New anti-mycobacterial entities with novel mechanisms of action are clinically needed for treating resistant forms of tuberculosis. The purpose of this study was to evaluate anti-tubercular activity and selectivity of seven recently isolated natural products from Colombian plants. MICs were determined using a liquid medium growth inhibition assay for Mycobacterium tuberculosis H₃₇Rv and both solid and liquid media growth inhibition assays for Mycobacterium bovis BCG. Escherichia coli growth inhibition and mammalian macrophage cell toxicity were evaluated to establish the degree of selectivity of the natural product against whole cell organisms. Enzymatic inhibition of ATP-dependent MurE ligase from M. tuberculosis was assayed using a colorimetric phosphate detection method. The most active compound, 3-methoxynordomesticine hydrochloride, was further investigated on M. bovis BCG for its inhibition of sigmoidal growth, acid-fast staining and viability counting analysis. Aporphine alkaloids were found to be potent inhibitors of slow-growing mycobacterial pathogens showing favourable selectivity and cytotoxicity. In terms of their endogenous action, the aporphine alkaloids were found inhibitory to M. tuberculosis ATP-dependent MurE ligase at micromolar concentrations. A significantly low MIC was detected for 3-methoxynordomesticine hydrochloride against both M. bovis BCG and M. tuberculosis H₃₇Rv. Considering all the data, 3-methoxynordomesticine hydrochloride was found to be a potent anti-tubercular compound with a favourable specificity profile. The alkaloid showed MurE inhibition and is considered an initial hit for exploring related chemical space.

Four aporphine alkaloids from the wood of Ocotea macrophylla (Lauraceae) were isolated and characterized as (S)-3-methoxy-nordomesticine (1), (S)-N-ethoxycarbonyl-3-methoxy-nordomesticine (2), (S)-N-formyl-3-methoxy-nordomesticine (3) and (S)-N-methoxycarbonyl-3-methoxy-nordomesticine (4); alkaloids 2-4 are being report for the first time. The structure the isolated compounds were determined based on their spectral data and by comparison of their spectral data with values described in literature. The alkaloid fraction and compound 1 showed antifungal activity against Fusarium oxysporum f. sp. lycopersici and also compound 1 showed antimicrobial activity towards Staphylococcus aureus, Enterococcus faecalis as well

The present study describes the anti-biofilm and quorum sensing (QS) inhibitory potential of extracts and chemical constituents from Piper bogotense. Antibiofilm potential was determined through crystal violet assay against Pseudomonas aeruginosa, while QS inhibition efficacy was determined through violacein inhibition assay using Chromobacterium violaceum as a bacterial model. Additionally, this study reports the effects of the chemical constituents isolated in P. bogotense against various virulent factors associated with QS, such as the percentage decrease in pyocyanin, elastase, and protease production. The chemical study led to the isolation and identification of two prenylated benzoic acids (1 and 2) and a prenylated hydroquinone 3, of which compounds 1 and 2 are reported for the first time for P. bogotense. The ethanolic extract and the DCM fraction from P. bogotense stand out for reducing violacein production in C. violaceum, as well as the biofilm formation in P. aeruginosa. Compounds 2 and 3 stand out for having the lowest violacein production (43.8% and 68.3%), as well as the lowest production of virulence factors such as elastase (60.2% and 51.4%) and pyocyanin (39.7% and 33.2%). These results demonstrate the potential of P. bogotense components to be used as an alternative control against multidrug-resistant P. aeruginosa.

Plants have phenolic compounds with antioxidant activity. These compounds are distributed in tissues and cells of plants and their abundance depends on the species, the part of the plant used, maturity stage, light hours, among others. On the other hand, the profile and quantity of phenolic compounds extracted from plant matrices changes depending on the species, cultivar, climate, and other factors. Plant extracts do not present a unique phenolic component, they correspond a mixture and its antioxidant activity will be affected by the concentration of each one and their action depends on this composition. In this chapter, some generalities about the phenolic compounds with antioxidant activity present in plant matrices will be exposed, also the principal methods for their extraction and quantification will be described and this information will be complemented with a review on applications of these compounds in food industry. In that sense, the reader can infer the importance of continue to studying and developing techniques to obtain, extract, and characterize this kind of compounds, also they can identify possible application of them, the most important, they can recognize them as an alternative to replace chemical synthetized antioxidants used in food industry improving the market of natural products.

: Antimicrobial Resistance (AMR) is one of the main challenges of today's medicine because it has become a global problem that affects the treatment of multiple infections and impacts public health. This resistance is caused as the bacteria generate selective pressure-promoting mechanisms to evade the action of conventional drugs, which are also associated with adverse effects. Infections caused by these multi-resistant bacteria potentially reduce the possibility of effective therapy; this situation increases morbidity and mortality and treatment costs. Therefore, to establish combined therapy as a strategy for the control of infections caused by multi-resistant bacteria, a bibliographic search was carried out between 2015 and 2020 in databases such as PubMed, Scopus and Science Direct. The exhaustive review of the articles allowed a critical analysis of the information. Mechanisms were identified for obtaining drugs with antimicrobial potential, their biological activity and the possible effect of their combination against multidrug-resistant bacteria as an alternative for infectious disease control and as a response to reduce the use of antibiotics. Combined therapy is presented as an innovative therapeutic alternative, which uses non-antibiotic substances that can be obtained by three routes: the repositioning of drugs, synthetic substances and natural products. In this way, important elements are provided to guide researches that seek to reduce antimicrobial resistance.

Introducción. La conjuntivitis bacteriana es una de las infecciones oculares con mayor tasa de consulta oftálmica, siendo el género Staphylococcus el agente etiológico que presenta mayor resistencia a los antibióticos. Objetivo. Determinar el potencial antimicrobiano de extractos de plantas medicinales y sus mezclas frente a bacterias asociadas con conjuntivitis. Métodos. A partir de plantas como Belladona, Caléndula, Albahaca, Achiote y Romerillo se prepararon los extractos etanólicos y se evaluó su potencial antibacteriano frente a S. aureus y S. epidermidis, mediante las técnicas de difusión en disco y dilución en tubo. El efecto de las mezclas se determinó para el extracto con mejor actividad y el antibiótico con mayor halo de inhibición a través de la técnica de tablero. Resultados. Se encontró que el extracto con mayor potencial para S. aureus fue el de achiote (hojas) con un halo de inhibición de 13 mm y CMIs de 15 mg/mL, mientras que para S. epidermidis fueron los de hojas y frutos de achiote con halos de 16,6 y 9,6 mm y CMIs de 15 y 30 mg/mL respectivamente. En relación con las combinaciones, el extracto de achiote y ciprofloxacina mostró un efecto de sinergia parcial para S. aureus con una CFI de 0,83 y un efecto aditivo para S. epidermidis con una CFI de 1,84. Conclusiones. Este trabajo se constituye en la base de futuras investigaciones orientadas hacia el desarrollo de bioproductos de uso ocular que puedan ser considerados como alternativa en el tratamiento de infecciones causadas por Staphylococcus.