Browsing by Author "Echeverria, Javier"

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    Chemical evidence of prehistoric passive tobacco consumption by a human perinate (early Formative Period, South-Central Andes)
    (2018) Niemeyer, Hermann M.; de Souza, Patricio; Camilo, Conrado; Echeverria, Javier
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    Exudate and Propolis from Escallonia pulverulenta: Phytochemical Characterization and Antibacterial Activity
    (2024) Jorquera, Bairon; Valenzuela-Barra, Gabriela; Mayorga, Ailin; Mejia, Jessica; Nunez, Gabriel; Gomez, Miguel; Montenegro, Gloria; Quezada, Waleska E. Vera; Echeverria, Javier; de Camargo, Adriano Costa; von Poser, Gilsane Lino; Bridi, Raquel
    Propolis is a complex mixture formed from exudates that bees collect from plants and then mix with beeswax and their own salivary enzymes. Chilean propolis is characterized by the presence of phenolic compounds, which are considered responsible for the biological activities. The endemic species Escallonia pulverulenta (Ruiz and Pav.) Pers. [Escalloniaceae] is a recognized source of exudate to produce propolis. This study reports for the first time the chemical profile and antibacterial activity of E. pulverulenta exudate and leaves, as well as two samples of Chilean propolis. Palynological and morphological analysis showed the presence of E. pulverulenta as one of the main species in the propolis samples. UPLC-MS/MS analyses enabled the identification of phenolic acids in the leaves and in the propolis. Conversely, flavonoids are mainly present in exudates and propolis. Quercetin is the most abundant flavonol in the exudate, with similar concentrations in the propolis samples. Nevertheless, the main compound present in both samples of propolis was the flavanone pinocembrin. The antibacterial results obtained for exudate and propolis have shown a similar behavior, especially in the inhibition of Streptococcus pyogenes. These results show the importance of the exudates collected by the bees in the chemical composition and antibacterial capacity of propolis.
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    Honeybee Pollen From Southern Chile: Phenolic Profile, Antioxidant Capacity, Bioaccessibility, and Inhibition of DNA Damage
    (2022) Bridi, Raquel; Echeverria, Javier; Larena, Arturo; Nunez Pizarro, Paula; Atala, Elias; De Camargo, Adriano Costa; Oh, Won Young; Shahidi, Fereidoon; Garcia, Olga; Ah-Hen, Kong S.; Montenegro, Gloria
    Honeybee pollen (HBP) chemical composition is highly variable conforming to the floral and geographical origin of the pollen grains. The beneficial effects and functional properties of the HBP are well-known and have been mainly attributed to their high content of antioxidant polyphenols. In this work, twelve HBPs samples from the Southern region of Chile (X Region de Los Lagos) were characterized for the first time according to their botanical origin, phenolic composition, and antioxidant activity. The in vitro gastrointestinal digestion assay was done to simulate the human upper digestive tract. Selected honeybee pollen extracts (HBPEs) were assessed as bioaccessible fractions during an in vitro gastrointestinal digestion. Contents of phenolic compounds, antioxidant capacity, and recovery index of quercetin, myricetin, and cinnamic acid were monitored in different steps of gastrointestinal digestion. Furthermore, the protective effect of in vitro digested HBP towards DNA damage induced by peroxyl radicals was evaluated. The introduced species Brassica rapa L. (Brassicaceae), Lotus pedunculatus Cav. (Fabaceae), and Ulex europaeus L. (Fabaceae) predominated in all the HBPs analyzed, while the native species Buddleja globosa Hope (Scrophulariaceae), Luma apiculata (DC.) Burret (Myrtaceae), Embothrium coccineum J.R. Forst. & G. Forst. (Proteaceae) and Eucryphia cordifolia Cav. (Cunoniaceae) appeared less frequently. The content of polyphenols and antioxidant capacity in HBPEs achieved full bioaccessibility at the end of the intestinal digestion step. However, results obtained by a state-of-the-art technique (i.e. HPLC-DAD) demonstrated relatively low values of bioaccessible quercetin and cinnamic acid after the digestion process. In contrast, myricetin showed a high bioaccessibility in the intestinal digestion steps. The protective effect of in vitro digested HBP towards DNA damage induced by peroxyl radicals showed promising results (up to 91.2% protection). In conclusion, HBPs from the X Region de Los Lagos are rich sources of phenolic antioxidants that protect DNA from strand breakage. Therefore, the potential of HBPEs in preventing gastric and/or intestinal cancer should be further considered.
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    In Vivo and in vitro antitumor activity of tomatine in hepatocellular carcinoma
    (2022) Echeverria, Cesar; Martin, Aldo; Simon, Felipe; Salas, Cristian O.; Nazal, Mariajesus; Varela, Diego; Perez-Castro, Ramon A.; Santibanez, Juan F.; Valdes-Valdes, Ricardo O.; Forero-Doria, Oscar; Echeverria, Javier
    Background: There is abundant ethnopharmacological evidence the uses of regarding Solanum species as antitumor and anticancer agents. Glycoalkaloids are among the molecules with antiproliferative activity reported in these species. Purpose: To evaluate the anticancer effect of the Solanum glycoalkaloid tomatine in hepatocellular carcinoma (HCC) in vitro (HepG2 cells) and in vivo models. Methods: The resazurin reduction assay was performed to detect the effect of tomatine on cell viability in human HepG2 cell lines. Programmed cell death was investigated by means of cellular apoptosis assays using Annexin V. The expression of cancer related proteins was detected by Western blotting (WB). Reactive oxygen species (ROS) and calcium were determined by 2,7-dichlorodihydrofluorescein diacetate and Fluo-4, respectively. Intrahepatic HepG2 xenograft mouse model was used to elucidate the effect of tomatine on tumor growth in vivo. Results and Discussion: Tomatine reduced HepG2 cell viability and induced the early apoptosis phase of cell death, consistently with caspase-3, -7, Bcl-2 family, and P53 proteins activation. Furthermore, tomatine increased intracellular ROS and cytosolic Ca+2 levels. Moreover, the NSG mouse xenograft model showed that treating mice with tomatine inhibited HepG2 tumor growth. Conclusion: Tomatine inhibits in vitro and in vivo HCC tumorigenesis in part via modulation of p53, Ca+2, and ROS signalling. Thus, the results suggest the potential cancer therapeutic use of tomatine in HCC patients.
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    Novel N-benzoylimidazolium ionic liquids derived from benzoic and hydroxybenzoic acids as therapeutic alternative against Biofilm-forming bacteria in skin and soft-tissue infections
    (2022) Forero-Doria, Oscar; Parra-Cid, Cristobal; Venturini, Whitney; Espinoza, Carolina; Araya-Maturana, Ramiro; Valenzuela-Riffo, Felipe; Saldias, Cesar; Leiva, Angel; Duarte, Yorley; Echeverria, Javier; Guzman, Luis
    The skin and soft tissue infections (SSTIs) -producing pathogens have acquired resistance to a wide range of antimicrobials, thus it is highly relevant to have new treatment alternatives. In this study, we report the synthesis, characterization, and antibacterial activity of three novel series of ionic liquids (ILs) derived from benzoic and hydroxybenzoic acids, with different lengths of the alkyl chain. The minimum inhibitory concentration (MIC) were tested in Gram positive: Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes, and Gram negative: Acinetobacter baumannii and Escherichia coli, showing a MIC range of 0.01562 2.0 mM, with the activity varying according to the aromatic ring functionalization and the length of the alkyl chains. Regarding the antibiofilm activity, different efficacy was observed among the different ILs, some of them presenting antibiofilm activities close to 80% as in the case of those derived from syringic acid with an alkyl chain of six carbon atoms against Pseudomonas aeruginosa. Furthermore, the cell viability in HaCaT cells was determined, showing a half maximal effective concentration (EC50) values higher than the MIC values. The antimicrobial and antibiofilm results, along with not producing cellular toxicity at the MIC values shows that these ILs could be a promising alternative against SSTIs.
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    Phytochemical variation of wild and farmed populations of boldo (Peumus boldus Molina)
    (2023) Fuentes-Barros, Gonzalo; Echeverria, Javier; Mattar, Cesar; Liberona, Leonel; Giordano, Ady; Suarez-Rozas, Cristian; Salas-Norambuena, Julio; Gonzalez-Cooper, Antonia; Cassels, Bruce K.; Castro-Saavedra, Sebastian
    The phytochemical profile of six wild and one cultivated Peumus boldus (boldo) populations from different regions of north-central, central and south-central Chile was studied. In leaves, wood, and bark, alkaloids and phenolics were analyzed by UHPLC-MS-MS and leaf essential oils by GC-MS. In each population, compounds were found to exhibit high variability, but important differences were recorded at the population level. The north-central wild populations showed higher concentrations of alkaloids and polyphenols in leaves and alkaloids in the bark compared to more southern populations. Saplings farmed under different shade conditions contained higher species-characteristic leaf polyphenolic concentrations with increasing light while most alkaloids increased with the shade. When analyzed the following year, higenamine, boldine, isocorydine and Nmethyllaurotetanine increased. The principal components of the leaf essential oils from the wild populations were p-cymene, ascaridole and 1,8-cineole, while in the farmed trees ascaridole was replaced by its precursor & alpha;-terpinene as the second most abundant constituent. Although multiple factors may affect the concentration of secondary metabolites and geographic provenances with its attending differences in sunlight and rainfall has been suggested as one of these, the present work shows that latitude by itself cannot explain differences that have a clear impact on quality from the medicinal standpoint.