New bisindole alkaloids isolated from Myxomycetes Arcyria cinerea and Lycogala epidendrum

Two new bisindole alkaloids, named cinereapyrrole A (1) and B (2), were isolated from wild fruit bodies of Arcyria cinerea and three new bisindole alkaloids (3-5) were isolated from wild fruit bodies of Lycogala epidendrum. Seven known bisindoles (6-12) were concomitantly obtained from them. The structures of the new compounds were elucidated by spectral data. Among these bisindole alkaloids, compound 12 showed cytotoxicity against cultured tumor cell lines.     

Semi-Synthesis of Small Molecules of Aminocarbazoles: Tumor Growth Inhibition and Potential Impact on p53

The tumor suppressor p53 is inactivated by mutation in approximately 50% of human cancers. Small molecules that bind and stabilize those mutants may represent effective anticancer drugs. Herein, we report the tumor cell growth inhibitory activity of carbazole alkaloids and amino derivatives, as well as their potential activation of p53. Twelve aminocarbazole alkaloids were semi-synthesized from heptaphylline (1), 7-methoxy heptaphylline (2), and 7-methoxymukonal (3), isolated from Clausena harmandiana, using a reductive amination protocol. Naturally-occurring carbazoles 1–3 and their amino derivatives were evaluated for their potential effect on wild-type and mutant p53 activity using a yeast screening assay and on human tumor cell lines. Naturally-occurring carbazoles 1–3 showed the most potent growth inhibitory effects on wild-type p53-expressing cells, being heptaphylline (1) the most promising in all the investigated cell lines. However, compound 1 also showed growth inhibition against non-tumor cells. Conversely, semi-synthetic aminocarbazole 1d showed an interesting growth inhibitory activity in tumor cells expressing both wild-type and mutant p53, exhibiting low growth inhibition on non-tumor cells. The yeast assay showed a potential reactivation of mutant p53 by heptaphylline derivatives, including compound 1d. The results obtained indicate that carbazole alkaloids may represent a promising starting point to search for new mutp53-reactivating agents with promising applications in cancer therapy.     

Two new monoterpenoid indole alkaloids from Tabernaemontana divaricata

Two new monoterpenoid indole alkaloids, tabervarines A (1) and B (2), along with seven known monoterpenoid indole alkaloids, were isolated from the methanol extract of the twigs and leaves of Tabernaemontana divaricata. The structures including the absolute configurations of the new alkaloids were elucidated based on MS, NMR, and ECD calculation. The in vitro cytotoxic activities of the isolated alkaloids against several human cancer cell lines were also evaluated.     

Two novel alkaloids from the stem of Saprosma hainanense and their cytotoxic activities in vitro

Two novel alkaloids, saprosmine A (1) and saprosmine B (2), were isolated from the stem of Saprosma hainanense MERR., along with five known alkaloids: marcanine A (3); cleistopholine (4); 4-methoxycarbonyl-5,10-benzogquinolinequinone (5); liriodenine (6); and quinoline (7). The chemical structures were established on the basis of extensive spectroscopic (IR, 1D-NMR, 2D-NMR, MS) data analysis and by comparison with spectroscopic data reported in the literature. Compounds 1 to 6 were evaluated for in vitro cytotoxic activities against the SPC-A-1 (human lung cancer), BEL-7402 (human hepatocellular carcinoma), SGC-7901 (human gastric cancer), and K-562 (human myelogenous leukaemia) cancer cell lines. Compounds 1 and 2 exhibited weak cytotoxic activities against K-562 cells. Compounds 3 and 5 showed cytotoxic activities against all four cancer cell lines.     

Capillary electrophoretic study of the synergistic biological effects of alkaloids from Chelidonium majus L. in normal and cancer cells

In this study, the synergistic biological action of five celandine alkaloids in normal and cancer cells was investigated by capillary electrophoresis with light-emitting diode-induced native fluorescence detection. The specific capacity of each alkaloid to penetrate into the cells was estimated by monitoring alkaloid concentration decreases in the cell medium during incubation with murine fibroblast NIH/3T3, mouse melanoma B16F10, and human breast cancer MCF7 cell lines. Mixtures of isoquinoline alkaloids containing protopine, chelidonine, sanguinarine, allocryptopine, and stylopine were applied to cell cultures for 20 and 40 min, and the content of alkaloids in the cell media was measured by capillary electrophoresis (CE). CE separation of isoquinoline alkaloids was performed in 30 mM phosphate buffer (pH 2.5). As these alkaloids have native fluorescence, they were directly detected using the commercially available UV light-emitting diode without troublesome fluorescent derivatization. The results showed a differential ability of celandine alkaloids to penetrate into the normal and cancer cell interior, which was inversely proportional to their cytotoxic activity. While the most effective transport of celandine alkaloids from the cell medium to the cell interior was observed for normal murine fibroblast NIH/3T3 cells (about 55% of total content), cytotoxicity tests demonstrated selective and profound apoptotic effects of a five-alkaloid combination in the mouse melanoma B16F10 cell line.     

Sartoryglabrins, analogs of ardeemins, from Neosartorya glabra

Chemical investigation of a collection of the fungus Neosartorya glabra from Thailand furnished sartoryglabins A-C (1a, 1b and 2) which are analogs of the reverse prenylated indole alkaloids known as (-) ardeemins. Structures of these compounds were established by NMR spectrometry and an X-ray analysis. Sartoryglabins A-C were evaluated for their in vitro growth inhibitory activity on three human tumor cell lines: MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer) and A375-C5 (melanoma). All the compounds exhibited strong to moderate activity against the MCF-7 cell line but weak or no activity against the NCI-H460 and A375-C5 cell lines. Sartoryglabin B was found to exhibit selectivity towards the MCF-7 cell line.     

Diterpenoid alkaloids from the Chinese traditional herbal "Fuzi" and their cytotoxic activity

Ten diterpenoid alkaloids, including eight aconitine-type C??-diterpenoid alkaloids and two hetisine-type C??-diterpenoid alkaloids, were isolated from the secondary roots of Aconitum carmichaeli Debx., known as "Fuzi" in Chinese traditional herbal medicine. Their structures were established on the basis of their spectroscopic data and comparison with those of the literature. Among these alkaloids, chasmanine, oxonitine and 15-acetylsongoramine were isolated for the first time from this medicinal plant. The cytotoxic activity of the alkaloids were tested against several cell lines by the MTT method in which aconitine, hypaconitine, mesaconitne and oxonitine were found to strongly inhibit the growth of the HePG2 cell line, which showed that the existence and quantity of the ester groups have a significant influence on the cytotoxicity of the diterpenoid alkaloids.     

Amaryllidaceae-Type Alkaloids from Pancratium maritimum: Apoptosis-Inducing Effect and Cell Cycle Arrest on Triple-Negative Breast Cancer Cells

Aiming to find Amaryllidaceae alkaloids against breast cancer, including the highly aggressive triple-negative breast cancer, the phytochemical study of Pancratium maritimum was carried out. Several Amaryllidaceae-type alkaloids, bearing scaffolds of the haemanthamine-, homolycorine-, lycorine-, galanthamine-, and tazettine-type were isolated (3–11), along with one alkamide (2) and a phenolic compound (1). The antiproliferative effect of compounds (1–11) was evaluated by the sulforhodamine B assay against triple-negative breast cancer cell lines MDA-MB-231 and MDA-MB-468, breast cancer cells MCF-7, and the non-malignant fibroblast (HFF-1) and breast (MCF12A) cell lines. The alkaloids 3, 5, 7, and 11 showed significant growth inhibitory effects against all breast cancer cell lines, with IC₅₀ (half-maximal inhibitory concentration) values ranging from 0.73 to 16.3 µM. The homolycorine-type alkaloid 7 was selected for further investigation in MDA-MB-231 cells. In the annexin-V assay, compound 7 increased cell death by apoptosis, which was substantiated, in western blot analyses, by the increased expression of the pro-apoptotic protein Bax, and the decreased expression of the anti-apoptotic protein Bcl-xL. Consistently, it further stimulated mitochondrial reactive oxygen species (ROS) generation. The antiproliferative effect of compound 7 was also associated with G2/M cell cycle arrest, which was supported by an increase in the p21 protein expression levels. In MDA-MB-231 cells, compound 7 also exhibited synergistic effects with conventional chemotherapeutic drugs such as etoposide.     

Four new neo-clerodane diterpenoid alkaloids from Scutellaria barbata with cytotoxic activities

Four new neo-clerodane diterpenoid alkaloids, named scutebarbatines C-F (1-4), were isolated from the whole plants of Scutellaria barbata D. DON. Their structures were elucidated by spectral analyses (UV, IR, FAB-MS, 1D-NMR and 2D-NMR). In vitro, compounds 1-4 showed significant cytotoxic activities against three human cancer cell lines, namely, HONE-1 nasopharyngeal, KB oral epidermoid carcinoma, and HT29 colorectal carcinoma cells, and gave IC(50) values in the range 3.9-7.8 muM.     

Biological activity of carbazole alkaloids and essential oil of Murraya koenigii against antibiotic resistant microbes and cancer cell lines

A total of three carbazole alkaloids and essential oil from the leaves of Murraya koenigii (Rutaceae) were obtained and examined for their effects on the growth of five antibiotic resistant pathogenic bacteria and three tumor cell lines (MCF-7, P 388 and Hela). The structures of these carbazoles were elucidated based on spectroscopy data and compared with literature data, hence, were identified as mahanine (1), mahanimbicine (2) and mahanimbine (3). The chemical constituents of the essential oil were identified using Gas Chromatography-Mass Spectroscopy (GCMS). These compounds exhibited potent inhibition against antibiotic resistant bacteria such as Staphylococcus aureus (210P JTU), Psedomonas aeruginosa (ATCC 25619), Klebsiella pneumonia (SR1-TU), Escherchia coli (NI23 JTU) and Streptococcus pneumoniae (SR16677-PRSP) with significant minimum inhibition concentration (MIC) values (25.0-175.0 mg/mL) and minimum bacteriacidal concentrations (MBC) (100.0-500.0 mg/mL). The isolated compounds showed significant antitumor activity against MCF-7, Hela and P388 cell lines. Mahanimbine (3) and essential oil in particular showed potent antibacteria and cytotoxic effect with dose dependent trends (≤5.0 μg/mL). The findings from this investigation are the first report of carbazole alkaloids' potential against antibiotic resistant clinical bacteria, MCF-7 and P388 cell lines.     

Pyrrolizidine Alkaloids and Bisabolane Sesquiterpenes from the Roots of Ligularia cymbulifera

The new pyrrolizidine alkaloid glycoside 1 , and the three new highly oxygenated bisabolane sesquiterpenes 4 – 6 , together with the two known pyrrolizidine alkaloids 2 and 3 , were isolated from the roots of Ligularia cymbulifera (W. W. Smith ) Hand .‐Mazz . Their structures were established on the basis of spectroscopic analysis, especially 1D‐ and 2D‐NMR data. The cytotoxic activities of compounds 1, 2 , and 4 – 6 were evaluated against hepatoma (BEL‐7402), human leukemia (HL‐60), human ovarian carcinoma (HO‐8910), and nasopharyngeal carcinoma (KB) cell lines (Tables 1–3). Compound 6 s howed weak cell‐growth inhibition of BEL‐7402 cell.     

Structure and cytotoxicity of phidianidines A and B: first finding of 1,2,4-oxadiazole system in a marine natural product

Two indole alkaloids, phidianidines A (1) and B (2), exhibiting an uncommon 1,2,4-oxadiazole ring linked to the indole system, have been isolated from the marine opisthobranch mollusk Phidiana militaris. The structures of the two metabolites have been elucidated by spectroscopic techniques. Phidianidines exhibit high cytotoxicity against tumor and nontumor mammalian cell lines in in vitro assays.     

Recent advances in the studies on luotonins

Luotonins are alkaloids from the aerial parts of Peganum nigellastrum Bunge. that display three major skeleton types. Luotonins A, B, and E are pyrroloquinazolino-quinoline alkaloids, luotonins C and D are canthin-6-one alkaloids, and luotonin F is a 4(3H)-quinazolinone alkaloid. All six luotonins have shown promising cytotoxicities towards selected human cancer cell lines, especially against leukemia P-388 cells. Luotonin A is the most active one, with its activity stemming from topoisomerase I-dependent DNA-cleavage. Such intriguing biological activities and unique structures have led not only to the development of synthetic methods for the efficient synthesis of these compounds, but also to interest in structural modifications for improving the biological properties. Recent progress in the study of luotonins is covered.     

Fluevirines E and F,two new alkaloids from Flueggea virosa

Abstract

Two new alkaloids, fluevirines E (1) and F (2), along with six known Securinega alkaloids, were isolated from the methanol extract of the twigs and leaves of Flueggea virosa. The structures and absolute configurations of the new compounds were elucidated by means of MS, NMR, and ECD analyses. Compound 1 is a new dimeric indole alkaloid while 2 is a new securinega-type alkaloid. The in vitro cytotoxic activities of the isolated alkaloids against several human cancer cell lines and their acetylcholinesterase inhibitory activity were also evaluated.     

Chemical constituents of Lycoris albiflora and their cytotoxic activities

An alcoholic extract of Lycoris albiflora (Amaryllidaceae) showed potent cytotoxic activity against HL-60 cells with an IC50 value of 1.7 microg/mL. Phytochemical examination of the extract resulted in the isolation of 15 alkaloids, including two phenanthridine-type alkaloids (1, 2), one benzylphenethylamine-type alkaloid (3), two crinane-type alkaloids (4, 5), one pyrrolophenanthridine-type alkaloid (6), six lycorenan-type alkaloids (7-12), and three galanthamine-type alkaloids (13-15), together with three neolignans (16-18), two flavans (19, 20), and two acetophenone derivatives (21, 22). Compound 3 (hostasinine A) has not been isolated from Amaryllidaceae plants, and 1, 2, 4, 5, 7-9, 11, 12 and 14-22 are the first isolation and identification from L. albiflora. The phenanthridine-type alkaloids (1, 2), as well as the alkaloids (3-5), exhibited potent cytotoxic activities against not only HL-60 cells but also HSC-2 cells, thus leading to the conclusion that these alkaloids are mainly responsible for the cytotoxicity of the L. albiflora extract. Compound 1 (lycoricidinol), with the most potent cytotoxic activities, induced apoptosis in both HL-60 cells and HSC-2 cells. It is notable that 1 induced transient autophagy and morphological changes in mitochondria in the early stages of the apoptotic cell death process in HSC-2 cells.     

苄基异喹啉生物碱Neolitacumonine、Mollinedine和Papaverine的全合成

研究了苄基异喹啉生物碱的一条新的通用合成路线.其关键步骤为1-苄基-3,4-二氢异喹啉的铜催化氧化芳构化串联反应.以胡椒醛或3,4-二甲氧基苯甲醛为起始原料,经8步反应,分别以42%、37%和37%的总收率实现了三个苄基异喹啉生物碱Neolitacumonine、Mollinedine和Papaverine的全合成.     

Cytotoxic and anti-HIV phenanthroindolizidine alkaloids from Cryptocarya chinensis

Bioassay-guided fractionation of the cytotoxic ethanol extract of Cryptocarya chinensis has led to the isolation of 11 compounds, including two phenanthroindolizidine alkaloids [(-)-antofine (1) and dehydroantofine (2)], five pavine alkaloids (3-7), and four proaporphine alkaloids (8-11). The structures of the isolated compounds were determined by means of NMR spectroscopic methods, and supported by HRMS and optical rotation data. Compounds 1 and 2 showed cytotoxic activity against four cancer cell lines, L1210, P388, A549, and HCT-8, with 1 being the most potent against A549 and HCT-8 with EC50 values of 0.002 and 0.001 microg/mL, respectively. In addition, 2 is first reported to exhibit significant anti-HIV activity.     

Kottamides A-D: novel bioactive imidazolone-containing alkaloids from the New Zealand ascidian Pycnoclavella kottae

Kottamides A-D (1-4), novel 2,2,5-trisubstituted imidazolone-containing alkaloids, were isolated from the New Zealand endemic ascidian Pycnoclavella kottae and structurally characterized using 15N natural abundance 2-D NMR in addition to standard spectroscopic methods. The kottamides exhibited anti-inflammatory and anti-metabolic activity as well as cytotoxicity toward tumor cell lines.     

Stephacidin A and B: two structurally novel,selective inhibitors of the testosterone-dependent prostate LNCaP cells

Two novel antitumor alkaloids, Stephacidin A and B, were isolated from the solid fermentation of Aspergillus ochraceus WC76466. Both alkaloids exhibit in vitro cytotoxicity against a number of human tumor cell lines; however, stephacidin B demonstrated more potent and selective antitumor activities, especially against prostate testeosterone-dependent LNCaP cells with IC50 value of 60 nM. The structures of stephacidin A and B were established on the basis of the NMR data and X-ray crystallography. With 15 rings and 9 chiral centers, stephacidin B represents one of the most structurally complex and novel alkaloids occurring in nature.     

Synthesis of A Natural Cytotoxic Alkaloid Artabotrine and its Analogue

Artabotrine 1 (Figure 1) was isolated from Artabotrys zeylanicus Hook.f. & Thoms., an endemic mainly in Sri Lanka1. The spectral data and single crystal X-ray analysis indicated that artabotrine is a novel and comparatively rare alkaloid characterized with N-methoxylated 4,5-dioxoaporphine, since most of the reported 4,5-dioxoaporphines are N-methylated or no substituted2-11. This highly oxidized aporphine alkaloid was found to possess notable inhibitory activity on P-388 leukemia cell lin…