Guang-Xiong Zhou

Quassidines A−D, Bis-β-carboline Alkaloids from the Stems of Picrasma quassioides

Four new bis-beta-carboline alkaloids, quassidines A-D (1-4), together with a known alkaloid, picrasidine C (5), were isolated from the stems of Picrasma quassioides. Quassidine A (1) is the first reported bis-beta-carboline alkaloid possessing a novel cyclobutane moiety. The structures of the new compounds were determined on the basis of their 1D and 2D NMR and X-ray diffraction data. A possible biogenetic pathway for these alkaloids was proposed, and all compounds were evaluated for anti-inflammatory activity. Only quassidine A (1) showed weak activity.

An acetyl flavonol from Nervilia fordii (Hance) Schltr

A new acetyl flavonol, named 3-O-acetyl-7-O-methyl kaemferol (1), together with the five known compounds rhamnocitrin (2), rhamnocitrin-3-O-β-d-glucoside (3), rhamnocitrin-4′-β-d-glucoside (4), rhamnazin (5), and p-hydroxyl benzoic acid (6) was isolated from Nervilia fordii (Hance) Schltr. The structures of the compounds were determined by spectroscopic analysis. All the compounds were evaluated against nitric oxide (NO) release, based on the production of NO in mice RAW264.7 stimulated by lipopolysaccharide (LPS). This new compound (1) showed potent inhibitory activity against the production of NO in RAW264.7 stimulated by LPS with the IC50 value of 16.79 μM.

A New Neolignan and a New Sesterterpenoid from the Stems of Picrasma quassioidesBennet

A new dihydrobenzofuran‐type neolignan, picrasmalignan A (1), and a new sesterterpene lactone, 2′‐isopicrasin A (4), were isolated from the stems of Picrasma quassioides Bennet, along with four known compounds, comprising two neolignans, 2 and 3, a sesterterpene lactone, 5, and a flavonol, 6. The structures of these compounds were determined by detailed analysis of NMR and MS data, and comparison with the literature data. Compounds 1–6 were tested for their anti‐inflammatory activity, and 1–3 and 6 showed potent inhibitory activities on nitric oxide, tumor necrosis factor‐α, and interleukin‐6 production in mouse monocyte‐macrophage RAW 264.7 stimulated by lipopolysaccharide (LPS).

Three polyoxygenated cyclohexenes from Uvaria calamistrata

Three new polyoxygenated cyclohexenes, named uvacanols F, G, H (1–3), were isolated from the roots of Uvaria calamistrata (Annonaceae). Their structures were determined to be 2-acetoxyl-5-chlorine-benzoyloxymethylcyclohex-1 (6)-ene-4-ol-3-benzoate (1), benzoyloxy-methylcyclohex-1 (6)-ene-2,3,4-triols-5-benzoate (2), 3-acetoxyl-benzoyloxymethylcyclohex-1 (6)-ene-4,5-diols-2-benzoate (3) by spectroscopic methods and chemical derivatization.

Manoalide derivatives from a sponge, Luffariella sp.

A new derivative of manoalide, 24-n-propyl-O-manoalide (1) together with manoalide (4) and four known derivatives (2, 3, 5, 6) were isolated from the methanolic extract of a sponge. Their structures were elucidated on the basis of spectroscopic method. All the compounds showed significant cytotoxicity against HCT-116 cell line by MTS assay. Secomanoalide indicated antifungal activity on fungal lines Candida glabrata, Candida krusei and Candida albicans by in vitro antibiotic assay.

Secondary metabolites from marine-derived Streptomyces antibioticus strain H74-21

Abstract A new secondary metabolite, (2S,3R)-l-threonine, N-[3-(formylamino)-2-hydroxybenzoyl]-ethyl ester (streptomyceamide C, 1), together with four known compounds 1, 4-dimethyl-3-isopropyl-2,5-piperidinedione (2), cyclo-((S)-Pro-8- hydroxy-(R)-Ile (3), cyclo-((S)-Pro-(R)-Leu (4), and seco-((S)-Pro-(R)-Val) (5), were isolated from the EtOH extract of the fermented mycelium of the marine-derived streptomycete strain H74-21, which was isolated from sea sediment in a mangrove site. The structure of the new compound was established on the basis of its spectroscopic data, including 1D and 2D NMR, HR-TOF-MS. Their antifungal activities against Candida albicans and cytotoxicities against human breast adenocarcinoma cell line MCF-7, human glioblastoma cell line SF-268 and human lung cancer cell line NCI-H460 were tested. Compounds 1 only displayed cytotoxicity against human breast adenocarcinoma cell line MCF-7 with the IC50 value of 27.0 μg/mL. However, compounds 1–5 do not show antifungal activities at the test concentration of 1 mg/mL, and 2–5 have no cytotoxicities at the test concentration of 50 μg/mL.

New Polyoxygenated Cyclohexenes fromUvaria Calamistrata

Five new polyoxygenated cyclohexenes, named uvacalol A (1), B (2), C (3), D (4) and E (5) were isolated from the roots of Uvaria calamistrata. On the basis of spectral analysis and chemical derivatization, including the preparation of Mosher esters, the structures of compound 1-5 were established as (2R,3S,4R,5S)-2-acetoxyl-5-ethoxyl-1-benzoyloxymethylcyclohex-1(6)-ene3,4-diol-3-benzoate, (2R,3S,4R,5S)-2-acetoxyl-5-ethoxyl-1-benzoyloxymethylcyclohex-1(6)-ene-3,4-diol-4-benzoate, (2R,3S,4R,5S)-5-ethoxyl-1-benzoyloxymethylcyclohex-1(6)-ene-2,3,4-triol-3-benzoate, (2R,3S,4R,5S)-3-methoxyl-1-benzoyloxymethylcyclohex-1(6)-ene-2,3,5-triol and (2R,3S,4R,5S)-2-acetoxyl-1-benzoyloxymethylcyclohex-1(6)-ene-3,4,5-triol-5-benzoate, respectively.

EM23, A Natural Sesquiterpene Lactone from Elephantopus mollis, Induces Apoptosis in Human Myeloid Leukemia Cells through Thioredoxin- and Reactive Oxygen Species-Mediated Signaling Pathways.

Elephantopus mollis (EM) is a traditional herbal medicine with multiple pharmacological activities. However, the efficacy of EM in treating human leukemia is currently unknown. In the current study, we report that EM23, a natural sesquiterpene lactone isolated from EM, inhibits the proliferation of human chronic myeloid leukemia (CML) K562 cells and acute myeloid leukemia (AML) HL-60 cells by inducing apoptosis. Translocation of membrane-associated phospholipid phosphatidylserines, changes in cell morphology, activation of caspases, and cleavage of PARP were concomitant with this inhibition. The involvement of the mitochondrial pathway in EM23-mediated apoptosis was suggested by observed disruptions in mitochondrial membrane potential. Mechanistic studies indicated that EM23 caused a marked increase in the level of reactive oxygen species (ROS). Pretreatment with N-acetyl-L-cysteine, a ROS scavenger, almost fully reversed EM23-mediated apoptosis. In EM23-treated cells, the expression levels of thioredoxin (Trx) and thioredoxinreductase (TrxR), two components of the Trx system involved in maintaining cellular redox homeostasis, were significantly down-regulated. Concomitantly, Trx regulated the activation of apoptosis signal-regulating kinase 1 (ASK1) and its downstream regulatory targets, the p38, JNK, and ERK MAPKs. EM23-mediated activation of ASK1/MAPKs was significantly inhibited in the presence of NAC. Furthermore, tumor necrosis factor alpha (TNF-α)-mediated activation of nuclear factor-κB (NF-κB) was suppressed by EM23, as suggested by the observed blockage of p65 nuclear translocation, phosphorylation, and reversion of IκBα degradation following EM23 treatment. Taken together, these results provide important insights into the anticancer activities of the EM component EM23 against human CML K562 cells and AML HL-60 cells.

A new triterpenoid from the fruits of Gardenia jasminoides var. radicans Makino

A novel triterpenoid 3α,16β,23,24-tetrahydroxy-28-nor-ursane-12,17,19,21-tetraen (1) was isolated from the fruits of Gardenia jasminoides var. radicans Makino. The structure of the new compounds was elucidated on the basis of spectroscopic analysis including MS and NMR data. Compound 1 was in vitro tested for cytostatic activity on human throat cancer (Hep-2) cell line by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide method and showed mild anticancer activity with the IC50 of 31.2 μM.

A new biflavonoid with antiviral activity from the roots of Wikstroemia indica

A new biflavonoid, 4′-methoxydaphnodorin E, was isolated from the antiviral fraction of Wikstroemia indica against respiratory syncytial virus (RSV). Its structure was determined on the basis of extensive spectroscopic data including HR-ESI-MS and 2D NMR. The biflavonoid was tested for its in vitro anti-RSV activity with cytopathic effect (CPE) reduction assay, and displayed potent effect with 50% inhibitory concentration (IC50) value of 2.8 μM and selective index (SI) value of 5.4.