Triplinones A-H: Anti-Inflammatory Arylalkenyl α,ß-Unsaturated-δ-Lactones Isolated from the Leaves of Australian Rainforest Plant Cryptocarya triplinervis (Lauraceae).

Our ongoing exploration of Australian rainforest plants for the biodiscovery of anti-inflammatory agents led to the isolation and structural elucidation of eight new arylalkenyl α,ß-unsaturated-δ-lactones, triplinones A-H (1-8), from the leaves of the Australian rainforest plant Cryptocarya triplinervis B. Hyland (Lauraceae). The chemical structures of these compounds were established by NMR spectroscopic data analysis, while their relative and absolute configurations were established using a combination of Mosher ester analysis utilizing both Riguera's and Kishi's methods, ECD experiments, and X-ray crystallography analysis. Compounds 1-8 exhibited good inhibitory activities toward nitric oxide (NO) production in lipopolysaccharide (LPS) and interferon (IFN)-γ induced RAW 264.7 macrophages, in particular compounds 1-3 and 5, with IC50 values of 7.3 ± 0.5, 6.0 ± 0.3, 5.6 ± 0.3, and 5.4 ± 2.5 µM, respectively.

Exploring the Anti-Inflammatory Potential of Australian Native Plants Based on their Ethnopharmacological Knowledge.

Inflammation represents the inherent protective reaction of the human body to various harmful agents and noxious stimuli. Standard anti-inflammatory therapy including nonsteroidal anti-inflammatory drugs are associated with several side effects. In the past decades, people rely on medicinal plants for the treatment of inflammation. The traditional utilization of medicinal plants is regarded as a safe, cost-effective, and broadly accepted approach. In this study, anti-inflammatory activity of plants traditionally utilized by the D'harawal people in Australia has been assessed in vitro. Eighty Australian native plants were screened based on the Dharawal Pharmacopeia for their inhibitory effect on the nitric oxide (NO) production in lipopolysaccharides (LPS) and interferon (IFN)-γ stimulated RAW 264.7 murine macrophages for their anti-inflammatory activity. From the eighty ethanolic extracts screened, seventeen displayed potent NO inhibition with an IC50 recorded below 15 µg/mL. The aim of this review was to utilise the ethnopharmacological knowledge and to correlate the anti-inflammatory activity of the seventeen plants with either their known or unknown phytochemicals reported in the literature. In doing so, we have created a snapshot of Australian native plant candidates that warrant further chemical investigation associated with their anti-inflammatory activity.

Identification of Nrf2 Activators from the Roots of Valeriana officinalis.

Various age-related chronic diseases have been linked to oxidative stress. The cellular antioxidant response pathway is regulated by the transcription factor nuclear erythroid factor 2. Therefore, plant-derived nuclear erythroid factor 2 activators might be useful therapeutics to stimulate the body's defense mechanisms. Our study focused on the discovery of potent nuclear erythroid factor 2 activators from medicinal plants. Initially, a variety of medicinal plant extracts were screened for nuclear erythroid factor 2 activity using a nuclear erythroid factor 2 luciferase reporter cell line. Among these, Valerian (Valeriana officinalis) root was identified as a potent candidate. Sequential extraction and bioassay-guided fractionation led to the isolation of four nuclear erythroid factor 2-active compounds, which were structurally identified by NMR and LC/HRMS as the known compounds isovaltrate, valtrate, jatamanvaltrate-P, and valerenic acid. These four compounds were then tested in relevant biological assays. Firstly, their effects on the expression of glutathione S-transferase, glutamate-cysteine ligase catalytic subunit, glutathione peroxidase, and heme oxygenase 1 were determined in HepG2 cells. Glutathione S-transferase P1 and glutamate-cysteine ligase catalytic subunit were upregulated by isovaltrate, valtrate, and jatamanvaltrate-P, while heme oxygenase 1 was upregulated by isovaltrate, jatamanvaltrate-P, and valerenic acid. The four compounds also increased the levels of glutathione and its metabolite, CysGly. As glutathione aids in the detoxification of hydrogen peroxide, cytoprotective effects of these four nuclear erythroid factor 2 activators against hydrogen peroxide toxicity were investigated, and indeed, the compounds significantly improved cell survival. This study provides evidence that four valepotriates from the roots of V. officinalis are activators of nuclear erythroid factor 2-mediated antioxidant and detoxification pathways. Our data might expand the medical use of this plant beyond its current application as a sleep aid.

A Method and Formula for the Quantitative Analysis of the Total Bioactivity of Natural Products.

Identification of bioactive natural products from plants starts with the screening of extracts for a desired bioactivity such as antimicrobial, antifungal, anti-cancer, anti-inflammatory, or neuroprotective. When the bioactivity shows sufficient potency, the plant material is subjected to bio-activity-guided fractionation, which involves, e.g., sequential extraction followed by chromatographic separation, including HPLC. The bioactive compounds are then structurally identified by high-resolution mass spectrometry and nuclear magnetic resonance (NMR). One of the questions that come up during the purification process is how much of the bioactivity originally present in the crude extract is preserved during the purification process. If this is the case, it is interesting to investigate if the loss of total bioactivity is caused by the loss of material during purification or by the degradation or evaporation of potent compounds. A further possibility would be the loss of synergy between compounds present in the mixture, which disappears when the compounds are separated. In this publication, a novel formula is introduced that allows researchers to calculate total bioactivity in biological samples using experimental data from our research into the discovery of anti-inflammatory compounds from Backhousia myrtifolia (Grey Myrtle). The results presented show that a raw ethanolic extract retains slightly more bioactivity than the sum of all sequential extracts per gram of starting material and that-despite a large loss of material during HPLC purification-the total bioactivity in all purified fractions is retained, which is indicative of rather an additive than a synergistic principle.

From the Bush to the Brain: Preclinical Stages of Ethnobotanical Anti-Inflammatory and Neuroprotective Drug Discovery-An Australian Example.

The Australian rainforest is a rich source of medicinal plants that have evolved in the face of dramatic environmental challenges over a million years due to its prolonged geographical isolation from other continents. The rainforest consists of an inherent richness of plant secondary metabolites that are the most intense in the rainforest. The search for more potent and more bioavailable compounds from other plant sources is ongoing, and our short review will outline the pathways from the discovery of bioactive plants to the structural identification of active compounds, testing for potency, and then neuroprotection in a triculture system, and finally, the validation in an appropriate neuro-inflammatory mouse model, using some examples from our current research. We will focus on neuroinflammation as a potential treatment target for neurodegenerative diseases including multiple sclerosis (MS), Parkinson's (PD), and Alzheimer's disease (AD) for these plant-derived, anti-inflammatory molecules and highlight cytokine suppressive anti-inflammatory drugs (CSAIDs) as a better alternative to conventional nonsteroidal anti-inflammatory drugs (NSAIDs) to treat neuroinflammatory disorders.

Myrtinols A-F: New Anti-Inflammatory Peltogynoid Flavonoid Derivatives from the Leaves of Australian Indigenous Plant Backhousia myrtifolia.

Our in-house ethnopharmacological knowledge directed our anti-inflammatory investigation into the leaves of Backhousia mytifolia. Bioassay guided isolation of the Australian indigenous plant Backhousia myrtifolia led to the isolation of six new rare peltogynoid derivatives named myrtinols A-F (1-6) along with three known compounds 4-O-methylcedrusin (7), 7-O-methylcedrusin (8) and 8-demethylsideroxylin (9). The chemical structures of all the compounds were elucidated by detailed spectroscopic data analysis, and absolute configuration was established using X-ray crystallography analysis. All compounds were evaluated for their anti-inflammatory activity by assessing the inhibition of nitric oxide (NO) production and tumor necrosis factor- α (TNF-α) in lipopolysaccharide (LPS) and interferon (IFN)-γ activated RAW 264.7 macrophages. A structure activity relationship was also established between compounds (1-6), noting promising anti-inflammatory potential by compounds 5 and 9 with an IC50 value of 8.51 ± 0.47 and 8.30 ± 0.96 µg/mL for NO inhibition and 17.21 ± 0.22 and 46.79 ± 5.87 µg/mL for TNF-α inhibition, respectively.

Pharmacological considerations for treating neuroinflammation with curcumin in Alzheimer's disease.

Prof. Dr. Peter Riederer, the former Head of the Neurochemistry Department of the Psychiatry and Psychotherapy Clinic at the University of Würzburg (Germany), has been one of the pioneers of research into oxidative stress in Parkinson's and Alzheimer's disease (AD). This review will outline how his scientific contribution to the field has opened a new direction for AD treatment beyond "plaques and tangles". In the 1990s, Prof. Riederer was one of the first scientists who proposed oxidative stress and neuroinflammation as one of the major contributors to Alzheimer's disease, despite the overwhelming support for the "amyloid-only" hypothesis at the time, which postulated that the sole and only cause of AD is ß-amyloid. His group also highlighted the role of advanced glycation end products, sugar and dicarbonyl-derived protein modifications, which crosslink proteins into insoluble aggregates and potent pro-inflammatory activators of microglia. For the treatment of chronic neuroinflammation, he and his group suggested that the most appropriate drug class would be cytokine-suppressive anti-inflammatory drugs (CSAIDs) which have a broader anti-inflammatory action range than conventional non-steroidal anti-inflammatory drugs. One of the most potent CSAIDs is curcumin, but it suffers from a variety of pharmacokinetic disadvantages including low bioavailability, which might have tainted many human clinical trials. Although a variety of oral formulations with increased bioavailability have been developed, curcumin's absorption after oral delivery is too low to reach therapeutic concentrations in the micromolar range in the systemic circulation and the brain. This review will conclude with evidence that rectally applied suppositories might be the best alternatives to oral medications, as this route will be able to evade first-pass metabolism in the liver and achieve high concentrations of curcumin in plasma and tissues, including the brain.

Tristaenone A: A New Anti-Inflammatory Compound Isolated from the Australian Indigenous Plant Tristaniopsis laurina.

Inspired by ethnopharmacological knowledge, we conducted a bioassay-guided fractionation of the leaves of Tristaniopsis laurina which led to the discovery of a new anti-inflammatory compound, tristaenone A (1). The structure was elucidated by detailed spectroscopic data analysis, and the absolute configuration was established using X-ray crystallography analysis. Tristaenone A (1) suppressed LPS and IFN-γ-induced NO, TNF-α and IL-6 production in RAW 264.7 cells with IC50 values of 37.58 ± 2.45 µM, 80.6 ± 5.82 µM and 125.65 ± 0.34 µM, respectively. It also inhibited NF-κB nuclear translocation by 52.93 ± 14.14% at a concentration of 31.85 µM.

Determination of glyoxal and methylglyoxal in serum by UHPLC coupled with fluorescence detection.

Glyoxal (GO) and methylglyoxal (MGO) are two important biomarkers in diabetes. Analytical methods for determination of GO and MGO in serum samples are either HPLC with UV-Vis (low sensitivity) or MS/MS (expensive) detection. These disadvantages have hampered the introduction of these biomarkers as a routine analyte for diabetes diagnostics into the clinical laboratory. In this study, we introduce a UHPLC method with fluorescence detection for the measurement of GO and MGO in serum samples by pre-column derivatization at neutral pH with 5, 6-diamino-2,4-dihydroxypyrimidine sulfate (DDP) to form lumazines. The method was validated as per FDA guidelines. Using this method, we have determined GO and MGO in a variety of animal serum samples, and for example, determined the GO and MGO concentration in adult bovine serum to be 852 ±â€¯27 and 192 ±â€¯10 nmol/L, respectively. In human serum, GO and MGO levels in non-diabetic subjects (n = 14) were determined to be 154 ±â€¯88 and 98 ±â€¯27 nmol/L, and in serum samples from subjects with diabetes (n = 14) 244 ±â€¯137 and 190 ±â€¯68 nmol/L, respectively. In addition, interference studies showed that physiological serum components did not lead to an artificial increase in the levels of GO and MGO.

Cytochalasins from an Australian Marine Sediment-Derived Phomopsis sp. (CMB-M0042F): Acid-Mediated Intramolecular Cycloadditions Enhance Chemical Diversity.

Chemical analysis of an Australian coastal marine sediment-derived fungus, Phomopsis sp. (CMB-M0042F), yielded the known cytochalasins J (1) and H (2), together with five new analogues, cytochalasins J1-J3 (3-5) and H1 and H2 (6 and 7). Structures of 1-7 were assigned on the basis of detailed spectroscopic analysis, chemical interconversion, and biosynthetic and mechanistic considerations. Of note, 1 and 2 proved to be highly sensitive to acid-mediated transformation, with 1 affording 3-5 and 2 affording 6 and 7. Whereas 1, 2, 4, and 5 were detected as natural products in crude culture extracts, 3, 6, and 7 were designated as acid-mediated handling artifacts. We propose novel stereo- and regiospecific intramolecular cycloadditions, under tight functional group control, that facilitate selective conversion of 1 and 2 to the rare 5/6/6/7/5- and 5/6/5/8-fused heterocycles 5 and 7, respectively. Knowledge of acid sensitivity within the cytochalasin family provides a valuable cautionary lesson that has the potential to inform our analysis of past and future investigations into this structure class and inspire novel biomimetic transformations leading to new chemical diversity.

Pyxipyrrolones: Structure Elucidation and Biosynthesis of Cytotoxic Myxobacterial Metabolites.

In the search for new secondary metabolites from myxobacteria, a strain from the genus Pyxidicoccus was investigated. This led to the identification of a new class of natural products showing structural novelty and interesting biological activity. Isolation and structure elucidation of two analogues led to the identification of pyxipyrrolone A and B, harboring the novel 3-methylene-2,3,4,5,6,7,8,9-octahydro-1H-benzo[e]isoindol-1-one scaffold. Mosher's ester analysis combined with NMR studies allowed the determination of all stereocenters but one. Genome sequencing of the producer strain led to the identification of a putative biosynthetic gene cluster for the pyxipyrrolones. The compounds showed activity against several cancer cell lines (µm range) with pyxipyrrolone B having 2- to 11-fold higher activity than A, although they differ only by one methylene group.

Anti-Inflammatory Chemical Profiling of the Australian Rainforest Tree Alphitonia petriei (Rhamnaceae).

Chronic inflammation is an important pathological condition in many human diseases, and due to the side effects of the currently used non-steroidal anti-inflammatory drugs, discovery of novel anti-inflammatory drugs is of general interest. Anti-inflammatory activity guided compound isolation from the plant Alphitonia petriei led to the isolation of the known plant sterols emmolic acid (1), alphitolic acid (2), trans- and cis-coumaroyl esters of alphitolic acid (3 and 4) and betulinic acid (5). A detailed spectroscopic analysis led to the structure elucidation of the alphitolic acid derivatives (1-5), and the semi-synthetic emmolic acid acetate (6). When tested in LPS (Lipopolysaccharides) + IFN-γ (Interferon gamma) activated RAW 264.7 macrophages, all compounds except (1) exhibited potent anti-inflammatory activity (IC50 values as low as 1.7 µM) in terms of downregulation of NO and TNF-α production, but also demonstrated some considerable cytotoxicity.

Aranciamycins I and J, Antimycobacterial Anthracyclines from an Australian Marine-Derived Streptomyces sp.

Chemical analysis of an Australian marine-derived Streptomyces sp. (CMB-M0150) yielded two new anthracycline antibiotics, aranciamycins I (1) and J (2), as well as the previously reported aranciamycin A (3) and aranciamycin (4). The aranciamycins 1-4, identified by detailed spectroscopic analysis, were noncytotoxic when tested against selected Gram-negative bacteria and fungi (IC50 >30 µM) and exhibited moderate and selective cytotoxicity against Gram-positive bacteria (IC50 >1.1 µM) and a panel of human cancer cell lines (IC50 > 7.5 µM). Significantly, 1-4 were cytotoxic (IC50 0.7-1.7 µM) against the Mycobacterium tuberculosis surrogate M. bovis bacille Calmette-Guérin.

Shornephine A: structure, chemical stability, and P-glycoprotein inhibitory properties of a rare diketomorpholine from an Australian marine-derived Aspergillus sp.

Chemical analysis of an Australian marine sediment-derived Aspergillus sp. (CMB-M081F) yielded the new diketomorpholine (DKM) shornephine A (1) together with two known and one new diketopiperazine (DKP), 15b-ß-hydroxy-5-N-acetyladreemin (2), 5-N-acetyladreemin (3), and 15b-ß-methoxy-5-N-acetyladreemin (4), respectively. Structure elucidation of 1-4 was achieved by detailed spectroscopic analysis, supported by chemical degradation and derivatization, and biosynthetic considerations. The DKM (1) underwent a facile (auto) acid-mediated methanolysis to yield seco-shornephine A methyl ester (1a). Our mechanistic explanation of this transformation prompted us to demonstrate that the acid-labile and solvolytically unstable DKM scaffold can be stabilized by N-alkylation. Furthermore, we demonstrate that at 20 µM shornephine A (1) is a noncytotoxic inhibitor of P-glycoprotein-mediated drug efflux in multidrug-resistant human colon cancer cells.

Cystobactamids: myxobacterial topoisomerase inhibitors exhibiting potent antibacterial activity.

The development of new antibiotics faces a severe crisis inter alia owing to a lack of innovative chemical scaffolds with activities against Gram-negative and multiresistant pathogens. Herein, we report highly potent novel antibacterial compounds, the myxobacteria-derived cystobactamids 1-3, which were isolated from Cystobacter sp. and show minimum inhibitory concentrations in the low µg mL(-1) range. We describe the isolation and structure elucidation of three congeners as well as the identification and annotation of their biosynthetic gene cluster. By studying the self-resistance mechanism in the natural producer organism, the molecular targets were identified as bacterial type IIa topoisomerases. As quinolones are largely exhausted as a template for new type II topoisomerase inhibitors, the cystobactamids offer exciting alternatives to generate novel antibiotics using medicinal chemistry and biosynthetic engineering.

Insignoic acids A - E, unusual α, ß-unsaturated keto fatty acids isolated from the exocarp of Australian rainforest tree Endiandra insignis (Lauraceae).

Anti-inflammatory bioassay-guided compound isolation from the exocarp of the Australian rainforest tree Endiandra insignis (family Lauraceae) has led to the discovery and structural elucidation of unusual α, ß-unsaturated twenty-four carbon fatty acids and their positional isomers, insignoic acids A - E (1a - 5c). The stereochemistry and position of the double bond within the aliphatic chain were independently determined via NMR spectroscopy and Ozone-Induced Dissociation (OzID) Mass Spectrometry, respectively. Compounds (1a - 5c) displayed good to moderate anti-inflammatory activity in the range of 8-84 µM. The low therapeutic index observed when assessing the cell viability in the RAW macrophage cell lines, prompted us to investigate the anticancer potential of these unusual fatty acids. The anti-cancer activity was assessed in A-431 carinoma cell lines and MM649 melanoma cell lines. Insignoic acid C (3a-f) exhibited the highest level of potency with an IC50 value of 5-7 µM against both the cell lines. The insignoic acids are the first of their kind known for incorporating an alpha-beta unsaturated system flanked next to a keto group with an additional level of oxygenation at C-6 in a 24­carbon fatty acid backbone.

Ternstroenol F: a new pentacyclic triterpenoid saponin isolated from the Australian rainforest plant Ternstroemia cherryi.

A detailed close phytochemical investigation of the fruits of Ternstroemia cherryi led to the isolation and identification of the minor metabolite, ternstroenol F, which possessed the usual barrigenol-like terpenoid backbone. The notable difference was that this minor metabolite had the 2(E)-4(Z)-6(E)-decatrienoic acid forming an ester bond at C-22 of the oleanane backbone. Ternstroenol F was evaluated for its inhibitory effects on NO inhibition, cell viability and TNF- α release in RAW 264.7 macrophages, displaying an IC50 values of 0.23, 0.81 and 1.84 µM respectively.

Polysciasoside B and C: new dammarane-type triterpene glycosides from the leaves of Australian rainforest plant Polyscias australiana (F.Muell.) Philipson (Araliaceae).

Phytochemical investigation of the leaves of Polyscias australiana (F.Muell.) Philipson (family Araliaceae) led to the isolation and identification of two new analogues belonging to the rare dammarane-type triterpene glycosides, polysciasosides B (1) and C (2). Also isolated in high yields from this plant was the known saponin, ß-hedrin (3). The two new polysciasoside analogues exhibited no anti-inflammatory activity (inhibitory effects on NO inhibition and cell viability in RAW 264.7 macrophages) or cytotoxic activity against AGS gastric adenocarcinoma or the MCF7 breast adenocarcinoma cell lines. In contrast, the known compound ß-hedrin exhibited potent anti-inflammatory and cytotoxicity in these biological assays.

Cryptocaryoic acids A - C: New phenyl alkyl acids isolated from the leaves of Australian rainforest plant Cryptocarya mackinnoniana.

Phytochemical investigation of the leaves of the Australian rainforest tree Cryptocarya mackinnoniana led to the discovery of three new oxygenated phenyl alkyl acids, cryptocaryoic acids A - C and two known compounds, cryptocaryone and 2',6'-dihydroxy-4'-methoxychalcone. The structures of all the compounds were determined by detailed spectroscopic analysis. Mosher's analysis was used for absolute stereochemistry determination at C-11, while the remaining stereochemistry determination of the one remaining stereocenter C-13 was based on NOESY correlations. All compounds isolated were also evaluated for their anti-inflammatory properties by assessing their inhibitory effects on LPS and interferon-γ induced nitric oxide (NO) production and TNF- α release in RAW 264.7 macrophages. The new cryptocaryoic acids exhibited weak to moderate anti-inflammatory activity (NO inhibition) ranging from (18.4-56 µM).

Acronyols A and B, new anti-inflammatory prenylated phloroglucinols from the fruits of Acronychia crassipetala.

Two new phloroglucinols, acronyols A (1) and B (2) along with the four known (3-6) pholoroglucinols were identified following anti-inflammatory activity guided fractionation from the fruits of Acronychia crassipetala (family Rutaceae). The pholoroglucinols (1-6) were evaluated for their inhibitory effects on NO production and downregulation of TNF-α in RAW 264.7 macrophage cell lines.