Three new indole alkaloid derivatives from Fissistigma oldhamii Levl. and their anti-inflammatory effects.

Three new indole alkaloid derivatives, fissindoalkas A-C (1-3) together with one known biogenetically related polysubstituted indole alkaloid (4) were isolated from the roots of Fissistigma oldhamii (Hemsl.) Merr. The structures of compounds 1-4 were elucidated using comprehensive spectroscopic methods. The inhibitory activities of compounds 1-4 against nitric oxide (NO) production induced by lipopolysaccharide (LPS) were evaluated in vitro using mouse macrophage RAW264.7 cells. Compounds 2 and 3 showed potent inhibitory activities on NO production with IC50 values of 2.52 ± 0.18 and 2.33 ± 0.16 µM. These results indicate that the discovery of indole alkaloid derivatives, from the roots of F. oldhamii, which show significant anti-inflammatory properties, could be of great importance to the research and for the development of novel natural anti-inflammatory agents.

Gelsemium elegans Benth: Chemical Components, Pharmacological Effects, and Toxicity Mechanisms.

Gelsemium elegans Benth (GEB), also known as heartbreak grass, is a highly poisonous plant belonging to the family Loganiaceae and genus Gelsemium that has broad application prospects in medicine. This article reviews its chemical components, pharmacological effects, toxicity mechanisms, and research progress in clinical applications in recent years. Indole alkaloids are the main active components of GEB and have a variety of pharmacological and biological functions. They have anti-tumor, anti-inflammatory, analgesic, and immunomodulation properties, with the therapeutic dose being close to the toxic dose. Application of small-dose indole alkaloids fails to work effectively, while high-dose usage is prone to poisoning, aggravating the patient's conditions. Special caution is needed, especially to observe the changes in the disease condition of the patients in clinical practice. In-depth research on the chemical components and mechanisms of GEB is essential to the development of promising lead compounds and lays the foundation for extensive clinical application and safe usage of GEB in the future.

Rutaecarpine, an Alkaloid from Evodia rutaecarpa, Can Prevent Platelet Activation in Humans and Reduce Microvascular Thrombosis in Mice: Crucial Role of the PI3K/Akt/GSK3ß Signal Axis through a Cyclic Nucleotides/VASP-Independent Mechanism.

The role of activated platelets in acute and chronic cardiovascular diseases (CVDs) is well established. Therefore, antiplatelet drugs significantly reduce the risk of severe CVDs. Evodia rutaecarpa (Wu-Chu-Yu) is a well-known Chinese medicine, and rutaecarpine (Rut) is a main bioactive component with substantial beneficial properties including vasodilation. To address a research gap, we investigated the inhibitory mechanisms of Rut in washed human platelets and experimental mice. At low concentrations (1-5 µM), Rut strongly inhibited collagen-induced platelet aggregation, whereas it exerted only a slight or no effect on platelets stimulated with other agonists (e.g., thrombin). Rut markedly inhibited P-selectin expression; adenosine triphosphate release; [Ca2+]i mobilization; hydroxyl radical formation; and phospholipase C (PLC)γ2/protein kinase C (PKC), mitogen-activated protein kinase, and phosphoinositide 3-kinase (PI3K)/Akt/glycogen synthase kinase-3ß (GSK3ß) phosphorylation stimulated by collagen. SQ22536 (an adenylate cyclase inhibitor) or ODQ (a guanylate cyclase inhibitor) did not reverse Rut-mediated antiplatelet aggregation. Rut was not directly responding to vasodilator-stimulated phosphoprotein phosphorylation. Rut significantly increased the occlusion time of fluorescence irradiated thrombotic platelet plug formation. The findings demonstrated that Rut exerts a strong effect against platelet activation through the PLCγ2/PKC and PI3K/Akt/GSK3ß pathways. Thus, Rut can be a potential therapeutic agent for thromboembolic disorders.

Sceletium tortuosum: A review on its phytochemistry, pharmacokinetics, biological and clinical activities.

ETHNOPHARMACOLOGICAL RELEVANCE: Sceletium tortuosum (L.) N.E.Br, the most sought after and widely researched species in the genus Sceletium is a succulent forb endemic to South Africa. Traditionally, this medicinal plant is mainly masticated or smoked and used for the relief of toothache, abdominal pain, and as a mood-elevator, analgesic, hypnotic, anxiolytic, thirst and hunger suppressant, and for its intoxicating/euphoric effects. Sceletium tortuosum is currently of widespread scientific interest due to its clinical potential in treating anxiety and depression, relieving stress in healthy individuals, and enhancing cognitive functions. These pharmacological actions are attributed to its phytochemical constituents referred to as mesembrine-type alkaloids. AIM OF THE REVIEW: The aim of this review was to comprehensively summarize and critically evaluate recent research advances on the phytochemistry, pharmacokinetics, biological and clinical activities of the medicinal plant S. tortuosum. Additionally, current ongoing research and future perspectives are also discussed. METHODS: All relevant scientific articles, books, MSc and Ph.D. dissertations on botany, behavioral pharmacology, traditional uses, and phytochemistry of S. tortuosum were retrieved from different databases (including Science Direct, PubMed, Google Scholar, Scopus and Web of Science). For pharmacokinetics and pharmacological effects of S. tortuosum, the focus fell on relevant publications published between 2009 and 2021. RESULTS: Twenty-five alkaloids belonging to four structural classes viz: mesembrine, Sceletium A4, joubertiamine, and tortuosamine, have been identified from S. tortuosum, of which the mesembrine class is predominant. The crude extracts and commercially available standardized extracts of S. tortuosum have displayed a wide spectrum of biological activities (e.g. antimalarial, anti-oxidant, immunomodulatory, anti-HIV, neuroprotection, enhancement of cognitive function) in in vitro or in vivo studies. This plant has not yet been studied in a clinical population, but has potential for enhancing cognitive function, and managing anxiety and depression. CONCLUSION: As an important South African medicinal plant, S. tortuosum has garnered many research advances on its phytochemistry and biological activities over the last decade. These scientific studies have shown that S. tortuosum has various bioactivities. The findings have further established the link between the phytochemistry and pharmacological application, and support the traditional use of S. tortuosum in the indigenous medicine of South Africa.

Bioactive indole alkaloids from insect derived endophytic Aspergillus lentulus.

As part of our program to discover new bioactive agents from endophytic fungi, three new indole alkaloids (1-2, 4) along with twelve known compounds were isolated from an inset derived endophytic strain Aspergillus lentulus. Their structures were determined by comprehensive spectroscopic analyses of 1D/2D NMR and HR-ESI-MS data. The absolute configurations were confirmed by ECD calculation using Time-dependent Density functional theory (TD-DFT) at the B3LYP/6-31 + g (d, p) level and Rh2(OCOCF3)4-induced ECD experiments. Compounds 2, 4, 5, 13 and 15 exhibited moderate cytotoxic effects on A549 cell line with IC50 in the range of 17.92-48.29 µM. Compounds 1, 2 and 13-15 displayed the anti-bacterial activity against Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola with MIC values ranging from 25 to 100 µg/mL.

Monoterpene indole alkaloids from the roots of Bousigonia mekongensis and their anti-diabetic nephropathy activity.

Four new monoterpene indole alkaloids (1-4) together with six known alkaloids (5-10) were isolated from the roots of Bousigonia mekongensis. Compounds 3 and 4 were the first examples of condylocarpan-adenine type alkaloids obtained from natural plant resource. Their structures were elucidated on the basis of spectroscopic data. All compounds were evaluated for their inhibiting glucose-induced mesanginal cell proliferation and protecting high glucose-evoked podocyte injury activities. (-)-demethoxycarbonyldihydrogambirtannine (5) can significantly antagonize glucose-induced podocyte injury with EC50 value of 6.5 ± 1.2 µM.

The indole alkaloids from the roots of Isatidis Radix.

The root of Isatis indigotica is used as a traditional Chinese medicine (termed Isatidis Radix) due to its antiviral effects. We examined compounds isolated from Isatidis Radix and elucidated the structures of three new natural alkaloids, and we examined the possible mechanisms or active targets of indole alkaloids occurring in blood of rats treated by gavage. Three new natural products were isolated from Radix Isatidis for the first time, including 1-methoxy-2-indoleacetonitrile, 1-hydroxy-3-indoleacetonitrile, 8-Methoxy-1, 2-dihydroquinoline, and 4 compounds isolated from this medicinal material for the first time. Their structures were elucidated using nuclear magnetic resonance. The components of Isatidis Radix were analysed using liquid chromatography tandem mass spectrometry, and 33 compounds were detected in plasma of treated rats; 24 of these compounds were indole alkaloids, and they included the newly identified compounds. Molecular docking and in vitro antithrombin activity tests showed HA inhibition activity of indoleacetonitriles.

Antiplasmodial activities of indole alkaloids from Tabernaemontana penduliflora K. Schum (Apocynaceae).

Five undescribed carboxy-indole alkaloids with corynanthe skeleton, penduflorines A-E (1-3) as well as a voacangine-N-oxide alkaloid, tabernaemontine (4), were isolated along with eight other known compounds (5-12) from the trunk bark of Tabernaemontana penduliflora K. Schum (Apocynaceae). Their structures were determined by means of spectroscopic and spectrometric methods such as UV, IR, NMR and HR-ESI-MS. Antiplasmodial activities of new isolates were evaluated against two strains of Plasmodium falciparum 3D7 and Dd2 by the Sybr green I-based fluorescence assay setup. Those compounds showed good in vitro activities. Among them, penduflorines A and B (1a and 1b) as well as tabernaemontine (4) showed significant inhibitory activities against the two strains with IC50 values ranged between 1.85 and 7.88 µg/mL. This is the first report of quaternary-N-indole alkaloids (1a, 1b, 2, 3a, 3b and 4) occurring in the form of zwitterion from Tabernaemontana genus.

New alkaloids from the noni juice with potential α-glucosidase inhibitory activity.

Four new alkaloids, nonialkaloids A-D (1-4) and six known analogues (5-10) were isolated from the noni juice. Among the new compounds, 1 and 2 are indole alkaloids with a seven-membered fused N-heterocyclic ring, 3 and 4 are quaternary ammonium derivatives. The structures were elucidated by extensive NMR and MS analysis, while the absolute configurations of the stereogenic carbons were established based on quantum-chemical electronic circular dichroism calculations or the modified Mosher's method. All the isolates were tested for α-glucosidase inhibitory activities. Compounds 1 and 3 displayed potent inhibitory activity against α-glucosidase with the IC50 values of 413.7 and 364.4 µM, respectively.

Salchaetoglobosins A and B: Cytochalasan alkaloids from Chaetomium globosum D38, a fungus derived from Salvia miltiorrhiza.

Chemical investigation on the solid rice culture of Chaetomium globosum D38, an endophytic fungus derived from Salvia miltiorrhiza, has afforded two new 19,20-seco-chaetoglobosins, salchaetoglobosins A (1) and B (2), along with three known analogues, chaetoglobosins E (3), Fex (4), and Vb (5). Their structures and absolute configurations were elucidated by a set of spectroscopy and single-crystal X-ray crystallography. Compounds 1-5 were evaluated for their cytotoxic activities against HCT-116 (colorectal carcinoma) and PC3 (prostate cancer) cells, as well as the NO production inhibitory effects in LPS-stimulated RAW264.7 cells.

Bioactivity and cytotoxicity profiling of vincosamide and strictosamide, anthelmintic epimers from Sarcocephalus latifolius (Smith) Bruce leaf.

ETHNOPHARMACOLOGICAL RELEVANCE: The leaf of Sarcocephalus latifolius is known to be used traditionally by the Fulanis in Nigeria to deworm animals. As helminthosis remains a major constraint to profitable livestock production worldwide, a precarious situation aggravated by the advent of resistant parasites, the discovery of new anthelmintics is a priority, necessitating exploration of medicinal plants for their anthelmintic principles. AIM OF THE STUDY: To identify and characterise compounds with anthelmintic activity from the leaf of Sarcocephalus latifolius. MATERIALS AND METHODS: Powdered S. latifolius leaves were extracted by successive maceration with n-hexane, chloroform and acetone. The dried extracts were evaluated for anthelmintic activity against Haemonchus placei adult worms, and the most active extract was subjected to bioassay-guided chromatographic separations. The isolated compounds were evaluated for cytotoxicity against the mammalian HeLa and MC3T3-E1 cell lines, using alamar blue and CellTitreGloTM to quantify cell viability. LC50 values were computed from the in vitro anthelmintic activity data by fitting to a non-linear regression equation (variable slope). Isolated compounds were characterized using spectroscopic and mass spectrometric analyses. RESULTS: Anthelmintic activity LC50 values for n-hexane, chloroform and acetone extracts were 47.85, 35.76 and 5.72 (mg/mL), respectively. Chromatographic separation of acetone extract afforded two bioactive epimers, identified as vincosamide (LC50 14.7 mg/mL) and strictosamide (LC50 12.8 mg/mL). Cytotoxicity evaluation showed that, below 200 µg/mL (400 µM), neither compound was toxic to the HeLa or MC3T3-E1 cells. CONCLUSION: Vincosamide and strictosamide could serve as novel scaffolds for the development of anthelmintic derivatives with improved potency and helminth selectivity.

Evaluation of analgesic and anti-inflammatory actions of indolealkylamines from toad venom in mice using lipidomics and molecular docking.

ETHNOPHARMACOLOGICAL RELEVANCE: Toad venom is one of widely used traditional Chinese medicines due to its analgesic and anti-inflammatory activities. However, hydrophilic alkaloids from toad venom, which may have certain pharmacological activities, have not been systematic studied. AIM OF THE STUDY: The aim of the study was to identify the indolealkylamines (IAAs) from toad venom and investigate the analgesic and anti-inflammatory actions. MATERIALS AND METHODS: The alkaloids were extracted and identified by high-resolution mass spectrometry. The analgesic abilities were determined using hot-plate test, formalin test and von Frey test. High-sensitivity lipidomics was used to investigate the regulatory function of IAAs on inflammatory eicosanoids. Besides, network pharmacology and molecular docking were used to demonstrate the candidate targets of IAAs. RESULTS: 22 constituents have been characterized by high performance liquid chromatography (HPLC)-Triple TOF 5600, including six specific IAAs (serotonin, N-methyl serotonin, bufotenine, bufotenidine, bufothionine and dehydrobufotenine). Pharmacological studies showed that the IAAs from toad venom exerted significant analgesic activities at doses of 5, 15 and 45 mg/kg in vivo. Moreover, lipids analysis revealed IAAs might down-regulate inflammatory mediators from COX, LOX, DHA and LA pathways in formalin models, thus showing anti-inflammatory effect. The potent pharmacological function might because of the binding of IAAs and protein targets, such as sigma-1 receptor. CONCLUSION: The studies provided a systemic evidence for the analgesic and anti-inflammatory activities of IAAs from toad venom. It suggested that IAAs might be a potential candidate to reduce inflammatory pain disorders.

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-ß (TGF-ß), hydroxyproline, type I collagen, and malonaldehyde, and enhanced the activity of superoxide dismutase in the serum and lung tissues. In addition, the enhanced TGF-ß 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-ß/MMP-1 pathway.

Indole alkaloids from Ophiorrhiza cantoniensis with immunosuppressive activity.

Three new indole alkaloids, ophiorrhines C-D (1-3), together with one known analogue, have been isolated from the plant of Ophiorrhiza cantoniensis Hace. The structures of the new alkaloids with the absolute configurations were elucidated by means of spectroscopic methods, electronic circular dichroism (ECD) and calculated nuclear magnetic resonance (NMR) with DP4+ analysis. Compounds 1 and 2 exhibited certain activity to Con-A induced T cell proliferation, and 1 exhibited good inhibition on LPS-induced B cell proliferation with an IC50 value of 8.7 µM.

New indole alkaloids from the seeds of Datura metel L.

Four new indole alkaloids, daturametelindoles A-D (1-4) were isolated from the EtOAc soluble partition of the ethanol extract of the Datura metel seeds. The structures of the new compounds were determined based on spectroscopic evidence, including their 1D- and 2D-NMR spectra and mass spectrometry. In particular, compounds 1-4 were all racemes, confirmed by the optical rotations and CD spectra. Unfortunately, the chiral monomers were not obtained due to the amount, but the developments of their chiral separation and chiral resolution were completed. All isolated compounds were evaluated for cytotoxic effects against human gastric adenocarcinoma cells (SGC-7901), human hepatoma (Hepg2), and human breast cancer (MCF-7).

Prenylated indole alkaloids and lignans from the flower buds of Tussilago farfara.

Six new compounds including four prenylated indole alkaloids (1-4) and two lignans (5-6), along with eight known cometabolites (7-14), were isolated from the flower buds of Tussilago farfara. Structures of the new compounds were elucidated by comparison with structurally related known analogues and also by comprehensive spectroscopic analyses. Their absolute configurations were determined by a variety of means including Mosher's method, Marfey's analysis, electronic circular dichroism (ECD) exciton chirality method and ECD calculations. Our bioassays have established that compounds 1 and 2 showed potent α-glucosidase inhibitory activity with IC50 values of 105 ± 4.7 and 35.2 ± 3.2 µM, respectively, while the known 13 and 14 exerted moderate DPPH radical scavenging activity with IC50 values of 45.2 ± 2.9 and 29.2 ± 2.0 µM, respectively.

Peraksine derivatives with potential anti-inflammatory activities from the stems of Rauvolfia vomitoria.

Five new peraksine derivatives rauvomine C-G (1-5) along with four known analogues (6-9) were isolated from the stems of Rauvolfia vomitoria Afzel. (Apocynaceae). Structural determinations of the new monoterpene indole alkaloids were elucidated via comprehensive spectroscopic analyses and ECD calculations. Rauvomine C (1) with an unprecedented framework type represents the first example of C18 peraksine-type nor-monoterpene indole alkaloid featuring a chlorine atom at C-16 and its plausible biosynthetic pathway was also proposed. All the isolates were evaluated for their anti-inflammatory, cytotoxic, and acetylcholinesterase inhibitory activities. Among them, the new framework alkaloid rauvomine C (1) showed significant anti-inflammatory activities on NO production in LPS-induced RAW264.7 mouse macrophages with IC50 value of 10.76 µM. Additionally, peraksine-type alkaloids featuring pyran ring (5, 8, and 9) exhibited potential anti-inflammatory activities with IC50 values ranging from 17.52 to 20.99 µM.

Alkaloids from the nearly ripe fruits of Evodia rutaecarpa and their bioactivities.

Two novel quinolone alkaloids (1 and 2) and two novel indole alkaloids (5 and 8), together with eleven known analogues, were isolated from the nearly ripe fruits of Evodia rutaecarpa. Their structures were determined by extensive spectroscopic data, including NMR, HRESIMS, and ECD. Additionally, the anti-tumor, hypoglycemic, and anti-bacterial activities of the isolated alkaloids were evaluated in vitro. Compound 5 as a new alkaloid displayed moderate inhibitory effect against four human cancer cell lines (MCF-7 IC50 = 30.7 µM, Hepg-2 IC50 = 65.2 µM, A549 IC50 = 39.1 µM, and SHSY-5Y IC50 = 24.7 µM), α-glucosidase (IC50 = 23.9 µM) and PTP1B (IC50 = 75.8 µM). Compound 11 showed better inhibitory effect against PTP1B (IC50 = 16.2 µM) compared with that of the positive control. Compounds 5, 13, and 14 showed moderate inhibitory effects against Bacillus cereus with MIC values of 50, 25, and 10 µM, respectively.

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)-1ß, monocyte-chemo attractive peptide 1, IL-11, matrix metalloproteinase-12, transforming growth factor-ß 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 ß-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.

The indole-based subincanadine alkaloids and their biogenetic congeners.

The tryptamine-derived polycyclic bridged bioactive indole alkaloids subincanadines A-G were isolated in 2002 by Ohsaki and coworkers from the bark of the Brazilian medicinal plant Aspidosperma subincanum. Kobayashi proposed that subincanadines D-F could be biosynthetically resulting from stemmadenine via two different pathways and, furthermore, that the subincanadines A-C could be biogenetically resulting from subincanadines D and E. Kam and coworkers, in their focused efforts, isolated five indole alkaloids from Malaysian Kopsia arborea species, namely valparicine, apparicine, arboridinine, arborisidine, and arbornamine in combination with subincanadine E. On the basis of structural features, it has been proposed and proved in some examples that subincanadine E is a biogenetic precursor of these five different bioactive indole alkaloids bearing complex structural architectures. All important information on isolation, characterization, bioactivity, probable biogenetic pathways, and more specifically racemic and enantioselective total synthesis of subincanadine alkaloids and their biogenetic congeners are summarized in the present chapter. Special importance is given to the total synthesis and the synthetic strategies intended therein, comprising a set of main reactions.