Cyclic peroxides and analogs: Antibacterial, antimalarial, and cytotoxic marine products from Xisha sponge Diacarnus sp.

A chemical investigation of the dichloromethane extract from the Xisha sponge Diacarnus sp. revealed seven undescribed norterpene cyclic peroxides, named diacarperoxides T-Z, and five unreported related norterpenes, named diacarnoids E-I, and eleven previously reported compounds. The structures of these isolated compounds, including their absolute configurations, were elucidated based on extensive spectroscopic analyses, electronic circular dichroism (ECD) calculations, Snatzke's method, [Rh2(OCOCF3)4]-induced ECD spectra, and modified Mosher's method. Bioassays were performed to assess the antibacterial activity against six pathogenic bacteria, cytotoxicities toward three cancer cell lines, and antimalarial activity against Plasmodium parasites. Most of the cyclic peroxides exhibited substantial antibacterial activity (MIC 1-8 µg/mL). Diacarperoxide W and nuapapuin A showed substantial antimalarial activity with IC50 values of 0.98 and 2.83 µM. Moreover, many compounds exhibited <50% cell survival rates, and IC50 values of 0.22-6.33 µM. The apoptosis assay showed that nuapapuin A induced cancer cell apoptosis in a dose-dependent manner.

Ergosterols with rare peroxide, oxetane ring moiety, and a lactone ring from Aspergillus spectabilis and their immunosuppressive activities.

Ten ergostane-type steroids, including seven undescribed ones named spectasteroids A-G, were obtained from Aspergillus spectabilis. Their structures and absolute configurations were determined based on HRESIMS, NMR, ECD calculations, and single-crystal X-ray diffraction analyses. Structurally, spectasteroid A was a unique example of aromatic ergostane-type steroid that featured a rare peroxide ring moiety; spectasteroid B contained a rare oxetane ring system formed between C-9 and C-14; and spectasteroid C was an unusual 3,4-seco-ergostane steroid with an extra lactone ring between C-3 and C-9. Spectasteroids F and G specifically showed inhibitory effects against concanavalin A-induced T lymphocyte proliferation and lipopolysaccharide-induced B lymphocyte proliferation, with IC50 values ranging from 2.33 to 4.22 µM. Spectasteroid F also showed excellent antimultidrug resistance activity, which remarkable enhanced the inhibitory activity of PTX on the colony formation of SW620/Ad300 cells.

Unusual polyoxygenated casbane diterpenoids from the South China Sea soft coral Sinularia erecta.

A further systematically chemical investigation of the South China Sea soft coral Sinularia erecta led to the discovery of two rare casbane diterpenoids with an uncommon 8,10-peroxide bridge, sinuereperoxides B (1) and C (2), five new casbanes with other oxygenated patterns (3-7), and seven known casbanes (8-14). The structures and absolute configurations of 1-7 were established by extensive spectroscopic data analyses, X-ray diffraction analysis, and/or quantum chemical calculations. In bioassay, compounds 2, 7, 11 and 12 exhibited considerable anti-inflammatory activity by the inhibition of TNF-α release, with IC50 values of 33.8 µM, 5 µM, 9.9 µM and 8 µM.

Trace multi-class organic explosives analysis in complex matrices enabled using LEGO®-inspired clickable 3D-printed solid phase extraction block arrays.

The development of a new, lower cost method for trace explosives recovery from complex samples is presented using miniaturised, click-together and leak-free 3D-printed solid phase extraction (SPE) blocks. For the first time, a large selection of ten commercially available 3D printing materials were comprehensively evaluated for practical, flexible and multiplexed SPE using stereolithography (SLA), PolyJet and fused deposition modelling (FDM) technologies. Miniaturised single-piece, connectable and leak-free block housings inspired by Lego® were 3D-printed in a methacrylate-based resin, which was found to be most stable under different aqueous/organic solvent and pH conditions, using a cost-effective benchtop SLA printer. Using a tapered SPE bed format, frit-free packing of multiple different commercially available sorbent particles was also possible. Coupled SPE blocks were then shown to offer efficient analyte enrichment and a potentially new approach to improve the stability of recovered analytes in the field when stored on the sorbent, rather than in wet swabs. Performance was measured using liquid chromatography-high resolution mass spectrometry and was better, or similar, to commercially available coupled SPE cartridges, with respect to recovery, precision, matrix effects, linearity and range, for a selection of 13 peroxides, nitramines, nitrate esters and nitroaromatics. Mean % recoveries from dried blood, oil residue and soil matrices were 79 ± 24%, 71 ± 16% and 76 ± 24%, respectively. Excellent detection limits between 60 fg for 3,5-dinitroaniline to 154 pg for nitroglycerin were also achieved across all matrices. To our knowledge, this represents the first application of 3D printing to SPE of so many organic compounds in complex samples. Its introduction into this forensic method offered a low-cost, 'on-demand' solution for selective extraction of explosives, enhanced flexibility for multiplexing/design alteration and potential application at-scene.

New Rare Ent-Clerodane Diterpene Peroxides from Egyptian Mountain Tea (Qourtom) and Its Chemosystem as Herbal Remedies and Phytonutrients Agents.

Genus Stachys, the largest genera of the family Lamiaceae, and its species are frequently used as herbal teas due to their essential oils. Tubers of some Stachys species are also consumed as important nutrients for humans and animals due to their carbohydrate contents. Three new neo-clerodane diterpene peroxides, named stachaegyptin F-H (1, 2, and 4), together with two known compounds, stachysperoxide (3) and stachaegyptin A (5), were isolated from Stachys aegyptiaca aerial parts. Their structures were determined using a combination of spectroscopic techniques, including HR-FAB-MS and extensive 1D and 2D NMR (1H, 13C NMR, DEPT, 1H-1H COSY, HMQC, HMBC and NOESY) analyses. Additionally, a biosynthetic pathway for the isolated compounds (1-5) was discussed. The chemotaxonomic significance of the isolated diterpenoids of S. aegyptiaca in comparison to the previous reported ones from other Stachys species was also studied.

Chemically modified carbon nitride-chitin-acetic acid hybrid as a metal-free bifunctional nanozyme cascade of glucose oxidase-peroxidase for "click off" colorimetric detection of peroxide and glucose.

Hybrid nanomaterials-based artificial enzymes with numerous utilities are necessary to develop future bionic devices in mimicking physiological processes. This paper demonstrates bifunctional enzyme mimicking roles of a metal-free nanozyme hybrid of chemically modified graphitic carbon nitride (MGCN), chitin and acetic acid (AcOH). The MGCN exhibited glucose oxidase-mimicking activity and chitin-AcOH mirrored peroxidase. MGCN-chitin-AcOH when in contact with glucose, oxidised glucose to gluconic acid and hydrogen peroxide (H2O2) while the chitin-AcOH decomposed the generated H2O2, as proved separately, by concurrent oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). The super-sensitive colorimetric process produced linear regression equation for H2O2 as A = 0.00105C + 0.0630 (C:µM, R2 = 0.9961) with a detection limit of 0.052 µM, whereas for glucose, the linear relationship was A = 0.00084C + 0.0458 (C:µM, R2 = 0.9952) having a detection limit of 0.055 µM. The developed method was also successfully applied for assessment of H2O2 and glucose in human serum and urine samples. Non-enzymatic glucose test strips from MGCN-chitin-AcOH based hydrogel were reported and verified for semi-quantitative analysis of glucose. These compared well with results from standard enzyme-based colorimetric procedure. The developed hybrid nanozyme provided feasible alternatives to the two natural enzymes (peroxidase and glucose oxidase) realized through real sample analysis. The developed hybrid nanozyme can be successfully used for colorimetric detection of peroxide and glucose in medical diagnostics.

Parameters of the Mouse Embryo Assay that affect detection of peroxides in mineral oil.

RESEARCH QUESTION: Can culture conditions influence the sensitivity of a Mouse Embryo Assay and its potential to detect peroxide-related toxicity in mineral oil samples? DESIGN: Protein type and concentration, embryo density and culture dish design were selected as the variables in the culture system with the potential to influence the assay's sensitivity. Fresh 1-cell mouse embryos were cultured under mineral oil samples with known peroxide concentrations. Protein type (human serum albumin [HSA] + α/ß-Globulins versus HSA versus bovine serum albumin [BSA]), concentration (5 mg/ml versus 0.5 mg/ml), embryo density (25 versus 3 µl/embryo) and culture dish (Petri versus micro-well dish) were adjusted to define the culture conditions with the highest sensitivity. RESULTS: High concentrations of peroxides can be easily detected by current quality control standards. However, for oil samples with a lower concentration of peroxides, supplementing the culture medium with 5 mg/ml of HSA + alpha/beta-globulins or with HSA resulted in an increased detection of embryo toxicity compared with when BSA was used as the protein supplement. The sensitivity of the assay was greatly reduced when embryos were cultured in groups and when certain micro-well dishes were used. CONCLUSIONS: Current quality control protocols may not be sensitive enough to identify low concentrations of peroxides, which, if undetected, can increase over time and become potentially harmful during gamete and embryo culture. The different parameters established in this study allow the sensitivity of the Mouse Embryo Assays to be optimized to specifically detect peroxides in mineral oil samples prior to their release into the market and their broad use in human IVF.

Bioactive Dimeric Abietanoid Peroxides from the Bark of Cryptomeria japonica.

Three new dimeric abietane-type diterpenoids, abieta-6,8,11,13-tetraen-12-yl 12-hydroxyabieta-8,11,13-trien-7α-yl peroxide (1), abieta-6,8,11,13-tetraen-12-yl 12-hydroxyabieta-8,11,13-trien-7ß-yl peroxide (2), and 12-hydroxyabieta-8,11,13-trien-7ß-yl 7-oxoabieta-5,8,11,13-tetraen-12-yl peroxide (3), together with four known abietane-type diterpenoids (4-7) were isolated from the methanol extract of the bark of Cryptomeria japonica. Their structures were elucidated on the basis of spectroscopic analysis and comparison of NMR data with those of known analogues. At a concentration of 50 µM, compounds 1, 2, and 3 showed 26.2%, 23.6%, and 35.7% inhibition towards xanthine oxidase enzyme, respectively. In addition, compound 3 also showed 24.9% inhibition toward angiotensin-converting enzyme (ACE).

Identification of urate hydroperoxide in neutrophils: A novel pro-oxidant generated in inflammatory conditions.

Uric acid is the final product of purine metabolism in humans and is considered to be quantitatively the main antioxidant in plasma. In vitro studies showed that the oxidation of uric acid by peroxidases, in presence of superoxide, generates urate free radical and urate hydroperoxide. Urate hydroperoxide is a strong oxidant and might be a relevant intermediate in inflammatory conditions. However, the identification of urate hydroperoxide in cells and biological samples has been a challenge due to its high reactivity. By using mass spectrometry, we undoubtedly demonstrated the formation of urate hydroperoxide and its corresponding alcohol, hydroxyisourate during the respiratory burst in peripheral blood neutrophils and in human leukemic cells differentiated in neutrophils (dHL-60). The respiratory burst was induced by phorbol myristate acetate (PMA) and greatly increased oxygen consumption and superoxide production. Both oxygen consumption and superoxide production were further augmented by incubation with uric acid. Conversely, uric acid significantly decreased the levels of HOCl, probably because of the competition with chloride by the catalysis of myeloperoxidase. In spite of the decrease in HOCl, the overall oxidative status, measured by GSH/GSSG ratio, was augmented in the presence of uric acid. In summary, the present results support the formation of urate hydroperoxide, a novel oxidant in neutrophils oxidative burst. Urate hydroperoxide is a strong oxidant and alters the redox balance toward a pro-oxidative environment. The production of urate hydroperoxide in inflammatory conditions could explain, at least in part, the harmful effect associated to uric acid.

Bioactive compounds from sclerotia extract of Poria cocos that control adipocyte and osteoblast differentiation.

Poria cocos Wolf confers edible sclerotia also known as 'Indian bread' in North America, that have been used for the treatment of various diseases in Asian countries. As part of our ongoing aim to identify biologically new metabolites from Korean edible mushrooms, we investigated the ethanol (EtOH) extract of the sclerotia of P. cocos by applying a comparative LC/MS- and bioassay-based analysis approach, since the EtOH extract reciprocally regulated adipocyte and osteoblast differentiation in mouse mesenchymal stem cells (MSCs). Bioassay-based analysis of the EtOH extract led to the successful isolation of two sterols, ergosterol peroxide (1) and 9,11-dehydroergosterol peroxide (2); three diterpenes, dehydroabietic acid (3), 7-oxocallitrisic acid, (4) and pimaric acid (5); and two triterpenes, dehydroeburicoic acid monoacetate (6) and eburicoic acid acetate (7) from the active hexane-soluble fraction. The isolated compounds (1-7) were examined for their effects on the regulation of MSC differentiation. The two sterols (1 and 2) were able to suppress MSC differentiation toward adipocytes. In contrast, the three diterpenes (3-5) showed activity to promote osteogenic differentiation of MSC. These findings demonstrate that the EtOH extract of P. cocos sclerotia is worth consideration as a new potential source of bioactive compounds effective in the treatment of osteoporosis in the elderly, since the extract contains sterols that inhibit adipogenic differentiation as well as diterpenes that promote osteogenic differentiation from MSCs.

New Cembranoids and a Biscembranoid Peroxide from the Soft Coral Sarcophyton cherbonnieri.

Six new cembranoids, cherbonolides A-E (1⁻5) and bischerbolide peroxide (6), along with one known cembranoid, isosarcophine (7), were isolated from the Formosan soft coral Sarcophyton cherbonnieri. The structures of these compounds were elucidated by detailed spectroscopic analysis and chemical methods. Compound 6 was discovered to be the first example of a molecular skeleton formed from two cembranoids connected by a peroxide group. Compounds 1⁻7 were shown to have the ability of inhibiting the production of superoxide anions and elastase release in N-formyl-methionyl-leucyl-phenyl-alanine/cytochalasin B (fMLF/CB)-induced human neutrophils.

Peroxy steroids derived from plant and fungi and their biological activities.

Peroxides represent a large and interesting group of biologically active natural compounds. All these metabolites contain a peroxide group (R-O-O-R). This review describes studies of more than 60 peroxides isolated from plants and fungi. Most of the plant peroxy steroids exhibit high antiprotozoal (Plasmodium) activity with a confidence of up to 95%, while steroids harvested from fungi show more antineoplastic activity with a confidence of up to 94%. In addition, more than 20 different activities of both groups of peroxides with a probability of 78 to 90% have also been predicted using computer program PASS.

Sponge symbioses between Xestospongia deweerdtae and Plakortis spp. are not motivated by shared chemical defense against predators.

The recently described epizoic sponge-sponge symbioses between Xestospongia deweerdtae and two species of Plakortis present an unusual series of sponge interactions. Sponges from the genus Plakortis are fierce allelopathic competitors, rich in cytotoxic secondary metabolites, and yet X. deweerdtae flourishes as an epizoic encrustation on Plakortis deweerdtaephila and Plakortis symbiotica. Our objective in this study was to evaluate the hypothesis that X. deweerdtae grows epizoic to these two species of Plakortis due to a shared chemical defense against predators. We collected free-living individuals of X. deweerdtae and symbiotic pairs from a wide geographical range to generate crude organic extracts and a series of polarity fractions from sponge extract. We tested the deterrency of these extracts against three common coral reef predators: the bluehead wrasse, Thalassoma bifasciatum, the Caribbean sharpnose puffer, Canthigaster rostrata, and the white spotwrist hermit crab, Pagurus criniticornis. While the chemical defenses of P. deweerdtaephila and P. symbiotica are more potent than those of X. deweerdtae, all of the sponge species we tested significantly deterred feeding in all three generalist predators. The free-living form of X. deweerdtae is mostly defended across the region, with a few exceptions. The associated form of X. deweerdtae is always defended, and both species of Plakortis are very strongly defended, with puffers refusing to consume extract-treated pellets until the extract was diluted to 1/256× concentration. Using diode-array high performance liquid chromatography (HPLC) coupled with high-resolution mass spectrometry (LC-MS/IT-TOF), we found two secondary metabolites from P. deweerdtaephila, probably the cyclic endoperoxides plakinic acid I and plakinic acid K, in low concentrations in the associated-but not the free-living-form of X. deweerdtae, suggesting a possible translocation of defensive chemicals from the basibiont to the epibiont. Comparing the immense deterrency of Plakortis spp. extracts to the extracts of X. deweerdtae gives the impression that there may be some sharing of chemical defenses: one partner in the symbiosis is clearly more defended than the other and a small amount of its defensive chemistry may translocate to the partner. However, X. deweerdtae effectively deters predators with its own defensive chemistry. Multiple lines of evidence provide no support for the shared chemical defense hypothesis. Given the diversity of other potential food resources available to predators on coral reefs, it is improbable that the evolution of these specialized sponge-sponge symbioses has been driven by predation pressure.

Plakortinic Acids A and B: Cytotoxic Cycloperoxides with a Bicyclo[4.2.0]octene Unit from Sponges of the Genera Plakortis and Xestospongia.

Plakortinic acids A (2) and B (3), two polyketide endoperoxides with a bicyclo[4.2.0]octene unit, were isolated as minor constituents from the sponge-sponge symbiotic association Plakortis halichondrioides-Xestospongia deweerdtae, along with known epiplakinic acid F (1). The structures of the mixture of two inseparable compounds were determined by spectroscopic analysis. Screening for cytotoxic activity of the mixture against two human tumor cell lines revealed that these compounds are very active at sub-micromolar concentration.

The First Casbane Hydroperoxides EBC-304 and EBC-320 from the Australian Rainforest.

Investigation of the Australian rainforest plant Croton insularis led to isolation of the first casbane hydroperoxide diterpenes EBC-304 and EBC-320. Extensive DFT and electronic circular dichroism (ECD) calculations in combination with 2D NMR spectroscopy determined the absolute configurations. EBC-304 and EBC-320 both display significant cytotoxicity.

A Norsesterterpene Peroxide from a Marine Sponge Hippospongia sp.

One new norsesterterpene peroxide, rhopaloic acid H (1), along with two known related metabolites 2 and 3, were isolated from a marine sponge Hippospongia sp. The structures of compounds were elucidated by means of IR, MS, and NMR techniques and comparison of the NMR data with those of known analogues. Evaluation of the cytotoxicities revealed that compound 2 exhibited significant cytotoxicity against DLD-1, Molt 4, T47D and K-562 cell lines, with IC50 values of 3.18, 0.69, 2.22 and 1.06 µg/mL, respectively. Moreover, compound 3 also showed significant K562 inhibitory activity, with IC50 value of 3.65 µg/mL.

New antimalarial norterpene cyclic peroxides from Xisha Islands sponge Diacarnus megaspinorhabdosa.

Four new norterpene cyclic peroxides (1-4), together with three known norterpene cyclic peroxides were isolated from the Xisha Islands Sponge Diacarnus megaspinorhabdosa. Their structures were elucidated on the basis of spectroscopic analyses and comparison with the related model compounds. The compounds (1-7) were evaluated for the inhibitory activity against the malaria parasite Plasmodium falciparum, all of them showed significant antimalarial activity with IC50 values in the range of 1.6-8.6 µM.

Peroxide Natural Products from Plakortis zyggompha and the Sponge Association Plakortis halichondrioides-Xestospongia deweerdtae: Antifungal Activity against Cryptococcus gattii.

Cryptococcus gattii is a human pathogen and causative agent of a pernicious, sometimes fatal, disseminated fungal disease. Investigation of antifungal extracts of the marine sponge association Plakortis halichondrioides-Xestospongia deweerdtae and the sponge Plakortis zyggompha from the Bahamas led to the discovery and isolation of 6-epi-7,8-dihydroplakortide K (1), plakortide AA (2), and three new plakinic acids, N-P (4-6; unstable 1,2-dioxolanes bearing benzyl-substituted conjugated dienes), along with known plakinic acids L, K, and M.5 Chiroptical comparisons and DFT calculations of (13)C NMR chemical shifts were used to assign the absolute stereostructure of 4. The stereospecific base-promoted rearrangement-saponification of 1 to 10 was briefly investigated and showed tight kinetic control and stereospecific formation of the new C-2 stereocenter with inversion at C-3. Plakinic acid M and plakortides 9 and 11 exhibited antifungal activity against C. gattii (MIC90 = 2.4 to 36 µM), but plakinic acids N-P were inactive under the same conditions.

Cytotoxic sesquiterpenes from the endophytic fungus Pseudolagarobasidium acaciicola.

Twenty previously unknown compounds and two known metabolites, merulin A and merulin D, were isolated from the endophytic fungus Pseudolagarobasidium acaciicola, which was isolated from a mangrove tree, Bruguiera gymnorrhiza. Structures of the 20 compounds were elucidated by analysis of spectroscopic data. The absolute configuration of seven of these compounds was addressed by a single crystal X-ray analysis using CuKα radiation and an estimate of the Flack parameter. Three compounds also possessed a tricyclic ring system. Terpene endoperoxides isolated exhibited cytotoxic activity, while those without an endoperoxide moiety did not show activity. The endoperoxide moiety of sesquiterpenes has significant impact on cytotoxic activity, and thus is an important functionality for cytotoxicity. One terpene endoperoxide displayed potent cytotoxic activity (IC50 0.28µM), and selectively exhibited activity against the HL-60 cell line.

New Metabolites from the South China Sea Sponge Diacarnus megaspinorhabdosa.

Chemical investigation on CH2Cl2 extract of the marine sponge Diacarnus megaspinorhabdosa resulted in the isolation of two new farnesylacetone derivatives 1-2, a new γ-lactone 3, a known dinorditerpenone 4 and four known norsesterterpene peroxides 5-8. Their structures were elucidated by using one and two dimensional (1D and 2D)-NMR, high resolution-electrospray ionization (HR-ESI)-MS, and comparison with the literature. Compounds 1 and 2 were cis/trans-olefinic isomers and determined through nuclear Overhauser effect spectroscopy (NOESY) experiment. The absolute configuration of 3 was established by comparison of circular dichroism (CD) data with known lactones. The cytotoxic activities of the compounds were evaluated against five cancer cell lines, and compound 3 showed moderate cytotoxicity activities against cancer cell lines HeLa, H446, NCI-H460, SGC-7901 and MCF-7, with IC50 values in the range of 18.5 to 47.1 µM.