Unique monoterpenoid indole alkaloids from Alstonia scholaris

Chromosome-level Alstonia scholaris genome unveils evolutionary insights into biosynthesis of monoterpenoid indole alkaloids

Alstonia scholaris of the Apocynaceae family is a medicinal plant with a rich source of bioactive monoterpenoid indole alkaloids (MIAs), which possess anti-cancer activity like vinca alkaloids. To gain genomic insights into MIA biosynthesis, we assembled a high-quality chromosome-level genome for A. scholaris using nanopore and Hi-C data. The 444.95 Mb genome contained 35,488 protein-coding genes. A total of 20 chromosomes were assembled with a scaffold N50 of 21.75 Mb. The genome contained a cluster of strictosidine synthases and tryptophan decarboxylases with synteny to other species and a saccharide-terpene cluster involved in the monoterpenoid biosynthesis pathway of the MIA upstream pathway. The multi-omics data of A. scholaris provide a valuable resource for understanding the evolutionary origins of MIAs and for discovering biosynthetic pathways and synthetic biology efforts for producing pharmaceutically useful alkaloids.

Exploring the Significance, Extraction, and Characterization of Plant-Derived Secondary Metabolites in Complex Mixtures

Secondary metabolites are essential components for the survival of plants. Secondary metabolites in complex mixtures from plants have been adopted and documented by different traditional medicinal systems worldwide for the treatment of various human diseases. The extraction strategies are the key components for therapeutic development from natural sources. Polarity-dependent solvent-selective extraction, acidic and basic solution-based extraction, and microwave- and ultrasound-assisted extraction are some of the most important strategies for the extraction of natural products from plants. The method needs to be optimized to isolate a specific class of compounds. Therefore, to establish the mechanism of action, the characterization of the secondary metabolites, in a mixture or in their pure forms, is equally important. LC-MS, GC-MS, and extensive NMR spectroscopic strategies are established techniques for the profiling of metabolites in crude extracts. Various protocols for the extraction and characterization of a wide range of classes of compounds have been developed by various research groups and are described in this review. Additionally, the possible means of characterizing the compounds in the mixture and their uniqueness are also discussed. Hyphenated techniques are crucial for profiling because of their ability to analyze a vast range of compounds. In contrast, inherent chemical shifts make NMR an indispensable tool for structure elucidation in complex mixtures.

Synthesis of 3-aminotetrahydro-1H-carbazols by visible-light photocatalyzed cycloaddition of cyclopropylanilines with 2-alkenylarylisocyanides

A visible-light-induced cycloaddition between 2-alkenylarylisocyanides and cyclopropylanilines is reported. This cascade radical reaction constructs two new C-C bonds and two rings to afford 3-aminotetrahydro-1H-carbazols with high atom and step economy. The mechanism is rationalized as involving sequential distonic radical cation formation/isocyanide insertion/5-exo-trig cyclization/intramolecular iminium ion addition/tautomerization.

Antispasmodic Effect of Alstonia boonei De Wild. and Its Constituents: Ex Vivo and In Silico Approaches

BACKGROUND

Alstonia boonei, belonging to the family Apocynaceae, is one of the best-known medicinal plants in Africa and Asia. Stem back preparations are traditionally used as muscle relaxants. This study investigated the antispasmodic properties of Alstonia boonei Stem back and its constituents.

METHOD

The freeze-dried aqueous Stem back extract of A. boonei, as well as dichloromethane (DCM), ethyl acetate, and aqueous fractions, were evaluated for their antispasmodic effect via the ex vivo method. Two compounds were isolated from the DCM fraction using chromatographic techniques, and their antispasmodic activity was evaluated. An in silico study was conducted by evaluating the interaction of isolated compounds with human PPARgamma-LBD and human carbonic anhydrase isozyme.

RESULTS

The Stem back crude extract, DCM, ethyl acetate, and aqueous fractions showed antispasmodic activity on high-potassium-induced (K+ 80 mM) contractions on isolated rat ileum with IC50 values of 0.03 ± 0.20, 0.02 ± 0.05, 0.03 ± 0.14, and 0.90 ± 0.06 mg/mL, respectively. The isolated compounds from the DCM fraction were β-amyrin and boonein, with only boonein exhibiting antispasmodic activity on both high-potassium-induced (IC50 = 0.09 ± 0.01 µg/mL) and spontaneous (0.29 ± 0.05 µg/mL) contractions. However, β-amyrin had a stronger interaction with the two proteins during the simulation.

CONCLUSION

The isolated compounds boonein and β-amyrin could serve as starting materials for the development of antispasmodic drugs.

Targeted quantitative analysis of monoterpenoid indole alkaloids in Alstonia scholaris by ultra-high-performance liquid chromatography coupled with quadrupole time of flight mass spectrometry

Monoterpene indole alkaloids exhibit structural diversity in herbal resources and have been developed as promising drugs owing to their significant biological activities. Confidential identification and quantification of monoterpene indole alkaloids is the key to quality control of target plants in industrial production but has rarely been reported. In this study, quantitative performance of three data acquisition modes of ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry including full scan, auto-MS2 and target-MS2 , was evaluated and compared for specificity, sensitivity, linearity, precision, accuracy, and matrix effect using five monoterpene indole alkaloids (scholaricine, 19-epi-scholaricine, vallesamine, picrinine, and picralinal). Method validations indicated that target-MS2 mode showed predominant performance for simultaneous annotation and quantification of analytes, and was then applied to determine monoterpene indole alkaloids in Alstonia scholaris (leaves, barks) after extraction procedures optimization using Box-Behnken design of response surface methodology. The variations of A. scholaris monoterpene indole alkaloids in different plant parts, harvest periods, and post-handling processes, were subsequently investigated. The results indicated that target-MS2 mode could improve the quantitative capability of ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry for structure-complex monoterpene indole alkaloids in herbal matrices. Alstonia scholaris, monoterpene indole alkaloids, quadrupole time of flight mass spectrometry, qualitative and quantitative analysis, ultra-high-performance liquid chromatography.

Pharmacological investigation of indole alkaloids from Alstonia scholaris against chronic glomerulonephritis

BACKGROUND

As one of the most commonly used folk medicines in "Dai" ethno-medicine system, Alstonia scholaris (l.) R. Br. has also been used for treat "water related diseases", such as chronic kidney disease. However, few study was reported for it on the intervention of chronic glomerulonephritis (CGN).

PURPOSE

To investigate the effect and potential mechanism of indole alkaloids from A. scholaris leaves in ICR mice with adriamycin nephropathy, as well as providing experimental evidence for the further application.

METHODS

ICR Mice were selected for injections of adriamycin (ADR) to induce the CGN model and administered total alkaloids (TA) and four main alkaloids continuously for 42 and 28 days, respectively. The pharmacological effects were indicated by serum, urine, and renal pathological observations. The targets and pathways of indole alkaloids on CGN intervention were predicted using the network pharmacology approach, and the immortalized mice glomerular podocyte (MPC5) cells model stimulated by ADR was subsequently selected to further verify this by western blotting and RT-qPCR methods.

RESULTS

TA and four major compounds dramatically reduced the levels of urinary protein, serum urea nitrogen (BUN), and creatinine (CRE) in ADR - induced CGN mice, while increasing serum albumin (ALB) and total protein (TP) levels as well as ameliorating kidney damage. Moreover, four alkaloids effected on 33 major target proteins and 153 pathways in the CGN, among which, PI3K-Akt as the main pathway, an important pathway for kidney protection by network pharmacology prediction, and then the four target proteins - HRAS, CDK2, HSP90AA1, and KDR were screened. As a result, Val-and Epi can exert a protective effect on ADR-stimulated MPC5 cells injury at a concentration of 50 μM. Furthermore, the proteins and RNA expression of HRAS, HSP90AA1, and KDR were down-regulated, and CDK2 was up-regulated after the intervention of Val-and Epi, which were supported by Western blotting and RT-qPCR. Additionally, Val-and Epi inhibited ROS production in the MPC5 cells model.

CONCLUSION

This study is the first to confirm the potential therapeutic effect of alkaloids from A. scholaris on CGN. TA with major bioactive components (vallesamine and 19‑epi-scholaricine) could exert protective effects against the ADR-induced CGN by regulating four key proteins: HRAS, CDK2, HSP90AA1, and KDR of the PI3K-Akt pathway.

Potential Plant-Based New Antiplasmodial Agent Used in Papua Island, Indonesia

Resistance to antimalarial medicine remains a threat to the global effort for malaria eradication. The World Health Organization recently reported that artemisinin partial resistance, which was defined as delayed parasite clearance, was detected in Southeast Asia, particularly in the Greater Mekong subregion, and in Africa, particularly in Rwanda and Uganda. Therefore, the discovery of a potential new drug is important to overcome emerging drug resistance. Natural products have played an important role in drug development over the centuries, including the development of antimalarial drugs, with most of it influenced by traditional use. Recent research on traditional medicine used as an antimalarial treatment on Papua Island, Indonesia, reported that 72 plant species have been used as traditional medicine, with Alstonia scholaris, Carica papaya, Andrographis paniculata, and Physalis minima as the most frequently used medicinal plants. This review aimed to highlight the current research status of these plants for potential novel antiplasmodial development. In conclusion, A. paniculata has the highest potential to be developed as an antiplasmodial, and its extract and known bioactive isolate andrographolide posed strong activity both in vitro and in vivo. A. scholaris and C. papaya also have the potential to be further investigated as both have good potential for their antiplasmodial activities in vivo. However, P. minima is a less studied medicinal plant; nevertheless, it opens the opportunity to explore the potential of this plant.

Plant Bioactives in the Treatment of Inflammation of Skeletal Muscles: A Molecular Perspective

Skeletal muscle mass responds rapidly to growth stimuli, precipitating hypertrophies (increased protein synthesis) and hyperplasia (activation of the myogenic program). For ages, muscle degeneration has been attributed to changes in the intracellular myofiber pathways. These pathways are tightly regulated by hormones and lymphokines that ultimately pave the way to decreased anabolism and accelerated protein breakdown. Despite the lacunae in our understanding of specific pathways, growing bodies of evidence suggest that the changes in the myogenic/regenerative program are the major contributing factor in the development and progression of muscle wasting. In addition, inflammation plays a key role in the pathophysiology of diseases linked to the failure of skeletal muscles. Chronic inflammation with elevated levels of inflammatory mediators has been observed in a spectrum of diseases, such as inflammatory myopathies and chronic obstructive pulmonary disease (COPD). Although the pathophysiology of these diseases varies greatly, they all demonstrate sarcopenia and dysregulated skeletal muscle physiology as common symptoms. Medicinal plants harbor potential novel chemical moieties for a plenitude of illnesses, and inflammation is no exception. However, despite the vast number of potential antiinflammatory compounds found in plant extracts and isolated components, the research on medicinal plants is highly daunting. This review aims to explore the various phytoconstituents employed in the treatment of inflammatory responses in skeletal muscles, while providing an in-depth molecular insight into the latter.

Anti-hyperuricemic bioactivity of Alstonia scholaris and its bioactive triterpenoids in vivo and in vitro

ETHNOPHARMACOLOGY RELEVANCE

One folk use of Alstonia scholaris (L.) R. Br. in "Dai" ethno-medicine system is to treat gouty arthritis, which might be caused by hyperuricemia, but anti-hyperuricemic investigation of A. scholaris were rarely reported.

AIM OF THE STUDY

To verify anti-hyperuricemic property of A. scholaris, and explore its bioactive compounds in vivo and in vitro.

MATERIALS AND METHODS

The anti-hyperuricemic bioactivity of the non-alkaloids fraction and compounds were evaluated with potassium oxonate (PO) induced hyperuricemia mice model in vivo, and monosodium urate (MSU) induced human renal tubular epithelial cells (HK-2) was selected to test in vitro, respectively, with benzobromarone as the positive control. 11 triterpenoids were isolated by phytochemical methods and their structures were elucidated by spectroscopic analysis and ECD calculation.

RESULTS

The non-alkaloids fraction of A. scholaris decreased the serum uric acid (UA) level in mice model significantly at the doses of 100 mg/kg and 200 mg/kg, and then nine ursane- and two oleanane-triterpenoids including four new compounds (1-3 and 10) were isolated from the bioactive fraction, in which compounds 1, 4, 5, 6 and 10 exhibited better anti-hyperuricemic tendency in vitro by promoting the excretion of UA in MSU-induced HK-2 cell model at a concentration of 5 μM. Furthermore, compounds 1 and 4 were proved to reduce the serum UA level in mice significantly at 5 mg/kg in vivo.

CONCLUSIONS

The results supported the traditional use of A. scholaris in treating gouty arthritis, and also provided new bioactive triterpenoids for further chemical and pharmacological investigation.

Indole alkaloids of Alstonia scholaris (L.) R. Br. alleviated nonalcoholic fatty liver disease in mice fed with high-fat diet

Alstonia scholaris (L.) R. Br (Apocynaceae) is a well-documented medicinal plant for treating respiratory diseases, liver diseases and diabetes traditionally. The current study aimed to investigate the effects of TA on non-alcoholic fatty liver disease (NAFLD). A NAFLD model was established using mice fed a high-fat diet (HFD) and administered with TA (7.5, 15 and 30 mg/kg) orally for 6 weeks. The biochemical parameters, expressions of lipid metabolism-related genes or proteins were analyzed. Furthermore, histopathological examinations were evaluated with Hematoxylin-Eosin and MASSON staining. TA treatment significantly decreased the bodyweight of HFD mice. The concentrations of low-density lipoprotein (LDL), triglyceride (TG), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were also decreased significantly in TA-treated mice group, accompanied by an increase in high-density lipoprotein (HDL). Furthermore, TA alleviated hepatic steatosis injury and lipid droplet accumulation of liver tissues. The liver mRNA levels involved in hepatic lipid synthesis such as sterol regulatory element-binding protein 1C (SREBP-1C), regulators of liver X receptor α (LXRα), peroxisome proliferator activated receptor (PPAR)γ, acetyl-CoA carboxylase (ACC1) and stearyl coenzyme A dehydrogenase-1 (SCD1), were markedly decreased, while the expressions involved in the regulation of fatty acid oxidation, PPARα, carnitine palmitoyl transterase 1 (CPT1A), and acyl coenzyme A oxidase 1 (ACOX1) were increased in TA-treated mice. TA might attenuate NAFLD by regulating hepatic lipogenesis and fatty acid oxidation.

The clinical population pharmacokinetics, metabolomics and therapeutic analysis of alkaloids from Alstonia scholaris leaves in acute bronchitis patients

BACKGROUND

Capsule of alkaloids from leaf of Alstonia scholaris (CALAS) is a new investigational botanical drug (No. 2011L01436) for respiratory disease. Clinical population pharmacokinetics (PK), metabolomics and therapeutic data are essential to guide dosing in patients. Previous research has demonstrated the potential therapeutic effect of CALAS on acute bronchitis. Further clinical trial data are needed to verify its clinical efficacy, pharmacokinetics behavior, and influence of dosage and other factors.

PURPOSE

To verify the clinical efficacy and explore the potential biomarkers related to CALAS treatment for acute bronchitis.

MATERIALS AND METHODS

Oral CALAS was assessed in a randomized, double-blind, placebo-controlled trial. Fifty-five eligible patients were randomly assigned to four cohorts to receive 20, 40 or 80 mg, of CALAS three times daily for seven days, or placebo. Each CALAS cohort included 15 subjects, and the placebo group included 10 subjects. A population PK model of CALAS was developed using plasma with four major alkaloid components. Metabolomics analysis was performed to identify biomarkers correlated with the therapeutic effect of CALAS, and efficacy and safety were assessed based on clinical symptoms and adverse events.

RESULTS

The symptoms of acute bronchitis were alleviated by CALAS treatment without serious adverse events or clinically significant changes in vital signs, electrocardiography or upper abdominal Doppler ultrasonography. Moreover, one compartment model with first-order absorption showed that an increase in aspartate transaminase will reduce the clearance (CL) of scholaricine, and picrinine CL was inversely proportional to body mass index, while 19-epischolaricine and vallesamine CL increased with aging. The serum samples from acute bronchitis patients at different time points were analyzed using UPLC-QTOF in combination with the orthogonal projection to latent structures-discriminant analysis, which indicated higher levels of lysophosphatidylcholines, lysophosphatidylethanolamines and amino acids with CALAS treatment than with placebo.

CONCLUSION

This is the first study to evaluate the clinical efficacy and explored the potential biomarkers related to CALAS therapeutic mechanism of acute bronchitis by means of clinical trial combined the metabolomics study. This exploratory study provides a basis for further research on clinical efficacy and optimal dosing regimens based on pharmacokinetics behavior. Additional acute bronchitis patients and CALAS PK samples collected in future studies may be used to improve model performance and maximize its clinical value.

The safety and tolerability of alkaloids from Alstonia scholaris leaves in healthy Chinese volunteers: a single-centre, randomized, double-blind, placebo-controlled phase I clinical trial

CONTEXT

Capsule of alkaloids from the leaf of Alstonia scholaris (L.) R.Br. (Apocynaceae) (CALAS) is a new investigational botanical drug (No. 2011L01436) for bronchitis, post-infectious cough and asthma.

OBJECTIVE

To observe the clinical safety and tolerability of CALAS.

MATERIALS AND METHODS

Subjects were assigned to eight cohorts, and each received randomly CALAS or placebo in one of single ascending dose (SAD) of 8, 40, 120, 240, 360, 480, or in one of multiple ascending dose (MAD) of 40 or 120 mg, three times daily for 7 days. Each cohort contained two placebo subjects.

RESULTS

Sixty-two enrolled volunteers completed the study and no serious adverse events and clinically significant changes in vital signs, electrocardiography, and upper abdominal Doppler ultrasonography were observed. The ratios of treatment-emergent adverse events (TEAEs) were reported in 11/46 (23.91%) of CALAS groups and 3/16 (18.75%) of the placebo group (p > 0.05), respectively, based on the results of SAD and MAD. All TEAEs were mild, transient, and disappeared without any intervention. The TEAEs possibly related to CALAS treatment were as followings: hiccups (4/46: 8%), dry mouth and nausea (3/46: 6%), increased sleep (2/46: 4%), abdominal distension (1/46: 2%), bilirubin elevated (1/46: 2%).

DISCUSSION AND CONCLUSIONS

CALAS is safe and well-tolerated with no unexpected or clinically relevant safety concerns up to a single dose of 360 mg and three times daily for 7 days up to 120 mg in healthy Chinese volunteers, supporting further Phase II studies.

Synthesis of indole derivatives as prevalent moieties present in selected alkaloids

Indoles are a significant heterocyclic system in natural products and drugs. They are important types of molecules and natural products and play a main role in cell biology. The application of indole derivatives as biologically active compounds for the treatment of cancer cells, microbes, and different types of disorders in the human body has attracted increasing attention in recent years. Indoles, both natural and synthetic, show various biologically vital properties. Owing to the importance of this significant ring system, the investigation of novel methods of synthesis have attracted the attention of the chemical community. In this review, we aim to highlight the construction of indoles as a moiety in selected alkaloids.

Alstoscholarisine K, an Antimicrobial Indole from Gall-Induced Leaves of Alstonia scholaris

Alstoscholarisine K, an indole alkaloid with eight chiral carbons and featuring a novel 6/5/6/6/6/6/6/5 octacyclic architecture, was found to be specific to the gall-infected leaves of Alstonia scholaris. Its structure was elucidated by spectroscopy, computational analysis, and single-crystal X-ray diffraction. The unusual highly fused cage-like pyrrolo[1,2-a]pyrimidine structure with an additional -C₄N unit is possibly derived from a combination of monoterpenoid indole and polyamine pathways. The fascinating compound exhibited significant antibacterial bioactivities by targeting cell membranes.

Pharmacological effects of indole alkaloids from Alstonia scholaris (L.) R. Br. on pulmonary fibrosis in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Alstonia scholaris (L.) R. Br. (Apocynaceae) is a Dai folk medicine for the treatment of lung diseases in China.

AIM OF THE STUDY

The present study investigated the anti-pulmonary fibrosis effects of total alkaloids (TA) and the potential active ingredients and its possible mechanism.

MATERIALS AND METHODS

After intratracheal instillation of bleomycin (BLM, 5 mg/kg), mice were divided into ten groups, and orally treated with the corresponding samples once daily for 28 days. The effect of indole alkaloids was determined through analysis of cytokines, as well as histopathological examinations and gene expressions.

RESULTS

Severe lung fibrosis was observed in the BLM-treated mice on day 28. However, the administration of TA significantly ameliorated the pathological changes in the lungs, decreased the content of Krebs von den Lungen-6, lactate dehydrogenase, transforming growth factor-β (TGF-β), hydroxyproline, type I collagen, and malonaldehyde, and enhanced the activity of superoxide dismutase in the serum and lung tissues. In addition, the enhanced TGF-β and matrix metalloproteinase-1 (MMP-1) expressions in BLM-induced mice were obviously weakened by indole alkaloids, as well as the ratio of matrix metalloproteinase-1 to tissue inhibitor of metalloproteinase-1 was decreased. Moreover, picrinine and scholaricine yielded markedly better values in the aforementioned indices than those in other samples, indicating that they may be the active ingredients of alkaloids.

CONCLUSIONS

TA exerted protective effects against BLM-induced pulmonary fibrosis by reducing collagen deposition through TGF-β/MMP-1 pathway.

Anti-microbial Effects In Vitro and In Vivo of Alstonia scholaris

Alstonia scholaris could be used as a traditional medicinal plant in China for the treatment of acute respiratory, which might be caused by respiratory tract infections. The investigation tested the anti-infective effects of total alkaloids extract (TA) from leaves of A. scholaris, and as a result, TA inhibited herpes simplex virus type 1 (HSV-1), respiratory syncytial virus (RSV) and influenza A virus (H1N1) in vitro respectively. In addition, the survival days of mice were prolonged, and the lung weights and mortality of mice were decreased significantly, after oral administrated TA in H1N1 and beta-hemolytic streptococcus infectious models in vivo respectively. The finding supported partly the traditional usage of A. scholaris in the treatment of respiratory infections.

Chemical Diversity and Bioactivities of Monoterpene Indole Alkaloids (MIAs) from Six Apocynaceae Genera

By the end of the twentieth century, the interest in natural compounds as probable sources of drugs has declined and was replaced by other strategies such as molecular target-based drug discovery. However, in the recent times, natural compounds regained their position as extremely important source drug leads. Indole-containing compounds are under clinical use which includes vinblastine and vincristine (anticancer), atevirdine (anti-HIV), yohimbine (erectile dysfunction), reserpine (antihypertension), ajmalicine (vascular disorders), ajmaline (anti-arrhythmic), vincamine (vasodilator), etc. Monoterpene Indole Alkaloids (MIAs) deserve the curiosity and attention of researchers due to their chemical diversity and biological activities. These compounds were considered as an impending source of drug-lead. In this review 444 compounds, were identified from six genera belonging to the family Apocynaceae, will be discussed. These genera (Alstonia, Rauvolfia, Kopsia, Ervatamia, and Tabernaemontana, and Rhazya) consist of 400 members and represent 20% of Apocynaceae species. Only 30 (7.5%) species were investigated, whereas the rest are promising to be investigated. Eleven bioactivities, including antibacterial, antifungal, anti-inflammatory and immunosuppressant activities, were reported. Whereas cytotoxic effect represents 47% of the reported activities. Convincingly, the genera selected in this review are a wealthy source for future anticancer drug lead.

Indole alkaloids from leaves of Alstonia scholaris (L.) R. Br. protect against emphysema in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Alstonia scholaris (L.) R. Br. (Apocynaceae) is a medicinal plant in China traditionally used to treat pulmonary diseases, including bronchitis, whooping cough, asthma and chronic obstructive pulmonary disease.

AIM OF THE STUDY

To provide experimental data supporting clinical adaptation of total indole alkaloids ( TA) from A. scholaris leaves for treating emphysema.

MATERIALS AND METHODS

An emphysema model was induced by a single intratracheal instillation of porcine pancreatic elastase followed by administration of TA and four main alkaloid components (scholaricine, 19-epischolaricine, vallesamine, and picrinine) for 30 consecutive days. Cytokine levels, histopathological parameters and protein expression in lung tissues were examined.

RESULTS

Administering the TA, picrinine, scholaricine, 19-epischolaricine and vallesamine for 30 days effectively inhibited inflammatory cell accumulation and invasion in the lung tissue and relieved pulmonary tissue injury. Oxygen saturation was enhanced, and interleukin (IL)-1β, monocyte-chemo attractive peptide 1, IL-11, matrix metalloproteinase-12, transforming growth factor-β and vascular endothelial growth factor levels were significantly reduced, likely by suppressing overactivation of alveolar macrophages and pulmonary fibrosis. The elastin content was markedly elevated, and fibronectin was reduced. Bcl-2 expression was significantly increased, and nuclear factor-κB and β-catenin levels were decreased.

CONCLUSIONS

TA can be potentially used as an effective novel drug for pulmonary emphysema and exerts its effects through not only inhibiting inflammation of the airway wall and airflow resistance but also promoting lung elastic recoil and protease/anti-protease balance.

Acute and Sub-chronic Toxicity of Indole Alkaloids Extract from Leaves of Alstonia scholaris (L.) R. Br. in Beagle Dogs

Alstonia scholaris (L.) R. Br., an evergreen tropical plant rich in indole alkaloids with significant physiological activity, is traditionally used to treat respiratory diseases in China. This study was conducted to establish the toxicity profile of the alkaloid extract (TA) of A. scholaris leaves in non-rodents. After oral administration of a single dose (4 g/kg.bw), a number of transient symptoms, such as unsteady gait, drooling, emesis, and reddening of peri-oral mucosa, were observed, but no treatment-related mortality. A sub-chronic toxicity study with a range of doses of TA (20, 60 and 120 mg/kg.bw) was conducted for a 13-week treatment period, followed by 4-week recovery observation. Except for emesis and drooling in majority of animals in 120 mg/kg.bw treatment group, no clinical changes were observed in TA-treated animals. Data from electrocardiography, bone marrow, urine, fecal, hematology and clinical chemistry analyses were comparable between TA-treated and control animals. No significant differences in the relative organ weights and histopathological characteristics were evident between the TA-treated and control groups. Accordingly, the non-observed-adverse-effect-level (NOAEL) of TA was established as 120 mg/kg.bw. Our results add further knowledge to the safety database for indole alkaloid extracts from A. scholaris with potential utility as novel drug candidates.

Genotoxicity and Safety Pharmacology Studies of Indole Alkaloids Extract from Leaves of Alstonia scholaris (L.) R. Br

Indole alkaloids extract (IAAS) was prepared from leaves of Alstonia scholaris (L.) R. Br., an evergreen tropical plant widely distributed throughout the world. This plant has been used historically by the Dai ethnic people of China to treat respiratory diseases. This study evaluated the genotoxicity and safety pharmacology of IAAS to support clinical use. The bacterial reverse mutation (Ames) test, in vitro mammalian chromosomal aberration test, and in vivo mammalian erythrocyte micronucleus (MN) test were performed to evaluate genotoxicity. Mice were administered IAAS (240, 480, or 960 mg/kg bw) once orally to observe adverse central nervous system effects. Furthermore, beagle dogs were administered IAAS (10, 30, 60 mg/kg bw) once via the duodenum to evaluate its effects on the cardiovascular and respiratory systems. IAAS with or without S9-induced metabolic activation showed no genotoxicity in the Ames test up to 500 μg/plate, in the mammalian chromosomal aberration test up to 710 μg/mL, or in the MN test up to 800 mg/kg bw. No abnormal neurobehavioral effects were observed in mice following treatment with up to 960 mg/kg bw of IAAS. Moreover, blood pressure, heart rate, electrocardiogram parameters, and depth and rate of breathing in anesthetized beagle dogs did not differ among the IAAS doses or from the vehicle group. These data indicated that IAAS did not induce mutagenicity, clastogenicity, or genotoxicity, and no pharmaco-toxicological effects were observed in the respiratory, cardiovascular, or central nervous systems. Our results increased understanding of safety considerations associated with IAAS, and may indicate that IAAS is a possible drug candidate.

Acute and Chronic Toxicity of Indole Alkaloids from Leaves of Alstonia scholaris (L.) R. Br. in Mice and Rats

Alstonia scholaris (L.) R. Br. (Apocynaceae) is an evergreen tree that has been used to treat lung diseases. In this study, the toxicity profile of indole alkaloids from leaves of A. scholaris was investigated. In acute toxicity tests, mice were administered total alkaloids (TA) and five indole alkaloids. In a chronic toxicity test, rats were continuously administered TA (50, 100, and 300 mg/kg bw) for 13 weeks, followed by a 4-week recovery. A single administration of TA affected the behavior of mice, and at 12.8 g/kg bw, prone position, shortness of breath, wheezing, and convulsion were observed. The half-lethal dose (LD50) in mice was 5.48 g/kg bw, almost 2740 times the clinical dose in humans. Among the five indole alkaloids, the maximum tolerance dose in mice ranged from 0.75 to 4 g/kg bw. The TA-treated rats did not die and showed no adverse effects or dose-dependent changes in weight or food and water consumption, despite fluctuations in hematological and biochemical parameters compared with historical data. Furthermore, both gross and histopathological observations revealed no abnormalities in any organ. With daily oral administration to rats, the non-observed-adverse-effect-level of TA was 100 mg/kg bw. The results indicate that TA is safe for clinical use.

Catalytic, Enantioselective Formal Synthesis of Monoterpene Indole Alkaloid (-)-Alstoscholarine

A catalytic, enantioselective formal synthesis of monoterpene indole alkaloid (-)-alstoscholarine is described. The synthesis employs an Ir-amine dual catalyzed asymmetric allylation of aldehyde 8 with 3-indolyl vinyl carbinol derivative 7 to furnish chiral aldehyde 6 as a key asymmetric step. Other key reactions include the construction of the 2-ketopyrrole moiety by Nicolaou's method and Tf₂O promoted Pictet-Spengler cyclization to access Zhu's intermediate 3.

Preparation and In Vitro Release of Total Alkaloids from Alstonia Scholaris Leaves Loaded mPEG-PLA Microspheres

Total alkaloids of Alstonia scholaris leaves (ASAs) are extracted from the lamp leaves, which have positive anti-inflammatory activity and remarkable effects in treating bronchitis. Due to its short half-life, we used a degradable mPEG-PLA to physically encapsulate the total alkali of the lamp stage, and prepared a sustained-release microsphere by double-emulsion method. The ASAs-loaded mPEG10000-PLA microspheres were screened for better performance by testing the morphology, average particle size, embedding rate and drug loading of different molecular weight mPEG-PLA microspheres, which can stably and continuously release for 15 days at 37 °C. The results of cytotoxicity and blood compatibility indicated that the drug-loaded microspheres have beneficial biocompatibility. Animal experiments showed that the drug-loaded microspheres had a beneficial anti-inflammatory effect. These results all indicated that mPEG-PLA is a controlled release carrier material suitable for ASAs.

Pharmacokinetics and safety evaluation in healthy Chinese volunteers of alkaloids from leaf of Alstonia scholaris: A multiple doses phase I clinical trial

BACKGROUND

Alstonia scholaris (Apocynaceae) was reported to be a rich source of indole alkaloids, which exhibited remarkably bioactivities. The leaf of A. scholaris has been used in 'dai' ethno-medicine for treatment of respiratory diseases, and the defined indole alkaloids from leaf of A. scholaris has been registered as investigational new botanical drug (No. 2011L01436) and was approved for phase I/II clinical trials by China Food and Drug Administration (CFDA).

PURPOSE

The aim of the trial is to evaluate the safety and explore the relationship of dosing frequency and pharmacokinetics after oral administration of capsule of alkaloids from leaf of A. scholaris (CALAS) at different doses.

METHODS

In this randomized, open-labelled, single-center clinical trial, the safety and pharmacokinetics of CALAS were assessed in eligible healthy Chinese volunteers after oral administration of different doses. Each volunteer (n = 10 per group) received single dose of CALAS from 20 mg, 40 mg, 80 mg to 120 mg orally. The pharmacokinetics of CALAS was investigated in healthy Chinese subjects' plasma by a fully-validated LC-MS/MS method. Safety was assessed biochemically and clinically throughout the study, and drug re-excitation research was conducted to verify the correlation between investigational product and minor adverse events. The trial was registered on August 26, 2015 (http://www.chictr.org.cn/showproj.aspx?proj=11736), number ChiCTR-IPR-15006976.

RESULTS

40 subjects completed the study, and as a result, vallesamine had the highest concentration in plasma of healthy volunteers, and the AUC exposure level in each compounds in turn is vallesamine > scholaricine > 19-epischolaricine > picrinine. For the safety evaluation of CALAS, two cases of minor adverse events were observed during the trial, but the drug re-excitation research indicated that these two adverse events were related to the individual's physiological variation.

CONCLUSION

Pharmacokinetic characteristics of each ingredient showed different patterns. 19-epischolaricine, vallesamine and picrinine were match to the linear pharmacokinetic characteristics, but scholaricine conformed to the characteristics of nonlinear pharmacokinetics. The CALAS was safe in healthy subjects under the current dose regimen.

Alstoscholactine and Alstolaxepine, Monoterpenoid Indole Alkaloids with γ-Lactone-Bridged Cycloheptane and Oxepane Moieties from Alstonia scholaris

Two new monoterpenoid indole alkaloids, alstoscholactine (1) and alstolaxepine (2), were isolated from Alstonia scholaris. Compound 1 represents a rearranged stemmadenine alkaloid with an unprecedented C-6-C-19 connectivity, whereas compound 2 represents a 6,7- seco-angustilobine B-type alkaloid incorporating a rare γ-lactone-bridged oxepane ring system. Their structures and absolute configurations were determined by spectroscopic analyses. Compound 1 was successfully semisynthesized from 19 E-vallesamine. Compound 2 induced marked vasorelaxation in rat isolated aortic rings precontracted with phenylephrine.

Bisindole alkaloids from Tabernaemontana corymbosa

Continued study in bioactive monoterpenoid alkaloids led to the isolation of nine undescribed alkaloids, taberyunines A-I, together with 32 known ones from the aerial parts of Tabernaemontana corymbosa Roxb. ex Wall (Apocynaceae). Among the undescribed alkaloids, taberyunines A-G and H-I were assigned to Aspidosperma-Aspidosperma and Vobasinyl-Ibogan type bisindoles, respectively. Their structures were determined by NMR spectra, MS data and X-ray diffraction. Taberyunine B showed significant cytotoxicity against three cancer cell lines.

Nepenthe-Like Indole Alkaloids with Antimicrobial Activity from Ervatamia chinensis

Two monoterpenoid indole alkaloid erchinines A (1) and B (2), possessing unique 1,4-diazepine fused with oxazolidine architecture and three hemiaminals, were isolated from Ervatamia chinensis. Their structures were elucidated on the basis of intensive spectroscopic analysis, and a plausible biosynthetic pathway from ibogaine was proposed. Both compounds exhibited significant antimicrobial activity against Trichophyton rubrum and Bacillus subtilis, and their activities were comparable to the first line antifungal drug griseofulvin and antibiotic cefotaxime.

Effects of indole alkaloids from leaf of Alstonia scholaris on post-infectious cough in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Leaf of Alstonia scholaris (L.) R. Br. (Apocynaceae), a wide used ethic-medicine in many Asia and Africa counties, has also been recorded as the common traditional Chinese medicine for treatment of illnesses in respiratory system by Dai people.

AIM OF THE STUDY

To provide experimental data of clinical adaption of total indole alkaloids (TA) from leaf of A. scholaris for treating post-infectious cough in phase II clinical trial.

MATERIALS AND METHODS

To model post-infectious cough, all animals except control group were instilled intra-tracheal with lipopolysaccharide (LPS) (80 μg/50 µL/mouse), followed by subsequent exposure to cigarette smoke (CS) for 30 min per day for a total of 30 days. Mice were orally given TA at dose of 10, 25, 50 mg/kg, and four main alkaloids (Sch: scholaricine, Epi: 19-epischolaricine, Val: vallesamine, Pic: picrinine) once daily. Cellular infiltration was assessed in the broncho-alveolar lavage fluid (BALF). Expression of interleukin-6 (IL-6) and C-reactive protein (CRP) in the serum was determined, the superoxide dismutase (SOD) activity as well as malondialdehyde (MDA) content in the serum and homogenate were examined. Finally, histopathological examination in the lungs was assessed by H. E. staining.

RESULTS

After administration of TA and four major alkaloids respectively, the symptoms of cough in mice were obviously attenuated. Total white blood cells (WBC) and neutrophils (NEU) amounts in BALF were reduced obviously and the pathological damage of lung was also attenuated. There was also significant reduction in IL-6, CRP, MDA and a marked improvement in SOD.

CONCLUSIONS

The efficacy of indole alkaloids against post-infectious cough (PIC) was shown in the down-regulation of inflammatory cells, cytokines, and the balance of antioxidants. What's more, the pharmacological effects of TA were better than single indole alkaloid, which might be related to the synergic effect of four major alkaloids.

Temperature-modulated diastereoselective transformations of 2-vinylindoles to tetrahydrocarbazoles and tetrahydrocycloheptadiindoles

The Fe(OTf)₃-catalyzed dimerization of 2-vinylindolesviadiastereoselective [4 + 2] or [4 + 3] cyclization gives rise to tetrahydrocarbazoles at low temperature or tetrahydrocycloheptadiindoles at high temperature.

Facile synthesis of pyrroloindoles via a rhodium(ii)-catalyzed annulation of 3-benzylidene-indolin-2-ones and α-imino carbenes

A novel carbenoid strategy to construct pyrrole-fused indole alkaloids.

Anti-Proliferative Activity of Triterpenoids and Sterols Isolated from Alstonia scholaris against Non-Small-Cell Lung Carcinoma Cells

(1) Background: In China and South Asia, Alstonia scholaris (Apocynaceae) is an important medicinal plant that has been historically used in traditional ethnopharmacy to treat infectious diseases. Although various pharmacological activities have been reported, the anti-lung cancer components of A. scholaris have not yet been identified. The objective of this study is to evaluate the active components of the leaf extract of A. scholaris, and assess the anti-proliferation effects of isolated compounds against non-small-cell lung carcinoma cells; (2) Methods: NMR was used to identify the chemical constitutes isolated from the leaf extract of A. scholaris. The anti-proliferative activity of compounds against non-small-cell lung carcinoma cells was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay; (3) Results: Eight triterpenoids and five sterols were isolated from the hexane portion of A. scholaris, and structurally identified as: (1) ursolic acid, (2) oleanolic acid, (3) betulinic acid, (4) betulin, (5) 2β,3β,28-lup-20(29)-ene-triol, (6) lupeol, (7) β-amyrin, (8) α-amyrin, (9) poriferasterol, (10) epicampesterol, (11) β-sitosterol, (12) 6β-hydroxy-4-stigmasten-3-one, and (13) ergosta-7,22-diene-3β,5α,6β-triol. Compound 5 was isolated from a plant source for the first time. In addition, compounds 9, 10, 12, and 13 were also isolated from A. scholaris for the first time. Ursolic acid, betulinic acid, betulin, and 2β,3β,28-lup-20(29)-ene-triol showed anti-proliferative activity against NSCLC, with IC50 of 39.8, 40.1, 240.5 and 172.6 μM, respectively.; (4) Conclusion: These findings reflect that pentacyclic triterpenoids are the anti-lung cancer chemicals in A. scholaris. The ability of ursolic acid, betulinic acid, betulin, and 2β,3β,28-lup-20(29)-ene-triol to inhibit the proliferative activity of NSCLC can constitute a valuable group of therapeutic agents in the future.

Monoterpenoid indole alkaloids from the leaves of Alstonia scholaris and their NF-κB inhibitory activity

Four new monoterpenoid indole alkaloids (MIAs), scholarisines P-S (1-4), and 14 known MIAs (5-18) were isolated from the leaves of Alstonia scholaris (L) R. Br. (Apocynaceae). Their structures were elucidated by analyzing their HRESIMS data and NMR spectroscopic data. All of the isolated MIAs were evaluated for their Nuclear Factor-kappa B (NF-κB) inhibitory activity in HepG2-NF-κB-Luc cells. Among them, five compounds (4, 7, 8, 13 and 16) exhibited significant NF-κB inhibitory activity.

Evaluation of in vivo antimycobacterial activity of some folklore medicinal plants and enumeration of colony forming unit in murine model

Objectives:

The present study was carried out to investigate the in vivo antimycobacterial activity of methanol extract of Alstonia scholaris and Mucuna imbricata in murine model.

Materials and Methods:

Female BALB/c mice were infected with the Mycobacterium tuberculosis H₃₇Rv suspension. Extracts were administered orally for 2 weeks from 7^th day postinfection at a dose of 200 mg/kg and rifampicin at 20 mg/kg as standard. The synergistic groups were 10 and 100 mg/kg for rifampicin and extract, respectively.

Results:

The final body weight of mycobacteria-infected group was significantly reduced (15.41 ± 0.42, P < 0.01), but following treatment with the plant extract plus rifampicin could elevate the body weight. Colony forming unit (CFU) count of lung (8.71 ± 0.01) and spleen (8.59 ± 0.01) was significantly higher in infected and untreated group (P < 0.01). It was observed that activity of the synergistic group displayed powerful and maximum response against tuberculosis (TB) infection with lower CFU counts. Histopathology study showed cells such as lymphocytes, epithelioid, Langhans giant cell, and fibrous tissue proliferation in lungs; depletion of lymphocytes in the spleen.

Conclusions:

The data indicate that methanol extract of A. scholaris has potential antimycobacterial activity, and the synergistic group consisting of rifampicin and A. scholaris could be a rational choice for the treatment of TB.

Alstoscholarisines H-J, Indole Alkaloids from Alstonia scholaris: Structural Evaluation and Bioinspired Synthesis of Alstoscholarisine H

Alstoscholarisines H-J (1-3), new monoterpenoid indole alkaloids with an unprecedented skeleton created via the formation of a C-3/N-1 bond, were isolated from Alstonia scholaris. Their structures were established by extensive spectroscopic analyses and the assessment of single-crystal X-ray diffraction data. The total synthesis of alstoscholarisine H was achieved via the regioselective nucleophilic addition of pyridinium through a bioinspired iminium ion intermediate followed by Pictet-Spengler-like cyclization.

Gold-catalyzed formation of indole derivatives from 2-alkynyl arylazides and oxygen-containing heterocycles

Gold-catalyzed ring-opening reactions of oxygen-containing heterocycles.

Enantioselective total synthesis and structural reassignment of (+)-alsmaphorazine E via a traceless chirality transfer strategy

The first enantioselective total synthesis of (+)-alsmaphorazine E was described, which led to the structural reassignment of the title molecule.