionization time of flight tandem mass spectrometry to extract and characterize steroidal alkaloids from the foraged plant and patients' serum.

RESULTS

Our V. parviflorum samples contained verazine, veratramine, veratridine, and cyclopamine.

DISCUSSION

Steroidal alkaloids have been previously isolated from Veratrum viride and Veratrum album and toxicity has been reported mainly from V. album species.

CONCLUSION

V. parviflorum toxicity manifests with gastrointestinal and cardiac symptoms. Treatment is symptomatic and supportive as with previous case reports of toxicity with other Veratrum species.

Targeting sonic hedgehog signaling in neurological disorders

Sonic hedgehog (Shh) signaling influences neurogenesis and neural patterning during the development of central nervous system. Dysregulation of Shh signaling in brain leads to neurological disorders like autism spectrum disorder, depression, dementia, stroke, Parkinson's diseases, Huntington's disease, locomotor deficit, epilepsy, demyelinating disease, neuropathies as well as brain tumors. The synthesis, processing and transport of Shh ligand as well as the localization of its receptors and signal transduction in the central nervous system has been carefully reviewed. Further, we summarize the regulation of small molecule modulators of Shh pathway with potential in neurological disorders. In conclusion, further studies are warranted to demonstrate the potential of positive and negative regulators of the Shh pathway in neurological disorders.

Cyclopamine bioactivity by extraction method from Veratrum californicum

Veratrum californicum, commonly referred to as corn lily or Californian false hellebore, grows in high mountain meadows and produces the steroidal alkaloid cyclopamine, a potent inhibitor of the Hedgehog (Hh) signaling pathway. The Hh pathway is a crucial regulator of many fundamental processes during vertebrate embryonic development. However, constitutive activation of the Hh pathway contributes to the progression of various cancers. In the present study, a direct correlation was made between the extraction efficiency for cyclopamine from root and rhizome by eight methods, and the associated biological activity in Shh-Light II cells using the Dual-Glo® Luciferase Assay System. Alkaloid recovery ranged from 0.39 to 8.03mg/g, with ethanol soak being determined to be the superior method for obtaining biologically active cyclopamine. Acidic ethanol and supercritical extractions yielded degraded or contaminated cyclopamine with lower antagonistic activity towards Hh signaling.

Elucidating steroid alkaloid biosynthesis in Veratrum californicum: production of verazine in Sf9 cells

Steroid alkaloids have been shown to elicit a wide range of pharmacological effects that include anticancer and antifungal activities. Understanding the biosynthesis of these molecules is essential to bioengineering for sustainable production. Herein, we investigate the biosynthetic pathway to cyclopamine, a steroid alkaloid that shows promising antineoplastic activities. Supply of cyclopamine is limited, as the current source is solely derived from wild collection of the plant Veratrum californicum. To elucidate the early stages of the pathway to cyclopamine, we interrogated a V. californicum RNA-seq dataset using the cyclopamine accumulation profile as a predefined model for gene expression with the pattern-matching algorithm Haystack. Refactoring candidate genes in Sf9 insect cells led to discovery of four enzymes that catalyze the first six steps in steroid alkaloid biosynthesis to produce verazine, a predicted precursor to cyclopamine. Three of the enzymes are cytochromes P450 while the fourth is a γ-aminobutyrate transaminase; together they produce verazine from cholesterol.