Restoring Ampicillin Sensitivity in Multidrug-Resistant Escherichia coli Following Treatment in Combination with Coffee Pulp Extracts

Escherichia coli, particularly multidrug-resistant (MDR) strains, is a serious cause of healthcare-associated infections. Development of novel antimicrobial agents or restoration of drug efficiency is required to treat MDR bacteria, and the use of natural products to solve this problem is promising. We investigated the antimicrobial activity of dried green coffee (DGC) beans, coffee pulp (CP), and arabica leaf (AL) crude extracts against 28 isolated MDR E. coli strains and restoration of ampicillin (AMP) efficiency with a combination test. DGC, CP, and AL extracts were effective against all 28 strains, with a minimum inhibitory concentration (MIC) of 12.5-50 mg/ml and minimum bactericidal concentration of 25-100 mg/ml. The CP-AMP combination was more effective than CP or AMP alone, with a fractional inhibitory concentration index value of 0.01. In the combination, the MIC of CP was 0.2 mg/ml (compared to 25 mg/ml of CP alone) and that of AMP was 0.1 mg/ml (compared to 50 mg/ml of AMP alone), or a 125-fold and 500-fold reduction, respectively, against 13-drug resistant MDR E. coli strains. Time-kill kinetics showed that the bactericidal effect of the CP-AMP combination occurred within 3 h through disruption of membrane permeability and biofilm eradication, as verified by scanning electron microscopy. This is the first report indicating that CP-AMP combination therapy could be employed to treat MDR E. coli by repurposing AMP.

Dinactin: A New Antitumor Antibiotic with Cell Cycle Progression and Cancer Stemness Inhibiting Activities in Lung Cancer

Lung cancer, especially non-small cell lung cancer (NSCLC), is one of the most complex diseases, despite the existence of effective treatments such as chemotherapy and immunotherapy. Since cancer stem cells (CSCs) are responsible for chemo- and radio-resistance, metastasis, and cancer recurrence, finding new therapeutic targets for CSCs is critical. Dinactin is a natural secondary metabolite produced by microorganisms. Recently, dinactin has been revealed as a promising antitumor antibiotic via various mechanisms. However, the evidence relating to cell cycle progression regulation is constrained, and effects on cancer stemness have not been elucidated. Therefore, the aim of this study is to evaluate the new function of dinactin in anti-NSCLC proliferation, focusing on cell cycle progression and cancer stemness properties in Lu99 and A549 cells. Flow cytometry and immunoblotting analyses revealed that 0.1-1 µM of dinactin suppresses cell growth through induction of the G₀/G₁ phase associated with down-regulation of cyclins A, B, and D3, and cdk2 protein expression. The tumor-sphere forming capacity was used to assess the effect of dinactin on the cancer stemness potential in NSCLC cells. At a concentration of 1 nM, dinactin reduced both the number and size of the tumor-spheres. The quantitative RT-PCR analyses indicated that dinactin suppressed sphere formation by significantly reducing expression of CSC markers (i.e., ALDH1A1, Nanog, Oct4, and Sox2) in Lu99 cells. Consequently, dinactin could be a promising strategy for NSCLC therapy targeting CSCs.

Potential Antimicrobial Properties of Coffee Beans and Coffee By-Products Against Drug-Resistant Vibrio cholerae

Vibrio cholerae is the causative organism of the cholera epidemic, and it remains a serious global health problem, particularly the multidrug-resistant strain, despite the development of several generic drugs and vaccines over time. Natural products have long been exploited for the treatment of various diseases, and this study aimed to evaluate the in vitro antibacterial activity of coffee beans and coffee by-products against V. cholerae antimicrobial resistant strains. A total of 9 aqueous extracts were investigated, including light coffee (LC), medium coffee (MC), dark coffee (DC), dried green coffee (DGC), dried red coffee (DRC), fresh red coffee (FRC), Arabica leaf (AL), Robusta leaf (RL), and coffee pulp (CP). The influential coffee phytochemicals, i.e., chlorogenic acid (CGA), caffeic acid (CA), and caffeine, were determined using HPLC. The antibacterial properties were tested by agar well-diffusion techniques, and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were further determined against 20 V. cholerae isolates. The results revealed that all tested strains were sensitive to coffee extracts, with MIC and MBC values in the range of 3.125-25.0 mg/mL and 12.5-50.0 mg/mL, respectively. With a MIC of 6.25 mg/mL, DGC, DRC, and CP appeared to be the most effective compounds against 65, 60, and 55% of clinical strains, respectively. The checkerboard assay revealed that the combination of coffee extract and tetracycline was greater than either treatment alone, with the fractional inhibitory concentration index (FICI) ranging from 0.005 to 0.258. It is important to note that CP had the lowest FICI (0.005) when combined with tetracycline at 60 ng/mL, which is the most effective dose against V. cholerae six-drug resistance strains (azithromycin, colistin, nalidixic acid, sulfamethoxazole, tetracycline, and trimethoprim), with a MIC of 47.5 μg/mL (MIC alone = 12.5 mg/mL). Time killing kinetics analysis suggested that CA might be the most effective treatment for drug-resistant V. cholerae as it reduced bacterial growth by 3 log10 CFU/mL at a concentration of 8 mg/mL within 1 h, via disrupting membrane permeability, as confirmed by scanning electron microscopy (SEM). This is the first report showing that coffee beans and coffee by-product extracts are an alternative for multidrug-resistant V. cholerae treatment.