A Validated HPLC-PDA-HRMS Method to Investigate the Biological Stability and Metabolism of Antiparasitic Triterpenic Esters

Pentacyclic triterpenes (PTs) are commonly found in medicinal plants with well-known antiparasitic effects. Previous research on C-3 and C-27 triterpenic esters showed effective and selective in vitro antiparasitic activities and in vivo effectiveness by parenteral routes. The aim of this study was to determine triterpenic esters’ stability in different biological-like media and the main microsomal degradation products. An HPLC-PDA method was developed and validated to simultaneously analyze and quantify bioactive triterpenic esters in methanol (LOQ: 2.5 and 1.25–100 µg/mL) and plasma (LOQ: 5–125 µg/mL). Overall, both triterpenic esters showed a stable profile in aqueous and buffered solutions as well as in entire plasma, suggesting gaining access to the ester function is difficult for plasma enzymes. Conversely, after 1 h, 30% esters degradation in acidic media was observed with potential different hydrolysis mechanisms. C-3 (15 and 150 µM) and C-27 esters (150 µM) showed a relatively low hepatic microsomal metabolism (<23%) after 1 h, which was significantly higher in the lowest concentration of C-27 esters (15 µM) (>40% degradation). Metabolic HPLC-PDA-HRMS studies suggested hydrolysis, hydroxylation, dehydration, O-methylation, hydroxylation and/or the reduction of hydrolyzed derivatives, depending on the concentration and the position of the ester link. Further permeability and absorption studies are required to better define triterpenic esters pharmacokinetic and specific formulations designed to increase their oral bioavailability.

Establishment of Reference Values of Gamma-Glutamyl-Transferase and Plasma Aminotransferases in Young Congolese

Objectives: Our goal was to contribute to the production of reference values ​​of plasma or serum biochemical markers by determining the reference values ​​of gamma-glutamyltransferase (GGT), aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) in young Congolese presumed to be healthy. Methods: 250 young Congolese presumed to be healthy (125 boys and 125 girls) aged 15 to 25 participated in the study. They were selected according to anamnestic and clinico-biological criteria. Samples were taken on a tube containing EDTA and the resulting plasma was stored at -20 ° C. The KENZA MAX spectrophotometer was used to analyze GGT, ASAT and ALAT. The median and the 2.5-97.5 percentiles were used to set the reference limits for each enzyme. The benchmarks determined were compared with those reported by other Africans, Europeans, Indians and Americans. Results: The established reference values ​​were: GGT 12.15-61.85 IU/L for boys and 7-51.95 IU / l for girls (p˂0.0001); ASAT 21.60-94.85 IU/L for boys and 17-84.85 IU/L for girls (p = 0.0003); ALAT 8.30-74.40 IU/L for boys and 8-53.85 IU/L for girls (p˂0.0001). In addition, the comparison between our values ​​and those of other populations showed significant differences. Conclusion: Our results underline the importance of establishing reference values ​​for plasma enzymes specific to the Congolese population. The use of the values ​​established in the ’other populations could induce errors of judgment by excess or by default. Key words: Gamma-glutamyltransferase, Aspartate aminotransferase, Alanine aminotransferase, Reference values, Congo.

Acetylcholinesterase inhibitory potential and lack of toxicity of Psychotria carthagenensis infusions

We aimed to evaluate the phytochemical composition of the aqueous extract of leaves of Psychotria carthagenensis, and its possible toxicological effects at 200 µg/Kg on Rattus norvegicus. The aqueous extract was used for preliminary phytochemical analyses using standard procedures. After, male albino Wistar rats (N= 6/group) received by gavage for 15 consecutive days, infusions with fresh (FL) and dry leaf (DL) at 200 µg/kg; controls received filtered water (negative) or clonazepam solution at 0.5 mg/kg (positive). Hematological analyses, determination of serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, uric acid, total plasma protein (TPP), quantification of serum cholinesterase (AChE), and histological analyses of kidneys and liver were carried out. By the phytochemical analysis of the aqueous leaf extract, it was possible to detect the total phenols, flavonoids, tannins and alkaloids, the latter having been recorded for the species for the first time in this study. ALT and AST levels indicated an increase in these plasma enzymes, but histological analysis of kidneys and liver showed only slight changes. Inhibition of AChE levels was related mainly to alkaloids. The infusion showed the pharmacological potential of the plant as an alternative in the treatment of neurodegenerative diseases.

Proteasome Activity in the Plasma as a Novel Biomarker in Mild Cognitive Impairment with Chronic Tinnitus

Background: Although the existence of proteasomes in human blood, termed circulating proteasomes (c-proteasomes), has been reported previously, their origin and pathophysiological functions remain largely unknown. Objective: Given that c-proteasome activity was significantly reduced in Alzheimer’s disease model mice and relatively high frequency of mild cognitive impairment (MCI) is accompanied by chronic tinnitus in aged patients, we examined whether c-proteasome activity in human plasma was associated with cognitive function in patients with chronic tinnitus. Methods: c-Proteasome activity in the plasma of tinnitus patients (N = 55) was measured with fluorogenic reporter substrate, suc-LLVY-AMC. To assess MCI, the Montreal Cognitive Assessment was conducted with a cut-off score of 22/23. All patients underwent audiological and psychoacoustic analyses. Levels of c-proteasomes, Aβ42, and Aβ40 were measured using ELISA, and their association with c-proteasome activity was evaluated. Results: The activity of circulating proteasomes was significantly lower in patients with chronic tinnitus and MCI (p = 0.042), whereas activities of other plasma enzymes showed little correlation. In addition, c-proteasome activity was negatively associated with the level of plasma Aβ and was directly dependent on its own concentration in the plasma of patients with chronic tinnitus. Conclusion: Our current work provides a new perspective for understanding the potential relationship between circulating proteasomes in the plasma and cognitive dysfunction, suggesting a novel, non-invasive biomarker in the context of MCI diagnosis.