The present study aimed at developing an original pre-column HPLC assay allowing rapid characterization of nitric oxide (NO) scavengers from complex plant extracts. Sodium nitroprusside (SNP) was ...employed as a NO donor and spiked with an aqueous extract from
leaves prior to HPLC analysis. Relying on the ability of radical scavenging constituents to be oxidized upon reaction with radicals, this assay successfully allowed direct identification of three potential NO scavengers, including verbascoside, isoverbascoside, and luteolin-7-
-diglucuronide. These three phenolics were also individually assessed for their NO scavenging activities by using a Griess colorimetric assay. With respective IC
values of 56 ± 4, 51 ± 3, and 69 ± 5 µg/mL, verbascoside, isoverbascoside, and luteolin-7-
-diglucuronide were all reported as potent NO scavenging compounds, confirming the efficiency of the SNP spiking HPLC assay. The present method can, thus, be considered as a valuable and effective approach for speeding up the discovery of NO scavenging constituents.
Arginase, a difficult-to-target metalloenzyme, is implicated in a wide range of diseases, including cancer, infectious, and cardiovascular diseases. Despite the medical need, existing inhibitors have ...limited structural diversity, consisting predominantly of amino acids and their derivatives. The search for innovative arginase inhibitors has now extended to screening approaches. Due to the small and narrow active site of arginase, screening must meet the criteria of fragment-based screening. However, the limited binding capacity of fragments requires working at high concentrations, which increases the risk of interference and false positives. In this study, we investigated three colorimetric assays and selected one based on interference for screening under these challenging conditions. The subsequent adaptation and application to the screening a library of metal chelator fragments resulted in the identification of four compounds with moderate activity. The synthesis and evaluation of a series of compounds from one of the hits led to compound
21a
with an IC
50
value of 91.1 μM close to the reference compound piceatannol. Finally, molecular modelling supports the potential binding of aurones and chalcones to the active site of arginase, suggesting them as new candidates for the development of novel arginase inhibitors.
Three colorimetric assays were investigated, and the selected one was applied to the screening of a library of metal chelator fragments. One of the hits was optimised to give the polyphenolic chalcone
21a
with an IC
50
value of 91.1 μM.
•The neurotoxins Annonaceous acetogenins (AAGs) were detected in the fruit of A. squamosa from various origins.•Squamocin was identified as the main AAG, and quantified by LC-UV.•Method development ...was performed for the annotation of the main AAGs, using HPLC-ESI-Q-TOF.•Common features and variations in qualitative composition are depicted.
Annonaceous acetogenins (AAGs) are neurotoxins possibly responsible for atypical Parkinsonism/dementia clusters, via the consumption of edible Annonaceae fruits. Their presence was investigated in fruit pulps of Annona squamosa from different locations. Qualitative analysis of other AAGs was performed. We here report the identification of squamocin in batches from Asia, the Caribbean Basin and the Indian Ocean. This molecule was quantified by HPLC-UV, evidencing a content of 13.5–36.4mg/fruit. HPLC-ESI-Q-TOF allowed the detection of 25 different raw formulas matching with AAGs. LC–MS/MS methodological development was performed using 4 representative standards. The main AAGs could be annotated, including bullatacin (rolliniastatin-2) and annonacin. This study evidences a remarkable homogeneity for the main AAGs within the species, and discrepancies for minor compounds. These findings indicate that A. squamosa should be considered a risk factor for neurodegenerative disorders.
The methanolic extract of the leaves of Macaranga hurifolia Beille showed arginase inhibitory activity (40% at 100 µg/mL) and was then fractionated to obtain nine polyphenolic compounds. Their ...structures were elucidated on the basis of NMR spectroscopic data, and by comparison with data previously reported in the literature, as gallic acid (1), 3,4-dihydroxybenzoic acid (2), chlorogenic acid, (3), corilagin (4), cynaroside (5), cosmosiin (6), hyperoside (7) isoquercitrin (8) and guajaverin (9). These compounds have been evaluated as arginase inhibitors. Compounds 4, 7, 8 and 9 showed varying arginase inhibitory activities with IC50 values ranging from 102 to 302 μM. All the isolated compounds were previously identified in this species but their activities on arginase are reported here for the first time.
Vaccinium myrtillus fruit (bilberry) is well known for its high richness in anthocyanins, which may be responsible for its preventive effects on several oxidative and carbonyl stress-related ...pathologies. However, limited data are available regarding the antioxidant and antiglycative contributions of its constituents. Spectrometric analyses were performed to evaluate anthocyanin content, radical scavenging and antiglycative properties of an anthocyanin-rich extract from bilberries. Additionally, original DPPH and methylglyoxal pre-column HPLC methods were instigated to allow straightforward identification of the main contributors to radical and carbonyl trapping effects. Finally, representative pure anthocyanins were evaluated using classical DPPH and antiglycation assays. Delphinidin, petunidin and cyanidin glycosides were identified as the most effective radical scavenging constituents in both HPLC and spectrometric DPPH evaluations. Potent antiglycative activities were also assessed for cyanidin, delphinidin and petunidin glucosides as attested by their respective IC50 values of 114.2 ± 7.8, 130.5 ± 2.8, and 132.4 ± 3.7 µM. Interestingly, methylglyoxal spiking evaluation demonstrated that all bilberry anthocyanins exerted noticeable and comparable α-dicarbonyl trapping effects. Anthocyanins can be regarded as potent antiglycoxidant agents that might account for some health benefits of bilberries consumption. Besides, significant differences in their contributions were successfully highlighted by the employed pre-column HPLC assays.
is a plant commonly used for the treatment of several pathologies, such as diarrhoea, ulcers, pain, stomach aches, fevers, and gout. Our study focused on the use of
for the treatment of gout disease. ...We first studied the chemical composition of a methanolic extract of the aerial parts and demonstrated its xanthine oxidase (XO) inhibitory activity. Then, we performed a fractionation and evaluated the most XO inhibitory active fractions by UV measurement. Purification of some fractions allowed the determination of the inhibitory activity of pure compounds. We demonstrated that spiraeoside, a glycosylated flavonoid, possesses an activity around 25 times higher than allopurinol, used as a reference in the treatment of gout disease. In order to easily and quickly identify potent inhibitors in complex matrix, we developed a complementary strategy based on an HPLC method and an Effect Directed Assay (EDA) method combining HPTLC and biochemical assays. The HPLC method, capable of determining compounds exhibiting interactions with the enzyme, could be an efficient strategy for evaluating potent enzyme inhibitors in a complex mixture. This strategy could be applied for quantitative assays using LC/MS experiments.
(1) Interest in the
family has risen as some members have shown anti-inflammatory properties and interesting compounds. In this regard, we decided to investigate the antioxidant and anti-inflammatory ...properties of
, a
not yet extensively studied, in the context of osteoarthritis. (2) The
Ethanol extract (LS-E) was used to test the production of reactive oxygen species (ROS) by leucocytes, the IL1β and PGE2 production by peripheral blood mononuclear cells (PBMCs), the production of EP4, and the activation of NFκB in THP-1, as well as the IL1β-activated normal human knee articular chondrocytes (NHAC-Kn) gene expression, grown in monolayers or maintained in alginate beads. (3) Organic acids, caffeoylquinic acids, quercetin and luteolin, compounds frequently found in this family were identified. The LS-E exhibited inhibited ROS formation. The LS-E did not affect NFκB activation and IL1β secretion but dampened the secretion of PGE2 by PBMCs and the presence of EP4 in THP-1. It also modulated the expression of NHAC-Kn in both models and inhibited the expression of several proteases and inflammatory mediators. (4)
might supply interesting antioxidant protection against cartilage damages and lessen joint inflammation, notably by decreasing PGE2 secretion in the synovial fluid. Moreover, it could act directly on chondrocytes by decreasing the expression of proteases and, thus, preventing the degradation of the extracellular matrix.
Excess weight and obesity are the fifth leading cause of death globally, and sustained efforts from health professionals and researchers are required to mitigate this pandemic-scale problem. ...Polyphenols and flavonoids found in
-a plant widely consumed as Rooibos tea-are increasingly being investigated for their positive effects on various health issues including inflammation. The aim of our study was to examine the effect of Rooibos extract on obesity and the associated low-grade chronic inflammatory state by testing antioxidant activity, cytokine secretions, macrophage polarization and the differentiation of human adipocytes through the development of adipospheroids. Rooibos extract significantly decreased ROS production and the secretion of pro-inflammatory cytokines (IFN-γ, IL-12, IL-2 and IL-17a) in human leukocytes. Additionally, Rooibos extract down-regulated LPS-induced macrophage M1 polarization, shown by a significant decrease in the expression of pro-inflammatory cytokines:
,
,
,
and
. In addition, Rooibos inhibited intracellular lipid accumulation and reduced adipogenesis by decreasing the expression of
,
and
in adipospheroids. A significant decrease in
expression was noted and this, more interestingly, was accompanied by a significant increase in
expression. Using a co-culture system between macrophages and adipocytes, Rooibos extract significantly decreased the expression of all studied pro-inflammatory cytokines and particularly
, and increased
expression. Thus, adding Rooibos tea to the daily diet is likely to prevent the development of obesity associated with chronic low-level inflammation.
The one‐step cascade assembly of the central core of halichonadins K and L, two dimeric sesquiterpenoids of marine origin, is described for a model system providing suitable conditions towards the ...total synthesis of the two molecules. A biomimetic multicomponent reaction involving a glycine, a C5 unit presumably derived from lysine, and an isocyanide mimic of the terpene decalins is studied.
A one‐pot multicomponent reaction involving the reaction of an isocyanide with an in situ generated dihydropyridinium salt permits a straightforward access to a biomimetic model of the recently isolated halichonadins K and L.
Anthocyanins from Vaccinium myrtillus fruits have been reported in vitro to exert potent radical scavenging and antiglycation activities. However, the physiological relevance of such properties ...remains unclear given the potential susceptibility of anthocyanin derivatives to digestive conditions. A simulated gastrointestinal tract model was thus implemented to assess the impact of gastric and intestinal phases on the chemical integrity of bilberry anthocyanins and their antiglycoxidant effects. Results demonstrated that the investigated activities as well as total and individual anthocyanin contents were marginally affected by gastric conditions. By contrast, with recoveries ranging from 16.1 to 41.2%, bilberry anthocyanins were shown to be highly sensitive to the intestinal phase. Of major interest, a much better preservation was observed for radical scavenging and antiglycation activities as attested by recovery rates ranging from 79.1 to 86.7%. Consistently with previous observations, the present study confirms the moderate bioaccessibility of anthocyanin constituents. It does however provide valuable information supporting the persistence of substantial radical scavenging and antiglycation activities at each step of the digestion process. Taken together, these data indicate that digestive conditions might not abolish the potential positive effects of bilberry consumption on both oxidative and carbonyl stresses.
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