CARBON QUANTUM DOTS (CQD) ARE AN EMERGENT NANOMATERIAL WITH UNIQUE OPTICAL AND BIOLOGICAL PROPERTIES. HOWEVER, THE PURIFICATION OF CQD IS ONE OF THE BOTTLENECKS THAT MAKES IT DIFFICULT TO SCALE FOR APPLICATION IN DIFFERENT AREAS. IN THIS WORK, WE EXPLORE FOR THE FIRST TIME THE POTENTIAL OF CENTRIFUGAL PARTITION CHROMATOGRAPHY (CPC) AS AN ALTERNATIVE PREPARATIVE TECHNOLOGY TO ACHIEVE THE PURIFICATION OF CQD AT THE GRAM SCALE. THE HYDROTHERMAL METHOD WAS USED TO SYNTHESIZE CQD FROM AVOCADO PEELS. AFTER 6 H AT 250 °C, A COMPLEX MIX OF STRONG BLUE-FLUORESCENT CQDS WERE OBTAINED AND SUBMITTED TO CPC FRACTIONATION WITHOUT PRETREATMENT. THE BEST RESULTS WERE OBTAINED WITH THE SOLVENT SYSTEM N-HEXANE?ETHYL ACETATE?METHANOL?WATER (1:2:1:2, V/V/V/V), IN AN ELUTION-EXTRUSION PROTOCOL. NINE FRACTIONS WERE OBTAINED AND WERE CHARACTERIZED BY UV-VIS SPECTROPHOTOMETRY, FOURIER TRANSFORM INFRARED (F-TIR), AND FIELD EMISSION SCANNING ELECTRON MICROSCOPY (FESEM), CONFIRMING THE PRESENCE OF CQD OF DIFFERENT SIZES. CPC FRACTIONATIONS INDICATE THAT A POLARITY-BASED SEPARATION MECHANISM CAN BE USED TO PURIFY CQD. INTERESTINGLY, FOUR FRACTIONS SHOWED ANTIBACTERIAL AND ANTI-BIOFILM EFFECTS ON PSEUDOMONAS PUTIDA AND LISTERIA MONOCYTOGENES. THEREFORE, CPC ALLOWS FOR BETTER REFINING OF THIS TYPE OF NANOMATERIAL, AND IN COMBINATION WITH OTHER TECHNIQUES, IT WOULD SERVE TO OBTAIN CQD OF HIGHER PURITY, FACILITATING THE PHYSICOCHEMICAL AND BIOACTIVITY CHARACTERIZATION OF THESE PARTICLES. CPC WOULD ALSO ALLOW THE USE OF WASTE, SUCH AS AVOCADO PEELS, TO OBTAIN NEW MATERIALS.

THE MISUSE OF ANTIBIOTICS HAS LED TO HIGH LEVELS OF DRUG-RESISTANCE IN SPECIFIC PATHOGENS, PROMOTING THE SEARCH OF MOLECULES FROM DIFFERENT NATURAL SOURCES OR THE DESIGN OF NOVEL DRUG CANDIDATES. MEDICINAL AND EDIBLE PLANTS ARE A RICH SOURCE OF BIOACTIVE COMPOUNDS, IN PARTICULAR THOSE OF POLYPHENOL CLASS. IN THE PRESENT WORK, WE SCREEN THE ANTIMICROBIAL PROPERTIES OF AN AQUEOUS EXTRACT PREPARED FROM THE LEAVES OF UGNI MOLINAE (TURZ) AGAINST A PANEL OF PATHOGENIC BACTERIA STRAINS FORMED BY HELICOBACTER PYLORI (ATCC 43504), LISTERIA MONOCYTOGENES (ATCC 7644), STAPHYLOCOCCUS AUREUS (ATCC 9144), ESCHERICHIA COLI (ATCC 11775),AND SALMONELLA ENTERICA (ATCC 13076). PRELIMINARY FAST HPLC-MICRO FRACTIONATION ALLOWS THE IDENTIFICATION OF POTENTIAL UREASE INHIBITORS USING HIGH THROUGHPUT UREA-PHENOL MICROPLATE ASSAY. AFTERWARDS, PREPARATIVE FRACTIONATION BY CENTRIFUGAL PARTITION CHROMATOGRAPHY (CPC) ALLOW TO SELECT THE SPECIFIC BIOACTIVE FRACTIONS. A COMBINATION OF ANTIMICROBIAL TESTS, ENZYME ASSAYS AND MOLECULAR DOCKING RESULTED IN THE IDENTIFICATION BY HPLC-MS/MS OF TWO QUERCETIN-O-(6´´-O-GALLOYL)-HEXOSIDES AS THE MOST DOMINANT COMPOUNDS IN THE ACTIVE CPC-FRACTIONS. THESE BIOACTIVE COMPOUNDS WERE QUERCETIN-3-O-(6´´-O-GALLOYL)-8-GALACTOPYRANOSIDE (HYPERIN 6?-GALLATE) AND QUERCETIN-3-O-?-D-(6´´-O-GALLOYL)- ?-GLUCOPYRANOSIDE (TELLIMOSIDE). THE MOLECULAR DOCKING EVALUATION REVEALED THAT HYPERIN-6´´-GALLATE ENTER THE BINDING SITE OF UREASE AND BIND IN THROUGH PI-CATION, PI?PI, AND H-BOND INTERACTIONS. IN CONCORDANCE WITH THE IN-SILICO ASSAY, THE CPC FRACTION CONTAINING THIS COMPOUND HAS THE LOWEST VALUES OF IC50 FOR JACK BEAN (0.41 ± 0.08 ?G/ML) AND HELICOBACTER PYLORI (0.28 ± 0.08 ?G/ML) UREASES, RESPECTIVELY. MOREOVER, LABEL-FREE MICROSCALE THERMOPHORESIS (MST) ANALYSIS SUGGEST THAT THIS FLAVONOID FORMS A COMPLEX WITH UREASE, EVEN INDUCING PROTEIN AGGREGATION.