Eutypellaolides A-J, Sesquiterpene diversity expansion of the polar fungus Eutypella sp. D-1

Eight new 12,8-eudesmanolide sesquiterpenes, eutypellaolides A-H (1-8), and two new eudesmane-type sesquiterpenes, eutypellaolides I-J (9-10), along with four known 12,8-eudesmanolide compounds 11-14, were isolated from the culture extract of the polar fungus Eutypella sp. D-1 by one strain many compounds (OSMAC) approach. The structures of these compounds were determined through comprehensive spectroscopic data and experimental and calculated ECD analysis. Antibacterial, immunosuppressive, and PTP1B inhibition activities of these compounds were evaluated. Compounds 1 and 11 exhibited strong inhibitory activities against Bacillus subtilis and Staphylococcus aureus, with each showing an MIC value of 2 μg/mL. Compound 9 displayed weak immunosuppressive activity against ConA-induced T-cell proliferation with an inhibitory rate of 61.7% at a concentration of 19.8 μM. Compounds 5, 11, and 14 exhibited weak PTP1B inhibition activities with IC50 values of 44.8, 43.2, and 49.5 μM, respectively.

Phyllofenones F-M, Scalarane Sesterterpenes from the Marine Sponge Phyllospongia foliascens

Eight new scalarane sesterterpenes, phyllofenones F-M (1-8), together with two known analogues, carteriofenones B and A (9-10), were isolated from the marine sponge Phyllospongia foliascens collected from the South China Sea. The structures of these compounds were determined based on extensive spectroscopic and quantum chemical calculation analysis. The antibacterial and cytotoxic activity of these compounds was evaluated. Among them, only compounds 4 and 6 displayed weak inhibitory activity against Staphylococcus aureus and Escherichia coli, with MIC values of 16 μg/mL and 8 μg/mL, respectively. Compounds 1-10 exhibited cytotoxic activity against the HeLa, HCT-116, H460, and SW1990 cancer cell lines, with IC50 values ranging from 3.4 to 19.8 μM.

Cytosporin Derivatives from Arctic-Derived Fungus Eutypella sp. D-1 via the OSMAC Approach

A chemical investigation of the Arctic-derived fungus Eutypella sp. D-1 based on the OSMAC (one strain many compounds) approach resulted in the isolation of five cytosporin polyketides (compounds 1-3 and 11-12) from rice medium and eight cytosporins (compounds 2 and 4-11) from solid defined medium. The structures of the seven new compounds, eutypelleudesmane A (1), cytosporin Y (2), cytosporin Z (3), cytosporin Y₁ (4), cytosporin Y₂ (5), cytosporin Y₃ (6), and cytosporin E₁ (7), were elucidated by analyzing their detailed spectroscopic data. Structurally, cytosporin Y₁ (4) may be a key intermediate in the biosynthesis of the isolated cytosporins, rather than an end product. Compound 1 contained a unique skeleton formed by the ester linkage of two moieties, cytosporin F (12) and the eudesmane-type sesquiterpene dihydroalanto glycol. Additionally, the occurrence of cyclic carbonate moieties in compounds 6 and 7 was found to be rare in nature. The antibacterial, immunosuppressive, and cytotoxic activities of all compounds derived from Eutypella sp. D-1 were evaluated. Unfortunately, only compounds 3, 6, 8, and 10-11 displayed immunosuppressive activity, with inhibitory rates of 62.9%, 59.5%, 67.8%, 55.8%, and 68.7%, respectively, at a concentration of 5 μg/mL.

Phyllospongianes A-E, Dinorscalarane Sesterterpenes from the Marine Sponge Phyllospongia foliascens

Phyllospongianes A-E (1-5), five new scalarane derivatives featuring an unprecedented 6/6/6/5 tetracyclic dinorscalarane scaffold, along with the known probable biogenetic precursor, 12-deacetylscalaradial (6), were isolated from the marine sponge Phyllospongia foliascens. The structures of the isolated compounds were determined by analysis of spectroscopic data and electronic circular dichroism experiments. Compounds 1-5 are the first 6/6/6/5 tetracyclic scalarane derivatives to be reported within the scalarane family. Compounds 1, 2, and 4 exhibited antibacterial activity against Vibrio vulnificus, Vibrio parahemolyticus, Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, and Pseudomonas aeruginosa with MIC values ranging from 1 to 8 μg/mL. Furthermore, compound 3 exhibited significant cytotoxic activity on MDA-MB-231, HepG2, C4-2-ENZ, MCF-7, H460, and HT-29 cancer cell lines with IC₅₀ values in the range between 0.7 and 13.2 μM.

Quality by design driven development and evaluation of thermosensitive hydrogel loaded with IgY and LL37-SLNs to combat experimental periodontitis

Egg yolk immunoglobulin (IgY) and LL37, potent antibacterial substances, can fight against periodontitis. This work aimed to develop a locally injectable hydrogel for potential co-delivery of special IgY and LL37-loaded solid lipid nanoparticles (LL37-SLNs) to synergistically inhibit the proliferation of oral pathogens, thus relieving periodontal inflammation and redness. The formulation of thermosensitive hydrogel loaded with IgY and LL37-SLNs was developed by adopting the Quality by Design approach. Then the formulations were optimized by two-factor three-level full factorial design by Design-Expert software. Finally, the optimized formulation was characterized and estimated in vitro and in vivo. In vitro release and antibacterial activity studies have revealed that the optimized formulation was homogeneous and can be released slowly, with sustainably antibacterial power. And the physical and chemical composition analysis and morphological observations further confirmed the sustained-release capability. On the other hand, in vivo studies proved that the optimized formulation significantly decreased gingival redness, bleeding, and plaque formation, avoided excessive resorption of alveolar bone, and reduced the levels of inflammatory factor in periodontitis rats. In conclusion, the optimized thermosensitive hydrogel loaded with IgY and LL37-SLNs may be a promising local sustained-release preparation for the effective treatment of periodontal diseases.

Bioactive Scalarane-Type Sesterterpenoids from Marine Sources

Scalarane-type sesterterpenoids have received considerable attention in the scientific literature due to their diverse carbon skeletons and various biological activities and pharmacological properties. Among all these derivatives are commonly isolated from marine sponges and are occasionally derived from shell-less mollusks, such as nudibranchs. This review comprehensively discusses the marine-derived natural sources that give rise to these scalarane-type sesterterpenoids, providing the names, their chemical structures, biological properties, with emphasis on anticancer activity and literature references related to these metabolites. A critical summary of the 221 compounds generated from January 2010 up to December 2021 for their potential as anticancer agents is presented.

Palitantin derivatives from the Antarctic fungus Geomyces sp. 3-1

Two new polyketides, palitantins B and C (1 and 2), along with one known related compound (+)-palitantin (3) were obtained from the culture of the Antarctic fungus Geomyces sp. 3-1. The structures of the new compounds were elucidated by detailed analysis of HRESIMS, NMR, CD, and ECD data. Compound 3 showed potent PTP1B inhibitory activity with an IC₅₀ value of 7.9 μM (ursolic acid as positive control, IC₅₀ = 8.3 μM).

Eutypellacytosporins A-D, Meroterpenoids from the Arctic Fungus Eutypella sp. D-1

The Arctic fungus Eutypella sp. D-1, previously found to produce a variety of cytotoxic cyclopropyl-fused and cyclobutyl-fused pimarane diterpenoids when grown in the defined medium, was induced to produce unusual metabolites by growing on solid rice medium. A chemical investigation on the rice medium extract led to the isolation of four new meroterpenoids, eutypellacytosporins A-D (1-4), along with the known biogenetically related compound cytosporin D (5). The structures of the new compounds were elucidated by their detailed spectroscopic analysis and modified Mosher's method. Compounds 1-4 may be formed by the 12,32-ester linkage of two moieties, cytosporin D (5) and decipienolide A or B. All isolated compounds, except 5, showed weak cytotoxicity against DU145, SW1990, Huh7, and PANC-1 cell lines with IC₅₀ values ranging from 4.9 to 17.1 μM.

Cytotoxic Microcolin Lipopeptides from the Marine Cyanobacterium Moorea producens

Nine new linear lipopeptides, microcolins E-M (1-9), together with four known related compounds, microcolins A-D (10-13), were isolated from the marine cyanobacterium Moorea producens using bioassay-guided and LC-MS/MS molecular networking approaches. Catalytic hydrogenation of microcolins A-D (10-13) yielded two known compounds, 3,4-dihydromicrocolins A and B (14, 15), and two new derivatives, 3,4-dihydromicrocolins C and D (16, 17), respectively. The structures of these new compounds were determined by a combination of spectroscopic and advanced Marfey's analysis. Structurally unusual amino acid units, 4-methyl-2-(methylamino)pent-3-enoic (Mpe) acid and 2-amino-4-methylhexanoic acid (N-Me-homoisoleucine), in compounds 1-3 and 8, respectively, are rare residues in naturally occurring peptides. These metabolites showed significant cytotoxic activity against H-460 human lung cancer cells with IC₅₀ values ranging from 6 nM to 5.0 μM. The variations in structure and attendant biological activities provided fresh insights concerning structure-activity relationships for the microcolin class of lipopeptides.

Furanone derivative and sesquiterpene from Antarctic marine-derived fungus Penicillium sp. S-1-18

A new furanone derivative, butanolide A (1), and a new sesquiterpene, guignarderemophilane F (2), together with six known compounds, were isolated from the fungus Penicillium sp. S-1-18 derived from Antarctic marine. The new structures were determined by spectroscopic studies such as 1D- and 2D-NMR and MS analyses. The absolute configuration of 1 was determined by the modified Mosher's method, while the absolute configuration of 2 was determined by calculated ECD spectroscopy. The isolated secondary metabolites were evaluated for their protein tyrosine phosphatase 1B (PTP1B) inhibitory activity. Compound 1 showed moderate inhibitory activity against PTP1B with IC₅₀ value of 27.4 μM.

Libertellenones O-S and Eutypellenones A and B, Pimarane Diterpene Derivatives from the Arctic Fungus Eutypella sp. D-1

Seven new pimarane-type diterpene derivatives, libertellenones O-S (1-5) and eutypellenones A and B (6 and 7), together with two known compounds (8 and 9), were isolated from the culture of Eutypella sp. D-1 obtained from high-latitude soil of the Arctic. Their structures were elucidated from spectroscopic data, as well as experimental and calculated electronic circular dichroism (ECD) analysis. Structurally, compounds 1-5 possess a cyclopropyl-fused pimarane diterpene moiety, whereas compounds 6 and 7 share an unusual cyclobutyl-fused pimarane diterpene skeleton. Compounds 1-9 exhibited cytotoxicities against HeLa, MCF-7, HCT-116, PANC-1, and SW1990 cells, with IC₅₀ values in the range of 0.3 to 29.4 μM. Compounds 6 and 7 could dose-dependently inhibit the activity of NF-κB and exhibited significantly inhibitory effects on nitric oxide production induced by lipopolysaccharide.

Biotransformation of total coumarins of Radix Glehniae by Lecanicillium attenuatum W-1-9

The biotransformation of total coumarins of Radix Glehniae by Lecanicillium attenuatum W-1-9 yielded three new products, lecaniside A (1), lecaniside B (2), and lecaniside C (3). The chemical structures of these metabolites were elucidated based on extensive spectral data, including 2D NMR and HRMS. The hydrogenation, dealkylation, glycosylation, and O-methylation reactions of these metabolites were observed in the present study. In the in vitro assays, compound 1 displayed a little PTP1B inhibitory activity.

Marine Antibody-Drug Conjugates: Design Strategies and Research Progress

Antibody-drug conjugates (ADCs), constructed with monoclonal antibodies (mAbs), linkers, and natural cytotoxins, are innovative drugs developed for oncotherapy. Owing to the distinctive advantages of both chemotherapy drugs and antibody drugs, ADCs have obtained enormous success during the past several years. The development of highly specific antibodies, novel marine toxins' applications, and innovative linker technologies all accelerate the rapid R&D of ADCs. Meanwhile, some challenges remain to be solved for future ADCs. For instance, varieties of site-specific conjugation have been proposed for solving the inhomogeneity of DARs (Drug Antibody Ratios). In this review, the usages of various natural toxins, especially marine cytotoxins, and the development strategies for ADCs in the past decade are summarized. Representative ADCs with marine cytotoxins in the pipeline are introduced and characterized with their new features, while perspective comments for future ADCs are proposed.

Crystal structure of (R)-1-(2,3-dihydro-1H-pyrrolizin-5-yl)-2,3-dihydroxypropan-1-one, C10H13NO3

C10H13NO3, monoclinic, P21 (no. 4), a = 11.8118(5) Å, b = 4.9299(2) Å, c = 14.5436(7) Å, β = 89.011(3)°, V = 945.28(7) Å3, Z = 4, R gt(F) = 0.0302, wR ref(F 2) = 0.0774, T = 170 K.

Loss of function of Notch1 identifies a poor prognosis group of early stage hepatocellular carcinoma following hepatectomy

Notch1 has previously been implicated in the carcinogenesis of hepatocellular carcinoma (HCC). The present study aimed to investigate the prognostic value of Notch1 in early stage HCC patients after hepatectomy. The differential expression of Notch1 in paired tumor and non-tumorous tissue was evaluated by RT-PCR, western blotting and immunohistochemistry. The correlation between Notch1 expression and the surgical outcome of patients at BCLC stage 0/A and its ≤5 cm subgroup was retrospectively investigated in 206 patients from the Eastern Hepatobiliary Surgery Hospital (training cohort), and prospectively validated in 185 patients from the same center and retrospectively verified in 129 patients from the Fujian Medical University (validation cohort 1 and 2, respectively). Compared with paired non-tumorous tissues, loss of Notch1 was observed in tumor tissue. Patients with normal Notch1 had better prognosis than those with loss of Notch1 in the training cohort and ≤5 cm subgroup (time to recurrence: 38.5±6.1 vs. 16.0±3.2 months, P<0.001 and 53.0±6.1 vs. 21.7±3.5 months, P=0.004; 1-, 3-, 5-year survival rates: 91, 64 and 49% vs. 73, 31 and 22%, P<0.001 and 93, 71, 57% vs. 76, 39, 24%, P<0.001). Notch1 expression was an independent factor for recurrence and survival (hazard ratio: 1.901, 2.154; 2.038 and 2.337). Moreover, Notch1 status affected early tumor recurrence, as the 2-year recurrence rate was 61.2 vs. 26.9% (P<0.001) and 51.2 vs. 21.3% (P=0.002) in tumors with reduced or increased Notch1 expression in this cohort and subgroup. These results were fully confirmed by the study in our prospective and retrospective validation cohorts. The status of Notch1 is useful for predicting the prognosis of patients with early stage HCC undergoing hepatectomy.

A saxitoxin-binding aptamer with higher affinity and inhibitory activity optimized by rational site-directed mutagenesis and truncation

Saxitoxin (STX), a member of the family of paralytic shellfish poisoning toxins, poses toxicological and ecotoxicological risks. To develop an analytical recognition element for STX, a DNA aptamer (APT(STX1)) was previously discovered via an iterative process known as Systematic Evolution of Ligands by Exponential Enrichment (SELEX) by Handy et al. Our study focused on generating an improved aptamer based on APT(STX1) through rational site-directed mutation and truncation. In this study, we generated the aptamer, M-30f, with a 30-fold higher affinity for STX compared with APT(STX1). The Kd value for M-30f was 133 nM, which was calculated by Bio-Layer Interferometry. After optimization, we detected and compared the interaction of STX with aptamers (APT(STX1) or M-30f) through several techniques (ELISA, cell bioassay, and mouse bioassay). Both aptamers' STX-binding ability was demonstrated in all three methods. Moreover, M-30f performs better than its parent sequence with higher suppressive activity against STX. As a molecular recognition element, M-30f has good prospects for practical application.

Traditional Chinese medicine--sea urchin

The sea urchin is an ancient, common, seafloor-dwelling marine invertebrate that belongs to the phylum Echinodermata. There are multiple species of sea urchin with resources that are widely distributed in China, where they were used in ancient times as Traditional Chinese Medicine for treating a variety of diseases. At present, it is known that the shell, spine and gonad of the sea urchin have many medicinal values determined through modern research. In this paper, we summarized the major chemical constituents and medicinal value of the sea urchin.

A new aromatic glycoside from Glehnia littoralis

A new aromatic glycoside (1) was isolated from the roots of Glehnia littoralis Fr. Schmidtex Miq. Its structure was elucidated as vanillic acid 1-O-[β-D-apiofuranosyl-(1 → 6)-β-D-glucopyranoside] ester mainly by analysing the NMR and MS spectral data. In the in vitro assays, compound 1 displayed some TNF-α secretion inhibitory activity.

S5a binds death receptor-6 to induce THP-1 monocytes differentiation via NF-κB pathway

Analyses of apoptotic cell supernatants have helped identify many signals that modulate the states of activation and differentiation in the congeneric or other cells. However, the current knowledge about these soluble factors that are released during apoptosis is rather limited. Previous studies have shown that S5a/Angiocidin induced human acute monocytic leukemia cells (THP-1 cells) to differentiation into macrophages, but the cell surface receptor of S5a has not been identified. In this study we show that apoptotic THP-1 cells released endogenous S5a, and S5a bound with death receptor-6, which was identified as an orphan receptor, to induce THP-1 cells differentiation. Furthermore, we found NF-κB pathway was activated and the transcription factor WT1 and c-myb mediated THP-1 differentiation induced by S5a. And we also show that the differentiation was blocked after anti-DR6 antibody, DR6 siRNA, DR6-Fc, NF-κB inhibitor, or WT1 siRNA treatment. Our finding indicated that the interaction between cells can determine their destination. And we provided evidence for a functional interaction between S5a and DR6, which provides a novel target that can induce the differentiation of cancer cells especially for biotherapy of leukemia.

Targeted induction of apoptosis in glioblastoma multiforme cells by an MRP3-specific TRAIL fusion protein in vitro

Single-chain Fv fragments (scFvs) consist of the variable heavy-chain (VH) and variable light-chain (VL) domains, which are the smallest immunoglobulin fragments containing the whole antigen-binding site. Human soluble tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) proves to acquire a potent pro-apoptotic activity only after selective binding to a predefined tumor cell surface antigen and has no off-target effects towards normal cells. Glioblastoma multiforme (GBM) is the most frequent and aggressive type of brain tumor and overexpresses human multidrug resistance protein 3 (MRP3). In this study, we designed a novel fusion protein, termed scFvM58-sTRAIL, in which the MRP3-specific scFv antibody M58 was genetically fused to the N-terminus of human soluble TRAIL (sTRAIL). The recombinant scFvM58-sTRAIL fusion protein, expressed in Escherichia coli, was purified by chromatography and tested for cytotoxicity. scFvM58-sTRAIL showed a significant apoptosis-inducing activity towards MRP3-positive GBM cells in vitro. The pro-apoptotic activity of scFvM58-sTRAIL towards GBM cells was strongly inhibited in the presence of the parental scFvM58 antibody, suggesting that cytotoxic activity is MRP3-restricted. In a control experiment with MRP3-negative Jurkat cells, scFvM58-sTRAIL did not induce apparent apoptosis. In addition, through target antigen-restricted binding, scFvM58-sTRAIL was capable of activating not only TRAIL-R1 but also TRAIL-R2. In conclusion, our results suggest that fusion protein scFvM58-sTRAIL with specificity for MRP3 is a highly selective therapeutic agent and may provide an alternative therapy for human GBM.

Bioactive natural products from the antarctic and arctic organisms

Polar regions are remote and challenging areas on the earth. In view of the unique environment and the severe competition in polar regions, it's considered that the ecological system might be the producer of new compounds with diversity biological activities. This review is an attempt to consolidate the studies about 97 natural products isolated from Antarctic and Arctic organisms including microbes, algae, sponges, bryozoans, and tunicates and so on published in the recent years. The emphasis is mainly about the new compounds, source organisms and biological activities, which signifies the immense competence of Antarctic and Arctic organisms as bioactive natural products producers.

A novel cold-adapted β-galactosidase isolated from Halomonas sp. S62: gene cloning, purification and enzymatic characterization

A novel 1,170 bp β-galactosidase gene sequence from Halomonas sp. S62 (BGalH) was identified through whole genome sequencing and was submitted to GenBank (Accession No. JQ337961). The BGalH gene was heterologously expressed in Escherichia coli BL21(DE3) cells, and the enzymatic properties of recombinant BGalH were studied. According to the polyacrylamide gel electrophoresis results and the sequence alignment analysis, BGalH is a dimeric protein and cannot be classified into one of the known β-galactosidase families (GH1, GH2, GH35, GH42). The optimal pH and temperature were determined to be 7.0 and 45 °C, respectively; the K m and K cat were 2.9 mM and 390.3 s(-1), respectively, for the reaction with the substrate ortho-nitrophenyl-β-D-galactopyranoside. At 0-20 °C, BGalH exhibited 50-70 % activity relative to its activity under the optimal conditions. BGalH was stable over a wide range of pHs (6.0-8.5) after a 1 h incubation (>93 % relative activity) and was thermostable at 50 °C and below (>60 % relative activity). The enzyme hydrolyzes lactose completely in milk over 24 h at 7 °C. The characteristics of this novel β-galactosidase suggest that BGalH may be a good candidate for medical researches and food industry applications.

Quantitative assessment of the association between MTHFR C677T polymorphism and colorectal cancer risk in East Asians

A great number of studies regarding the association between MTHFR C677T polymorphism and risk of colorectal cancer (CRC) in East Asians were published, but the results were inconsistent. Thus, a meta-analysis was performed to investigate the association. PubMed, Embase, and CBM databases were searched for eligible publications. Pooled odds ratios (ORs) with 95 % confidence intervals (95 % CIs) were calculated using random or fixed effect models. Finally, 24 case-control studies with a total of 7,230 CRC cases and 9,285 controls were included. Meta-analyses of a total of 24 studies showed there was a statistically significant association between MTHFR C677T polymorphism and decreased CRC risk in East Asians under four genetic models (T versus C, OR = 0.92, 95 % CI 0.85-0.99; TT versus CC, OR = 0.80, 95 % CI 0.69-0.94; TT versus CT/CC, OR = 0.82, 95 % CI 0.71-0.95; TT/CT versus CC, OR = 0.92, 95 % CI 0.86-0.98). The cumulative meta-analyses for the allele contrast (T versus C), homozygote (TT versus CC), dominant (TT/CT versus CC), and recessive (TT versus CT/CC) models all showed a trend of more obvious association as information accumulated by year. Subgroup analyses by country further identified this association in Korea and Japan. This meta-analysis suggests that MTHFR C677T polymorphism is associated with decreased risk of colorectal cancer in East Asians, and MTHFR 677T variant has a protective effect on colorectal cancer.

Null genotype of glutathione S-transferase Tl contributes to colorectal cancer risk in the Asian population: a meta-analysis

BACKGROUND AND AIM

Previous studies investigating the association between the glutathione S-transferase Tl (GSTT1) null genotype and colorectal cancer (CRC) risk in the Asian population have reported controversial results. Thus, a meta-analysis was performed to clarify the effect of the GSTT1 null genotype on CRC risk in the Asian population.

METHODS

A comprehensive study was conducted, and 12 case-control studies were finally included, involving a total of 4517 CRC cases and 6607 controls. Subgroup analyses were performed by the sample size.

RESULTS

A meta-analysis of all 12 studies showed that the GSTT1 null genotype was significantly associated with an increased CRC risk in the Asian population (odds ratio [OR] = 1.10, 95% confidence interval [CI] = 1.02-1.19, the P-value of the OR [P(OR)] = 0.02, the value of the heterogeneity analysis [I(2)] = 42%). A more obvious association was observed after the heterogeneity was eliminated by excluding one study (OR = 1.15, 95% CI: 1.06-1.25, P(OR) = 0.001, I(2) = 0%). This association was further identified by both subgroup analyses and a sensitivity analysis.

CONCLUSIONS

This meta-analysis suggests that the GSTT1 null genotype contributes to an increased colorectal cancer risk in the Asian population.

Purification and characterization of gigantoxin-4, a new actinoporin from the sea anemone Stichodactyla gigantea

A new Cytolysin, termed as Gigantoxin-4, was isolated from the sea anemone Stichodactyla gigantea and found to be highly homologous with Cytolysin-3 (HMg III) from Heteractis magnifica, RTX-A from Radianthus macrodactylus, and Sticholysin-1 (St I) and Sticholysin-2 (St II) from Stichodactyla helianthus (homology 82%, 86%, 82% and 86% respectively). Its 20 N-terminal residues were identified and the full-length cDNA sequence was obtained by reverse transcription-polymerase chain reaction (RT-PCR). Multiple sequence alignments with other Cytolysins of the actinoporin family clearly indicated that Gigantoxin-4 belongs to this protein family. SDS-PAGE electrophoresis showed that this new actinoporin had a molecular mass of about 19 kDa, and possessed a high hemolytic activity to human erythrocytes (HA₅₀= 40 ng/ml), which was inhibited by pre-incubation with sphingomyelin (SM) or SM-cholesterol mixtures. Our in vivo experiments showed that Gigantoxin-4 had wide toxicity to the rat cardiovascular system and the respiratory system. A concentration of 30μg/kg Gigantoxin-4, i.v. produced a positive inotropic effect on the rat heart although final cardiovascular failure was inevitable, and 60μg/kg Gigantoxin-4 caused respiratory arrest rapidly resulting in rat death. HE staining indicated pathological changes in various organs and tissues after i.v. administration of Gigantoxin-4.

β-D-Glucosyl-(1-4)-α-L-thevetosides of 17β-digitoxigenin from seeds of Cerbera manghas L. induces apoptosis in human hepatocellular carcinoma HepG2 cells

β-D-Glucosyl-(1-4)-α-L-thevetosides of 17β-digitoxigenin (GHSC-73) is a cardiac glycoside isolated from the seeds of Cerbera manghas L. GHSC-73 reduced viability of HepG2 cells in a time- and dose-dependent manner without decreasing the viability of Chang human liver cells and Swiss albino 3T3 fibroblasts, induced efficiently stimulated apoptosis in HepG2 cells as evidenced by DNA fragmentation, annexin V/PI binding assay and DAPI staining. This apoptotic process was accompanied by the activation of the effector caspase-3, the loss of mitochondrial membrane potential (ΔΨ(m)) and translocation of AIF from the mitochondrion to the nucleus in HepG2 cells. In addition, a broad-spectrum caspase inhibitor (z-VAD-fmk) tested in this experiment partially prevent HepG2 cells from GHSC-73-induced cell death, but did not affect translocation of AIF from the mitochondrion to the nucleus after GHSC-73 treatment. Our results firstly show that GHSC-73 inhibits the growth of HepG2 cells through caspase-dependent and -independent apoptosis pathways.

Iridoid glycosides from Saprosma ternatum

Three new iridoid glycosides, epiasperuloside (1), epipaederosidic acid (2), and epipaederoside (3), together with 7 known compounds, were isolated from the 85% ethanol extract of the leaves of Saprosma ternatum Hook. f. Their structures were determined by application of spectroscopic (NMR, MS) and chemical methodologies. The antioxidant activity was evaluated for all isolates in terms of both DPPH and ABTS bioassays. Epiasperuloside (1) showed some antioxidant activity.

Changes in mitochondrial ultrastructure and malondialdehyde level in regenerating liver tissue in rats

AIM: To investigate the role of mitochondria permeability transition (MPT) in liver regeneration.

METHODS: One hundred and five male Sprague-Dawley rats were randomly divided into three groups: partial hepatectomy (PH) group, cyclosporin A (CsA) group and sham-operated (SH) group. Animals in the PH and CsA groups underwent 2/3 partial hepatectomy. Animals in the CsA group were administered CsA before the surgery. The animals in each group were further divided into seven sub-groups. Ultrastructural morphology of mitochondria in remnant liver after PH was determined by electron microscopy. The content of malondialdehyde (MDA) in liver tissue was also measured.

RESULTS: Remarkable changes were observed in the morphology and ultrastructure of the liver mitochondria at 24 h after PH, including conspicuous swelling, increased membrane permeability, reduced number of cristae, and matrix vacuolation. At 72 h, moderate mitochondrial swelling was observed, while, at other time points, mild mitochondrial swelling was seen. Mitochondrial permeability increased at 0, 3 and 6 h in the CsA group, but decreased at 24 and 72 h when compared with the PH group. Similar changes in endoplasmic reticulum were also noted. The content of MDA increased at 3 h after PH, peaked at 24 h, and then decreased and returned to normal level at 120 h. The contents of MDA at all time points in the CsA group were significantly higher than those in the PH group.

CONCLUSION: The changes in mitochondrial ultrastructure and MDA level are closely associated with MPT during live regeneration in rats, especially prominent at 24 h after PH. The changes in mitochondrial ultrastructure and MDA level in liver tissue is possibly related to the initiation of liver regeneration after PH.

Tanghinigenin from seeds of Cerbera manghas L. induces apoptosis in human promyelocytic leukemia HL-60 cells

Tanghinigenin, a cardiac glycoside, is isolated from the seeds of Cerbera manghas L. In this study, we demonstrated that tanghinigenin reduced the viability of human promyelocytic leukemia HL-60 cells in a time- and dose-dependent manner, and efficiently induced apoptosis in HL-60 cells as evidenced by the Annexin V/PI binding assay, DNA fragmentation and AO/EB staining studies. In addition, stimulation of HL-60 cells with tanghinigenin induced a series of intracellular events including the activation of caspase-3, -8, and -9, as well as up-regulation of Fas and FasL protein level. Taken together, caspase activation and Fas/FasL interaction was found to be involved in tanghinigenin-induced HL-60 cell apoptosis.

Two new cytotoxic disulfated holostane glycosides from the sea cucumber Pentacta quadrangularis

Two new disulfated triterpene glycosides, pentactasides B and C (1 and 2, resp.), were isolated from the sea cucumber Pentacta quadrangularis collected from the South China Sea. Their structures were elucidated by extensive spectral analysis (2D-NMR and MS) and chemical methods. The compounds 1 and 2 possess the same tetrasaccharide moieties with two sulfated groups, but are different in the side chains of the triterpene aglycone. Pentactasides B and C (1 and 2, resp.) showed significant cytotoxicities (IC(50) 0.09-2.30 microM) against different human tumor cell lines.

Function analysis of a new type I PKS-SAT domain by SAT-EAT domain replacement

The function of a new starter unit acyltransferase (SAT) domain SAT-EF080951 (GenBank accession number) encoded in a new type I polyketide synthase (PKS) gene cluster EF568935 (GenBank accession number) isolated for this study was analyzed by domain replacement with an extender unit AT (EAT) domain of avermectin PKS. It was shown that the SAT-EF080951 incorporated malonyl-CoA specifically in vivo, which contradicted the specificity that we had previously determined by substrate binding test in vitro. The result of this study indicates that type I PKS-SAT can alter its specificity in vivo and functions well in extender units and proved the feasibility of the SAT-EAT domain replacement in type I PKS. We propose that SAT-EAT replacement strategy could be a novel route for increasing the diversity of new polyketides combinatorially biosynthesized. The new type I PKS-SAT-EF080951 studied herein may be further employed for related studies on enzymology or combinatorial biosynthesis of polyketides.

Marine drugs--macrolactins

The increasing demands for new lead compounds in pharmaceutical and agrochemical industries have driven scientists to search for new bioactive natural products. Marine microorganisms are rich sources of novel, bioactive secondary metabolites, and have attracted much attention of chemists, pharmacologists, and molecular biologists. This mini-review mainly focuses on macrolactins, a group of 24-membered lactone marine natural products, aiming at giving an overview on their sources, structures, biological activities, as well as their potential medical applications.

Mitochondrial ultrastructure & release of proteins during liver regeneration

BACKGROUND & OBJECTIVES

It has been reported that some proteins are released from mitochondria during liver regeneration after partial hepatectomy (PH), but the relationship between proteins release and mitochondrial permeability transition (MPT) remains unclear. We undertook this study to demonstrate the changes of mitochondrial ultrastructure and proteins release during liver regeneration and to determine the relationship between proteins release and MPT in liver regeneration in rats.

METHODS

After PH and administration of cyclosporin-A (CsA, a specific inhibitor of MPT), ultrastructural morphology of mitochondria in the remnant liver were determined by electron microscopy. Catalytic activity of mitochondrial and cytosolic proteins including aspartate aminotransferase (AST) and glutamic acid dehydrogenase (GDH) was measured.

RESULTS

The liver mitochondria at 24 and 72 h were quite variable in morphology and ultrastructure. The enzyme activities of AST and GDH in cytosol released from mitochondrial matrix changed significantly at 24 and 72 h. CsA can inhibit the permeability of mitochondria partly at the same time.

INTERPRETATION & CONCLUSIONS

The changes of mitochondria in ultrastructure reflected the feature of MPT, and the changes of enzymes activities released from mitochondrial matrix were consistent with those of mitochondrial ultrastructure. CsA can inhibit these changes to some extent. There was a close relationship of MPT with mitochondrial ultrastructure and proteins release during liver regeneration.

Expression of soluble, biologically active recombinant human tumstatin in Escherichia coli

Tumstatin, a 28-kDa C-terminal fragment of collagen IV, is a potent anti-angiogenic protein and inhibitor of tumour growth. Recombinant tumstatin was prepared from Escherichia coli deposited as insoluble, inactive inclusion bodies. In the present study, we produced soluble and biologically active recombinant human tumstatin in E. coli by the coding region of tumstatin being linked to the 3'-end of the maltose-binding protein (MBP) gene. The fusion protein was expressed as the soluble form after induction by isopropylthio-beta-D-galactoside (IPTG). MBP-tumstatin was purified by amylose affinity chromatography. MBP can be removed by digestion with factor Xa. Expression could represent 20% of the total soluble protein in E. coli, allowing approximately 8.6 mg of highly purified protein to be obtained per litre of bacterial culture. The purified tumstatin specifically inhibited the proliferation of endothelial cells in a dose-dependent manner. Annexin V-FITC apoptotic assay showed that recombinant tumstatin induced significant increase of apoptotic endothelial cells after 20 h of exposure to 20 microg/ml tumstatin, and when tumstatin was incubated on the chicken embryo, chorioallantoic membrane at doses of 1-15 microg, there was a dramatic decrease in the microvasculature allantoids of chicken embryos neovascular vessel test in vivo demonstrated that tumstatin treatment at doses of 1-15 microg gives rise to dramatically decrease the number of neovascular vessel. Our study provides a feasible and convenient approach to produce soluble and biologically active tumstatin.

Proteome analysis of hepatocellular carcinoma cell lines with different metastasis potentials by two-dimensional liquid chromatography

AIM: To analyze the proteome of hepatocellular carcinoma cell lines, MHCC97-H (high metastasis) and MHCC97-L (low metastasis), with different metastasis potentials by two-dimentional liquid phase chromatographic fractionation followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS).

METHODS: Cell lysates of MHCC97-H and MHCC97-L were fractionated according to PI using chromatofocusing with analytical columns in the first dimension, followed by separation of the proteins in each PI fraction using nonporous reversed-phase high performance liquid chromatography (HPLC). A two-dimensional map of the protein content for each cell line based upon pI versus hydrophobicity as detected by UV absorption was generated and a differential display map indicating the presence of up- or down-regulated proteins was exhibited using ProteoVue and DltaVue software. The different proteins were digested by trypsin and MALDI-TOF/MS was performed.

RESULTS: Image analysis of two-dimensional map revealed 72 differentially expressed proteins between MHCC97-H and MHCC97-L cells, and 9 protein peaks (including M2 pyruvate kinase, α-subunit of ATP synthase, heat shock protein 60, Toll-like receptor 9, flavoprotein oxygenase, pro-calreticulin, manganese superoxide dismutase, nm23-H1, and G-protein-coupled receptor kinase 5) were further identified by tryptic digestion, peptide mass fingerprinting and mass spectrometry. Four proteins were up-regulated while 5 were down-regulated in MHCC97-H cells.

CONCLUSION: The identified differentially expressed proteins may play important roles in the metastasis of hepatocellular carcinoma.

Construction, expression, and characterization of a new targeted bifunctional fusion protein: tumstatin45-132-TNF

The anti-angiogenic activity of tumstatin45-132 is mediated by binding to alphaVbeta3 on endothelial cells and tumor vascular endothelium showing increased expression of alphaVbeta3. Tumor necrosis factor alpha (TNF-alpha) is known to not only possess direct cytotoxicity against tumor cells, but also induces tumor vessel disruption, however, clinical use of TNF-alpha as an anticancer drug is hampered by severe systemic toxicity. In this study, we explore the possibility of fusing tumstatin45-132 with human TNF-alpha in the hope of generating a targeting, bi-functional protein in tumor treatment. Tumstatin45-132-TNF was constructed and expressed in E. coli. The recombinant fusion protein was shown to be insoluble and in an inclusion body form. An effective strategy for refolding and purification of tumstatin45-132-TNF resulted in final purified yields of 3 mg purified fusion protein recovered from 1 liter of E. coli culture. The refolded tumstatin45-132-TNF with a purity of 98% assessed by denaturing SDS - PAGE showed a single band on gels. Endothelial cell proliferation assay and standard cytolytic assays against L929 indicated that the fusion protein maintains tumstatin45-132 and TNF-alpha activity. More importantly, tumstatin45-132-TNF inhibits endothelial cell proliferation more than tumstatin45-132 alone. Cell adhesion assays and competitive binding experiments with anti-integrin antibodies showed that the tumstatin45-132 moiety specifically interacts with alphaVbeta3 integrin. These results lay the solid foundation for further investigation of antitumor activity of tumstatin45-132-TNF in vivo.

WITHDRAWN: Combining tumstatin45-132 with tumor necrosis factor-α improves its antineoplastic activity

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Transfer of an expression YAC into goat fetal fibroblasts by cell fusion for mammary gland bioreactor

Yeast artificial chromosomes (YACs) as transgenes in transgenic animals are likely to ensure optimal expression levels. Microinjection of YACs is the exclusive technique used to produce YACs transgenic livestock so far. However, low efficiency and high cost are its critical restrictive factors. In this study, we presented a novel procedure to produce YACs transgenic livestock as mammary gland bioreactor. A targeting vector, containing the gene of interest-a human serum albumin minigene (intron 1, 2), yeast selectable marker (G418R), and mammalian cell resistance marker (neo(r)), replaced the alpha-lactalbumin gene in a 210kb human alpha-lactalbumin YAC by homogeneous recombination in yeasts. The chimeric YAC was introduced into goat fetal fibroblasts using polyethylene glycol-mediated spheroplast fusion. PCR and Southern analysis showed that intact YAC was integrated in the genome of resistant cells. Perhaps, it may offer a cell-based route by nuclear transfer to produce YACs transgenic livestock.

Effects of shark hepatic stimulator substance on the function and antioxidant capacity of liver mitochondria in an animal model of acute liver injury

This study was carried out to investigate whether shark hepatic stimulator substance (HSS) can prevent acute liver injury and affect mitochondrial function and antioxidant defenses in a rat model of thioacetamide (TAA)-induced liver injury. The acute liver injury was induced by two intraperitoneal injections of TAA (400 mg/kg) in a 24 h interval. In the TAA plus shark HSS group, rats were treated with shark HSS (80 mg/kg) 1 h prior to each TAA injection. In this group, serum liver enzyme activities were significantly lower than those in the TAA group. The mitochondrial respiratory control ratio was improved, and the mitochondrial respiratory enzyme activities were increased in the TAA plus shark HSS group. The mitochondrial antioxidant enzyme activities and glutathione level were higher in the TAA plus shark HSS group than in the TAA group. These results suggest that the protective effect of shark HSS against TAA-induced acute liver injury may be a result of the restoration of the mitochondrial respiratory function and antioxidant defenses and decreased oxygen stress.

[High-cell density cultivation of recombinant Escherichia coli for production of TRAIL by using a 2-stage feeding strategy]

Escherichia coli was genetically engineered to produce recombinant tumor necrosis factor-related apoptosis inducing ligand (Apo2L/TRAIL) using a temperature-inducible expression system. To create a fed-batch culture condition that allows efficient production of TRAIL, different feeding strategy including discontinuous, DO-stat and pH-stat feeding strategies were compared. Then, a special 2-stage feeding strategy was developed. High concentration of biomass (300g wet cell weight per liter of culture broth) and active soluble TRAIL protein (1.1g/L) was obtained by applying a high-cell-density cultivation procedure with the 2-stage feeding strategy. Cultivation of recombinant E. coli was started as a batch process at 30 degrees C and then followed by fed-batch culture when the dissolved oxygen concentration presented a steep increase resulted from the exhaustion of glucose in the medium. At the first phase of fermentation (batch phase), agitation rate was enhanced to control dissolved oxygen at 30 percent. When glucose in the medium was used up, indicated by a sudden rise in pH value and dissolved oxygen, the second phase (fed-batch phase) was started with glucose and nitrogen resource being supplied automatically. At the beginning of fed-batch operation, stirrer rate was cascaded with dissolved oxygen signals to keep it at 20 percent (DO-stat). During the fed-batch phase, glucose was limited to control the specific growth rate under the critical value microcrit, to avoid acetic acid excretion. When the stirrer speed arrived at its up-limit, the flow rate of feed was kept constant. In the inducing phase(42 degrees C for 4h) glucose was fed as a pH regulating agent (pH-stat) and the specific growth rate and dissolved oxygen decreased sharply. Aqueous ammonia was used for maintaining pH value at 7.0 throughout the first two phases. In the whole fermentation, acetic acid concentration didn't exceed 2.9 g/L. At the end of the high-cell-density cultivation process, no acetic acid could be detected in the medium. These results indicated that our fed-batch strategy was able to prevent acetate accumulation significantly. Although high cell density has been achieved, the induction process was not optimized satisfactorily and much work should be done further. Furthermore, since no special ways, like pure oxygen, pressure, has been used in our experiments, this efficient approaches would be useful not only in a pilot scale but also in an industry scale. Finally, simple purification procedure based on immobilized metal affinity column (IMAC) and CM-Sepharose column was implemented to isolate the TRAIL. Yields of more than 800mg TRAIL per liter of culture broth were obtained, the final purity reaching more than 95%. The purified TRAIL showed strong cytotoxity activity against human pancreatic 1990 tumor cells, with ED50 about 1.6 microg/mL.

Expression of metallothionein gene at different time in testicular interstitial cells and liver of rats treated with cadmium

AIM: Rodent testes are generally more susceptible to cadmium (Cd)-induced toxicity than liver. To clarify the molecular mechanism of Cd-induced toxicity in testes, we compared metallothionein (MT) gene expression, MT protein accumulation, and Cd retention at different time in freshly isolated testicular interstitial cells and liver of rats treated with Cd.

METHODS: Adult male Sprague-Dawley rats weighing 250-280 g received a s.c injection of 4.0 μmol Cd/kg and were euthanized by CO₂ asphyxiation 1 h, 3 h, 6 h, or 24 h later. Tissue was sampled and testicular interstitial cells were isolated. There were three replicates per treatment and 3 animals per replicate for RNA analyses, others, three replicates per treatment and one animal per replicate. MT1 and MT2 mRNA levels were determined by semi-quantitative RT-PCR analysis followed by densitometry scanning, and MT was estimated by the enzyme-linked immunosorbent assay (ELISA) method. Cadmium content was determined by atomic absorption spectrophotometry. The same parametersd were also analyzed in the liver, since this tissue unquestionably accumulate MT.

RESULTS: The rat testis expressed MT1 and MT2, the major isoforms. We also found that untreated animals contained relatively high basal levels of both isoform mRNA, which were increased after Cd treatment in liver and peaked at 3 h, followed by a decline. In contrast, the mRNA levels in interstitial cells peaked at 6 h. Interestingly, the induction of MT1 mRNA was lower than MT2 mRNA in liver of rat treated with Cd, but it was opposite to interstitial cells. Cd exposure substantially increased hepatic MT (3.9-fold increase), but did not increase MT translation in interstitial cells.

CONCLUSION: Cd-induced expression of MT isoforms is not only tissue dependent but also time-dependent. The inability to induce the metal-detoxicating MT-protein in response to Cd, may account for a higher susceptibility of testes to Cd toxicity and carcinogenesis compared to liver.

[Effects of A3243G point mutation on aminoacylation of human mitochondrial tRNALeu(UUR)]

The wild-type and mutant-type human mitochondrial tRNALeu(UUR) genes were synthesized and transcribed in vitro with T7 RNA polymerase. The kinetic parameters of human mitochondrial leucyl-tRNA synthetase(mtLeuRS) were determined with wild-type and mutant-type human mitochondrial tRNALeu(UUR) respectively. The results show that the value of Km/Kcat of mtLeuRS for the mutant-type tRNALeu(UUR) is 63.9% as compared with the wild-type. Human mitochondrial tRNALeu(UUR) gene A3243G point mutant can remarkably reduce it's aminoacylation activity, suggesting it would be one of the mechanisms that the mutation could produce such clinical phenotypes.

Detection of mitochondrial DNA deletion by a modified PCR method in a 60Co radiation-exposed patient

A new PCR based method was developed to detect deleted mitochondrial DNA (mtDNA). Peripheral blood cell DNA was obtained from a victim who was accidently exposed to a 60Co radiation source in 1990. Using the DNA as template, first PCR was performed to generate multiple products including true deletions and artifacts. The full length product was recovered and used as template of secondary PCR. The suspicious deletion product of mtDNA could be confirmed only if it was yielded by first PCR. Using either original primers or their nested primers, the suspicious deletion product was amplified and authenticated as a true deletion product. The template was recovered and determined to be a deletion by sequencing directly. The results show that a new mtDNA deletion, which spans 889 bp from nt 11688 to nt 12576, was detected in the peripheral blood cells of the victim. It indicates that this new PCR-based method was more efficient at detecting small populations of mtDNA deletion than other routine methods. MtDNA deletion was found in the victim, suggesting the relationship between the deletion and phenotypes of the disease.

Search for difference in aminoacylation of mitochondrial DNA-encoded wild-type and mutant human tRNALeu (UUR)

The pathogenetic mechanism of the most extensively investigated A3243G mutated tRNALeu(UUR) gene, which causes the MELAS encephalomyopathy, maternally inherited diabetes, or chronic progressive external ophlthalmoplegia, is still unresolved, despite the numerous investigations on the topic. Previous evidences presented in published work suggested that the mitochondrial DNA harboring A3243G mutation result decreases in the rates of mitochondrial protein synthesis. To search for differences in aminoacylation of mitochondrial DNA-encoded wild-type and mutant human tRNALeu(UUR), we have expressed and purified the two kinds of tRNAsLeu(UUR), and have expressed human mitochondrial leucyl-tRNA synthetase for in vitro assays of aminoacylation of wild-type and mutant human tRNALeu(UUR). The results indicate human mitochondrial tRNALeu(UUR) gene A3243G point mutant can remarkably reduce its aminoacylation, suggesting it could be one of the mechanisms that the mutation can produce in such clinical phenotypes.

Purification, crystallization and preliminary X-ray studies of human augmenter of liver regeneration

Human augmenter of liver regeneration has been expressed in Escherichia coli, purified and crystallized. The crystals belong to space group C222, with unit-cell parameters a=51.7 A, b=78.8 A, c=63.7 A. Diffraction data were collected to 2.80 A with a completeness of 99.9% (99.9% for the last shell), a R(sym) value of 0.092(0.236) and an I/sigma(I) value of 6.2(2.7).