Polyprenylated polycyclic acylphloroglucinol: Angiogenesis inhibitor from Garcinia multiflora

A new polyprenylated polycyclic acylphloroglucinol, garcimultiflorone K (1), has been isolated from the stems of Garcinia multiflora, together with two known compounds, garcimultiflorone A (2) and garcimultiflorone B (3). The structure of new compound 1 was determined through spectroscopic methods including 1D and 2D NMR and MS analyses. The anti-angiogenic and anti-cancer effects of compounds 1–3 were evaluated in human endothelial progenitor cells (EPCs) and cancer cells. Of these, garcimultiflorone K (1) displayed the most potent anti-angiogenic property by suppressing cell growth and tube formation of EPCs. Compound 1 also exhibited growth-inhibitory activities against human hepatocellular carcinoma cell line SK-Hep-1 and hormone refractory prostate cancer cell line PC-3 with GI₅₀ values of 4.3?±?1.6 and 6.6?±?0.4?μM, respectively.     

Triterpenoids as inhibitors of erythrocytic and liver stages of Plasmodium infections

Bioassay-guided fractionation of the methanol extract of Momordica balsamina led to the isolation of two new cucurbitane-type triterpenoids, balsaminol F (1) and balsaminoside B (2), along with the known glycosylated cucurbitacins, cucurbita-5,24-diene-3β,23(R)-diol-7-O-β-D-glucopyranoside (3) and kuguaglycoside A (4). Compound 1 was acylated yielding two new triesters, triacetylbalsaminol F (5) and tribenzoylbalsaminol F (6). The structures were elucidated based on spectroscopic methods including 2D-NMR experiments (COSY, HMQC, HMBC and NOESY). Compounds 1-6, were evaluated for their antimalarial activity against the erythrocytic stages of the Plasmodium falciparum chloroquine-sensitive strain 3D7 and the chloroquine-resistant clone Dd2. Assessment of compounds (1-3 and 5, 6) activity against the liver stage of Plasmodium berghei was also performed, measuring the luminescence intensity in Huh-7 cells infected with a firefly luciferase-expressing P. berghei line, PbGFP-Luc(con). Active compounds were shown to inhibit the parasite's intracellular development rather than its ability to invade hepatic cells. Toxicity of compounds (1-3 and 5, 6) was assessed on the same cell line and on mouse primary hepatocytes through the fluorescence measurement of cell confluency. Furthermore, toxicity of compounds 1-6 towards human cells was also investigated in the MCF-7 breast cancer cell line, showing that they were not toxic or exhibited weak toxicity. In blood stages of P. falciparum, compounds 1-5 displayed antimalarial activity, revealing triacetylbalsaminol F (5) the highest antiplasmodial effects (IC(50) values: 0.4μM, 3D7; 0.2μM, Dd2). The highest antiplasmodial activity against the liver stages of P.berghei was also displayed by compound 5, with high inhibitory activity and no toxicity.     

4-Phenylcoumarins from Mesua elegans with acetylcholinesterase inhibitory activity

A significant acetylcholinesterase (AChE) inhibitory activity was observed for the hexane extract from the bark of Mesua elegans (Clusiaceae). Thus, the hexane extract was subjected to chemical investigation, which led to the isolation of nine 4-phenylcoumarins, in which three are new; mesuagenin A (1), mesuagenin C (3), mesuagenin D (4) and one new natural product; mesuagenin B (2). The structures of the isolated compounds were characterized by spectroscopic data interpretation, especially 1D and 2D NMR. Four compounds showed significant AChE inhibitory activity, with mesuagenin B (2) being the most potent (IC(50)=0.7μM).     

Anti-inflammatory sesquiterpene lactones from the flower of Vernonia cinerea

Bioassay-guided fractionation of the hexane extract from the flowers of Vernonia cinerea (Asteraceae) led to the isolation of a new sesquiterpene lactone, 8α-hydroxyhirsutinolide (2), and a new naturally occurring derivative, 8α-hydroxyl-1-O-methylhirsutinolide (3), along with seven known compounds (1 and 4-9). The structures of the new compounds were determined by 1D and 2D NMR experiments and by comparison with the structure of compound 1, whose relative stereochemistry was determined by X-ray analysis. The isolated compounds were evaluated for their cancer chemopreventive potential based on their ability to inhibit nitric oxide (NO) production and tumor necrosis factor alpha (TNF-α)-induced NF-κB activity. Compounds 1, 2, 4, 5, and 9 inhibited TNF-α-induced NF-κB activity with IC(50) values of 3.1, 1.9, 0.6, 5.2, and 1.6μM, respectively; compounds 4 and 6-9 exhibited significant NO inhibitory activity with IC(50) values of 2.0, 1.5, 1.2, 2.7, and 2.4μM, respectively.     

Suppressive effects of coumarins from Mammea siamensis on inducible nitric oxide synthase expression in RAW264.7 cells

A methanol extract of the flowers of Mammea siamensis (Calophyllaceae) was found to inhibit nitric oxide (NO) production in lipopolysaccharide-activated RAW264.7 cells. From the extract, two new geranylated coumarins, mammeasins A (1) and B (2), were isolated together with 17 known compounds including 15 coumarins. The structures of 1 and 2 were determined on the basis of their spectroscopic properties as well as of their chemical evidence. Among the isolates, 1 (IC(50)=1.8μM), 2 (6.4μM), surangins B (3, 5.0μM), C (4, 6.8μM), and D (5, 6.2μM), kayeassamins E (7, 6.1μM), F (8, 6.0μM), and G (9, 0.8μM), mammea A/AD (11, 1.3μM), and mammea E/BB (16, 7.9μM) showed NO production inhibitory activity. Compounds 1, 9, and 11 were found to inhibit induction of inducible nitric oxide synthase (iNOS). With regard to mechanism of action of these active constituents (1, 9, and 11), suppression of STAT1 activation is suggested to be mainly involved in their suppression of iNOS induction.     

Phenolic constituents from the rhizomes of Acorus gramineus and their biological evaluation on antitumor and anti-inflammatory activities

On the search for anti-cancer compounds from natural Korean medicinal sources, a bioassay-guided fractionation and chemical investigation of the MeOH extract from the rhizomes of Acorus gramineus resulted in the isolation and identification of thirteen phenolic derivatives (1–13) including two new 8-O-4′-neolignans, named surinamensinols A (1) and B (2) and a new phenolic compound, named acoramol (9). The structures of these new compounds were elucidated on the basis of 1D and 2D NMR spectroscopic data analyses as well as circular dichroism (CD) spectroscopy studies. The cytotoxic activities of the isolates (1–13) were evaluated by determining their inhibitory effects on human tumor cell lines. The new 8-O-4′-neolignans, compounds 1 and 2, showed moderate antiproliferative activities against A549, SK-OV-3, SK-MEL-2, and HCT-15 cell lines with IC₅₀ values in the range of 4.17–26.18 μM. On the basis of the expanded understanding that inflammation is a crucial cause of tumor progression, anti-inflammatory activities of these compounds were determined by measuring nitric oxide (NO) levels in the medium using murine microglia BV-2 cells. Compounds 1, 2, 4, 7 and 10 inhibited NO production in BV-2 stimulated by lipopolysaccharide with IC₅₀ values of 8.17–18.73 μM via NO scavenging, inhibition of iNOS activity, and/or suppression of iNOS expression.     

Identification and evaluation of apoptotic compounds from Garcinia paucinervis

Four new compounds, paucinervins A–D (1–4), and 15 known ones were isolated from the leaves of Garcinia paucinervis. The structures of the new compounds were elucidated by spectroscopic evidences. All of the 19 compounds were evaluated for their apoptosis-inducing effects using HeLa-C3 cells which have been genetically engineered to possess a fluorescent biosensor capable of detecting caspase-3 activation. Eight of them were found to activate caspase-3 in HeLa-C3 cells within 72 h at the concentration of 25 μM. Moreover, the values of IC₅₀ were measured for all four new compounds on HeLa cells using the MTT assay. Among them, compound 2 (paucinervin B) had the lowest IC₅₀ value of 9.5 μM, while the other three new compounds had much higher IC₅₀ values of 29.5, 52.5, and 95.6 μM, respectively. This result shows that paucinervin B has the strongest inhibitory effect against HeLa cell growth among these four newly identified paucinervins and it may have the potential to be developed into a new anticancer candidate.     

Antioxidative oligostilbenes from Caragana sinica

Two new oligostilbenes, caragasinins A (5) and B (10), and eight known compounds, kobophenol A (1), (+)-α-viniferin (2), (+)-ampelopsin F (3), pallidol (4), (+)-isoampelopsin F (6), miyabenol C (7), carasinaurone (8) and caraphenol B (9) were isolated from the ethylacetate-soluble extract of the roots of Caragana sinica. The structures of the isolates were determined on the basis of extensive spectroscopic analysis including 1D, 2D NMR and HRESI-MS. These compounds were assessed for antioxidant activities. Caragasinin A (5), caraphenol B (9), and caragasinin B (10) showed moderate DPPH scavenging activity and lipid peroxidation inhibitory activities with IC(50) values ranging from 34.7±1.0 to 89.1±2.3μM.     

Two new rotenoids from the roots of Millettia speciosa

Two new rotenoids, named millettiaosas A–B (1–2), together with four known compounds were isolated from the roots of Millettia speciosa. Their structures were elucidated on the basis of spectroscopic analysis including 1D and 2D NMR techniques and HRESIMS. Evaluation of the two new compounds for cytotoxicity against four human cancer cell lines (MCF-7, HCT-116, A549 and HepG-2) showed moderate activities (10 μM < IC₅₀ < 26 μM).     

Differential requirements for cellular cytoskeleton in human macrophage complement receptor- and Fc receptor-mediated phagocytosis.

We investigated the requirement for cellular cytoskeleton in CR- and FcR-mediated phagocytosis by human monocyte-derived macrophages (M phi). Inhibition of actin microfilament (MF) assembly and stability by cytochalasins B and D completely inhibited M phi phagocytosis of sheep E coated with C3b (EC3b), iC3b (EC3bi), and IgG (EIgG) via CR1, CR3, and FcR, respectively. Ligand-binding to either CR or FcR was not effected by cytochalasins. Nocodazole (NOC), which prevents microtubule (MT) polymerization, and taxol, which causes random polymerization of MT inhibited M phi phagocytosis of EC3b(i) but not EIgG. However, the combination of taxol (5 x 10(-4) M) and NOC (2 x 10(-6) M) augmented M phi CR-mediated phagocytosis. In addition, agents known to increase intracellular cGMP augmented phagocytosis of EC3b(i). Conversely, agents that increase intracellular cAMP inhibited CR-mediated phagocytosis. These agents had no effect on FcR-mediated phagocytosis, and did not effect ligand-binding to CR or FcR. PMA markedly enhanced CR- but not FcR-mediated phagocytosis, and augmentation of CR-mediated phagocytosis by PMA was inhibited by both CD and NOC. In contrast, the synthetic diacylglycerol, 1-oleoyl-2-acetoyl-sn-3-glycerol augmented, and inhibitors of protein kinase C inhibited M phi phagocytosis via CR and FcR. These data indicate that for adherently cultured human M phi: 1) binding of ligand-coated E to CR or FcR does not require an intact cytoskeleton; 2) intact actin microfilament are required for phagocytosis via CR and FcR; 3) phagocytosis via CR1 and CR3 but not FcR is dependent on MT assembly; 4) PMA most likely augments CR-mediated phagocytosis through promotion of MT assembly; and 5) PKC activity is involved in the phagocytic signal generated by both CR and FcR.     

Pendulaosides A and B. Two acylated triterpenoid saponins from Harpullia pendula seed extract

Two new acylated triterpenoid saponins named pendulaosides A and B as well as the known phenolic compounds methyl gallate, gallic acid, 1,2,3,6-tera-O-galloyl-β-d-glucose and 1,2,3,4,6-penta-O-galloyl-β-d-glucose, were isolated from the seeds of Harpullia pendula. The structures of pendulaosides A and B were determined using extensive 1D and 2D NMR analysis and mass spectrometry as well as acid hydrolysis, as 3-O-β-d-glucopyranosyl-(1→2)-[α-L-arabinofuranosyl-(1→3)]-β-d-glucuronopyranosyl-22-O-angeloyl-3β,16α,22α,24β,28-pentahydroxylolean-12-ene and 3-O-β-d-glucopyranosyl-(1→2)-[α-L-arabinofuranosyl-(1→3)]-β-d-glucuronopyranosyl-16-O-(2-methylbutyroyl)-3β,16α,22α,24β,28-pentahydroxylolean-12-ene, respectively. To the best of our knowledge the two triterpene parts 22-O-angeloyl-3β,16α,22α,24β,28-pentahydroxylolean-12-ene and16-O-(2-methylbutyroyl)-3β,16α,22α,24β,28-pentahydroxylolean-12-ene have never been characterized before. The two isolated saponins were assayed for their in-vitro cytotoxic activity against the three human tumor cell lines HepG2, MCF7 and PC3. The results showed that pendulaoside A exhibited moderate activity on PC3 cell line with IC50value equal to 13.0 μM and weak activity on HepG2 cell line with IC50 value equal to 41.0 μM. Pendulaoside B proved to be inactive against the three used cell lines.     

Two new alkaloids with carboxylic acid moieties from Portulaca oleracea and their anti-inflammatory effects

Two new alkaloids with carboxyl, identified as 8-(6,7-dihydroxy-1,2,3,4-tetrahydroisoquinolin-1-yl) octanoic acid and 5-(diethylamino)-2-(3-(diethylamino)-3-oxopropyl)-2-hydroxy-5-oxopentanoic acid named oleralkacid A and oleralkacid B, were isolated from Portulaca oleracea L. for the first time, whose structures were determined using spectroscopic methods including ¹D NMR, ²D NMR, UHPLC-ESI-QTOF/MS and circular dichroism (CD). Subsequently, the anti-inflammatory effects of compounds on lipopolysaccharide-stimulated macrophages were studied, and the results showed that the compound 1 and 2 at 5 μM and 10 μM could significantly inhibit inflammatory mediator IL-1β, respectively.     

Melanogenesis-Inhibitory and Cytotoxic Activities of Diarylheptanoids from Acer nikoense Bark and Their Derivatives

Nine cyclic diarylheptanoids, 1-9, including two new compounds, i.e., 9-oxoacerogenin A (8) and 9-O-β-D-glucopyranosylacerogenin K (9), along with three acyclic diarylheptanoids, 10-12, and four phenolic compounds, 13-16, were isolated from a MeOH extract of the bark of Acer nikoense (Aceraceae). Acid hydrolysis of 9 yielded acerogenin K (17) and D-glucose. Two of the cyclic diarylheptanoids, acerogenin A (1) and (R)-acerogenin B (5), were converted to their ether and ester derivatives, 18-24 and 27-33, respectively, and to the dehydrated derivatives, 25, 26, 34, and 35. Upon evaluation of compounds 1-16 and 18-35 for their inhibitory activities against melanogenesis in B16 melanoma cells, induced with α-melanocyte-stimulating hormone (α-MSH), eight natural glycosides, i.e., six diarylheptanoid glycosides, 2-4, 6, 9, and 12, and two phenolic glycosides, 15 and 16, exhibited inhibitory activities with 24-61% reduction of melanin content at 100?μM concentration with no or almost no toxicity to the cells (88-106% of cell viability at 100?μM). In addition, when compounds 1-16 and 18-35 were evaluated for cytotoxic activity against human cancer cell lines, two natural acyclic diarylheptanoids, 10 and 11, ten ether and ester derivatives, 18-22 and 27-31, and two dehydrated derivatives, 34 and 35, exhibited potent cytotoxicities against HL60 human leukemia cell line (IC(50) 8.1-19.3?μM), and five compounds, 10, 11, 20, 29, and 30, against CRL1579 human melanoma cell line (IC(50) 10.1-18.4?μM).     

Triterpenoid saponins from Xanthoceras sorbifolia Bunge and their inhibitory activity on human cancer cell lines

Xanthoceras sorbifolia Bunge is widely used as healthy food material and folk medicine in China. Phytochemical investigation on its seeds oil leavings has led to the isolation and identification of seven new oleanane-type triterpenoid saponins named sorbifoliasides A-F (1-6) and bunkankasaponin F (7), along with five known ones (8-12). The structures of the new compounds were elucidated through spectroscopic analysis and chemical derivatization. Among the isolated compounds, 16-oxo-3, 28-O-bidesmosidic triterpenoid saponins (2, 3, 5) were isolated from this plant for the first time. The cytotoxicity of all compounds against the ten selected human cancer cell lines was assayed. Compounds 7 and 9 showed significant activity against all the ten cancer cell lines (IC(50) <10μM), while compounds 8, 10 and 11 exhibited moderate activity against most of these cancer cell lines.     

Triterpenes and triterpene glucosides with their oxidative stress injury protective activity from Rubus lambertianus

Two new 18,19-secoursane triterpenes and three triterpene glucosides, together with twelve known compounds, were isolated from the aerial parts of Rubus lambertianus Ser. The structures of the new compounds were determined by spectroscopic analyses (HR-ESI-MS, 1D/2D NMR). The protective effects of compounds 1–17 on high glucose-induced oxidative stress injury in human umbilical vein endothelial cells (HUVECs) were evaluated using cell viability assay. Compounds 1, 2, 7, 10, 12, 15 and 17 significantly attenuated high glucose-induced oxidative damage on HUVECs at the concentration of 3.10 μM.     

Xanthine oxidase inhibitors isolated from Piper nudibaccatum

Two new hydroxychavicol analogs nudibaccatumin A (1) and B (2), together with twenty known compounds were isolated from the methanol extract of Piper nudibaccatum. Their structures were elucidated by extensive spectroscopic analyses (1D and 2D NMR, HRESIMS, UV, IR and polarimetry). Hydroxychavicol is a known inhibitor of xanthine oxidase (XO). In the present study, hydroxychavicol and 5 natural analogs (1–5) were evaluated for their XO inhibitory activity. Neotaiwanensol B (3) (IC₅₀ = 0.28 μM) showed a greater inhibitory effect than hydroxychavicol and allopurinol (the positive control). Two new compounds 1 and 2 showed a moderate inhibition activity with an IC₅₀ value of 62.94 μM and 70.67 μM, respectively.     

Antiplasmodial and cytotoxic activity of lanostane type triterpenoids isolated from Leplaea mayombensis

Leplaeric acid E 5, leplazarin 6a and 21-epileplazarin 6b, three new 3,4-seco-lanostane type triterpenes have been isolated from the stem bark of Leplaea mayombensis (Pellegr.) Staner along with fourteen known compounds from the fruits and roots. Leplaeric acid E, leplazarin and 21-epileplazarin, 15-α-hydroxy-3,4-seco-lanosta-4(28),8,24-triene-3,21-dioic acid, mayomlactones A and B, lanosta-7,24-dien-3-one, leplaeric acid A, B and C were screened in vitro for antiplasmodial activity against chloroquine-sensitive (Pf3D7) and chloroquine-resistant (PfINDO) strains of Plasmodium falciparum and for cytotoxicity against CAL-27, CaCo2, Skov-3, and HepG2 cells line. Three compounds including 15-α-hydroxy-3,4-seco-lanosta-4(28),8,24-triene-3,21-dioic acid (IC₅₀ 5.65–7.09 μM), lanosta-7,24-dien-3-one (IC₅₀ 7.18–9.07 μM), and leplaeric acid C (IC₅₀ 7.59–8.47 μM) were the most active against both strains of P. falciparum. All the compounds exhibited cytotoxicity against the three-cell lines with IC₅₀ ranging from 12.30 to 181.88 μM. These results confirm the usage of the medicinal plant L. mayombensis for the management of malaria and suggest that further lead optimization studies on potent compounds identified from this study could lead to the identification of potential of lead molecules as scaffold for new antimalarial drug discovery.     

Cytotoxic cycloartane triterpenoids from the leaves of Markhamia stipulata var. canaense

From the most cytotoxic fraction of the ethyl acetate extract of Markhamia stipulata var. canaense V.S. Dang leaves, two new cycloartane-type triterpenoids, named Markhacanasin A (1) and Markhacanasin B (2); were isolated by various chromatographic methods Their structures were elucidated by IR, UV, HR-ESI–MS, NMR (1D & 2D) experiments. The cytotoxicity of two new compounds against five human cancer cell lines (HeLa, HepG2, MCF-7, Jurkat and NCI-H460) were evaluated by SRB assay. As results, 1 exhibited significant cytotoxic activity against all cancer cell lines (IC₅₀ ranged from 14.72 to 29.55 μM) while 2 did not show activity.     

Synthesis and antirhinovirus activity of new 3-benzyl chromene and chroman derivatives

A series of 3-benzyl chromenes and chromans were synthesized and tested in vitro against human rhinovirus (HRV) 1B and 14, two representative serotypes for rhinovirus group B and A, respectively. All the new compounds, with the exception of 3-benzyl-2H-chromene (3a), showed a potent activity against HRV serotype 1B within micro or submicromolar range (IC₅₀s from 0.11 to 6.62 μM). The low cytotoxicity of all the derivatives resulted in compounds with high therapeutic index (TI). On the contrary, HRV 14 infection was only weakly inhibited by the majority of these compounds. The 3-benzylidenechromans 2b and 2c showed the highest anti-HRV 1B activity (IC₅₀ 0.12 and 0.11 μM, respectively) coupled with remarkable TI (625.00 and 340.91, respectively). Mechanism of action studies on (Z)-3-(4-chlorobenzylidene)chroman (2b) suggest that the new compounds behave as capsid binders and interfere with very early stages of HRV 1B replication, similarly to related flavanoids.     

Lactarane sesquiterpenoids from Lactarius subvellereus and their cytotoxicity

Subvellerolactones B (1), D (2), and E (3), structurally unusual lactarane sesquiterpenoids, were isolated from the fruiting bodies of Lactarius subvellereus together with four known lactarane sesquiterpenes (4–7). The chemical structures and stereochemistries of compounds 1–3 were determined on the basis of spectroscopic analyses, including 1D and 2D NMR experiments and a convenient Mosher ester procedure. Subvellerolactone B (1) exhibited cytotoxicity against the A549, SK-MEL-2, and HCT-15 cell lines with IC₅₀ values of 26.5, 18.3, and 14.2 μM, respectively, and subvellerolactones D (2) and E (3) showed cytotoxicity against the A549 and HCT-15 cell lines (IC₅₀ (2): 25.1 and 17.8 μM, and IC₅₀ (3): 19.6 and 28.7 μM, respectively).