Alstomaphylines A-K, monoterpenoid bisindole alkaloids from Alstonia macrophylla with AChE inhibitory activity and cytotoxicity.

Eleven undescribed monoterpenoid bisindole alkaloids, alstomaphyines A-K (1-11), along with three known analogues were isolated from the leaves and stem bark of the Alstonia macrophylla. Compounds 1-3 were unprecedented dimerization alkaloids incorporating a macroline-type motif with an ajmaline-type motif via a C-C linkage. Their structures and absolute configurations were elucidated by extensive spectroscopic analysis, electronic circular dichroism (ECD) calculation, and CD exciton chirality method. Compounds 1-3 displayed potential inhibitory bioactivity against AChE with IC50 values of 4.44 ± 0.35, 3.59 ± 0.18, and 3.71 ± 0.23 µM, respectively. Enzyme kinetic study revealed compounds 1-3 as mixed competitive AChE inhibitors. Besides, compounds 8 and 12-14 exhibited better cytotoxicity against human cancer cell line HT-29 than cisplatin. Flow cytometry data revealed that compounds 8, 13, and 14 significantly induced the HT-29 cells arrest in G0/G1 phase in a concentration-dependent manner.

Alstoboonine, an Ulean-Type Indole Alkaloid from Alstonia boonei Leaves.

Alstonia boonei De Wild is a common plant in West Africa used in traditional medicine for various indications. While the stem bark has frequently been investigated, not much is known about the phytochemistry and bioactivity of the leaves. Within the current study, the major alkaloids of a hydroethanolic leaf extract were therefore isolated and characterized by MS, NMR, and ECD. This led to the identification of alstoboonine 1, a new ulean-type alkaloid, along with eight previously reported indole alkaloids, 15-hydroxyangustilobine A (2), 6,7-seco-angustilobine B (3), 6,7-seco-19,20-α-epoxyangustilobine B (4), alstrostine E (5), alstrostine C (6), alstrostine D (7), 12-methoxyechitamidine (8), and 19-oxo-12-methoxyechitamidine (9). 1 was moderately active in vitro against Plasmodium falciparum NF54 (IC50 6.9 µM), but inactive against other protozoan parasites (Trypanosoma brucei, Trypanosoma cruzi, Leishmania donovani). No significant cytotoxic effects were observed in L6 rat skeletal myoblast cells and MCF-7 breast cancer cells. Similarly, compounds 3 to 9 did not show cytotoxicity in MCF-7 cells. Due to the reported traditional use of the plant as an anthelmintic, the major alkaloids 2, 5, 6, and 8 were tested against the nematode Caenorhabditis elegans. Nematicidal effects were observed for 6 (LC50 400 µM), whereas 2, 5, and 8 were inactive.

Urease inhibition and DPPH radical scavenging potential of phytoconstituent from Alstonia scholaris and molecular docking interactions of bioactive luteolin with target proteins.

A polyphenolic flavone Luteolin (3',4',5,7-tetrahydroxyflavone) is found in various plants and is traditionally used in Chinese medicine. It is obtained from Alstonia scholaris (L.) R.Br Flower belonging to the family Apocynaceae while investigation. Various studies have been demonstrated the antioxidant or antiulcer potential of luteolin from different plant sources. In the present investigation the antioxidant or antiulcer effect of the Luteolin has been carried out using molecular docking simulations. The objective of this study was to analyze the antioxidant and antiulcer potential of luteolin obtained during isolation. The in vitro biological evaluation has been supported by the in silico studies using Autodock vina 4 shows the ligand-protein interaction of lute olin with 1HD2, 4GY7 and 3O1Q. Luteolin showed significant DPPH scavenging and urease inhibition activity i.e., 23.4 ± 0.87, 6.21±0.45 IC50 (uM) respectively as compared to the standard BHA and thiourea 44.2±0.45, 22.4±0.29 IC50 (uM) respectively. The docking simulations showed significant binding pocket sites with the respective proteins1HD2, 4GY7 and 3O1Q with the least binding energy -6.8, -8.0 and -8.2 kcal/mol respectively. Thus, Strong evidence has been presented with their confirmation structural interaction via molecular docking with proteins that serve as binding sites for available Luteolin molecule. The findings justify the application of the compound as a novel antioxidant and antiulcer agent.

Therapeutic potential of indole alkaloids in respiratory diseases: A comprehensive review.

BACKGROUND: Indole alkaloids are very promising for potential therapeutic purposes and appear to be particularly effective against respiratory diseases. Several experimental studies have been performed, both in vivo and in vitro, to evaluate the effectiveness of indole alkaloids for the management of respiratory disorders, including asthma, emphysema, tuberculosis, cancer, and pulmonary fibrosis. PURPOSE: The fundamental objective of this review was to summarize the in-depth therapeutic potential of indole alkaloids against various respiratory disorders. STUDY DESIGN: In addition to describing the therapeutic potential, this review also evaluates the toxicity of these alkaloids, which have been utilized for therapeutic benefits but have demonstrated toxic consequences. Some indole alkaloids, including scholaricine, 19-epischolaricine, vallesamine, and picrinine, which are derived from the plant Alstonia scholaris, have shown toxic effects in non-rodent models. METHODS: This review also discusses clinical studies exploring the therapeutic efficacy of indole alkaloids, which have confirmed the promising benefits observed in vivo and in vitro. RESULTS: The indole alkaloidal compounds have shown efficacy in subjects with respiratory diseases. CONCLUSION: The available data established both preclinical and clinical studies confirm the potential of indole alkaloids to treat the respiratory disorders.

The Bisindole Alkaloids Angustilongines M and A from Alstonia penangiana Induce Mitochondrial Apoptosis and G0/G1 Cell Cycle Arrest in HT-29 Cells through Promotion of Tubulin Polymerization.

A new linearly fused macroline-sarpagine bisindole, angustilongine M (1), was isolated from the methanolic extract of Alstonia penangiana. The structure of the alkaloid was elucidated based on analysis of the spectroscopic data, and its biological activity was evaluated together with another previously reported macroline-akuammiline bisindole from the same plant, angustilongine A (2). Compounds 1 and 2 showed pronounced in vitro growth inhibitory activity against a wide panel of human cancer cell lines. In particular, the two compounds showed potent and selective antiproliferative activity against HT-29 cells, as well as strong growth inhibitory effects against HT-29 spheroids. Cell death mechanistic studies revealed that the compounds induced mitochondrial apoptosis and G0/G1 cell cycle arrest in HT-29 cells in a time-dependent manner, while in vitro tubulin polymerization assays and molecular docking analysis showed that the compounds are microtubule-stabilizing agents, which are predicted to bind at the ß-tubulin subunit at the Taxol-binding site.

In vitro screening of plant extracts traditionally used as cancer remedies in Ghana - 15-Hydroxyangustilobine A as the active principle in Alstonia boonei leaves.

ETHNOPHARMACOLOGICAL RELEVANCE: Cancer represents a major health burden and drain on the global healthcare systems. Traditional African medicine widely use a variety of plant species for treatment of different kinds of cancer. A previous systematic survey by traditional healers in the Ashanti region of Ghana revealed a good overview on the plant species and herbal materials used for the different types of cancer. AIMS OF THE STUDY: The following study aimed to investigate 18 herbal materials from 10 plant species based on the cancer survey in Ghana regarding potential cytotoxicity against different cancer cell lines under in vitro conditions followed by subsequent bioassay-guided fractionation towards the active principle. MATERIALS AND METHODS: Ethanol-water (1:1) extracts were tested (1-100 µg/mL) against a panel of cancer cell lines according to their respective traditional use. Selected extracts with relevant cytotoxicity in this screening were also tested against common pediatric malignancies (leukemias (HL-60, REH) and Ewing sarcoma (RD-ES and CADO-ES1)). Bioassay-guided fractionation of the hydroalcoholic extract from Alstonia boonei was performed by liquid-liquid chromatography and preparative HPLC. Preliminary mechanistic studies on the mode of action were performed by flow cytometric cell cycle analysis as well as apoptosis and necrosis staining. RESULTS: Screening of plant extracts revealed relevant cytotoxicity against all tested cancer cell lines for Alstonia boonei leaves and stem of Paulinia pinnata. The A. boonei extract was additionally found to be active against common pediatric tumor types (leukemias and Ewing sarcoma). Bioassay-guided fractionation of the A. boonei extract revealed the presence of 15-hydroxyangustilobine A 1 as the active principle (IC50 26 µM against MCF-7 cells). This is the first report of this compound in A. boonei. 1 was shown to lead to cell cycle arrest in the G2/M-phase (MCF-7 cells), triggering cells at least partially into apoptosis. CONCLUSION: In summary, an appreciable in vitro activity was revealed for the leaf extract from A. boonei and the isolated vallesamine type indole alkaloid 1, which has to be investigated in future studies towards a potential clinical use.

Phytochemical screening of Alstonia venenata leaf and bark extracts and their antimicrobial activities.

Alstonia venenata is a plant commonly found in South India and used in traditional medicine. The aim of this study was to characterize the phytochemicals present in A. venenata leaf and bark extracts and study their antimicrobial activities. Solvent extractions with Soxhlet apparatus of leaves and bark were obtained using hexane, benzene, isopropanol, methanol, and water. The crude extracts were concentrated and screened for qualitative phytochemical content and analyzed by thin layer chromatography. The antibacterial, antifungal and antiviral activities of crude extracts were measured by in vitro methods. Alkaloids, carbohydrates, tannins, phenolic compounds, terpenoids, cardiac glycosides and amino acids were found in the different crude extracts analyzed. Isopropanol extracts showed antifungal activity and it was more pronounced in the bark extract than the leaf extract. Moreover, the isopropanol extract exhibited antibacterial and antiviral activity. In conclusion, the leaves and bark of A. venenata have antimicrobial components which are more present in the isopropanol fraction.

Phytochemical screening of Alstonia scholaris leaf and bark extracts and their antimicrobial activities.

Alstonia sholaris is an evergreen tree commonly found in South East Asia. In traditional medicine pharmacological activities are attributed to the leaves and bark of this plant. The aim of this study is characterizing the chemicals present in A. sholaris leaves and bark extracts and study their antimicrobial activities. Solvent extractions with Soxhlet apparatus of leaves and bark were obtained using hexane, benzene, isopropanol, methanol, and water. The crude extracts were concentrated and screened for qualitative phytochemical analysis and thin layer chromatography, and the antibacterial, antifungal an antiviral activity of crude extracts were measured by in vitro methods. Isopropanol and methanol extracts showed significant antibacterial activity and it was more pronounced against Gram positive than against Gram negative bacteria. Hexane, benzene, isopropanol and methanol fractions of A. scholaris bark and leaf showed activity against Enterobacter cloacae. Isopropanol extract showed maximum activity against selected human pathogenic fungus. In conclusion, the leaves and bark of A. scholaris are rich in phytochemicals with antimicrobial activities against human pathogens, being the isopropanol fraction the one with the highest antibacterial, antifungal, antiviral and anti-mycobacterial activities.

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.

Macroline-Sarpagine Bisindole Alkaloids with Antiproliferative Activity from Alstonia penangiana.

A methanol extract of the stem bark of the Malayan Alstonia penangiana provided seven new bisindole alkaloids, comprising six macroline-sarpagine alkaloids (angustilongines E-K, 1-6) and one macroline-pleiocarpamine bisindole alkaloid (angustilongine L, 7). Analysis of the spectroscopic data (NMR and MS) of these compounds led to the proposed structures of these alkaloids. The macroline-sarpagine alkaloids (1-6) showed in vitro growth inhibitory activity against a panel of human cancer cell lines, inclusive of KB, vincristine-resistant KB, PC-3, LNCaP, MCF7, MDA-MB-231, HT-29, HCT 116, and A549 cells (IC50 values: 0.02-9.0 µM).

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.

Novel nor-monoterpenoid indole alkaloids inhibiting glioma stem cells from fruits of Alstonia scholaris.

BACKGROUND: Glioblastoma multiforme (GBM) is a highly aggressive and frequently recurrent malignant brain tumor, and to date, the clinically effective drugs against GBM remain scarce. Natural products play an important role in drug discovery, and might be the resource of antitumor agents for GSCs. Alstonia scholaris (L.) R. Br. is rich in monoterpenoid indole alkaloids (MIAs) and used extensively for treatment of tumor in the traditional medicine system of Asia. PURPOSE: To search for new MIAs with antitumor activity against glioma stem cells from clinical patients and explore their mechanism. METHODS: Compounds were obtained from the fruits of A. scholaris by chromatographic separation, including silica gel, Sephadex LH-20 and recrystallization. Their structures were elucidated by the use of UV, IR, NMR and MS spectra. The antitumor activity of the compounds against the glioma stem cells (GSC-3#, GSC-12#, GSC-18#) were investigated by phenotypic screening and MTS assays. Cell proliferation assay by BrdU immunofluorescence staining, and apoptosis assay by cleaved-caspase-3 immunofluorescence staining and real-time PCR assay. The soft-agar clonal formation assay was performed to determine the antitumor efficacy of the compounds in vitro. RESULTS: Two new nor-monoterpenoid indole alkaloids were isolated from the fruits of A. scholaris. They exhibited selective antitumor activity against glioma stem cells (GSC-3#, GSC-12#, GSC-18#) with IC50 values of 15-25 µg/ml. Furthermore, they inhibited GSCs proliferation, induced GSCs apoptosis by increasing the expression of TNF-α and cleavage of caspase-3, and significantly damaged colony forming capacity of GSCs. CONCLUSION: New nor-monoterpenoid indole alkaloids from the fruits of A. scholaris provide new type promising molecule for the selective killing of human glioma stem cells.

Ajmaline, Oxindole, and Cytotoxic Macroline-Akuammiline Bisindole Alkaloids from Alstonia penangiana.

Examination of the EtOH extract of the Malayan Alstonia penangiana resulted in the isolation of 10 new alkaloids, comprising two ajmaline (1, 2), four macroline oxindole (3-6), and four macroline-akuammiline bisindole alkaloids (7-10). The structures of these alkaloids were determined based on analysis of the spectroscopic data and, in the case of the oxindole 6 and the bisindole alkaloid 7, also confirmed by X-ray diffraction analysis. The bisindole alkaloids 7 and 8 showed pronounced in vitro growth inhibitory activity against an array of human cancer cell lines, including KB, vincristine-resistant KB, PC-3, LNCaP, MCF7, MDA-MB-231, HT-29, HCT 116, and A549 cells with IC50 values in the 0.3-8.3 µM range.

Unprecedented sugar bridged bisindoles selective inhibiting glioma stem cells.

Unlike reported bisindoles linked by single bond directly, alstoniasidines A (1) and B (2), from Alstonia scholaris featuring unprecedented skeleton with two indole moieties bridged by a sugar, represented a novel bisindole type having strictosamide-glucopyranose-picraline scaffold. Both compounds exhibited selective cytotoxicity against human glioma stem cells (GSCs) and induced caspase-3 dependent extrinsic apoptosis by increasing the expression of interleukin 1 (IL-1), tumor necrosis factor (TNF-α), and the cleaved caspase-3, while damaged the unlimited proliferation and self-renewal capacity of GSCs. This finding might provide new type of leads for the selective killing of human glioma stem cells.

Protective effect of Alstonia scholaris Linn. R. Br. against Bleomycin induced chromosomal damage in cultured human lymphocytes, in vitro.

It is both interesting and necessary to identify and develop nontoxic radioprotective compounds. Bleomycin (BLM), a known radiomimetic drug was used as a clastogen in the present study. The possible protective effects against BLM (15 µg/ml) induced clastogenicity by aqueous and methanolic extracts from Alstonia scholaris bark, stem and leaves were compared. The treatment of bark extracts significantly (p < 0.01) reduced total chromosomal aberrations. Such a reduction was not seen in case of stem and leaf treatments. The dose of 50 µg/ml was fixed for all extracts throughout the study. To understand the mechanism involved with the protective property of bark extracts, sensitive G2 assay was performed. Lymphocyte cultures from 12 healthy volunteers were exposed to aqueous (50 µg/ml) and methanolic (50 µg/ml) extracts of A. scholaris bark alone as well as in combination with Bleomycin under two different growth phases, G0 and G2. There was a statistically significant reduction (p < 0.05) in the total chromatid breaks in all cultures which were exposed at G2 phase as compared to respective cultures exposed at G0 phase. The highest level (p < 0.0001) of reduction in total chromatid breaks was observed in cultures treated with aqueous bark extracts at G2 phase than those at G0 phase. This indicated that there could be certain compound(s) present in aqueous bark extracts which enhance DNA repair capacity. Therefore, the bark of A. scholaris could be further utilized to identify and bring out front line radio protective agents in the market with effective formulations.

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.

Two new monoterpenoid indole alkaloids from Alstonia rostrata.

Two new indole alkaloids, winphyllines A (1) and B (4), along with four known alkaloids, Nb-demethylechitamine (2), 17-O-acetylnorechitamine (3), 12-methoxyechitamidine (5), and N(4)-demethylastogustine (6), were isolated from the methanol extract of the twigs of Alstonia rostrata. The structures of 1 and 4 were elucidated by means of HRMS and NMR spectroscopic methods. The in vitro cytotoxic activity of the isolated alkaloids against several human cancer cell lines was evaluated.

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) 2ß,3ß,28-lup-20(29)-ene-triol, (6) lupeol, (7) ß-amyrin, (8) α-amyrin, (9) poriferasterol, (10) epicampesterol, (11) ß-sitosterol, (12) 6ß-hydroxy-4-stigmasten-3-one, and (13) ergosta-7,22-diene-3ß,5α,6ß-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 2ß,3ß,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 2ß,3ß,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 Alstonia mairei and their cytotoxicity.

Phytochemical investigation on the 70% ethanol extract of the leaves of Alstonia mairei resulted in the isolation of three new monoterpenoid indole alkaloids, alstomairines A-C (1-3), along with one known compound, alpneumine A (4). Structural elucidation of all the compounds was accomplished by spectral methods such as 1D and 2D NMR, IR, UV, and HRESIMS. The isolated compounds were tested in vitro for cytotoxic activities against four osteosarcoma cell lines. Consequently, alkaloids 2 and 3 exhibited cytotoxic activities for all tested tumor cell lines with IC50 values from 9.2 to 13.0 µM.

Cytotoxic monoterpenoid indole alkaloids from Alstonia yunnanensis Diels.

The ethanol extract of the aerial parts of Alstonia yunnanensis Diels afforded five new monoterpenoid indole alkaloids, alstiyunnanenines A-E (1-5), along with one known compound, alstoniascholarine I (6). The structures of the isolated compounds were established based on 1D and 2D (1H-1H COSY, HMQC, and HMBC) NMR spectroscopy, in addition to high resolution mass spectrometry. The isolated compounds were tested in vitro for cytotoxic potential using eight tumor cell lines. As a result, alkaloids 4-6 exhibited cytotoxicities against all tested tumor cell lines, especially against osteosarcoma cell lines (SOSP-9607, MG-63, Saos-2, M663) with IC50 values<6µM.