Clionasterol, a triterpenoid from the Kenyan marine green macroalga halimeda macroloba

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Clionasterol, a Triterpenoid from the Kenyan Marine Green Macroalga Halimeda macroloba

The triterpenoid clionasterol (1), a 29 carbon structure compound was isolated from the less polar extract (20% EtOAc in hexanes) of the green alga Halimeda macroloba collected at Shimoni near Mombasa, Kenya. The structure and relative stereochemistry of this compound was elucidated by spectroscopic data, mainly NMR and mass spectrometry. This metabolite was inactive against DLD-1 cells on the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Further experiments on mosquito larvae and brine shrimp lethality confirmed this result

Butremycin, the 3-Hydroxyl Derivative of Ikarugamycin and a Protonated Aromatic Tautomer of 5′-Methylthioinosine from a Ghanaian Micromonospora sp. K310

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Antiparasitic activity of bromotyrosine alkaloids and new analogues isolated from the Fijian marine Sponge Aplysinella rhax

Ten bromotyrosine alkaloids( 1 ‐ 10 ) were isolated and characterised from the marine sponge Aplysinella rhax ( de Laubenfels 1954) collected from the Fiji Islands, which included one new bromotyrosine analogue, psammaplin P ( 6 ) and two other analogues, psammaplins O ( 5 ) and 4‐bromo‐6‐carbomethoxy salicylic acid ( 7 ), which have not been previously reported from natural sources. HRESIMS, 1D and 2D NMR spectroscopic methods were used in the elucidation of the compounds. Bisaprasin, a biphenylic dimer of psammaplin A, showed moderate activity with IC 50 at 19+/‐ 5 and 29+/‐ 6 μM against Trypanzoma cruzi Tulahuen C4, and the lethal human malaria species Plasmodium falciparum clone 3D7, respectively, while psammaplins A ( 1 ) and D ( 4 ) exhibited low activity against both parasites. This is the first report of the antimalarial and antitrypanosomal activity of the psammaplin‐type compounds. Additionally, the biosynthesis hypotheses of the three natural products ( 5 , 6 and 7 ) were proposed

CHEMICAL COMPOSITION OF TEN ESSENTIAL OILS FROM CALOPHYLLUM INOPHYLLUM LINN AND THEIR TOXICITY AGAINST ARTEMIA SALINA

Essential oils from ten different parts of Calophyllum inophyllum were analyzed by Gas Chromatography-Mass Spectrometry (GC-MS) to study their chemical compositions. The yields were between 0.219 and 0.506 %. A total of 102 compounds were identified in the ten C. inophyllum essential oils, which are mostly monoterpenes, sesquiterpenes and their oxygenated derivatives. The numbers and percentages of identified compounds varied in the different parts of the plant: leaf (71, 54.94%), leaf stalk (22, 79.55%), flower (25, 51.24%), seed (25, 89.39%), seed-coat (69, 73.80%) fruit-pulp (15, 46.10%), stem wood (55, 59.40%), stem bark (9, 69.38%) root wood (51, 58.73%), and root bark (24, 74.66%). High content of cymene, terpinene, and limonene in the oils may be responsible for the vast ethno-medicinal applications of the plant. Toxicity experiments show that the oils were fairly toxic. Each part after 24 hours of exposure against Artemia salina gave the following LC50 values in μg/mL: leaf (68.8740 μg/mL), leaf-stalk (102.5692 μg/mL), flower (114.4410 μg/mL), seed (132.2324 μg/mL), seed coat (137.1206 μg/mL), fruit-pulp (135.0350 μg/mL) stem wood (126.1410 μg/mL), stem bark (149.7237 μg/mL), root wood (110.6539 μg/mL) and root bark (110.6539 μg/mL). The chemical compositions and toxicity levels of these ten Calophyllum inophyllum essential oils are reported for the first time in literature

Tavarua Deoxyriboside A and Jasplakinolide as Potential Neuroprotective Agents: Effects on Cellular Models of Oxidative Stress and Neuroinflammation

The oceans harbor a great reservoir of molecules with unknown bioactivities, which could be useful for the treatment of illnesses that nowadays have no cure, such as neurodegenerative diseases. In this work, we evaluated the neuroprotective potential of the marine Fijian compounds tavarua deoxyriboside A and jasplakinolide against oxidative stress and neuroinflammation, crucial mechanisms in neurodegeneration. Both metabolites protected SH-SY5Y human neuroblastoma cells from H2O2 damage, improving mitochondrial function and activating the antioxidant systems of cells. These effects were mediated by their ability of inducing Nrf2 translocation. In BV2 microglial cells activated with lipopolysaccharide, Fijian metabolites also displayed promising results, decreasing the release of proinflammatory mediators (ROS, NO, cytokines) through the reduction of gp91 and NFkB–p65 expression. Finally, we performed a coculture among both cell lines, in which treatment with compounds protected SH-SY5Y cells from activated microglia, corroborating their neuroprotective effects. These results suggest that tavarua deoxyriboside A and jasplakinolide could be used as candidate molecules for further studies against neurodegeneration

Evaluation of the Antioxidant Activity of the Marine Pyrroloiminoquinone Makaluvamines

Makaluvamines are pyrroloiminoquinones isolated from Zyzzya sponges. Until now, they have been described as topoisomerase II inhibitors with cytotoxic effects in diverse tumor cell lines. In the present work, seven makaluvamines were tested in several antioxidant assays in primary cortical neurons and neuroblastoma cells. Among the alkaloids studied, makaluvamine J was the most active in all the assays. This compound was able to reduce the mitochondrial damage elicited by the well-known stressor H2O2. The antioxidant properties of makaluvamine J are related to an improvement of the endogenous antioxidant defenses of glutathione and catalase. SHSY5Y assays proved that this compound acts as a Nrf2 activator leading to an improvement of antioxidant defenses. A low concentration of 10 nM is able to reduce the reactive oxygen species release and maintain a correct mitochondrial function. Based on these results, non-substituted nitrogen in the pyrrole plus the presence of a p-hydroxystyryl without a double bond seems to be the most active structure with a complete antioxidant effect in neuronal cells

Dermacozine N, the First Natural Linear Pentacyclic Oxazinophenazine with UV–Vis Absorption Maxima in the Near Infrared Region, Along with Dermacozines O and P Isolated from the Mariana Trench Sediment Strain Dermacoccus abyssi MT 1.1T

Three dermacozines, dermacozines N–P (1–3), were isolated from the piezotolerant Actinomycete strain Dermacoccus abyssi MT 1.1T, which was isolated from a Mariana Trench sediment in 2006. Herein, we report the elucidation of their structures using a combination of 1D/2D NMR, LC-HRESI-MSn, UV–Visible, and IR spectroscopy. Further confirmation of the structures was achieved through the analysis of data from density functional theory (DFT)–UV–Visible spectral calculations and statistical analysis such as two tailed t-test, linear regression-, and multiple linear regression analysis applied to either solely experimental or to experimental and calculated 13C-NMR chemical shift data. Dermacozine N (1) bears a novel linear pentacyclic phenoxazine framework that has never been reported as a natural product. Dermacozine O (2) is a constitutional isomer of the known dermacozine F while dermacozine P (3) is 8-benzoyl-6-carbamoylphenazine-1-carboxylic acid. Dermacozine N (1) is unique among phenoxazines due to its near infrared (NIR) absorption maxima, which would make this compound an excellent candidate for research in biosensing chemistry, photodynamic therapy (PDT), opto-electronic applications, and metabolic mapping at the cellular level. Furthermore, dermacozine N (1) possesses weak cytotoxic activity against melanoma (A2058) and hepatocellular carcinoma cells (HepG2) with IC50 values of 51 and 38 μM, respectively

Antimicrobial Activity of Monoramnholipids Produced by Bacterial Strains Isolated from the Ross Sea (Antarctica)

Microorganisms living in extreme environments represent a huge reservoir of novel antimicrobial compounds and possibly of novel chemical families. Antarctica is one of the most extraordinary places on Earth and exhibits many distinctive features. Antarctic microorganisms are well known producers of valuable secondary metabolites. Specifically, several Antarctic strains have been reported to inhibit opportunistic human pathogens strains belonging to Burkholderia cepacia complex (Bcc). Herein, we applied a biodiscovery pipeline for the identification of anti-Bcc compounds. Antarctic sub-sea sediments were collected from the Ross Sea, and used to isolate 25 microorganisms, which were phylogenetically affiliated to three bacterial genera (Psychrobacter, Arthrobacter, and Pseudomonas) via sequencing and analysis of 16S rRNA genes. They were then subjected to a primary cell-based screening to determine their bioactivity against Bcc strains. Positive isolates were used to produce crude extracts from microbial spent culture media, to perform the secondary screening. Strain Pseudomonas BNT1 was then selected for bioassay-guided purification employing SPE and HPLC. Finally, LC-MS and NMR structurally resolved the purified bioactive compounds. With this strategy, we achieved the isolation of three rhamnolipids, two of which were new, endowed with high (MIC < 1 μg/mL) and unreported antimicrobial activity against Bcc strains

Whole Genome Sequence of Dermacoccus abyssi MT1.1 Isolated from the Challenger Deep of the Mariana Trench Reveals Phenazine Biosynthesis Locus and Environmental Adaptation Factors

Dermacoccus abyssi strain MT1.1T is a piezotolerant actinobacterium that was isolated from Mariana Trench sediment collected at a depth of 10898 m. The organism was found to produce ten dermacozines (A‒J) that belonged to a new phenazine family and which displayed various biological activities such as radical scavenging and cytotoxicity. Here, we report on the isolation and identification of a new dermacozine compound, dermacozine M, the chemical structure of which was determined using 1D and 2D-NMR, and high resolution MS. A whole genome sequence of the strain contained six secondary metabolite-biosynthetic gene clusters (BGCs), including one responsible for the biosynthesis of a family of phenazine compounds. A pathway leading to the biosynthesis of dermacozines is proposed. Bioinformatic analyses of key stress-related genes provide an insight into how the organism adapted to the environmental conditions that prevail in the deep-sea