Unusual bridged angucyclinones and potent anticancer compounds from Streptomyces bulli GJA1.

Two new unique angucyclinones (1 and 2) with unprecedented ether bridges connecting carbons 5 and 7 were isolated from the cultures of Streptomyces bulli GJA1, an endophyte of Gardenia jasminoides, together with two known ones (3 and 4). The MS2-based molecular networking system facilitated the isolation of compounds with target functionalities. The stereochemistry of 1 was completely established by ROESY and ECD experiments. Compound 3 showed antivirulence activities by inhibiting the peptide toxin (PSMs) production and the biofilm formation of MRSA. Compounds 3 and 4 showed very potent anti-proliferative effects against OV1 and ES2 ovarian cancer cells.

New Hydroxydecanoic Acid Derivatives Produced by an Dndophytic Yeast Aureobasidium pullulans AJF1 from Flowers of Aconitum carmichaeli.

Endophytes have been recognized as a source for structurally novel and biologically active secondary metabolites. Among the host plants for endophytes, some medicinal plants that produce pharmaceuticals have been reported to carry endophytes, which could also produce bioactive secondary metabolites. In this study, the medicinal plant Aconitum carmichaeli was selected as a potential source for endophytes. An endophytic microorganism, Aureobasidium pullulans AJF1, harbored in the flower of Aconitum carmichaeli, was cultured on a large scale and extracted with an organic solvent. Extensive chemical investigation of the extracts resulted in isolation of three lipid type compounds (1-3), which were identified to be (3R,5R)-3,5-dihydroxydecanoic acid (1), (3R,5R)-3-(((3R,5R)-3,5-dihydroxydecanoyl)oxy)-5-hydroxydecanoic acid (2), and (3R,5R)-3-(((3R,5R)-5-(((3R,5R)-3,5-dihydroxydecanoyl)oxy)-3-hydroxydecanoyl)oxy)-5-hydroxydecanoic acid (3) by chemical methods in combination with spectral analysis. Compounds 2 and 3 had new structures. Absolute configurations of the isolated compounds (1-3) were established using modified Mosher's method together with analysis of NMR data for their acetonide derivatives. All the isolates (1-3) were evaluated for antibiotic activities against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and their cytotoxicities against MCF-7 cancer cells. Unfortunately, they showed low antibiotic activities and cytotoxic activities.

Cytotoxic pterosins from Pteris multifida roots against HCT116 human colon cancer cells.

Two new pterosin glycosides, (2S,3S)-pterosin C 3-O-ß-d-(4'-(E)-caffeoyl)-glucopyranoside (1) and (2S,3S)-pterosin C 3-O-ß-d-(6'-(E)-p-coumaroyl)-glucopyranoside (2), were isolated from Pteris multifida (Pteridaceae) roots along with ten known pterosin compounds (3-12). The chemical structures of the isolated compounds were elucidated by extensive analysis of the 1D, 2D NMR, HRESIMS, and CD spectroscopic data. The cytotoxicities of 1-12 against HCT116 human colorectal cancer cell line were evaluated. Among the isolates, compound 1 showed moderate antiproliferative activity in HCT116 cells with an IC50 value of 8.0±1.7µM. Additionally, 1 induced the upregulation of the caspase-9 and procaspase-9 levels in Western blots and increased the annexin V/propidium iodide (PI)-positive cell population in flow cytometry.

Catechin-Bound Ceanothane-Type Triterpenoid Derivatives from the Roots of Zizyphus jujuba.

Three unprecedented ceanothane-type triterpenoids, ent-epicatechinoceanothic acid A (1), ent-epicatechinoceanothic acid B (2), and epicatechino-3-deoxyceanothetric acid A (3), containing C-C bond linkages with catechin moieties, were isolated from the roots of Zizyphus jujuba. Their chemical structures, including absolute configurations, were established by spectroscopic analysis and calculation of their ECD spectra. A possible biogenetic pathway for C-C bond formation between the catechin and the triterpenoid moieties is presented. Compound 1 was evaluated for its antiproliferative activity on HSC-T6 hepatic stellate cells.

Lignans from Opuntia ficus-indica seeds protect rat primary hepatocytes and HepG2 cells against ethanol-induced oxidative stress.

Bioactivity-guided isolation of Opuntia ficus-indica (Cactaceae) seeds against ethanol-treated primary rat hepatocytes yielded six lignan compounds. Among the isolates, furofuran lignans 4-6, significantly protected rat hepatocytes against ethanol-induced oxidative stress by reducing intracellular reactive oxygen species levels, preserving antioxidative defense enzyme activities, and maintaining the glutathione content. Moreover, 4 dose-dependently induced the heme oxygenase-1 expression in HepG2 cells.

Cytotoxic Ceanothane- and Lupane-Type Triterpenoids from the Roots of Ziziphus jujuba.

Ziziphus jujuba, a plant in the family Rhamnaceae, is used in several Asian countries as a food and traditional medicine. Fifteen new ceanothane-type (1-15) and three new lupane-type triterpenoids (16-18) were isolated from the roots of Z. jujuba, as well as 12 previously known triterpenoids (19-30). Their structures were elucidated by 1D and 2D NMR spectroscopic and HR mass spectrometric data analysis. Compounds 12 and 13 were found to possess a rare E-ring γ-lactone structure, and 14 was assigned as the first 2,28-dinorlupane derivative isolated as a natural product. Twenty-five of the isolates were examined for cytotoxicity against human hepatocellular carcinoma HepG2 cells, and compounds 6-8, 14, 17, 23, 25, 29, and 30 showed cytotoxicity with IC50 values ranging from 1.9 to 5.9 µM.

Anti-Neuroinflammatory ent-Kaurane Diterpenoids from Pteris multifida Roots.

Activated microglia are known to be a major source of cellular neuroinflammation which causes various neurodegenerative diseases, including Alzheimer's disease. In our continuing efforts to search for new bioactive phytochemicals against neuroinflammatory diseases, the 80% methanolic extract of Pteris multifida (Pteridaceae) roots was found to exhibit significant NO inhibitory activity in lipopolysaccharide (LPS)-activated BV-2 microglia cells. Three new ent-kaurane diterpenoids, pterokaurane M1 2-O-ß-d-glucopyranoside (4), 2ß,16α-dihydroxy-ent-kaurane 2,16-di-O-ß-d-glucopyranoside (10), and 2ß,16α,17-trihydroxy-ent-kaurane 2-O-ß-d-glucopyranoside (12), were isolated along with nine other known compounds from P. multifida roots. The chemical structures of the new compounds were determined by 1D- and 2D-NMR, HR-ESI-MS, and CD spectroscopic data analysis. Among the isolates, compounds 1 and 7 significantly inhibited NO production in LPS-stimulated BV-2 cells reducing the expression of the cyclooxygenase-2 (COX-2) protein and the level of pro-inflammatory mediators such as prostaglandin E2 (PGE2), tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-6. These results suggest that ent-kaurane diterpenes from P. multifida could be potential lead compounds that act as anti-neuroinflammatory agents.

Stereoisomer-specific anticancer activities of ginsenoside Rg3 and Rh2 in HepG2 cells: disparity in cytotoxicity and autophagy-inducing effects due to 20(S)-epimers.

Autophagy has been an emerging field in the treatment of hepatic carcinoma since anticancer therapies were shown to ignite autophagy in vitro and in vivo. Here we report that ginsenoside Rg3 and Rh2, major components of red ginseng, induce apoptotic cell death in a stereoisomer-specific fashion. The 20(S)-forms of Rg3 and Rh2, but not their respective 20(R)-forms, promoted cell death in a dose-dependent manner accompanied by downregulation of Bcl2 and upregulation of Fas, resulting in apoptosis of HepG2 cells with poly ADP ribose polymerase cleavage. The LD50 value [45 µM for Rg3(S), less than 10 µM for Rh2(S)] and gross morphological electron microscopic observation revealed more severe cellular damage in cells treated with Rh2(S) than in those treated with Rg3(S). Both Rg3(S) and Rh2(S) also induced autophagy when undergoing induced apoptosis. Inhibition of autophagy with lysosomotrophic agents significantly potentiated the cellular damage, implying a favorable switch of the cell fate to tumor cell death. Blocking intracellular calcium with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester) (BAPTA-AM) restored the cell death induced by both Rg3(S) and Rh2(S). Our results suggest that the 20(S)-forms of Rg3 and Rh2 in red ginseng possess more potent antitumor activity with autophagy than their 20(R)-forms via calcium-dependent apoptosis.

Chemical constituents isolated from Disporum viridescens leaves and their inhibitory effect on nitric oxide production in BV2 microglial cells.

Excessive NO (nitric oxide) has been associated with the pathogenesis of various neurodegenerative diseases including Alzheimer's disease (AD). In our screening system using LPS-activated BV2 microglial cells, the methanolic extract of Disporum viridescens leaves was found to have significant NO inhibitory activity. Bioactivity-guided isolation yielded a new phenylpropanoid characterized as 4-ally-2,6-dimethoxyphenyl 1-O-ß-D-apiofuranosyl (1→6)-ß-D-glucopyranoside (12) with 21 known compounds from the leaves of D. viridescens. Among them, compounds 2 and 4 significantly inhibited NO production. Thus, we further elucidated the anti-inflammatory mechanism of these lignans. Especially, compound 4 inhibited the expression of both inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) through the suppression of the MAPK signaling pathway. Taken together, the anti-inflammatory activities of the active constituents isolated from D. viridescens leaves could have therapeutic potential against neurodegenerative diseases.

The fungus Colletotrichum as a source for bioactive secondary metabolites.

Colletotrichum sp. is a widely distributed fungal genus, which is mainly known to cause anthracnose on cereals, legumes, fruit trees, and vegetables. Even though many of the Colletotrichum sp. are plant pathogens, a variety of secondary metabolites with diverse bioactivities have been reported to be produced by this fungus. At least 109 secondary metabolites from the fungus Colletotrichum have been reported to date. They mostly include nitrogen-containing metabolites, sterols, terpenes, pyrones, phenolics, and fatty acids. Herein, the authors review the structurally interesting secondary metabolites produced by Colletotrichum and their biological activities.

Bioactive secondary metabolites from an endophytic fungus Phoma sp. PF2 derived from Artemisia princeps Pamp.

Two new isochromanone derivatives, (3S,4S)-3,8-dihydroxy-6-methoxy-3,4,5-trimethylisochroman-1-one (1) and methyl (S)-8-hydroxy-6-methoxy-5-methyl-4a-(3-oxobutan-2-yl)benzoate (2), together with six known compounds (3‒8) were isolated from the cultures of an endophytic fungus Phoma sp. PF2 obtained from Artemisia princeps. The chemical structures of the isolated compounds were elucidated by interpretation of spectroscopic data (1D, 2D NMR, HRESIMS, and CD) and calculation of ECD. All the isolated compounds (1‒8) showed moderate inhibitory activities on nitric oxide levels in lipopolysaccharide-induced RAW264.7 machrophage cells.

Chromones with lipoprotein oxidation inhibitory activity from an endophytic fungus Alternaria brassicae JS959 derived from Vitex rotundifolia.

Chemical investigation of the ethyl acetate extract of an endophytic fungus, Alternaria brassicae JS959 derived from a halophyte, Vitex rotundifolia, led to the isolation of a new chromone, (2'S)-2-(2-acetoxypropyl)-7-hydroxy-5-methylchromone (1), along with sixteen known compounds: a chromone (2), twelve benzopyranones (3-14) and three perylenequinones (15-17). The chemical structures of the isolated compounds were identified by extensive spectroscopic data analysis including 1D, 2D NMR, HRESIMS, and optical rotation. Of these compounds, 1 and 2 showed inhibitory activity on Cu2+‒induced low density lipoprotein (LDL) and high density lipoprotein (HDL) oxidation in human blood plasma. The results suggest that metabolites of endophytic microbes could provide the basis for developing treatments for heart disease.

Hepatoprotective Flavonoids in Opuntia ficus-indica Fruits by Reducing Oxidative Stress in Primary Rat Hepatocytes.

BACKGROUND: Liver disorder was associated with alcohol consumption caused by hepatic cellular damages. Opuntia ficus-indica fruit extracts (OFIEs), which contain betalain pigments and polyphenols including flavonoids, have been introduced as reducing hangover symptoms and liver protective activity. OBJECTIVE: To evaluate hepatoprotective activity of OFIEs and isolated compounds by high-speed countercurrent chromatography (HSCCC). MATERIALS AND METHODS: The extract of O. ficus-indica fruits was fractionated into methylene chloride and n-butanol. The n-butanol fraction was isolated by HSCCC separation (methylene chloride-methanol-n-butanol-water, 5:4:3:5, v/v/v/v). The hepatoprotective activity of OFIEs and isolated compounds was evaluated on rat primary hepatocytes against ethanol-induced toxicity. Antioxidative parameters such as glutathione reductase and glutathione peroxidase (GSH-Px) enzymes and the GSH content were measured. RESULTS: Two flavonoids, quercetin 3-O-methyl ester (1) and (+)-taxifolin, and two flavonoid glycosides, isorhamnetin 3-O-ß-d-glucoside (3) and narcissin (4), were isolated from the n-butanol fraction by HSCCC separation. Among them, compound 2 significantly protected rat primary hepatocytes against ethanol exposure by preserving antioxidative properties of GR and GSH-Px. CONCLUSIONS: OFIEs and (+)-taxifolin were suggested to reduce hepatic damage by alcoholic oxidative stress. SUMMARY: Hepatoprotective Flavonoids were isolated from Opuntia ficus-indica by high -speed countercurrent chromatography (HSCCC).

Ceanothane- and lupane-type triterpene esters from the roots of Hovenia dulcis and their antiproliferative activity on HSC-T6 cells.

Three ceanothane-type and three lupane-type triterpenoids, as well as three known compounds, were isolated from the roots of Hovenia dulcis (Rhamnaceae), based on LC-MS dereplication. The previously undescribed compounds were determined to be 27-O-protocatechuoyl-3-dehydroxyisoceanothanolic acid, 27-O-protocatechuoyl-3-dehydroxycolubrinic acid, 27-O-protocatechuoyl-3-dehydroxyepicolubrinic acid, 27-O-protocatechuoylbetulinic acid, 27-O-p-hydroxybenzoylbetulinic acid, and 27-O-syringoylbetulinic acid by 1D and 2D NMR spectroscopic and HR mass spectrometric data analysis. The isolates were examined for their antiproliferative activity in HSC-T6 hepatic stellate cells; compounds 1, 2, 3, and 6 showed IC50 values in the range of 15-50 µM.

Hepatoprotective constituents of Firmiana simplex stem bark against ethanol insult to primary rat hepatocytes.

BACKGROUND: Ethanol causes hepatic cellular damage by alterations in biological functions. This study evaluated the hepatoprotective potential of the methanolic extract originating from Firmiana simplex (Sterculiaceae) stem bark against the ethanol-induced hepatotoxicity in rat primary hepatocytes. MATERIALS AND METHODS: The extract of F. simplex stem bark was successively fractionated into n-hexane, chloroform, ethyl acetate (EtOAc), and n-butanol. Column chromatography with silica gel and sephadex LH-20 was used to isolate the EtOAc fraction. Rat primary hepatocytes were cultured to study the hepatoprotective activity of isolated substances against ethanol-induced toxicity. Intracellular reactive oxygen species (ROS) levels, the antioxidant activities of glutathione reductase (GR) and glutathione peroxidase (GSH-PX) enzymes, and the GSH content were measured to examine the antioxidative property of the isolated compounds. RESULTS: Two flavonoid glycosides, quercitrin (1) and tamarixetin 3-O-rhamnopyranoside (2), were isolated from the active EtOAc fraction. Compound 1 significantly protected rat primary hepatocytes against ethanol-induced oxidative stress by reducing the intracellular ROS level and preserving antioxidative defense systems such as GR, GSH-PX, and total GSH. CONCLUSION: This is the first report on the hepatoprotective activities of the extract of F. simplex. The EtOAc fraction of F. simplex stem bark and its major constituent quercitrin (1) could function as hepatoprotective agents to attenuate the development of alcoholic liver disease.

Prickly pear cactus (Opuntia ficus indica var. saboten) protects against stress-induced acute gastric lesions in rats.

The protective activity of prickly pear cactus (Opuntia ficus indica var. saboten) fruit juice and its main constituent, betanin, were evaluated against stress-induced acute gastric lesions in rats. After 6 h of water immersion restraint stress (WIRS), gastric mucosal lesions with bleeding were induced in Sprague-Dawley rats. Pretreatment of a lyophilized powder containing O. ficus indica var. saboten fruit juice and maltodextrin (OFSM) and betanin significantly reduced stress lesions (800-1600 mg/kg). Both OFSM and betanin effectively prevented the decrease in gastric mucus content as detected by alcian blue staining. In addition, OFSM significantly suppressed WIRS-induced increases in the level of gastric mucosal tumor necrosis factor-α and myeloperoxidase (MPO). Betanin alone was only effective in decreasing MPO. These results revealed the protective activity of OFSM against stress-induced acute gastric lesions and that betanin may contribute to OFSM's gastric protective activity, at least in part. When OFSM and betanin were taken together, OFSM exerted gastroprotective activity against stress-induced gastric lesions by maintaining gastric mucus, which might be related to the attenuation of MPO-mediated damage and proinflammatory cytokine production.