Antiplasmodial prenylated flavanonols from Tephrosia subtriflora

The CH₂Cl₂/MeOH (1:1) extract of the aerial parts of Tephrosia subtriflora afforded a new flavanonol, named subtriflavanonol (1), along with the known flavanone spinoflavanone B, and the known flavanonols MS-II (2) and mundulinol. The structures were elucidated by the use of NMR spectroscopy and mass spectrometry. The absolute configuration of the flavanonols was determined based on quantum chemical ECD calculations. In the antiplasmodial assay, compound 2 showed the highest activity against chloroquine-sensitive Plasmodium falciparum reference clones (D6 and 3D7), artemisinin-sensitive isolate (F32-TEM) as well as field isolate (KSM 009) with IC₅₀ values 1.4–4.6 μM without significant cytotoxicity against Vero and HEp2 cell lines (IC₅₀ > 100 μM). The new compound (1) showed weak antiplasmodial activity, IC₅₀ 12.5–24.2 μM, but also showed selective anticancer activity against HEp2 cell line (CC₅₀ 16.9 μM).     

Antileishmanial diterpenoid alkaloids from Aconitum spicatum (Bruhl) Stapf

The crude extracts of tubers of Aconitum spicatum (Bruhl) Stapf were investigated for in vitro antileishmanial activity against Leishmania major. The dichloromethane extract at pH 2.5 showed antileishmanial activity with IC₅₀ value of 27.10 ± 0.0 μg/mL. Chromatographic purification of the dichloromethane extract led to isolation of three C-19 norditerpenoid alkaloids indaconitine (1), chasmaconitine (2) and ludaconitine (3). Compounds 3 and 2 showed antileishmanial activity with IC₅₀ = 36.10 ± 3.4 and 56.30 ± 2.1 μg/mL, respectively. Compound 1 was less effective (IC₅₀ > 100 μg/mL). The cytotoxicity of compounds 1, 2 and 3 studied against MCF7, HeLa and PC3 cancer cell lines and 3T3 normal fibroblast cell line did not show cytotoxicity at 30 μM.     

Calaxanthones A-C,three new xanthones from the roots of Calophyllum calaba and the cytotoxicity

Three new xanthones, named calaxanthones A-C (1–3), along with 17 known xanthones (4–20) were isolated from the roots of Calophyllum calaba. Their structures were determined by spectroscopic analysis. All isolated compounds were evaluated for their cytotoxicity against five cancer cell lines (KB, HeLa S-3, HT-29, MCF-7 and HepG-2). Compound 3 showed potent cytotoxicity against all the five cancer cell lines with IC₅₀ values in the range of 0.82–5.04 μM. Furthermore, compound 6 showed potent cytotoxicity against KB, HeLa S-3 and HepG2 cells with IC₅₀ values of 7.06, 5.27 and 9.64 μM, respectively. Additionally, compound 7 showed potent cytotoxicity against KB cell with an IC₅₀ value of 4.62 μM.     

Betulinic acid derivatives: a new class of α-glucosidase inhibitors and LPS-stimulated nitric oxide production inhibition on mouse macrophage RAW 264.7 cells

Chemical manipulation studies were conducted on betulinic acid (1), twenty-one new rationally designed analogues of 1 with modifications at C-28 were synthesized for their evaluation of inhibitory effects on α-glucosidase and LPS-stimulated nitric oxide production in mouse macrophage RAW 264.7 cells. Compound 2 (IC₅₀ = 5.4 μM) exhibited an almost 1.4-fold increase in α-glucosidase inhibitory activity on yeast α-glucosidase while analogues 5 (IC₅₀ 16.4 μM) and 11 (IC₅₀ 16.6 μM) exhibited a 2-fold enhanced inhibitory activity on NO-production than betulinic acid.     

New macrocyclic diterpenes from Euphorbia connata Boiss. with cytotoxic activities on human breast cancer cell lines

Acetone:chloroform (1:2) extract of the aerial parts of Euphorbia connata Boiss. (Euphorbiaceae) was investigated for its diterpenoids. This led to the isolation of one known and two new diterpenes, belonging to the pentahydroxy-13(17)-epoxy-8,10(18)-myrsinadiene and tetrahydroxy-5,6-epoxy-14-oxo-jatropha-11(E)-ene classes. The structures were elucidated based on ¹³C and ¹H NMR as well as 2D NMR, IR and MS spectra and the cytotoxicity for compounds 1–3 were evaluated by using MTT assay against two human breast cancer cell lines. Myrsinane-type compounds – 3,7,14,15-tetraacetyl-5-propanoyl-13(17)-epoxy-8,10(18)-myrsinadiene (1) and 3,7,10,14,15-pentaacetyl-5-butanoyl-13,17-epoxy-8-myrsinene (2) – exhibited moderate inhibitory effects, with IC₅₀ values of 24.53 ± 3.39 and 26.67 ± 1.41 μM against the MDA-MB cell line, and 37.73 ± 3.41 and 34.57 ± 2.12 μM against the MCF-7 cell line, respectively. Jatrophane-type diterpene – 5,6-epoxy-8,9,15-triacetyl-3-benzoyl-14-oxo-jatropha-11(E)-ene (3) – showed weak cytotoxicity, with IC₅₀ values of 55.67 ± 7.09 μM against MDA-MB, and moderate cytotoxicity with IC₅₀ values of 24.33 ± 3.21 μM against MCF-7 cell line.     

Anti-infective assessment of Senecio smithioides (Asteraceae) and isolation of 9-oxoeuryopsin,a furanoeremophilane-type sesquiterpene with antiplasmodial activity

The search for anti-infective activity in the antipyretic plant Senecio smithioides was conducted. Petroleum ether (PE), dichloromethane (CH₂Cl₂), ethyl acetate (EtOAc) and hydroethanolic (96% EtOH) extracts, and compounds 9-oxoeuryopsin (1), epoxydecompostin (2) and senecionine (3) were obtained from the aerial parts. All extracts and 1 were tested against chloroquine-resistant strain of Plasmodium falciparum (ref. chloroquine), Trypanosoma cruzi (ref. nifurtimox), Leishmania braziliensis, Leishmania amazonensis and Leishmania donovani (ref. pentamidine), Staphylococcus aureus and Escherichia coli (ref. gentamicin) and, Neurospora crassa and Candida albicans (ref. ketoconazole). The PE extract exhibited the strongest in vitro activity against Plasmodium falciparum IC₅₀ < 1.0 μg/mL. 1 was established as a potent antiplasmodial compound with an IC₅₀ = 1.2 μg/mL, 5.2 μM. Other antiparasitic activities were recorded for all extracts and 1. Antibacterial and antifungal activity was negligible.     

Antiproliferative and cytotoxic secondary metabolites from fruits of Leplaea mayombensis

Two new seco-lanostane-type triterpenes, named mayomlactones A (1) and B (2) were isolated from the fruits of Leplaea mayombensis together with 10 known compounds (3–12). Structures of the new compounds were elucidated by extensive spectroscopic studies. Except compounds 11 and 12, all the other chemical compounds are newly reported from Leplaea genus. From the results of this investigation, compounds 1–10 were examined for antiproliferative activity against HeLa cells as well as cytotoxicity against 3T3 cell line. Compounds 3 and 4 showed moderate antiproliferative activity with IC₅₀ values of 10.4 ± 0.1 and 18.6 ± 0.2 μM, respectively. On the other hand, compounds 1, 4 and 9 showed weak cytotoxicity with IC₅₀ values 44.1 ± 0.5, 55.8 ± 0.7 and 55.1 ± 0.5 μM. Overall, none of the tested compounds showed good selectivity (SI ranging from 0.51 to 3.06) but high toxicity against the 3T3 cell line.     

New salen-type manganese(III) Schiff base complexes derived from meso-1,2-diphenyl-1,2-ethylenediamine: In vitro anticancer activity,mechanism of action,and molecular docking studies

Four new manganese(III) Schiff base complexes (1–4) were synthesized and characterized. The complexes have general formula [MnClL^x] in which L represents a Schiff base ligand derived from condensation of meso-1,2-diphenyl-1,2-ethylenediamine with salicylaldehyde or its 3-OMe-, 5-Br-, or 5-OMe-derivatives (x = 1–4, respectively). The crystal structure of [MnClL¹] (1) was characterized by X-ray crystallography. The in vitro anticancer activity of these complexes was evaluated by MTT and apoptosis assays against human breast (MCF-7) and liver (Hep G2) cancer cells. The complexes exhibited considerable antiproliferative activity against both cell lines (IC₅₀ = 10.8–21.02 μM) comparable to cis-platin, except 4 (MCF-7). The highest activity was found for 1 with IC₅₀ values of 13.62 μM (MCF-7) and 10.8 μM (Hep G2). Flow cytometry experiments showed that 1 induced apoptosis on MCF-7 tumor cell line. Docking simulations using AUTODOCK were also carried out. The results showed that all complexes fitted into the minor groove region of DNA.     

Synthesis and antiproliferative activities of thioxoflavonoids on three human cancer cells

Two series of fifteen novel thioxoflavonoids 2a-2h and 4a-4g were synthesized from corresponding flavonoids 1a-1h and 3a-3g by reacting with Lawesson’s reagent, respectively. Their in vitro antiproliferative activities were evaluated on a panel of three human cancer cell lines (Hela, HCC1954 and SK-OV-3) using cell counting kit-8 (CCK-8) assay. The results showed that most of the target compounds exhibited moderate to good antiproliferative activities against the three human cancer cell lines. In particular, thioxoflavonoids 2f and 2g showed the strongest antiproliferative activity on all three human cancer cell lines with IC₅₀ values ranging from 3.34 to 4.67 μM, 4f showed the best antiproliferative activity on Hela cells (IC₅₀ 2.30 μM), 2e showed the best antiproliferative activity on HCC1954 cells (IC₅₀ 2.13 μM) and SK-OV-3 cells (IC₅₀ 2.33 μM). The antiproliferative activities may be involved in their antioxidant activity, which can be speculated by their ability to scavenge free radicals and by their capacity of affecting key redox enzymes.     

New lignan from the rattan stems of Schisandra chinensis

A new lignan named schilignan F (1), together with twelve known ones (2–13), were isolated from the rattan stems of Schisandra chinensis. Their chemical structures were elucidated by spectroscopic methods including one and two-dimensional NMR spectra referring to the literatures as well as high-resolution mass spectrometric analysis. All compounds were evaluated for their cytotoxicities against human Hela cancer cell lines in vitro. The results showed that compounds 2, 6 and 8 exhibited weak cytotoxic activity with IC₅₀ values of 30.6, 86.3 and 41.0 μM, and cisplatin showed cytotoxic activity with IC₅₀ value of 27.3 μM.     

Isolation and structural modifications of ananixanthone from Calophyllum teysmannii and their cytotoxic activities

Two naturally occurring xanthones, ananixanthone (1) and β-mangostin (2), were isolated using column chromatographic method from the n-hexane and methanol extracts of Calophyllum teysmannii, respectively. The major constituent, ananixanthone (1), was subjected to structural modifications via acetylation, methylation and benzylation yielding four new xanthone derivatives, ananixanthone monoacetate (3), ananixanthone diacetate (4), 5-methoxyananixanthone (5) and 5-O-benzylananixanthone (6). Compound 1 together with its four new derivatives were subjected to MTT assay against three cancer cell lines; SNU-1, K562 and LS174T. The results indicated that the parent compound has greater cytotoxicity capabilities against SNU-1 and K562 cell lines with IC₅₀ values of 8.97 ± 0.11 and 2.96 ± 0.06 μg/mL, respectively. Compound 5 on the other hand exhibited better cytotoxicity against LS174T cell line with an IC₅₀ value of 5.76 ± 1.07 μg/mL.     

New cytotoxic isoprenoid derivatives from the Red Sea soft coral Sarcophyton glaucum

Chemical investigation of the soft coral Sarcophyton glaucum collected from the Red Sea led to isolation of 11 isoprenoidal metabolites (1–11). A new sesquiterpenoid, 6-oxo-germacra-4(15),8,11-triene (1), a new natural cembranoid, sarcophinediol, along with two known sesquiterpenoids (2 and 3) and seven known cembranoids (5–11) was obtained. The structures of the compounds were established based on their NMR, MS, IR and UV spectral data. All compounds were evaluated for their cytotoxicity employing three cancer cell lines (HepG2, MCF-7 and HCT116). Compounds 4 and 6 showed significant cytotoxicity towards HepG2 with IC₅₀ values of 18.8 ± 0.07 and 19.9 ± 0.02 μM; respectively. Compounds 5–7 exhibited potent cytotoxicity against MCF-7 cells with IC₅₀ values of 9.9 ± 0.03, 2.4 ± 0.04 and 3.2 ± 0.02 μM, respectively. Compounds 1, 4 and 5 showed significant activities towards HCT116 cells with IC₅₀ values of 29.4 ± 0.03, 19.4 ± 0.02 and 25.8 ± 0.03 μM, respectively.     

A new butenolide cinnamate and other biological active chemical constituents from Polygonum glabrum

Phytochemical investigation of the methanol extract of the aerial parts of Polygonum glabrum afforded one new natural product ( ? )-2-methoxy-2-butenolide-3-cinnamate (1) along with six known compounds, β-hydroxyfriedalanol (2), 3-hydroxy-5-methoxystilbene (3), ( ? ) pinocembrin (4), sitosterol-(6′-O-palmitoyl)-3-O-β-d-glucopyranoside (5), ( ? ) pinocembrin-5-methyl ether (6) and sitosterol-3-O-β-d-glucopyranoside (7). Compound 1 showed promising in vitro anti-HIV-1 activity against primary isolates HIV-1_UG070 (X4, subtype D) and HIV-1_VB59 (R5, subtype C) assayed using TZM-bl cell line with IC₅₀ in the range of 15.68–22.43 μg/mL. The extract showed TI in the range of 19.19–27.37 with IC₅₀ in the range of 10.90–15.55 μg/mL. Compounds 1, 3 and 4 exhibited in vitro anti-mycobacterium activity against Mycobacterium tuberculosis H37Ra with IC₅₀ values of 1.43, 3.33 and 1.11 μg/mL in dormant phase and 2.27, 3.33 and 1.21 μg/mL in active phase, respectively. Compound 4 was found to be the most active antiproliferative with IC₅₀ values of 1.88–11.00 μg/mL against THP-1, A549, Panc-1, HeLa and MCF7 cell lines.     

Chemical characterization of constituents from Polygonatum cyrtonema Hua and their cytotoxic and antioxidant evaluation

Abstract

Twenty-four compounds were isolated from the roots of Polygonatum cyrtonema Hua, including a new octopamine dimer, named trans-bis(N-feruloyl)octopamine (1). The structure was established on the basis of spectroscopic and chemical methods. All the extracts and compounds were evaluated for cytotoxic and antioxidant activities by using MTT and chemiluminescence assay. The extracts showed activity against MCF-7 and HepG-2 cell lines from IC₅₀ 0.30 to 1.01 mg mL^?1. Compound 3 exhibited activity against HepG-2 cell lines with IC₅₀ 8.99?μM. Compound 7 exhibited activity against Hela cell lines with IC₅₀ 2.53?μM and BGC-823 cell lines with IC₅₀ 7.77?μM. Moreover, compound 7 showed antioxidant with IC₅₀ 12?µM compared to the positive control with IC₅₀ 77?µM. Compound 16 exhibited activity against HepG-2 cell lines with IC₅₀ 1.05?μM and MCF-7 cell lines with IC₅₀ 1.89?μM. These results indicated that this plant might be potential in natural medicine and healthy food.     

Anticancer activity of Ophiobolin A,isolated from the endophytic fungus Bipolaris setariae

The present work describes the anticancer activity of Ophiobolin A isolated from the endophytic fungus Bipolaris setariae. Ophiobolin A was isolated using preparative HPLC and its structure was confirmed by HRMS, ¹H NMR, ¹³C NMR, COSY, DEPT, HSQC and HMBC. It inhibited solid and haematological cancer cell proliferation with IC₅₀ of 0.4–4.3 μM. In comparison, IC₅₀ against normal cells was 20.9 μM. It was found to inhibit the phosphorylation of S6 (IC₅₀ = 1.9 ± 0.2 μM), ERK (IC₅₀ = 0.28 ± 0.02 μM) and RB (IC₅₀ = 1.42 ± 0.1 μM), the effector proteins of PI3K/mTOR, Ras/Raf/ERK and CDK/RB pathways, respectively. It induced apoptosis and inhibited cell cycle progression in MDA-MB-231 cancer cells with concomitant inhibition of signalling proteins. Thus, this study reveals that anticancer activity of Ophiobolin A is associated with simultaneous inhibition of multiple oncogenic signalling pathways namely PI3K/mTOR, Ras/Raf/ERK and CDK/RB.     

Carbazole-pyranocoumarin conjugate and two carbazole alkaloids from the stems of Clausena excavata

A carbazole-pyranocoumarin conjugate, carbazomarin B (1), and two carbazole alkaloids, 6-methoxymukonidine (2) and 2-hydroxy-3-methoxycarbazole (3), together with 27 known compounds (4–30), were isolated from the stems of Clausena excavata. Their structures have been elucidated by spectroscopic analyses. Compound 2 showed moderate cytotoxicity to HuCCA-1, MOLT-3 and HepG2 cancer cell lines with IC₅₀ values of 15.09–28.50 μg/mL, but none to A549 cell line. Heptaphylline (6) and nordentatin (23) were found to show moderate cytotoxic activity against HepG2 cell line with IC₅₀ values of 12.33 and 11.33, respectively, while clausine K (27) exhibited strong cytotoxicity with IC₅₀ value of 1.05 μg/mL, better than a standard drug (etoposide, IC₅₀ 13.40 μg/mL).     

Cytotoxic agents for KB and SiHa cells from n-hexane fraction of Cissampelos pareira and its chemical composition

Eleven constituents were characterised by gas chromatography–mass spectrometry analysis, and five molecules were isolated using column chromatography. The in vitro study of the extract and isolated molecules against KB and SiHa cell lines revealed oleanolic acid (1) and oleic acid (2) as potent cytotoxic molecules with potential anticancer activity. The IC₅₀ values of n-hexane extract (CPHF), oleanolic acid (1) and oleic acid (2) were >300, 56.08 and 70.7 μg/mL (μM), respectively, against KB cell lines and >300, 47.24 and 80.2 μg/mL (μM), respectively, against SiHa cell lines.     

β-Secretase inhibition by C-methylisoflavones from Abronia nana

The methanol extract of Abronia nana suspension cultures were subjected to column chromatography to identify potential inhibitors of β-secretase, which is a major factor in Alzheimer’s disease development. Two new C-methylisoflavones boeravinone T (1) and U (4) were isolated with three knowns boeravinone B (2), J (3) and X (5). The half-maximal inhibitory concentration (IC₅₀) values of compounds 1–5 were 18.29, 8.57, 7.87, 12.02 and 5.30 μM, respectively. The most potent 5, non-competitively inhibited β-secretase [inhibition constant (K_i) = 3.79 μM]. Compounds 1–5 did not inhibit other proteases such as chymotrypsin, trypsin and elastase at concentrations up to 1 mM, indicating that they were relatively specific inhibitors of β-secretase. A free hydroxyl group at C-3 position of the C-methylisoflavone skeleton appeared to be responsible for the stronger inhibitory activity against β-secretase.     

Marcanine G,a new cytotoxic 1-azaanthraquinone from the stem bark of Goniothalamus marcanii Craib

The ethanolic extract from the stem bark of Goniothalamus marcanii Craib was shown in preliminary brine shrimp lethality data having good cytotoxic activity. Further bioassay guided isolation was done by means of solvent partition, chromatography and precipitation to provide four isolated compounds: a novel compound 1 with the core structure of 1-azaanthraquinone moiety referred as marcanine G; as well as compounds 2–4 with known aristolactam structures namely, piperolactam C, cepharanone B and taliscanine. These compounds were characterised by spectroscopic techniques. The assessment of cytotoxicity was established on an SRB assay using doxorubicin as a positive control. Marcanine G (1) was considered the most active compound indicating the IC₅₀ values of 14.87 and 15.18 μM against human lung cancer cells (A549) and human breast cancer cells (MCF7), respectively. However, 2 showed mild activity with the IC₅₀ values of 83.72 and 82.32 μM against A549 and MCF7 cells, respectively.     

Officinalioside,a new lignan glucoside from Borago officinalis L.

A new lignan glucoside, officinalioside (1), was isolated from n-BuOH fraction of the aerial parts of Borago officinalis L., together with four known compounds: actinidioionoside (2), roseoside (3), crotalionoside C (4) and kaempferol 3-O-β-D-galactopyranoside (5). The structure of the new compound was established by means of spectroscopic and chemical analyses. Compounds 1 and 2 showed a moderate DPPH radical scavenging activity (IC₅₀: 52.6 ± 1.70 and 41.3 ± 0.25 μM, respectively) comparable with that of the standard trolox (16.6 ± 2.2 μM) without any significant cytotoxicity towards human cell line A549 (IC₅₀ > 100 μM).