In vitro metabolism of helenalin and its inhibitory effect on human cytochrome P450 activity.

Sesquiterpene lactone helenalin is used as an antiphlogistic in European and Chinese folk medicine. The pharmacological activities of helenalin have been extensively investigated, yet insufficient information exists about its metabolic properties. The objectives of the present study were (1) to investigate the in vitro NADPH-dependent metabolism of helenalin (5 and 100 µM) using human and rat liver microsomes and liver cytosol, (2) to elucidate the role of human cytochrome P450 (CYP) enzymes in its oxidative metabolism, and (3) to study the inhibition of human CYPs by helenalin. Five oxidative metabolites were detected in NADPH-dependent human and rat liver microsomal incubations, while two reduced metabolites were detected only in NADPH-dependent human microsomal and cytosolic incubations. In human liver microsomes, the main oxidative metabolite was 14-hydroxyhelenalin, and in rat liver microsomes 9-hydroxyhelenalin. The overall oxidation of helenalin was several times more efficient in rat than in human liver microsomes. In humans, CYP3A4 and CYP3A5 followed by CYP2B6 were the main enzymes responsible for the hepatic metabolism of helenalin. The extrahepatic CYP2A13 oxidized helenalin most efficiently among CYP enzymes, possessing the Km value of 0.6 µM. Helenalin inhibited CYP3A4 (IC50 = 18.7 µM) and CYP3A5 (IC50 = 62.6 µM), and acted as a mechanism-based inhibitor of CYP2A13 (IC50 = 1.1 µM, KI = 6.7 µM, and kinact = 0.58 ln(%)/min). It may be concluded that the metabolism of helenalin differs between rats and humans, in the latter its oxidation is catalyzed by hepatic CYP2B6, CYP3A4, CYP3A5, and CYP3A7, and extrahepatic CYP2A13.

Arglabin could target inflammasome-induced ARDS and cytokine storm associated with COVID-19.

Arglabin (l(R),10(S)-epoxy-5(S),5(S),7(S)-guaia-3(4),ll(13)-dien-6,12-olide), is a natural sesquiterpene γ-lactone which was first isolated from Artemisia glabella. The compound has been shown to possess anti-inflammatory activity through inhibition of the NLR Family pyrin domain-containing 3 (NLRP3) inflammasome and production of proinflammatory cytokines including interleukin (IL)-1ß and IL-18. A more hydrophilic derivative of the compound also exhibited antitumor activity in the breast, colon, ovarian, and lung cancer. Some other synthetic derivatives of the compound have also been synthesized with antitumor, cytotoxic, antibacterial, and antifungal activities. Since both NLRP3 inflammasome and cytokine storm are associated with the pathogenesis of COVID-19 and its lethality, compounds like arglabin might have therapeutic potential to attenuate the inflammasome-induced acute respiratory distress syndrome and/or the cytokine storm associated with COVID-19.

Comprehensive review on ethnobotanical uses, phytochemistry, biological potential and toxicology of Parthenium hysterophorus L.: A journey from noxious weed to a therapeutic medicinal plant.

ETHNO-PHARMACOLOGICAL RELEVANCE: Parthenium hysterophorus L. is a noxious weed and a species of flowering plant in the Asteraceae family. It is regarded as the seventh most deadly weed in the world: harmful to both humans and livestock. It is widely known as Congress Grass or Feverfew. Despite its pitfalls, P. hysterophorus bestows medicinal effects. Although prolific in nature and difficult to control, many novel applications of this controversial herb have been discovered as an approach to manage the weed. AIM: The current review aims to compile all the ethnobotanical, phytochemistry, biological activities and utilities, clinical studies and toxicity data available on P. hysterophorus and its major chemical constituent parthenin. MATERIALS AND METHODS: Extensive literature surveyed Google search, Google scholar, Wiley online library, Elsevier, Springer, Science direct, American Chemical Society, Royal Society of Chemistry and Research Gate. RESULT: According to the study, P. hysterophorus is utilized as a traditional medicine throughout Central America and the Caribbean. It can be used to treat skin infections, dermatitis, amoebic dysentery, and as an analgesic in the treatment of muscular rheumatism. The extracts obtained from P. hysterophorus have anti-inflammatory, antioxidant, larvicidal, anti-microbial, insecticidal, hypoglycaemic and anti-cancer activity. CONCLUSION: The earlier investigations confirmed that P. hysterophorus has numerous traditional and biological applications. However, the scientific data are limited in clinical and toxicological studies. Therefore, further research is required on clinical and toxicological aspects to understand the complete potential and effects of P. hysterophorus.

Helenalin Facilitates Reactive Oxygen Species-Mediated Apoptosis and Cell Cycle Arrest by Targeting Thioredoxin Reductase-1 in Human Prostate Cancer Cells.

BACKGROUND Helenalin is a pseudoguaianolide natural product with anti-cancer activities. This study investigated the underlying mechanism of the anti-prostate cancer effects of helenalin in vitro. MATERIAL AND METHODS CCK-8 assay was performed to detect the optimal concentrations of helenalin in DU145 and PC-3 cells. After exposure to helenalin and/or reactive oxygen species (ROS) inhibitor, ROS production was assessed by DCFH-DA staining. Thioredoxin reductase-1 (TrxR1) expression was detected by RT-qPCR and western blot. Moreover, apoptosis and cell cycle were evaluated by flow cytometry. Following TrxR1 knockdown or overexpression, TrxR1 expression, ROS generation, apoptosis, cell cycle, migration, and invasion were examined in cells co-treated with helenalin. RESULTS Helenalin distinctly repressed the viability of prostate cancer cells in a concentration-dependent manner. We chose 8 µM and 4 µM as the optimal concentrations of helenalin for DU145 and PC-3 cells, respectively. Helenalin treatment markedly triggered ROS production and lowered TrxR1 expression, which was ameliorated by ROS inhibitor. Exposure to helenalin facilitated apoptosis as well as G0/G1 cell cycle arrest, which was reversed by ROS inhibitor. Helenalin relieved the inhibitory effect of TrxR1 on ROS production. Furthermore, helenalin ameliorated the decrease in apoptosis rate and the shortening of G0/G1 phase as well as the increase in migration and invasion induced by TrxR1 overexpression. CONCLUSIONS Our findings revealed that helenalin accelerated ROS-mediated apoptosis and cell cycle arrest via targeting TrxR1 in human prostate cancer cells.

Epigenetic Manipulation to Trigger Production of Guaiane-Type Sesquiterpenes from a Marine-Derived Spiromastix sp. Fungus with Antineuroinflammatory Effects.

Epigenetic manipulation of a deep-sea sediment-derived Spiromastix sp. fungus using suberoylanilide hydroxamic acid (SAHA) induction resulted in the activation of a terpene-related biosynthetic gene cluster, and nine new guaiane-type sesquiterpenes, spiromaterpenes A-I (1-9), were isolated. Their structures were determined using various spectroscopic techniques, in association with the modified Mosher's method, computed electronic circular dichroism (ECD) spectra, and chemical conversion for configurational assignments. Compounds 4-6 exhibited significant effects against the NO production on lipopolysaccharide (LPS)-induced microglia cells BV2, and the preliminary SAR analyses demonstrated that a 2(R),11-diol unit is favorable. The most active 5 abolished LPS-induced NF-κB translocation from the cytosol to the nucleus in BV-2 microglial cells, accompanied by the marked reduction of the transcription levels of pro-inflammatory cytokines, including IL-1ß, IL-6, and TNF-α dose-dependently in both LPS-induced BV-2 and BV-2 cells, as well as the protein and mRNA levels of iNOS and COX-2. This study complements the gap in knowledge regarding the anti-neuroinflammatory activity of guaiane-type sesquiterpenoids at the cellular level and suggests that 5 is promising for further optimization as a multifunctional agent for antineuroinflammation.

Guaiazulene derivative 1,2,3,4-tetrahydroazuleno[1,2-b] tropone reduces the production of ATP by inhibiting electron transfer complex II.

Molecularly targeted therapy has been used for treatment of various types of cancer. However, cancer cells often acquire resistance to molecularly targeted drugs that inhibit specific molecular abnormalities, such as constitutive activation of kinases. Even in cancer cells that have acquired resistance, enhanced anabolism, including the synthesis of nucleotides, amino acids and lipids, is common to normal cancer cells. Therefore, there is a renewed interest in effectively eliminating cancer cells by specifically targeting their abnormal energy metabolism. Multiple strategies are currently being developed for mitochondrial-targeted cancer therapy, with agents targeting oxidative phosphorylation, glycolysis, the tricarboxylic acid cycle and apoptosis. In this study, we found that one of the guaiazulene derivatives, namely, 1,2,3,4-tetrahydroazuleno[1,2-b] tropone (TAT), inhibited the proliferation of cancer cell lines stronger than that of normal cells. In addition, we showed that TAT inhibited energy production in cancer cell lines, resulting in apoptosis. Analyses done in cancer cell lines and in the animal model Caenorhabditis elegans suggested that TAT acts on the mitochondrial electron transfer complex II and suppresses cellular energy production by inhibiting oxidative phosphorylation across species. These results suggest that TAT could represent a novel anticancer agent that selectively targets mitochondria.

Characterization of Guaiene Synthases from Stellera chamaejasme L. Flowers and Their Application in De novo Production of (-)-Rotundone in Yeast.

Four terpene synthases for the biosynthesis of volatile terpenoids were identified from the transcriptome of Stellera chamaejasme L. flowers, including SchTPS1, SchTPS2, SchTPS3, and SchTPS4. Their functions were characterized by synthetic biology approaches in Escherichia coli and in vitro enzymatic assays. SchTPS1, SchTPS2, and SchTPS3 are guaiene synthases, while SchTPS4 is an (E,E)-geranyl linalool synthase. Next, SchTPS1 and α-guaiene 2-oxidase VvSTO2 were co-expressed in Saccharomyces cerevisiae to reconstruct the biosynthetic pathway of (-)-rotundone, which is a unique aroma compound in fruits, vegetables, and wines. This is the first report for the construction of a (-)-rotundone-producing microbial platform.

A Wheat ß-Patchoulene Synthase Confers Resistance Against Herbivory in Transgenic Arabidopsis.

Terpenoids play important roles in plant defense. Although some terpene synthases have been characterized, terpenoids and their biosynthesis in wheat (Triticumaestivum L.) still remain largely unknown. Here, we describe the identification of a terpene synthase gene in wheat. It encodes a sesquiterpene synthase that catalyzes ß-patchoulene formation with E,E-farnesyl diphosphate (FPP) as the substrate, thus named as TaPS. TaPS exhibits inducible expression in wheat in response to various elicitations. Particularly, alamethicin treatment strongly induces TaPS gene expression and ß-patchoulene accumulation in wheat. Overexpression of TaPS in Arabidopsis successfully produces ß-patchoulene, verifying the biochemical function of TaPS in planta. Furthermore, these transgenic Arabidopsis plants exhibit resistance against herbivory by repelling beet armyworm larvae feeding, thereby indicating anti-herbivory activity of ß-patchoulene. The catalytic mechanism of TaPS is also explored by homology modeling and site-directed mutagenesis. Two key amino acids are identified to act in protonation and stability of intermediates and product formation. Taken together, one wheat sesquiterpene synthase is identified as ß-patchoulene synthase. TaPS exhibits inducible gene expression and the sesquiterpene ß-patchoulene is involved in repelling insect infestation.

Structure-Function Relationship and Physiological Roles of Transient Receptor Potential Canonical (TRPC) 4 and 5 Channels.

The study of the structure-function relationship of ion channels has been one of the most challenging goals in contemporary physiology. Revelation of the three-dimensional (3D) structure of ion channels has facilitated our understanding of many of the submolecular mechanisms inside ion channels, such as selective permeability, voltage dependency, agonist binding, and inter-subunit multimerization. Identifying the structure-function relationship of the ion channels is clinically important as well since only such knowledge can imbue potential therapeutics with practical possibilities. In a sense, recent advances in the understanding of the structure-relationship of transient receptor potential canonical (TRPC) channels look promising since human TRPC channels are calcium-permeable, non-selective cation channels expressed in many tissues such as the gastrointestinal (GI) tract, kidney, heart, vasculature, and brain. TRPC channels are known to regulate GI contractility and motility, pulmonary hypertension, right ventricular hypertrophy, podocyte injury, seizure, fear, anxiety-like behavior, and many others. In this article, we tried to elaborate recent findings of Cryo-EM (cryogenic-electron microscopy) based structural information of TRPC 4 and 5 channels and domain-specific functions of the channel, such as G-protein mediated activation mechanism, extracellular modification of the channel, homo/hetero-tetramerization, and pharmacological gating mechanisms.

Pharmacokinetics, tissue distribution and excretion of ACT001 in Sprague-Dawley rats and metabolism of ACT001.

This study investigated pharmacokinetics, tissue distribution and excretion of ACT001 in Sprague-Dawley rats. Stability study and metabolism study of ACT001 are conducted. The absolute bioavailability of ACT001 is 50.82%. ACT001 has no accumulation effect and displayed wide tissue distribution. ACT001 can be rapidly distributed to tissues after oral administration and can diffuse through the blood-brain barrier. The total cumulative excretion of ACT001 in feces, urine and bile were found to be 0.05, 3.42 and 0.012%, respectively. UPLC/ESI-QTOF-MS coupled with MetaboLynx XS software was utilized to detect the metabolites of ACT001 in vitro. Five metabolites (M1, M2, M3, M4 and M5) were detected. M2 wasn't discovered in human liver microsome samples and bile samples. M1 and M2 weren't discovered in rat plasma and human plasma. M3, M4 and M5 weren't discovered in bile samples. M5 is an active metabolite named micheliolide (MCL). There is no significant difference in half-life, type of identified metabolites and the amount of each metabolites between using rat plasma and human plasma. Owing to the species differences of hepatomicrosome enzymes, significant differences were shown in half-life, type of identified metabolites and the amount of each metabolites between using rat liver microsome and human liver microsome.

Two key polymorphisms in a newly discovered allele of the Vitis vinifera TPS24 gene are responsible for the production of the rotundone precursor α-guaiene.

Rotundone was initially identified as a grape-derived compound responsible for the peppery aroma of Shiraz wine varieties. It has subsequently been found in black and white pepper and several other spices. Because of its potent aroma, the molecular basis for rotundone formation is of particular relevance to grape and wine scientists and industry. We have identified and functionally characterized in planta a sesquiterpene synthase, VvGuaS, from developing grape berries, and have demonstrated that it produces the precursor of rotundone, α-guaiene, as its main product. The VvGuaS enzyme is a novel allele of the sesquiterpene synthase gene, VvTPS24, which has previously been reported to encode VvPNSeInt, an enzyme that produces a variety of selinene-type sesquiterpenes. This newly discovered VvTPS24 allele encodes an enzyme 99.5% identical to VvPNSeInt, with the differences comprising just 6 out of the 561 amino acid residues. Molecular modelling of the enzymes revealed that two of these residues, T414 and V530, are located in the active site of VvGuaS within 4 Å of the binding-site of the substrate, farnesyl pyrophosphate. Mutation of these two residues of VvGuaS into the corresponding polymorphisms in VvPNSeInt results in a complete functional conversion of one enzyme into the other, while mutation of each residue individually produces an intermediate change in the product profile. We have therefore demonstrated that VvGuaS, an enzyme responsible for production of the rotundone precursor, α-guaiene, is encoded by a novel allele of the previously characterized grapevine gene VvTPS24 and that two specific polymorphisms are responsible for functional differences between VvTPS24 alleles.

Cytochrome P450 CYP71BE5 in grapevine (Vitis vinifera) catalyzes the formation of the spicy aroma compound (-)-rotundone.

(-)-Rotundone is a potent odorant molecule with a characteristic spicy aroma existing in various plants including grapevines (Vitis vinifera). It is considered to be a significant compound in wines and grapes because of its low sensory threshold and aroma properties. (-)-Rotundone was first identified in red wine made from the grape cultivar Syrah and here we report the identification of VvSTO2 as a α-guaiene 2-oxidase which can transform α-guaiene to (-)-rotundone in the grape cultivar Syrah. It is a cytochrome P450 (CYP) enzyme belonging to the CYP 71BE subfamily, which overlaps with the very large CYP71D family and, to the best of our knowledge, this is the first functional characterization of an enzyme from this family. VvSTO2 was expressed at a higher level in the Syrah grape exocarp (skin) in accord with the localization of (-)-rotundone accumulation in grape berries. α-Guaiene was also detected in the Syrah grape exocarp at an extremely high concentration. These findings suggest that (-)-rotundone accumulation is regulated by the VvSTO2 expression along with the availability of α-guaiene as a precursor. VvSTO2 expression during grape maturation was considerably higher in Syrah grape exocarp compared to Merlot grape exocarp, consistent with the patterns of α-guaiene and (-)-rotundone accumulation. On the basis of these findings, we propose that VvSTO2 may be a key enzyme in the biosynthesis of (-)-rotundone in grapevines by acting as a α-guaiene 2-oxidase.

(-)-Englerin†A is a potent and selective activator of TRPC4 and TRPC5 calcium channels.

Current therapies for common types of cancer such as renal cell cancer are often ineffective and unspecific, and novel pharmacological targets and approaches are in high demand. Here we show the unexpected possibility for the rapid and selective killing of renal cancer cells through activation of calcium-permeable nonselective transient receptor potential canonical (TRPC) calcium channels by the sesquiterpene (-)-englerin A. This compound was found to be a highly efficient, fast-acting, potent, selective, and direct stimulator of TRPC4 and TRPC5 channels. TRPC4/5 activation through a high-affinity extracellular (-)-englerin A binding site may open up novel opportunities for drug discovery aimed at renal cancer.

Isolation and characterization of terpene synthases in cotton (Gossypium hirsutum).

Cotton plants accumulate gossypol and related sesquiterpene aldehydes, which function as phytoalexins against pathogens and feeding deterrents to herbivorous insects. However, to date little is known about the biosynthesis of volatile terpenes in this crop. Herein is reported that 5 monoterpenes and 11 sesquiterpenes from extracts of a glanded cotton cultivar, Gossypium hirsutum cv. CCRI12, were detected by gas chromatography-mass spectrometry (GC-MS). By EST data mining combined with Rapid Amplification of cDNA Ends (RACE), full-length cDNAs of three terpene synthases (TPSs), GhTPS1, GhTPS2 and GhTPS3 were isolated. By in vitro assays of the recombinant proteins, it was found that GhTPS1 and GhTPS2 are sesquiterpene synthases: the former converted farnesyl pyrophosphate (FPP) into ß-caryophyllene and α-humulene in a ratio of 2:1, whereas the latter produced several sesquiterpenes with guaia-1(10),11-diene as the major product. By contrast, GhTPS3 is a monoterpene synthase, which produced α-pinene, ß-pinene, ß-phellandrene and trace amounts of other monoterpenes from geranyl pyrophosphate (GPP). The TPS activities were also supported by Virus Induced Gene Silencing (VIGS) in the cotton plant. GhTPS1 and GhTPS3 were highly expressed in the cotton plant overall, whereas GhTPS2 was expressed only in leaves. When stimulated by mechanical wounding, Verticillium dahliae (Vde) elicitor or methyl jasmonate (MeJA), production of terpenes and expression of the corresponding synthase genes were induced. These data demonstrate that the three genes account for the biosynthesis of volatile terpenes of cotton, at least of this Upland cotton.

A comparison of headspace solid-phase microextraction and classic hydrodistillation for the identification of volatile constituents from Thapsia spp. provides insights into guaianolide biosynthesis in Apiaceae.

INTRODUCTION: Thapsia spp. (Apiaceae) are the major natural source of polyoxygenated guaianolide sesquiterpene lactones known as thapsigargins, which induce apoptosis in mammalian cells via a high affinity inhibition of the sarco/endoplasmic reticulum Ca(2+) ATPase. The mechanism of biosynthesis of thapsigargins has not been elucidated, and probable biochemical precursors such as hydrocarbon or oxygenated sesquiterpenes have not been identified in previous phytochemical analyses of essential oils from this genus. OBJECTIVE: To investigate the utility of solid phase micro-extraction (SPME), when compared with classical essential oil distillates, for identifying potential precursors of guaianolide sesquiterpene lactones from Thapsia garganica L. and Thapsia villosa L. type II. METHODOLOGY: A systematic description of the volatile components of roots, flowers, stems and fruits of T. villosa and of root, flower and fruits of T. garganica was constructed via GC-MS analyses of SPME-adsorbed compounds and of essential oils obtained through hydrodistillation of the same tissues. RESULTS: The sesquiterpenoids δ-cadinene, α- and δ-guaiene, elemol and guaiols were found to be major volatile constituents of the roots of T. garganica and T. villosa trapped using SPME. In contrast, these sesquiterpenoids were not detected or were at negligible levels in essential oils, where sesquiterpenoids are potentially converted to azulenes during hydrodistillation. CONCLUSION: The new data reported in this study demonstrates that SPME is a valuable tool for the identification of volatile sesquiterpenes when compared with analysis of essential oils, and we postulate that guaiene is the likely precursor of guaianolide sesquiterpenes from Thapsia.

The development of an improved preclinical mouse model of intracerebral hemorrhage using double infusion of autologous whole blood.

The present study was conducted in mice to validate a double blood infusion model of intracerebral hemorrhage (ICH) that does not use anticoagulant. We investigated the effect of intrastriatal infusion of blood on hematoma volume, neurologic function, brain edema and swelling, and markers of neuroinflammation and oxidative DNA damage. Anesthetized C57BL/6 adult male mice were infused in the left striatum with 4 microl of blood over 20 min at 0.2 microl /min; the needle was left in place for 7 min, and the remaining 6 microl of blood was then infused over 30 min. The injection needle was slowly withdrawn 20 min after the second injection. Sham-operated control mice received only needle insertion. The hematoma produced in this model was primarily restricted to the striatum, and the mice demonstrated severe neurologic deficits that appeared within 60 min and remained evident at 72 h. Brain water content and swelling were significantly increased and were associated with a marked increase in ICH-induced neutrophil infiltration, microglial/macrophage and astrocyte activation, cytochrome c release, and oxidative DNA damage. Other groups have mixed the anticoagulant heparin with the infused blood, an agent that could affect in vivo clot formation. We believe that this double blood infusion model that does not use anticoagulant improves upon the procedure and provides an easy and reproducible alternative for inducing ICH in mice; it should be useful for studying the pathophysiology of ICH and for testing potential pharmaceutical and surgical interventions.