Bioassay-guided detection, identification and assessment of antibacterial and anti-inflammatory compounds from olive tree flower extracts by high-performance thin-layer chromatography linked to spectroscopy.

Olive trees are one of the most widely cultivated fruit trees in the world. The chemical compositions and biological activities of olive tree fruit and leaves have been extensively researched for their nutritional and health-promoting properties. In contrast, limited data have been reported on olive flowers. The present study aimed to analyse bioactive compounds in olive flower extracts and the effect of fermentation-assisted extraction on phenolic content and antioxidant activity. High-performance thin-layer chromatography (HPTLC) hyphenated with the bioassay-guided detection and spectroscopic identification of bioactive compounds was used for the analysis. Enzymatic and bacterial in situ bioassays were used to detect COX-1 enzyme inhibition and antibacterial activity. Multiple zones of antibacterial activity and one zone of COX-1 inhibition were detected in both, non-fermented and fermented, extracts. A newly developed HPTLC-based experimental protocol was used to measure the high-maximal inhibitory concentrations (IC50) for the assessment of the relative potency of the extracts in inhibiting COX-1 enzyme and antibacterial activity. Strong antibacterial activities detected in zones 4 and 7 were significantly higher in comparison to ampicillin, as confirmed by low IC50 values (IC50 = 57-58 µg in zone 4 and IC50 = 157-167 µg in zone 7) compared to the ampicillin IC50 value (IC50 = 495 µg). The COX-1 inhibition by the extract (IC50 = 76-98 µg) was also strong compared to that of salicylic acid (IC50 = 557 µg). By comparing the locations of the bands to coeluted standards, compounds from detected bioactive bands were tentatively identified. The eluates from bioactive HPTLC zones were further analysed by FTIR NMR, and LC-MS spectroscopy. Multiple zones of antibacterial activity were associated with the presence of triterpenoid acids, while COX-1 inhibition was related to the presence of long-chain fatty acids.

Detection of low concentrations of ampicillin in milk.

Ampicillin, a common antibiotic, is detected at trace concentrations in milk using surface enhanced Raman spectroscopy in a microfluidic device, using less than 20 µL of sample, in 10 minutes, with minimal off-chip preparation. The device is configured so as to favor the interaction of the analyte with colloidal silver, and the optimization of the aggregation of the silver nanoparticles so as to increase the SERS intensity and the consequential sensitivity of analyte detection.

Spectrophotometric determination of penicillins in pure and pharmaceutical formulations using Folin-Ciocalteu reagent.

A new combination of time, temperature, and alkali is described for the spectrophotometric determination of amoxicillin and ampicillin using Folin-Ciocalteu reagent. The method is based on the development of blue-coloured product due to the reduction of tungstate and/or molybdate in Folin-Ciocalteu reagent by amoxicillin and ampicillin in alkaline medium. The chromogenic reaction has λ(max) at 720 and 740 nm with molar absorptivity 1.6295 × 104 and 0.1085 × 104 l mol⁻¹ cm⁻¹ in the Beer's Law range 2-10 µg mL⁻¹ and 10-70 µg mL⁻¹ for amoxicillin and ampicillin, respectively. The method is reproducible, quick, inexpensive, and particularly helpful in determining the drug content in commercial dosage forms.

Dextran-coated gold nanoparticles for the assessment of antimicrobial susceptibility.

Bacteria rapidly evolve mechanisms to become resistant to antibiotics. Therefore, identifying an effective antibiotic or antibacterial agent and administering it at concentrations that will successfully prevent bacterial growth (antimicrobial susceptibility) is critical for health care decision making and vital for the battle against multi-drug-resistant bacteria. Currently, the determination of antimicrobial susceptibility requires at least 24 h. Herein, we describe a nanoparticle-based antimicrobial susceptibility assay based on the concanavalin A-induced clustering of dextran-coated gold nanoparticles, which sense the presence of available complex carbohydrates in bacterial suspension. Under conditions of bacterial growth inhibition, addition of concanavalin A results in the formation of extensive dextran gold nanoassemblies, which are facilitated by the presence of free carbohydrates in solution and result in large shifts in the surface plasmon band of the nanoparticles. Meanwhile, at conditions of increased bacterial growth, a decrease in the amount of free carbohydrates in solution will occur due to an increased carbohydrate uptake by the proliferating bacteria. This will result in a decrease in the size of the gold nanoparticle clusters and an increase in the number of nanoparticles that bind to bacterial surface carbohydrates, causing lower shifts in the plasmonic band. The gold nanoparticle-based assessment of antimicrobial susceptibility yields results within 3 h and can be used for the high-throughput screening of samples during epidemics and identification of potential antimicrobial agents to expedite clinical decision-making in point-of-care diagnostics.