Anti-inflammatory constituents of the red alga Gracilaria verrucosa and their synthetic analogues

Discovery and Anti-Inflammatory Activity of a Cyanobacterial Fatty Acid Targeting the Keap1/Nrf2 Pathway

The monounsaturated fatty acid 7(E)-9-keto-hexadec-7-enoic acid (1) and three structurally related analogues with different oxidation states and degrees of unsaturation (2-4) were discovered from a marine benthic cyanobacterial mat collected from Delta Shoal, Florida Keys. Their structures were elucidated using NMR spectroscopy and mass spectrometry. The structure of 1 contained an α,β-unsaturated carbonyl system, a key motif required for the activation of the Keap1/Nrf2-ARE pathway that is involved in the activation of antioxidant and phase II detoxification enzymes. Compounds 1-4 were screened in ARE-luciferase reporter gene assay using stably transfected HEK293 cells, and only 1 significantly induced Nrf2 activity at 32 and 10 µM, whereas 2-4 were inactive. As there is crosstalk between inflammation and oxidative stress, subsequent biological studies were focused on 1 to investigate its anti-inflammatory potential. Compound 1 induced Nqo1, a well-known target gene of Nrf2, and suppressed iNos transcript levels, which translated into reduced levels of nitric oxide in LPS-activated mouse macrophage RAW264.7 cells, a more relevant model for inflammation. RNA sequencing was performed to capture the effects of 1 on a global level and identified additional canonical pathways and upstream regulators involved in inflammation and immune response, particularly those related to multiple sclerosis. A targeted survey of marine cyanobacterial samples from other geographic locations, including Guam, suggested the widespread occurrence of 1. Furthermore, the previous isolation of 1 from marine diatoms and green algae implied a potentially important ecological role across marine algal eukaryotes and prokaryotes. The previous isolation from sea lettuce raises the possibility of dietary intervention to attenuate inflammation and related disease progression.

Analogues of natural products yaequinolones as potential inflammatory inhibitors: Design, synthesis and biological evaluation

Inflammation is connected with a variety of diseases and there is still a need to develop more effective and safer anti-inflammatory drugs. Herein, we synthesized, resolved, and characterized eight enantiopure isomers of yaequinolone J1 (1), yaequinolone J2 (2), 4'-desmethoxyyaequinolone J1 (3), and 4'-desmethoxyyaequinolone J2 (4). The key synthetic steps were extended and 34 racemic analogues modified at the 4-aryl, the N-position, and the pyran ring were designed and synthesized. All the synthesized compounds were evaluated for their anti-inflammatory activities in RAW 264.7 cells of which 13 compounds showed significant inhibition of nitric oxide (NO) production at a concentration of 0.1 μM, which was more potent than that of indomethacin. Furthermore, compounds (-)-3, (-)-4, 5h, and 6g reduced the production of IL-6 in LPS-stimulated RAW 264.7 cells at a concentration of 50 nM. A preliminary SAR indicated that 3'-Br (5h), 4'-NO₂ (6g) on 4-phenyl and 3-bromobenzyl (7f) on the N-position were the most effective substituents. This is the first report of the anti-inflammatory yaequinolone alkaloids and the present study provided evidence for exploiting this series of highly efficacious derivatives for new anti-inflammatory agents.

Streptoglycerides E-H, Unsaturated Polyketides from the Marine-Derived Bacterium Streptomyces specialis and Their Anti-Inflammatory Activity

Four new streptoglycerides E-H (1-4), with a rare 6/5/5/-membered ring system, were isolated from a marine-derived actinomycete Streptomyces specialis. The structures of 1-4 were elucidated by detailed analysis of HRESIMS, 1D and 2D NMR data and ECD spectra as well as comparison of their spectroscopic data with those reported in literature. Compounds 1-4 showed significant anti-inflammatory activity by inhibiting lipopolysaccharide (LPS)-induced nitric oxide (NO) production in Raw 264.7 cells with IC₅₀ values ranging from 3.5 to 10.9 µM. Especially, 2 suppressed mRNA expression levels of iNOS and IL-6 without cytotoxicity.

Red Seaweed-Derived Compounds as a Potential New Approach for Acne Vulgaris Care

Acne vulgaris (AV) is a chronic skin disease of the pilosebaceous unit affecting both adolescents and adults. Its pathophysiology includes processes of inflammation, increased keratinization, sebum production, hormonal dysregulation, and bacterial Cutibacterium acnes proliferation. Common AV has been treated with antibiotics since the 1960s, but strain resistance has emerged and is of paramount concern. Macroalgae are known producers of substances with bioactive properties, including anti-viral, antibacterial, antioxidant, and anti-inflammatory properties, among several others. In particular, red algae are rich in bioactive compounds such as polysaccharides, phenolic compounds, lipids, sterols, alkaloids, and terpenoids, conferring them antioxidant, antimicrobial, and anti-inflammatory activities, among others. Thus, the exploration of compounds from marine resources can be an appealing approach to discover new treatment options against AV. The aim of this work is to provide an overview of the current knowledge of the potentialities of red macroalgae in the treatment of AV by reviewing the main therapeutic targets of this disease, and then the existence of compounds or extracts with bioactive properties against them.

Protective Effects of Ulva lactuca Polysaccharide Extract on Oxidative Stress and Kidney Injury Induced by D-Galactose in Mice

Reactive oxygen species (ROS) are the key factors that cause many diseases in the human body. Polysaccharides from seaweed have been shown to have significant antioxidant activity both in vivo and in vitro. The ameliorative effect of Ulva lactuca polysaccharide extract (UPE) on renal injury induced by oxidative stress was analyzed. As shown by hematoxylin–eosin staining results, UPE can significantly improve the kidney injury induced by D-galactose (D-gal). Additionally, the protective mechanism of UPE on the kidney was explored. The results showed that UPE could decrease the levels of serum creatinine (Scr), blood urea nitrogen (BUN), serum cystatin C (Cys-C), lipid peroxidation, protein carbonylation, and DNA oxidative damage (8-OHdG) and improve kidney glutathione content. Moreover, UPE significantly increased the activities of superoxide dismutase and glutathione peroxidase and total antioxidant activity in mice. UPE also decreased the levels of inflammatory cytokines TNF-α and IL-6. Further investigation into the expression of apoptotic protein caspase-3 showed that UPE decreased the expression of apoptotic protein caspase-3. These results indicate that UPE has a potential therapeutic effect on renal injury caused by oxidative stress, providing a new theoretical basis for the treatment of oxidative damage diseases in the future.

In vitro and in vivo evaluation of the wound healing properties and safety assessment of two seaweeds (Sargassum ilicifolium and Ulva lactuca)

Seaweeds have been regarded as a reservoir of biologically active molecules that are important in the pharmaceutical industry. The aim of the present study was to explore the wound healing properties and to assess the safety of the seaweed Sargassum ilicifolium and Ulva lactuca. Enhanced cell proliferation and cell migration activities were observed in L929 cells treated with S. ilicifolium extract compared to U. lactuca extract treated cells and the control group. In-vivo experiments were conducted using five groups (10 in each) of Albino mice (BALB/c). Mice in group I and group II were treated (Orally, 100 mg/kg BW/day) with aqueous extracts of S. ilicifolium and U. lactuca, respectively for 14 days. Treatment group III received a topical application of the aqueous extract of S. ilicifolium (25% w/w) and ointment base (75% w/w) (2 g/kg BW/day, for 14 days). Group IV (Control) received an equal amount of distilled water, orally and mice in group V kept without wounds. The extract from S. ilicifolium showed stronger wound healing properties than the one from Ulva lactuca. Histopathological findings also revealed that the healing process was significantly enhanced in the mice group treated orally with S. ilicifolium aqueous extract. These findings show that S. ilicifolium species possess promising wound healing properties in-vitro and in-vivo.

Total Synthesis and Anti-Inflammatory Bioactivity of (-)-Majusculoic Acid and Its Derivatives

The first total synthesis of marine natural product, (−)-majusculoic acid (1) and its seven analogs (9–15), was accomplished in three to ten steps with a yield of 3% to 28%. The strategy featured the application of the conformational controlled establishment of the trans-cyclopropane and stereochemical controlled bromo-olefination or olefination by Horner–Wadsworth–Emmons (HWE) reaction. The potential anti-inflammatory activity of the eight compounds (1 and 9–15) was evaluated by determining the nitric oxide (NO) production in the lipopolysaccharide (LPS)-induced mouse macrophages RAW264.7. (−)-Majusculoic acid (1), methyl majusculoate (9), and (1R,2R)-2-((3E,5Z)-6-bromonona-3,5-dien-1-yl)cyclopropane-1-carboxylic acid (12) showed significant effect with inhibition rates of 33.68%, 35.75%, and 43.01%, respectively. Moreover, they did not show cytotoxicity against RAW264.7 cells, indicating that they might be potential anti-inflammatory agents.

Inhibition of Biofilm Formation by Modified Oxylipins from the Shipworm Symbiont Teredinibacter turnerae

The bioactivity-guided purification of the culture broth of the shipworm endosymbiont Teredinibacter turnerae strain 991H.S.0a.06 yielded a new fatty acid, turneroic acid (1), and two previously described oxylipins (2–3). Turneroic acid (1) is an 18-carbon fatty acid decorated by a hydroxy group and an epoxide ring. Compounds 1–3 inhibited bacterial biofilm formation in Staphylococcus epidermidis, while only 3 showed antimicrobial activity against planktonic S. epidermidis. Comparison of the bioactivity of 1–3 with structurally related compounds indicated the importance of the epoxide moiety for selective and potent biofilm inhibition.

Algicidal hydroxylated C18 unsaturated fatty acids from the red alga Tricleocarpa jejuensis: Identification, synthesis and biological activity

Bioassay-guided separation of a methanol extract of Tricleocarpa jejuensis by monitoring algicidal activity against the red tide phytoplankton Chattonella antiqua led to the isolation of an active fraction consisting of a mixture of four isomeric compounds. The active compounds were identified as (E)-9-hydroxyoctadec-10-enoic acid (1), (E)-10-hydroxyoctadec-8-enoic acid (2), (E)-11-hydroxyoctadec-12-enoic acid (3) and (E)-12-hydroxyoctadec-10-enoic acid (4) by NMR, IR and mass spectral data. The structures were confirmed by comparison of the NMR and MS data with those of authentic samples of 1-4 obtained by unambiguous syntheses. Synthesized hydroxy acids 1-4 and related compounds were assessed for algicidal activity against C. antiqua and it was found that all of 1-4 had high activity (>80% mortality at 24 h) at a concentration of 20 μg/mL. A structure-activity relationship study using 11 related compounds revealed that the presence of the hydroxyl group is important for the activity and the double bond may be replaced with a triple bond.

Strategies for UHPLC-MS/MS-Based Analysis of Different Classes of Acyl Chain Oxidation Products Resulting from Thermo-Oxidation of Sitostanyl Oleate

Phytostanyl fatty acid esters, which are being added to a variety of foods owing to their cholesterol-lowering properties, are susceptible to thermally induced oxidation reactions. Using sitostanyl oleate as an example, we, in this study, aimed at developing strategies for the detection and the quantitation of acyl chain oxidation products (ACOPs). The elaborated ultra high performance liquid chromatography-mass spectrometry MS/MS-based approach involves (i) derivatizations of hydroxy and oxo groups, (ii) combined use of atmospheric pressure chemical ionization and electrospray ionization as ionization techniques, and (iii) establishment of selective multireaction monitoring transitions. These strategies allow the identification of a broad spectrum of nonpolar short-chain as well as polar short- and long-chain hydroxy, epoxy, and oxo ACOPs. Semiquantitative assessments showed that sitostanyl 9,10-epoxystearate was the predominating ACOP resulting from thermo-oxidation of sitostanyl oleate at 180 °C for 30 min. The elaborated analytical approach paves the way to narrow the existing knowledge gap on the fate of phytostanyl fatty acid esters upon heat treatments.

An Algal Metabolite-Based PPAR-γ Agonist Displayed Anti-Inflammatory Effect via Inhibition of the NF-κB Pathway

In our previous study, a synthetic compound, (+)-(R,E)-6a1, that incorporated the key structures of anti-inflammatory algal metabolites and the endogenous peroxisome proliferator-activated receptor γ (PPAR-γ) ligand 15-deoxy-∆^12,14-prostaglandin J₂ (15d-PGJ₂), exerted significant PPAR-γ transcriptional activity. Because PPAR-γ expressed in macrophages has been postulated as a negative regulator of inflammation, this study was designed to investigate the anti-inflammatory effect of the PPAR-γ agonist, (+)-(R,E)-6a1. Compound (+)-(R,E)-6a1 displayed in vitro anti-inflammatory activity in lipopolysaccharides (LPS)-stimulated murine RAW264.7 macrophages. Compound (+)-(R,E)-6a1 suppressed the expression of proinflammatory factors, such as nitric oxide (NO), inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), possibly by the inhibition of the nuclear factor-κB (NF-κB) pathway. In macrophages, (+)-(R,E)-6a1 suppressed LPS-induced phosphorylation of NF-κB, inhibitor of NF-κB α (IκBα), and IκB kinase (IKK). These results indicated that PPAR-γ agonist, (+)-(R,E)-6a1, exerts anti-inflammatory activity via inhibition of the NF-κB pathway.

Bioactivity-based analysis and chemical characterization of cytotoxic compounds from a poisonous mushroom, Amanita spissacea, in human lung cancer cells in vitro

As part of our systematic study on Korean toxic mushrooms, bioactivity-guided fractionation of the MeOH extract of Amanita spissacea (Amanitaceae) fruiting bodies and chemical investigation of its cytotoxic fractions led to the isolation of (9E)-8-oxo-9-octadecenoic acid (1), (10E)-9-oxo-10-octadecenoic acid (2), (9E)-8-oxo-9-octadecenoate methyl ester (3), (9Z)-9-octadecenoate-(2'S)-2',3'-dihydroxypropyl ester (4), (9Z)-9-octadecenoic acid (5), and palmitic acid (6). The structures of the isolates were elucidated by NMR spectroscopic analysis and LC/MS analysis. Among the isolated compounds, compounds 1 and 2 exhibited the most potent cytotoxic activity in all human lung cancer cell lines examined, with IC₅₀ values ranging from 255.7 to 321.0 μM and 250.2 to 322.5 μM, respectively. The cytotoxicity of these compounds was also found to be mediated by apoptosis associated with caspase-3 activation. These findings provide experimental evidence suggesting the potential of A. spissacea as a promising natural source for the discovery of novel anticancer drug candidates.

Marine unsaturated fatty acids: structures, bioactivities, biosynthesis and benefits

Unsaturated fatty acids (UFAs) are an important category of monounsaturated and polyunsaturated fatty acids with nutritional properties.

Design of PPAR-γ agonist based on algal metabolites and the endogenous ligand 15-deoxy-Δ12, 14-prostaglandin J2

In a previous study, we synthesized endocyclic enone jasmonate derivatives that function as anti-inflammatory and PPAR-γ-activating entities by using key functional moieties of anti-inflammatory algal metabolites. Herein, we designed additional derivatives containing an exocyclic enone moiety that resembles the key structure of the natural PPAR-γ ligand, 15-deoxy-Δ^{12, 14}-prostaglandin J₂ (15 d-PGJ₂). The exocyclic enone moiety of 15 d-PGJ₂ is essential for covalent bonding with the Cys²⁸⁵ residue in the PPAR-γ ligand-binding domain (LBD). In silico analysis of the designed compounds indicated that they may form hydrogen bonds with key amino acid residues in the PPAR-γ LBD, and thus, secure a position in the bioactive cavity in a similar fashion as does rosiglitazone and 15 d-PGJ₂. By a luciferase reporter assay on rat liver Ac2F cells, the synthesized compounds were evaluated for PPAR-γ transcriptional activity. The differential PPAR-γ transcriptional activities of the geometric and enantiomeric isomers of the selected analog were also evaluated; based on our results, the enantiopure compound (+)-(R,E)-6a1 was suggested as a potential PPAR-γ ligand.

Two Isomeric C16 Oxo-Fatty Acids from the Diatom Chaetoceros karianus Show Dual Agonist Activity towards Human Peroxisome Proliferator-Activated Receptors (PPARs) α/γ

The peroxisome proliferator-activated receptors (PPARs) function as ligand-activated transcription factors that convert signals in the form of lipids to physiological responses through the activation of metabolic target genes. Due to their key roles in lipid and carbohydrate metabolism, the PPARs are important drug targets. However, for several of the PPAR drugs currently in use, adverse side effects have been reported. In an effort to identify compounds from marine organisms that may serve as molecular scaffolds for the development of novel and safer PPAR-targeting drugs, we performed a bioassay-guided screening of organic extracts made from organisms supplied by the Norwegian Biobank of Arctic Marine Organisms (Marbank). Among several interesting hits, we identified two poorly described isomeric oxo-fatty acids from the microalgae Chaetoceros karianus for which we provide the first evidence that they might display dual specificity towards human PPARα and PPARγ. Principal component analysis showed that C. karianus stood out from other Chaetoceros species, both with respect to the metabolic profile and the PPAR activity. The isolation of these compounds holds the potential of uncovering a PPAR pharmacophore with tunable activity and specificity.

Ulva lactuca polysaccharides prevent Wistar rat breast carcinogenesis through the augmentation of apoptosis, enhancement of antioxidant defense system, and suppression of inflammation

BACKGROUND

Recently, several research studies have been focused on the isolation and function of the polysaccharides derived from different algal species, which revealed multiple biological activities such as antioxidant and antitumor activities. This study assesses the possible breast cancer chemopreventive properties of common seaweeds, sea lettuce, Ulva lactuca (ulvan) polysaccharides using in vitro bioassays on human breast cancer cell line (MCF-7) and an in vivo animal model of breast carcinogenesis.

METHODS

Cytotoxic effect of ulvan polysaccharides on MCF-7 was tested in vitro. For an in vivo investigation, a single dose of 25 mg/kg body weight 7,12-dimethylbenz[a]anthracene (DMBA) and ulvan polysaccharides (50 mg/kg body weight every other day) for 10 weeks were administered orally to the Wistar rats.

RESULTS

Deleterious histopathological alterations in breast tissues including papillary cyst adenoma and hyperplasia of ductal epithelial lining with intraluminal necrotic materials and calcifications were observed in the DMBA-administered group. These lesions were prevented in the DMBA-administered group treated with ulvan polysaccharides. The immunohistochemical sections depicted that the treatment of DMBA-administered rats with ulvan polysaccharides markedly increased the lowered pro-apoptotic protein, p53, and decreased the elevated anti-apoptotic marker, bcl2, expression in the breast tissue. The elevated lipid peroxidation and the suppressed antioxidant enzyme activities in DMBA-administered control were significantly prevented by the treatment with ulvan polysaccharides. The elevated levels of inflammatory cytokines tumor necrosis factor-α and nitric oxide were significantly ameliorated in DMBA-administered rats treated with ulvan polysaccharides as compared to DMBA-administered control.

CONCLUSION

In conclusion, ulvan polysaccharides at the level of initiation and promotion might have potential chemopreventive effects against breast carcinogenesis. These preventive effects may be mediated through the augmentation of apoptosis, suppression of oxidative stress and inflammation, and enhancement of antioxidant defense system.

Potential anti-inflammatory natural products from marine algae

Inflammatory diseases have become one of the leading causes of health issue throughout the world, having a considerable influence on healthcare costs. With the emerging developments in natural product, synthetic and combinatorial chemistry, a notable success has been achieved in discovering natural products and their synthetic structural analogs with anti-inflammatory activity. However, many of these therapeutics have indicated detrimental side effects upon prolonged usage. Marine algae have been identified as an underexplored reservoir of unique anti-inflammatory compounds. These include polyphenols, sulfated polysaccharides, terpenes, fatty acids, proteins and several other bioactives. Consumption of these marine algae could provide defense against the pathophysiology of many chronic inflammatory diseases. With further investigation, algal anti-inflammatory phytochemicals have the potential to be used as therapeutics or in the synthesis of structural analogs with profound anti-inflammatory activity with reduced side effects. The current review summarizes the latest knowledge about the potential anti-inflammatory compounds discovered from marine algae.

The Algal Meroterpene 11-Hydroxy-1'-O-Methylamentadione Ameloriates Dextran Sulfate Sodium-Induced Colitis in Mice

Inflammatory bowel disease (IBD) is a complex class of immune disorders. Unfortunately, a treatment for total remission has not yet been found, while the use of natural product-based therapies has emerged as a promising intervention. The present study was aimed to investigate the anti-inflammatory effects of the algal meroterpene 11-hydroxy-1'-O-methylamentadione (AMT-E) in a murine model of dextran sodium sulphate (DSS)-induced colitis. AMT-E was orally administered daily (1, 10, and 20 mg/kg animal) to DSS treated mice (3% w/v) for 7 days. AMT-E prevented body weight loss and colon shortening and effectively attenuated the extent of the colonic damage. Similarly, AMT-E increased mucus production and reduced myeloperoxidase activity (marker for anti-inflammatory activity). Moreover, the algal meroterpene decreased the tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-10 levels, and caused a significant reduction of the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Our results demonstrate the protective effects of AMT-E on experimental colitis, provide an insight of the underlying mechanisms of this compound, and suggest that this class of marine natural products might be an interesting candidate for further studies on the prevention/treatment of IBD.

Cystoseira usneoides: A Brown Alga Rich in Antioxidant and Anti-inflammatory Meroditerpenoids

Twelve new meroditerpenoids, 1-12, along with eight known compounds, have been isolated from the brown alga Cystoseira usneoides collected off the coast of Tarifa (Spain). The structures of the new metabolites have been established by spectroscopic techniques. All of the new compounds consist of a toluhydroquinone-derived nucleus linked to a regular diterpenoid moiety, which can either be acyclic or contain an ether ring. Most structural diversity arises from the presence of different oxygenated functionalities and unsaturations along the two terminal isoprenoid units of the diterpene backbone. Twelve of the isolated meroditerpenes have been tested in antioxidant assays. All of them have shown radical-scavenging activity. The most active compounds were cystodiones G (1) and H (2), 11-hydroxyamentadione (15), and amentadione (16), which exhibited antioxidant activities in the range of 77-87% that of the Trolox standard. In anti-inflammatory assays, cystodiones G (1) and M (6), cystone C (9), 11-hydroxyamentadione (15), and amentadione (16) showed significant activity as inhibitors of the production of the proinflammatory cytokine TNF-α in LPS-stimulated THP-1 human macrophages.

Marine Isonitriles and Their Related Compounds

Marine isonitriles represent the largest group of natural products carrying the remarkable isocyanide moiety. Together with marine isothiocyanates and formamides, which originate from the same biosynthetic pathways, they offer diverse biological activities and in spite of their exotic nature they may constitute potential lead structures for pharmaceutical development. Among other biological activities, several marine isonitriles show antimalarial, antitubercular, antifouling and antiplasmodial effects. In contrast to terrestrial isonitriles, which are mostly derived from α-amino acids, the vast majority of marine representatives are of terpenoid origin. An overview of all known marine isonitriles and their congeners will be given and their biological and chemical aspects will be discussed.

The Edible Marine Alga Gracilariopsis chorda Alleviates Hypoxia/Reoxygenation-Induced Oxidative Stress in Cultured Hippocampal Neurons

Age-related neurological disorders are of growing concern among the elderly, and natural products with neuroprotective properties have been attracting increasing attention as candidates for the prevention or treatment of neurological disorders induced by oxidative stress. In an effort to explore natural resources, we collected some common marine seaweed from the Korean peninsula and Indonesia and screened them for neuroprotective activity against hypoxia/reoxygenation (H/R)-induced oxidative stress. Of the 23 seaweeds examined, the ethanol extract of Gracilariopsis chorda (GCE) provided maximum neuroprotection at an optimum concentration of 15 μg/mL, followed by Undaria pinnatifida. GCE increased cell viability after H/R, decreased the formation of reactive oxygen species (measured by 2',7'-dichlorodihydrofluorescein diacetate [DCF-DA] staining), and inhibited the double-stranded DNA breaks (measured by H2AX immunocytochemistry), apoptosis (measured by Annexin V/propidium iodide staining), internucleosomal DNA fragmentation (measured by DNA laddering), and dissipation of mitochondrial membrane potential (measured by JC-1 staining). Using reverse-phase high-pressure liquid chromatography, we quantitated the arachidonic acid (AA) in GCE, which provides neuroprotection against H/R-induced oxidative stress. This neuroprotective effect of AA was comparable to that of GCE. These findings suggest that the neuroprotective effect of GCE against H/R-induced neuronal death is due, at least in part, to the AA content that suppresses neuronal apoptosis.

Antibiotic oxylipins from Alternanthera brasiliana and its endophytic bacteria

Bioassay-guided fractionation of Alternanthera brasiliana stem extracts resulted in the isolation of an antibiotically active fraction. Five human pathogenic bacteria were used to guide the fractionation process for the isolation of antimicrobial compounds. Finally, 17 linoleate oxylipins were identified by LC-MS/MS and NMR spectroscopy. Five of the isolated compounds present in A. brasiliana tissues were also detected to be synthesized by endophytic bacteria of the genus Bacillus that were isolated from A. brasiliana. It is speculated that the antibiotic oxylipins from A. brasiliana might derive from bacteria and be involved in an ecological relationship between this plant and its endophytes.

Antiulcer, wound healing and hepatoprotective activities of the seaweeds Gracilaria crassa, Turbinaria ornata and Laurencia papillosa from the southeast coast of India

Seaweeds have bioactive compounds of interest in the pharmaceutical industry. In India, seaweeds are used exclusively for phycocolloids production and have not yet received consideration as a dietary supplement. So, it has become imperative to explore the biomedical potential of seaweeds and promote their utilization as a functional food. The seaweeds Turbinaria ornata, Gracillaria crassa and Laurencia papillosa, collected from the Tuticorin coast of the Southeast coast of India and selected based on preliminary screening, were extracted with acetone and evaluated for antiulcer, wound healing and hepatoprotective activities. L. papillosa showed the highest level of gastric protection activity (81%) at 200 mg/kg, comparable to the standard drug ranitidine (90%). G. crassa followed with 76%. G. crassa and L. papillosa, showed marked wound-healing activity. G. crassa at 200 mg/kg, showed a marked effect on the serum marker enzymes indicating prominent hepatoprotective activity. The noteworthy wound-healing and hepato-protective properties of G. crassa besides anti-ulcer activity next to L. papillosa were indicative of its potential for further consideration.

Aqueous extract of the edible Gracilaria tenuistipitata inhibits hepatitis C viral replication via cyclooxygenase-2 suppression and reduces virus-induced inflammation

Hepatitis C virus (HCV) is an important human pathogen leading to hepatocellular carcinoma. Using an in vitro cell-based HCV replicon and JFH-1 infection system, we demonstrated that an aqueous extract of the seaweed Gracilaria tenuistipitata (AEGT) concentration-dependently inhibited HCV replication at nontoxic concentrations. AEGT synergistically enhanced interferon-α (IFN-α) anti-HCV activity in a combination treatment. We found that AEGT also significantly suppressed virus-induced cyclooxygenase-2 (COX-2) expression at promoter transactivation and protein levels. Notably, addition of exogenous COX-2 expression in AEGT-treated HCV replicon cells gradually abolished AEGT anti-HCV activity, suggesting that COX-2 down-regulation was responsible for AEGT antiviral effects. Furthermore, we highlighted the inhibitory effect of AEGT in HCV-induced pro-inflammatory gene expression such as the expression of tumour necrosis factor-α, interleukin-1β, inducible nitrite oxide synthase and COX-2 in a concentration-dependent manner to evaluate the potential therapeutic supplement in the management of patients with chronic HCV infections.

The anti-cancer activities of jasmonates

Jasmonates, plant stress hormones protecting the plant from microbial pathogens and environmental stresses, were also discovered to have toxic activities toward mammalian cancer cells. Methyl jasmonate (MJ) was found to be the most active anti-cancer derivate among natural jasmonates, exhibiting a specific cell death-induction effect toward several cancer cells. Since that discovery of jasmonates-inducing cancer cell death, the molecular mechanism of action of jasmonates leading to cell death was deciphered. Moreover, in addition to the direct effects of MJ on cancer cell death, it was found to deregulate several genes and affect various intracellular factors and cellular processes, such as sensitization of apoptotic cell death induced by TRAIL, cancer cell migration attenuation, cell cycle arrest, and differentiation. This mini-review summarizes over a decade of research of jasmonates as anti-cancer agents.

Aqueous extracts of the edible Gracilaria tenuistipitata are protective against H₂O₂-induced DNA damage, growth inhibition, and cell cycle arrest

Potential antioxidant properties of an aqueous extract of the edible red seaweed Gracilaria tenuistipitata (AEGT) against oxidative DNA damage were evaluated. The AEGT revealed several antioxidant molecules, including phenolics, flavonoids and ascorbic acid. In a cell-free assay, the extract exhibited 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity that significantly reduced H₂O₂-induced plasmid DNA breaks in a dose-response manner (P < 0.001). The AEGT also suppressed H₂O₂-induced oxidative DNA damage in H1299 cells by reducing the percentage of damaged DNA in a dose-response manner (P < 0.001) as measured by a modified alkaline comet-nuclear extract (comet-NE) assay. The MTT assay results showed that AEGT confers significant protection against H₂O₂-induced cytotoxicity and that AEGT itself is not cytotoxic (P < 0.001). Moreover, H₂O₂-induced cell cycle G2/M arrest was significantly released when cells were co-treated with different concentrations of AEGT (P < 0.001). Taken together, these findings suggest that edible red algae Gracilaria water extract can prevent H₂O₂-induced oxidative DNA damage and its related cellular responses.

In vitro stability and in vivo anti-inflammatory efficacy of synthetic jasmonates

A chlorinated methyl jasmonate analog (J7) was elaborated as an in vitro anti-inflammatory lead. However, its in vitro efficacy profile was not reproduced in a subsequent in vivo evaluation, presumably due to its rapid enzymatic hydrolysis in a biological system. In an attempt to improve the metabolic stability of the lead J7 by replacement of its labile methyl ester with reasonable ester groups, several analogs resistant to enzymatic hydrolysis were synthesized. In vivo evaluation of the stability-improved analogs showed that these compounds displayed higher efficacy than the lead J7, suggesting that these new jasmonate analogs may serve as potential anti-inflammatory leads.

Biofiltration of fishpond effluents and accumulation of N-compounds (phycobiliproteins and mycosporine-like amino acids) versus C-compounds (polysaccharides) in Hydropuntia cornea (Rhodophyta)

The biofiltration capacity, biomass-yield and accumulation of N- and C-compounds of Hydropuntia cornea were analyzed. Algae were grown in different conditions for 28 d: outdoor and indoor, with or without fishpond effluents. N-uptake efficiency of these effluents was higher than 95% after 7 d both outdoors and indoors. N-enriched conditions reduced the extent of photoinhibition and increased the maximal quantum yield in H. cornea. The biomass-yield was higher in outdoor grown-algae after 7 d and decreased independently of the treatment after 28 d. N, acid polysaccharide (AP) and mycosporine-like amino acid (MAA)-yields decreased throughout the experiment in all conditions. The highest MAA-yield was observed in fishpond effluent outdoor-grown algae, indicating a positive effect of increased radiation on MAA accumulation. However, APs were higher under N-depleted conditions. The use of MAAs as UV-screening and antioxidants, and the use of AP as immunostimulants are discussed.

Efficacy of albendazole combined with a marine fungal extract (m2-9) against Angiostrongylus cantonensis-induced meningitis in mice

The pathogenesis of angiostrongyliasis, resulting from Angiostrongylus cantonensis invasion of the human central nervous system, remains elusive. Anthelmintics are usually used to kill worms, although dead worms in the brain may cause severe inflammation which will lead to central nervous system damage. Therefore, combination therapy with anthelmintics and anti-inflammatory drugs in the treatment of human angiostrongyliasis needs further study. To evaluate the efficacy of albendazole combined with a marine fungal extract (m2-9) in A. cantonensis infection, BALB/c mice infected by the third-stage larvae of A. cantonensis were divided into three groups: mice treated with albendazole or m2-9 alone or in combination from day 5 post-inoculation (PI). Several efficacy parameters were recorded, including weight change, worm recovery, neurological function, behavioural analysis, eosinophil and leucocyte counts. The results showed that combination therapy increased body weight, reduced worm burden, improved learning ability, memory and action, decreased neurological dysfunction and leucocyte response in these mice. The combination of albendazole and m2-9 treatment significantly decreased leucocyte response and increased the frequency of rearing, compared to infected mice treated with either drug alone. Therefore, m2-9 is a natural product with potentially significant therapeutic value for angiostrongyliasis and is worthy of further study.

Marine pharmacology in 2007-8: Marine compounds with antibacterial, anticoagulant, antifungal, anti-inflammatory, antimalarial, antiprotozoal, antituberculosis, and antiviral activities; affecting the immune and nervous system, and other miscellaneous mechanisms of action

The peer-reviewed marine pharmacology literature in 2007-8 is covered in this review, which follows a similar format to the previous 1998-2006 reviews of this series. The preclinical pharmacology of structurally characterized marine compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, anticoagulant, antifungal, antimalarial, antiprotozoal, antituberculosis and antiviral activities were reported for 74 marine natural products. Additionally, 59 marine compounds were reported to affect the cardiovascular, immune and nervous systems as well as to possess anti-inflammatory effects. Finally, 65 marine metabolites were shown to bind to a variety of receptors and miscellaneous molecular targets, and thus upon further completion of mechanism of action studies, will contribute to several pharmacological classes. Marine pharmacology research during 2007-8 remained a global enterprise, with researchers from 26 countries, and the United States, contributing to the preclinical pharmacology of 197 marine compounds which are part of the preclinical marine pharmaceuticals pipeline. Sustained preclinical research with marine natural products demonstrating novel pharmacological activities, will probably result in the expansion of the current marine pharmaceutical clinical pipeline, which currently consists of 13 marine natural products, analogs or derivatives targeting a limited number of disease categories.

Evaluation of endogenous fatty acid amides and their synthetic analogues as potential anti-inflammatory leads

A series of endogenous fatty acid amides and their analogues (1-78) were prepared, and their inhibitory effects on pro-inflammatory mediators (NO, IL-1β, IL-6, and TNF-α) in LPS-activated RAW264.7 cells were evaluated. Their inhibitory activity on the pro-inflammatory chemokine MDC in IFN-γ-activated HaCaT cells was also examined. The results showed that the activity is strongly dependent on the nature of the fatty acid part of the molecules. As expected, the amides derived from enone fatty acids showed significant activity and were more active than those derived from other types of fatty acids. A variation of the amine headgroup also altered bioactivity profile remarkably, possibly by modulating cell permeability. Regarding the amine part of the molecules, N-acyl dopamines exhibited the most potent activity (IC(50) ∼2 μM). This is the first report of the inhibitory activity of endogenous fatty acid amides and their analogues on the production of nitric oxide, cytokines (IL-1β, IL-6, and TNF-α) and the chemokine MDC. This study suggests that the enone fatty acid-derived amides (such as N-acyl ethanolamines and N-acyl amino acids) and N-acyl dopamines may be potential anti-inflammatory leads.

The occurrence of 15-keto-prostaglandins in the red alga Gracilaria verrucosa

New 15-keto-prostaglandins (1-4) were isolated from the MeOH extract of the red alga, Gracilaria verrucosa. Their structures were determined to be prostaglandin B congeners (1-3) and a prostaglandin E congener (4) based on the NMR and MS data. Prostaglandins with a C-15 keto function are rare from natural sources. The presence of these metabolites in the alga is notable because 15-keto-prostaglandins (15-keto-PGs) are considered to be the metabolic products of regular prostaglandins in mammals. The occurrence of different prostaglandins in this alga might be due to the existence of different oxidative enzymes, as previously mentioned for oxygenated fatty acids of the red alga Gracilariopsis lemaneiformis. The antiinflammatory activity of these prostaglandins was examined by evaluating their inhibitory effects on nitric oxide production in lipopolysaccharide (LPS)-activated RAW264.7 murine macrophage cells. These prostaglandins showed weak activity on nitric oxide production.

Inhibitory effect of Jeju endemic seaweeds on the production of pro-inflammatory mediators in mouse macrophage cell line RAW 264.7

Seaweed has been used in traditional cosmetics and as a herbal medicine in treatments for cough, boils, goiters, stomach ailments, and urinary diseases, and for reducing the incidence of tumors, ulcers, and headaches. Despite the fact that seaweeds are frequently used in the practice of human health, little is known about the role of seaweed in the context of inflammation. This study aimed to investigate the influence of Jeju endemic seaweed on a mouse macrophage cell line (RAW 264.7) under the stimulation of lipopolysaccharide (LPS). Ethyl acetate extracts obtained from 14 different kinds of Jeju seaweeds were screened for inhibitory effects on pro-inflammatory mediators. Our results revealed that extracts from five seaweeds, Laurencia okamurae, Grateloupia elliptica, Sargassum thunbergii, Gloiopeltis furcata, and Hizikia fusiformis, were potent inhibitors of the production of pro-inflammatory mediators such as nitric oxide (NO), prostaglandin E(2) (PGE(2)), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha). Based on these results, the anti-inflammatory effects and low cell toxicity of these seaweed extracts suggest potential therapeutic applications in the regulation of the inflammatory response.

Lactarane sesquiterpenoids from Lactarius subvellereus and their cytotoxicity

Subvellerolactones B (1), D (2), and E (3), structurally unusual lactarane sesquiterpenoids, were isolated from the fruiting bodies of Lactarius subvellereus together with four known lactarane sesquiterpenes (4-7). The chemical structures and stereochemistries of compounds 1-3 were determined on the basis of spectroscopic analyses, including 1D and 2D NMR experiments and a convenient Mosher ester procedure. Subvellerolactone B (1) exhibited cytotoxicity against the A549, SK-MEL-2, and HCT-15 cell lines with IC50 values of 26.5, 18.3, and 14.2 microM, respectively, and subvellerolactones D (2) and E (3) showed cytotoxicity against the A549 and HCT-15 cell lines (IC50 (2): 25.1 and 17.8 microM, and IC50 (3): 19.6 and 28.7 microM, respectively).

Ceratodictyols, 1-glyceryl ethers from the red alga-sponge association Ceratodictyon spongiosum/Haliclona cymaeformis

Six 1-glyceryl ethers (1-6) were isolated from the red alga-sponge assemblage Ceratodictyon spongiosum/Haliclona cymaeformis. Structural assignments were conducted by interpretation of spectroscopic data and the modified Mosher's method. Four allylic alcohols were obtained as a pair of epimeric mixtures (3/4 and 5/6). These glyceryl ethers exhibited weak cytotoxic activity against HeLa human cervical cancer cells.