Flavonoids from Ericameria nauseosa inhibiting PI3K/AKT pathway in human melanoma cells.

The PI3K/AKT and MAPK/ERK pathways are frequently mutated in metastatic melanoma. In a screen of over 2500 plant extracts, the dichloromethane extract of Ericameria nauseosa significantly inhibited oncogenic activity of AKT in MM121224 human melanoma cells. This extract was analyzed by analytical HPLC, and the column effluent was fractionated and tested for activity to generate the so-called HPLC-based activity profile. Compounds eluting within active time-windows of the chromatogram were subsequently isolated in a larger scale to afford 11 flavones (1-11), four flavanones (12-15), two diterpenes (16, 17), and a seco-caryophyllene (18). All isolated compounds were tested for activity, whereby only flavonoids were found active. Of these, flavones were shown to be more active than the flavanones. The most potent flavone was compound 9, that was displaying an IC50 of 14.7 ± 1.4 µM on AKT activity in MM121224 cells. The terpenoids (16-18) were found to be inactive in the assay. Both diterpenes, a grindelic acid derivative (16) and an ent-neo-clerodane (17) were identified as new natural products. Their absolute configuration was established by ECD. Compound 17 is the first description of a clerodane type diterpene in the genus Ericameria

Saffron Flower Extract Promotes Scratch Wound Closure of Keratinocytes and Enhances VEGF Production

During saffron (Crocus sativus) spice production, large amounts of floral biowaste are generated. It was the aim of this study to develop a value-added product from saffron floral biowaste to be used as a natural cosmetic ingredient. HPLC-PDA-MS analysis of saffron flower extracts revealed the presence of flavonols with the highest amounts in the acetone extract. Kaempferol-3-O-sophoroside was identified as the main flavonoid in the acetone extract (saffron flower acetone extract). Saffron flower acetone extract and kaempferol-3-O-sophoroside were tested in HaCaT cells for potential effects on cell migration, proliferation, and for anti-inflammatory properties. Saffron flower acetone extract concentration dependently (50–200 µg/mL) augmented cell proliferation, as indicated by an increased BrdU-incorporation, while kaempferol-3-O-sophoroside (1–50 µM) had no effect. Furthermore, treatment of HaCaT cells with saffron flower acetone extract, but not with kaempferol-3-O-sophoroside, concentration-dependently increased vascular endothelial growth factor secretion (control 49.72 pg/mL vs. saffron flower acetone extract at 200 µg/mL 218.60 pg/mL). Cell migration was determined using time-lapse microscopy and a modification of the scratch-wound assay in which saffron flower acetone extract significantly improved wound closure compared to the untreated control. Overproduction of the proinflammatory cytokines interleukin-8 and interleukin-6 in HaCaT cells was induced by TNF-α. Kaempferol-3-O-sophoroside (10–50 µM), but not saffron flower acetone extract, inhibited TNF-α-induced IL-8 secretion. The effect was comparable to 10 µM hydrocortisone (positive control). Interestingly, saffron flower acetone extract further increased IL-6 levels in TNF-α-treated HaCaT cells in a concentration-dependent manner. In summary, the pronounced wound healing properties of saffron flower acetone extract present a promising application for the cosmetic industry

Tyrosinase inhibitory constituents from a polyphenol enriched fraction of rose oil distillation wastewater

During the water steam distillation process of rose flowers, the non-volatile phenolic compounds remain in the waste. We recently developed a strategy to separate rose oil distillation water (RODW) into a polyphenol depleted water fraction and a polyphenol enriched fraction (RF20-SP207). Bioassay-guided investigation of RF20-SP207 led to the isolation of quercetin, kaempferol and ellagic acid. Their structures were elucidated by spectroscopic analysis as well as by comparison with literature data. Tyrosinase inhibition studies were performed with RF20-SP207, fractions I–IV, and the isolated compounds of the most active fraction. RF20-SP207 strongly inhibited the enzyme with an IC50 of 0.41 μg/mL. From the tested fractions only fraction IV (IC50 = 5.81 μg/mL) exhibited strong anti-tyrosinase activities. Quercetin, kaempferol and ellagic acid were identified in fraction IV and inhibited mushroom tyrosinase with IC50 values of 4.2 μM, 5.5 μM and 5.2 μM, respectively, which is approximately 10 times more potent than that of the positive control kojic acid (56.1 μM). The inhibition kinetics, analyzed by Lineweaver–Burk plots, indicated that RF20-SP207 and fraction IV are uncompetitive inhibitors of tyrosinase when l-tyrosine is used as a substrate. A mixed inhibition was determined for ellagic acid, and a competitive inhibition for quercetin and kaempferol. In conclusion, the recovered polyphenol fraction RF20-SP207 from RODW was found to be a potent tyrosinase inhibitor. This value-added product could be used as an active ingredient in cosmetic products related to hyperpigmentation

A Dimerosesquiterpene and Sesquiterpene Lactones from Artemisia argyi Inhibiting Oncogenic PI3K/AKT Signaling in Melanoma Cells.

A library of more than 2500 plant extracts was screened for activity on oncogenic signaling in melanoma cells. The ethyl acetate extract from the aerial parts of Artemisia argyi displayed pronounced inhibition of the PI3K/AKT pathway. Active compounds were tracked with the aid of HPLC-based activity profiling, and altogether 21 active compounds were isolated, including one novel dimerosequiterpenoid (1), one new disesquiterpenoid (2), three new guaianolides (3-5), 12 known sesquiterpenoids (6-17), and four known flavonoids (19-22). A new eudesmanolide derivative (13b) was isolated as an artifact formed by methanolysis. Compound 1 is the first adduct comprising a sesquiterpene lactone and a methyl jasmonate moiety. The absolute configurations of compounds 1 and 3-18 were established by comparison of their experimental and calculated ECD spectra. The absolute configuration for 2 was determined by X-ray diffraction analysis. Guaianolide 8 was the most potent sesquiterpene lactone, inhibiting the PI3K/AKT pathway with an IC50 value of 8.9 ± 0.9 μM

Dimerosesquiterpene and sesquiterpene lactones from Artemisia argyi inhibiting oncogenic PI3K/AKT signaling in melanoma cells

A library of more than 2’500 plant extracts were screened for their activity on oncogenic signaling in melanoma cells. The ethyl acetate extract from aerial parts of Artemisia argyi displayed pronounced inhibition of the PI3K/AKT pathway. Active compounds were tracked with the aid of HPLC-based activity profiling, and a total of 21 active compounds were isolated, including one novel dimerosequiterpenoid (1), one new disesquiterpenoid (2), three new guaianolides (3-5), 12 known sesquiterpenoids (6-17), as well as four known flavonoids (19-22). A new eudesmanolide derivative (13b) was isolated as an artifact formed by methanolysis. Compound 1 is the first adduct comprising a sesquiterpene lactone and a methyl jasmonate moiety. The absolute configurations of compounds 1 and 3-18 were established by comparison of experimental and calculated ECD spectra. The absolute configuration for 2 was determined by X-ray diffraction. Guaianolide 8 was the most potent sesquiterpene lactone, inhibiting the PI3K/AKT pathway with an IC50 of 8.9 ± 0.9 μ

Automated Comparative Metabolite Profiling of Large LC-ESIMS Data Sets in an ACD/MS Workbook Suite Add-in, and Data Clustering on a New Open-Source Web Platform FreeClust

The technological development of LC-MS instrumentation has led to significant improvements of performance and sensitivity, enabling high-throughput analysis of complex samples, such as plant extracts. Most software suites allow preprocessing of LC-MS chromatograms to obtain comprehensive information on single constituents. However, more advanced processing needs, such as the systematic and unbiased comparative metabolite profiling of large numbers of complex LC-MS chromatograms remains a challenge. Currently, users have to rely on different tools to perform such data analyses. We developed a two-step protocol comprising a comparative metabolite profiling tool integrated in ACD/MS Workbook Suite, and a web platform developed in R language designed for clustering and visualization of chromatographic data. Initially, all relevant chromatographic and spectroscopic data (retention time, molecular ions with the respective ion abundance, and sample names) are automatically extracted and assembled in an Excel spreadsheet. The file is then loaded into an online web application that includes various statistical algorithms and provides the user with tools to compare and visualize the results in intuitive 2D heatmaps. We applied this workflow to LC-ESIMS profiles obtained from 69 honey samples. Within few hours of calculation with a standard PC, honey samples were preprocessed and organized in clusters based on their metabolite profile similarities, thereby highlighting the common metabolite patterns and distributions among samples. Implementation in the ACD/Laboratories software package enables ulterior integration of other analytical data, and in silico prediction tools for modern drug discovery

Asiatic Acid and Corosolic Acid Enhance the Susceptibility of Pseudomonas aeruginosa Biofilms to Tobramycin

Asiatic acid and corosolic acid are two natural products identified as biofilm inhibitors in a biofilm inhibition assay. We evaluated the activities of these two compounds on Pseudomonas aeruginosa biofilms grown in rotating disk reactors (RDRs) in combination with tobramycin and ciprofloxacin. To determine the ruggedness of our systems, the antibiotic susceptibilities of these biofilms were assessed with tobramycin and ciprofloxacin. The biofilm bacteria produced in the RDR were shown to display remarkable tolerance to 10 μg/ml of ciprofloxacin, thus mimicking the tolerance observed in recalcitrant bacterial infections. These studies further demonstrate that a nonmucoid strain of P. aeruginosa can form a biofilm that tolerates ciprofloxacin at clinically relevant concentrations. Neither asiatic acid nor corosolic acid reduced the viable cell density of P. aeruginosa biofilms. However, both compounds increased the susceptibility of biofilm bacteria to subsequent treatment with tobramycin, suggesting asiatic acid and corosolic acid to be compounds that potentiate the activity of antibiotics. A similar statistical interaction was observed between ciprofloxacin and subsequent treatment with tobramycin