New cytotoxic alkaloids from the wood of Vepris punctata from the Madagascar rainforest

Evaluating Phytochemical Profiles, Cytotoxicity, Antiviral Activity, Antioxidant Potential, and Enzyme Inhibition of Vepris boiviniana Extracts

In the present study, we performed comprehensive LC-MS chemical profiling and biological tests of Vepris boiviniana leaves and stem bark extracts of different polarities. In total, 60 bioactive compounds were tentatively identified in all extracts. The 80% ethanolic stem bark extract exhibited the highest activity in the ABTS assay, equal to 551.82 mg TE/g. The infusion extract of stem bark consistently demonstrated elevated antioxidant activity in all assays, with values ranging from 137.39 mg TE/g to 218.46 mg TE/g. Regarding the enzyme inhibitory assay, aqueous extracts from both bark and leaves exhibited substantial inhibition of AChE, with EC50 values of 2.41 mg GALAE/g and 2.25 mg GALAE/g, respectively. The 80% ethanolic leaf extract exhibited the lowest cytotoxicity in VERO cells (CC50: 613.27 µg/mL) and demonstrated selective cytotoxicity against cancer cells, particularly against H1HeLa cells, indicating potential therapeutic specificity. The 80% ethanolic bark extract exhibited elevated toxicity in VERO cells but had reduced anticancer selectivity. The n-hexane extracts, notably the leaves' n-hexane extract, displayed the highest toxicity towards non-cancerous cells with selectivity towards H1HeLa and RKO cells. In viral load assessment, all extracts reduced HHV-1 load by 0.14-0.54 log and HRV-14 viral load by 0.13-0.72 log, indicating limited antiviral activity. In conclusion, our research underscores the diverse bioactive properties of Vepris boiviniana extracts, exhibiting potent antioxidant, enzyme inhibitory, and cytotoxicity potential against cancer cells.

Soyauxinine, a New Indolopyridoquinazoline Alkaloid from the Stem Bark of Araliopsis soyauxii Engl. (Rutaceae)

The chemical investigation of the total alkaloid extract (TAE) of the stem bark of Araliopsis soyauxii (Rutaceae) afforded an unreported indolopyridoquinazoline (compound 1) along with nine previously known alkaloids 2–10. In addition, six semi-synthetic derivatives 3a–c, 4b, 5a and 6a were prepared by allylation and acetonidation of soyauxinium nitrate (5), edulinine (3), ribalinine (4) and arborinine (6). The structures and spectroscopic data of five of them are reported herein for the first time. The suggested mechanism for the formation of the new N-allylindolopyridoquinazoline 5a is presented. The structures of natural and derived compounds were determined employing extensive NMR and MS techniques. The absolute configuration of stereogenic centers in compounds 2–4 were determined using NOESY technique and confirmed by the single-crystal X-ray diffraction (SC-XRD) technique. The use of SC-XRD further enabled us to carry out a structural revision of soyauxinium chloride recently isolated from the same plant to soyauxinium nitrate (5). The TAE, fractions, compounds 1–7 and 9, and semi-synthetic derivatives 3a–c, 4b, 5a and 6a were evaluated for their cytotoxic activity towards the cervix carcinoma cell line KB-3-1. No significant activity was recorded for most of the compounds except for 9, which showed moderate activity against the tested cancer cell lines.

Pd/Cu catalyzed carbonylation of α-aminoaryl-tethered alkylidenecyclopropanes: synthesis of furoquinoline derivatives

A Pd/Cu catalyzed carbonylation of α-aminoaryl-tethered ACPs for the synthesis of furoquinoline derivatives has been developed. Oxygen was used as the terminal oxidant.

Ethnomedicinal uses, phytochemistry, and pharmacology of the genus Vepris (Rutaceae): A review

ETHNOPHARMACOLOGICAL RELEVANCE

Species of the genus Vepris are used in traditional African pharmacopeia for the treatment of various conditions, including chronic diseases and other parasitic. Further uses are against whooping cough and colic in children and as an antidote against snakebite. Data presented will enable the interested scientists to work on this genus applying the so-called "ethnopharmacologic approach", which may lead towards the discovery of the effective, safe plant medicinal products.

AIM OF THE REVIEW

This review article aims to collate and analyse the available information on the traditional uses, phytochemistry, pharmacology, and toxicological aspects of Vepris species in order to explore the trends and perspectives for further studies.

METHODOLOGY

The present review paper collected the literature published prior to August 2020 on the ethnomedicinal uses, phytochemistry, and pharmacology of the genus Vepris. The available information about the genus Vepris was collected via Google Books, Google Scholar, PubMed, ScienceDirect, SciFinder, Web of Science, and other internet sources. The Global Biodiversity Information Facility (www.gbif.org), Plants of the world online (www.plantsoftheworldonline.org), and The Plant List (www.theplantlist.org) databases were used to verify the scientific names and provide distribution information of Vepris species.

RESULTS

Comprehensive analysis of the literature provided information on ethnopharmacological uses of 30 species out of 83 members in the genus. A total of 213 compounds - predominantly alkaloids - were reported together with results from antioxidant, cytotoxic, antimicrobial, antiplasmodial, antitrypanosomal, antileishmanial, antidiabetic, antipyretic, analgesic, insect antifeedant, and toxicity assays. Arborinine (49) and skimmianine (4) isolated from the leaves of V. trichocarpa were tested toxic in rat skeletal myoblast cell line L6, a stable skeletal muscle progenitor cell line, while the leaves of V. heterophylla, the stem bark of V. louisii, and the roots of V. uguenensis were shown to be toxic against model organisms T. castaneum (Tenebrionidae), H. bakeri (Trychostrongylidae), and M. domestica (Muscidae), respectively. In addition, 6,7-methylenedioxy-5-hydroxy-8-methoxy-dictamnine (40) isolated from the leaves of a combined sample of V. renieri + V. suaveolens displayed an extremely low IC₅₀ of 0.67 μM against the normal fibroblastic lung cell line MRC-5 indicating high toxicity. Thus, medical use of these plant parts, as well of the stem bark of V. verdoorniana used locally in poison fishing, should be avoided if alternative treatments exist. Furthermore, a good number of significantly in vitro bioactive compounds have been reported from the genus Vepris: against malaria and against microbial infections.

CONCLUSIONS

Various Vepris species were found to be used in traditional African pharmacopeia. However, few of these species were studied for their bioactive chemical constituents with even fewer bioassay-guided isolation studies being reported. Moreover, detailed pharmacological studies in animal models to explore their mode of action were not reported. Therefore, future studies should focus on these aspects. In addition, we would like to recommend further research on some significantly bioactive crude extracts that were identified in this review: V. leandriana; V. lanceolata; V. nobilis; and V. trichocarpa, as well as those plants reported to be used against chronic diseases.

Bio-Guided Fractionation of Ethanol Extract of Leaves of Esenbeckia alata Kunt (Rutaceae) Led to the Isolation of Two Cytotoxic Quinoline Alkaloids: Evidence of Selectivity Against Leukemia Cells

Bio-guided fractionation performed on the leaves-derived ethanol extract of Esenbeckia alata (Rutaceae), a plant used in traditional medicine, led to the isolation of two alkaloids, kokusaginine 1 and flindersiamine 2, as main cytotoxic agents. Primary ethanolic extract and raw fractions exhibited cell inhibition against five cancer cell lines at different levels (25-97% inhibition at 50 µg/mL) as well as isolated alkaloids 1-2 (30-90% inhibition at 20 µM). Although alkaloid 2 generally was the most active compound, both alkaloids showed a selective effect on K562, a human chronic myelogenous leukemia cell line. The E1-like ubiquitin-activating enzymes (e.g., UBA5) have been recently described as important targets for future treatment of cancer progression, such as leukemia, among others. Therefore, as a rationale to the observed cytotoxic selectivity, an in-silico evaluation by molecular docking and molecular dynamics was also explored. Compounds 1-2 exhibited good performance on the interaction within the active site of UBA5.

Direct access to benzofuro[2,3-b]quinoline and 6H-chromeno[3,4-b]quinoline cores through gold-catalyzed annulation of anthranils with arenoxyethynes and aryl propargyl ethers

This work reports a facile annulation of anthranils with aryloxyethynes or aryl propargyl ethers to construct useful benzofuro[2,3-b]quinoline and 6H-chromeno[3,4-b]quinoline frameworks, respectively.

Biologically active quinoline and quinazoline alkaloids part I

Quinoline and quinazoline alkaloids, two important classes of N-based heterocyclic compounds, have attracted tremendous attention from researchers worldwide since the 19th century. Over the past 200 years, many compounds from these two classes were isolated from natural sources, and most of them and their modified analogs possess significant bioactivities. Quinine and camptothecin are two of the most famous and important quinoline alkaloids, and their discoveries opened new areas in antimalarial and anticancer drug development, respectively. In this review, we survey the literature on bioactive alkaloids from these two classes and highlight research achievements prior to the year 2008 (Part I). Over 200 molecules with a broad range of bioactivities, including antitumor, antimalarial, antibacterial and antifungal, antiparasitic and insecticidal, antiviral, antiplatelet, anti-inflammatory, herbicidal, antioxidant and other activities, were reviewed. This survey should provide new clues or possibilities for the discovery of new and better drugs from the original naturally occurring quinoline and quinazoline alkaloids.

Antimicrobial Furoquinoline Alkaloids from Vepris lecomteana (Pierre) Cheek & T. Heller (Rutaceae)

Three new prenylated furoquinoline alkaloids named lecomtequinoline A (1), B (2), and C (3), together with the known compounds anhydroevoxine (4), evoxine (5), dictamnine (6), N-methylflindersine (7), evoxanthine (8), hesperidin, lupeol, β-sitosterol, stigmasterol, β-sitosterol-3-O-β-d-glucopyranoside, stearic acid, and myristyl alcohol, were isolated by bioassay-guided fractionation of the methanolic extracts of leaves and stem of Vepris lecomteana. The structures of compounds were determined by spectroscopic methods (NMR, MS, UV, and IR) and by comparison with previously reported data. Crude extracts of leaves and stem displayed high antimicrobial activity, with Minimum Inhibitory Concentration (MIC) (values of 10.1-16.5 and 10.2-20.5 µg/mL, respectively, against Escherichia coli, Bacillus subtilis, Pseudomonas agarici, Micrococcus luteus, and Staphylococcus warneri, while compounds 1-6 showed values ranging from 11.1 to 18.7 µg/mL or were inactive, suggesting synergistic effect. The extracts may find application in crude drug preparations in Western Africa where Vepris lecomteana is endemic, subject to negative toxicity results in vivo.

Chalepin: A Compound from Ruta angustifolia L. Pers Exhibits Cell Cycle Arrest at S phase, Suppresses Nuclear Factor-Kappa B (NF-κB) Pathway, Signal Transducer and Activation of Transcription 3 (STAT3) Phosphorylation and Extrinsic Apoptotic Pathway in Non-small Cell Lung Cancer Carcinoma (A549)

Background

Plants have been a major source of inspiration in developing novel drug compounds in the treatment of various diseases that afflict human beings worldwide. Ruta angustifolia L. Pers known locally as Garuda has been conventionally used for various medicinal purposes such as in the treatment of cancer.

Objective

A dihydrofuranocoumarin named chalepin, which was isolated from the chloroform extract of the plant, was tested on its ability to inhibit molecular pathways of human lung carcinoma (A549) cells.

Materials and Methods

Cell cycle analysis and caspase 8 activation were conducted using a flow cytometer, and protein expressions in molecular pathways were determined using Western blot technique.

Results

Cell cycle analysis showed that cell cycle was arrested at the S phase. Further studies using Western blotting technique showed that cell cycle-related proteins such as cyclins, cyclin-dependent kinases (CDKs), and inhibitors of CDKs correspond to a cell cycle arrest at the S phase. Chalepin also showed inhibition in the expression of inhibitors of apoptosis proteins. Nuclear factor-kappa B (NF-κB) pathway, signal transducer and activation of transcription 3 (STAT-3), cyclooxygenase-2, and c-myc were also downregulated upon treatment with chalepin. Chalepin was found to induce extrinsic apoptotic pathway. Death receptors 4 and 5 showed a dramatic upregulation at 24 h. Analysis of activation of caspase 8 with the flow cytometer showed an increase in activity in a dose- and time-dependent manner. Activation of caspase 8 induced cleavage of BH3-interacting domain death agonist, which initiated a mitochondrial-dependent or -independent apoptosis.

Conclusion

Chalepin causes S phase cell cycle arrest, NF-κB pathway inhibition, and STAT-3 inhibition, induces extrinsic apoptotic pathway, and could be an excellent chemotherapeutic agent.

SUMMARY

This study reports the capacity of an isolated bioactive compound known as chalepin to suppress the nuclear factor kappa-light-chain-enhancer of activated B cells pathway, signal transducer and activation of transcription 3, and extrinsic apoptotic pathway and also its ability to arrest cell cycle in S phase. This compound was from the leaves of Ruta angustifolia L. Pers. It provides new insight on the ability of this plant in suppressing certain cancers, especially the nonsmall cell lung carcinoma according to this study. Abbreviations used: °C: Degree Celsius, ANOVA: Analysis of variance, ATCC: American Type Culture Collection, BCL-2: B-Cell CLL/Lymphoma 2, Bcl-xL: B-cell lymphoma extra-large, BH3: Bcl-2 homology 3, BID: BH3-interacting domain death agonist, BIR: Baculovirus inhibitor of apoptosis protein repeat, Caspases: Cysteinyl aspartate-specific proteases, CDK: Cyclin-dependent kinase, CO₂: Carbon dioxide, CST: Cell signaling technologies, DISC: Death-inducing signaling complex, DMSO: Dimethyl sulfoxide, DNA: Deoxyribonucleic acid, DR4: Death receptor 4, DR5: Death receptor 5, E1a: Adenovirus early region 1A, ECL: Enhanced chemiluminescence, EDTA: Ethylenediaminetetraacetic acid, ELISA: Enzyme-linked immunosorbent assay, etc.: Etcetera, FADD: Fas-associated protein with death domain, FBS: Fetal bovine serum, FITC: Fluorescein isothiocyanate, G1: Gap 1, G2: Gap 2, HPLC: High-performance liquid chromatography, HRP: Horseradish peroxidase, IAPs: Inhibitor of apoptosis proteins, IC50: Inhibitory concentration at half maximal inhibitory, IKK-α: Inhibitor of nuclear factor kappa-B kinase subunit alpha, IKK-β: Inhibitor of nuclear factor kappa-B kinase subunit beta, IKK-γ: Inhibitor of nuclear factor kappa-B kinase subunit gamma, IKK: IκB kinase, IkBα: Nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha, m: Meter, M: Mitotic, mm: Millimeter, mRNA: Messenger ribonucleic acid, NaCl: Sodium chloride, NaVO4: Sodium orthovanadate, NEMO: NF-Kappa-B essential modulator, NF-κB: Nuclear factor kappa-light chain-enhancer of activated B cells, NSCLC: Nonsmall cell lung carcinoma, PBS: Phosphate buffered saline, PGE2: Prostaglandin E2, PI: Propidium iodide, PMSF: Phenylmethylsulfonyl fluoride, pRB: Phosphorylated retinoblastoma, R. angustifolia: Ruta angustifolia L. Pers, Rb: Retinoblastoma, rpm: Rotation per minute, RPMI: Roswell Park Memorial Institute, S phase: Synthesis phase, SD: Standard deviation, SDS-PAGE: Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Smac: Second mitochondria-derived activator of caspase, SPSS: Statistical Package for the Social Sciences, STAT3: Signal transducer and activation of transcription 3, tBID: Truncated BID, TNF: Tumor necrosis factor, TRADD: Tumor necrosis factor receptor type-1 associated death domain, TRAIL: TNF-related apoptosis- inducing ligand, USA: United States of America, v/v: Volume over volume.

Chemical composition and in vitro biological activities of the essential oil of Vepris macrophylla (BAKER) I.VERD. endemic to Madagascar

Vepris macrophylla is an evergreen tree occurring in sub-humid forest of Madagascar and traditionally used in the Island to treat several complaints as well as to prepare aromatic teas and alcoholic drinks. In the present work, the essential oil distilled from the leaves was analyzed for the first time by gas chromatography (GC-FID) and gas chromatography/mass spectrometry (GC/MS). The major compounds were citral (56.3%), i.e., mixture of neral (23.1%) and geranial (33.2%), citronellol (14.5%), and myrcene (8.3%). The essential oil exhibited antimicrobial activity against S. aureus, P. aeruginosa, and C. albicans as determined by vapor-diffusion assay, supporting the traditional use of the plant for preparing steam bath for the treatment of infectious diseases. The essential oil was evaluated for cytotoxic activity on human tumor cell lines by MTT (=3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay, showing inhibitory effects comparable to those of cisplatin, notably on MDA-MB 231 (human breast adenocarcinoma) and HCT116 (human colon carcinoma) cell lines. Finally, the essential oil was also subjected to screening for its antioxidant activity and the free radical scavenging capacity.

A Novel Flavonoid and Furoquinoline Alkaloids from Vepris glomerata and their Antioxidant Activity

The dichloromethane extract of the aerial part of the plant Vepris glomerata (Rutaceae) yielded a new flavonoid, which was accorded the trivial name veprisinol (1), together with four known furoquinoline alkaloids: haplopine-3,3′-dimethylallyl ether (2), anhydroevoxine (3), evoxine (4) and skimmianine (5). The structures of the compounds were established by 1D and 2D NMR spectroscopy, as well as HREIMS. Compounds 1 and 2 have strong antioxidant potential, similar to and in some instances better than ascorbic acid and can be used as beneficial additives to antioxidant supplements.

Quinoline alkaloids as intercalative topoisomerase inhibitors

Quinoline alkaloids are abundant in the Rutaceae, and many have exhibited cytotoxic activity. Because structurally related antitumor alkaloids such as camptothecin and fagaronine are known to function as intercalative topoisomerase poisons, it is hypothesized that cytotoxic Stauranthus alkaloids may also serve as intercalative topoisomerase inhibitors. To test this hypothesis theoretically, ten Stauranthus quinoline alkaloids were examined for potential intercalation into DNA using a molecular docking approach. Four of the alkaloids (stauranthine, skimmianine, 3',6'-dihydroxy-3',6'-dihydrostauranthine, and trans-3',4'-dihydroxy-3',4'-dihydrostauranthine) were able to intercalatively dock consistently into DNA. In order to probe the intermolecular interactions that may be responsible for intercalation of these quinoline alkaloids, density functional calculations have been carried out using both the B3LYP and M06 functionals. M06 calculations indicated favorable pi-pi interactions between either skimmianine or stauranthine and the guanine-cytosine base pair. Furthermore, the lowest-energy face-to-face orientation of stauranthine with guanine is consistent with favorable dipole-dipole orientations, favorable electrostatic interactions, and favorable frontier molecular orbital interactions. Likewise, the lowest-energy face-to-face orientation of stauranthine with the guanine-cytosine base pair reveals favorable electrostatic interactions as well as frontier molecular orbital interactions. Thus, not only can quinoline alkaloids dock intercalatively into DNA, but the docked orientations are also electronically favorable.

Oxidative burst inhibitory and cytotoxic indoloquinazoline and furoquinoline alkaloids from Oricia suaveolens

Two new β-indoloquinazoline alkaloids, orisuaveoline A (1) and orisuaveoline B (2), two new furoquinoline alkaloids, quinosuaveoline A (5) and quinosuaveoline B (6), and 12 known compounds were isolated from Oricia suaveolens. The structures of the new compounds were deduced by spectroscopic studies. The absolute configuration of nkolbisine (4) was also determined. Compounds 2, 3, 6-8, 10, and 14 were evaluated for oxidative burst inhibitory activity in a chemoluminescence assay and for cytotoxicity against A549 lung carcinoma cells.

HPLC quantification of alkaloids from Haplophyllum extracts and comparison with their cytotoxic properties

An efficient system for the analysis of total alkaloids extracted from the aerial parts from different species of genus Haplophyllum (Rutaceae) by HPLC on a reversed-phase column is described. The HPLC method described was validated for its specificity, linearity and precision using external standards (haplopine, skimmianine and haplamine). The chromatographic conditions allowed the separation of alkaloids and the quantification of haplopine, skimmianine and haplamine in different samples of species of Haplophyllum collected in Uzbekistan. The alkaloidal contents of samples were compared with their in vitro cytotoxic properties against two cancer cell lines (HeLa and HCT-116). The cytotoxicity of extracts was correlated with the concentration of haplopine, skimmianine or haplamine in aerial parts of species of Haplophyllum.

Aegle marmelos (L.) CORREA Inhibits the Proliferation of Transplanted Ehrlich Ascites Carcinoma in Mice

The anticancer effect of hydroalcoholic extract of Aegle marmelos (AME) was studied in the Ehrlich ascites carcinoma bearing Swiss albino mice. The spatial effect of various AME administration schedules showed that six-day administration increased the survival of tumor bearing mice. The best antineoplastic action of AME was obtained when AME administered through intraperitoneal route than the oral route at equimolar dose. Administration of AME once daily for six consecutive days to the tumor bearing mice caused a dose dependent remission of the tumor at 400 mg/kg body weight, where the greatest antitumor effect was observed and the higher doses showed toxic manifestations. A 24-d lengthening in life span was observed in EAC animals treated with 400 mg/kg AME. This dose of 400 mg/kg was considered as the best dose, where the animals survived up to 43 d post-tumor-cell inoculation as against no survivors in the saline treated control group. The antitumor activity when tested for different schedules for triple administrations, the best effect was observed for 1-2-3, followed by 1-3-5 and 1-5-9 days, respectively. Stage specific evaluation of AME inhibited the increase in body weight gain in animals due to tumor development during early stages only. The AME treatment resulted in a dose dependent elevation in the median survival time (MST) and average survival time (AST) up to 400 mg/kg AME and decline thereafter. The effective dose of 400 mg of AME is 1/6th of the LD50 dose, which increased the MST and AST up to 29 and 27 d, respectively. The acute toxicity study of AME showed that the drug was non-toxic up to a dose of 1750 mg/kg b. wt. The LD10 and LD50 was found to be 2000 and 2250 mg/kg.