Antioxidant and antimicrobial properties of dihydroquercetin esters

Abstract Flavonoids display various beneficial biological properties, such as antioxidant activity and low cytotoxicity, which make them useful ingredients in foods, pharmaceuticals, and functional cosmetics. In particular, dihydroquercetin (DHQ) is found in various forms, and its derivatives exhibit interesting biological properties. Herein, we report the synthesis of acetylated and butyrylated dihydroquercetin derivatives and their antimicrobial and antioxidant properties. The DHQ derivatives were identified using 1H and 13C NMR spectroscopies and high-performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry. The chemical stabilities of the acetylated dihydroquercetin derivatives were found to depend on the number of acetate groups, with 3,3',4',4,7-pentaacetyldihydroquercetin found to be the most stable acetylated dihydroquercetin. Furthermore, 7,3',4'-triacetyl- dihydroquercetin exhibited potent antioxidant activity, with an IC50 of 56.67 ± 4.79 µg/mL in the 1,1-diphenyl-2-picrylhydrazyl assay, with DHQ exhibiting a value of 32.41 ± 3.35 µg/mL. The reactive-oxygen-species-scavenging activity of 7,3',4'-triacetyldihydroquercetin was highest among the esters in the ferric reducing ability of plasma assay, but lower than that of DHQ. Overall, both DHQ and 7,3',4'-triacetyldihydroquercetin exhibited antimicrobial behavior against S. aureus and P. acnes using the paper disc assay. DHQ displayed a higher antimicrobial activity, with minimum inhibitory concentrations of 625 µg/mL (P. acnes), 2,500 µg/mL (S. aureus), and 5,000 µg/mL (E. coli). DHQ and acetylated dihydroquercetins are potentially useful as complex antioxidant and antimicrobial materials

Taxifolin stability:In silico prediction and in vitro degradation with HPLC-UV/UPLC-ESI-MS monitoring / 药物分析学报

Taxifolin has a plethora of therapeutic activities and is currently isolated from the stem bark of the tree Larix gmelinni(Dahurian larch).It is a flavonoid of high commercial interest for its use in supplements or in antioxidant-rich functional foods.However,its poor stability and low bioavailability hinder the use of flavonoid in nutritional or pharmaceutical formulations.In this work,taxifolin isolated from the seeds of Mimusops balata,was evaluated by in silico stability prediction studies and in vitro forced degradation studies(acid and alkaline hydrolysis,oxidation,visible/UV radiation,dry/humid heating)monitored by high performance liquid chromatography with ultraviolet detection(HPLC-UV)and ultrahigh perfor-mance liquid chromatography-electrospray ionization-mass spectrometry(UPLC-ESI-MS).The in silico stability prediction studies indicated the most susceptible regions in the molecule to nucleophilic and electrophilic attacks,as well as the sites susceptible to oxidation.The in vitro forced degradation tests were in agreement with the in silico stability prediction,indicating that taxifolin is extremely unstable(class 1)under alkaline hydrolysis.In addition,taxifolin thermal degradation was increased by humidity.On the other hand,with respect to photosensitivity,taxifolin can be classified as class 4(stable).Moreover,the alkaline degradation products were characterized by UPLC-ESI-MS/MS as dimers of taxifolin.These results enabled an understanding of the intrinsic lability of taxifolin,contributing to the development of stability-indicating methods,and of appropriate drug release systems,with the aims of preserving its stability and improving its bioavailability.

Phytochemical Screening of Callus and Cell Suspensions Cultures of Thevetia peruviana

Abstract Thevetia peruviana is an ornamental shrub grown-up in many tropical region of the world. This plant produces secondary metabolites with biological properties of interest for the pharmaceutical industry. The objective was to determine the secondary metabolites profile of callus and cell suspension cultures of T. peruviana and compare them with those from explant (fruit pulp). Extracts in 50% aqueous ethanol and ethyl acetate were prepared. The phytochemical analysis was performed using standard chemical tests and thin layer chromatography. In addition, total phenolic and flavonoids compounds (TPC and TFC), total cardiac glycosides (TCG) and total antioxidant activity (TAA) was determined during the cell suspension growth. Phenolic chemical profile was also analyzed by high performance liquid chromatography (HPLC). Common metabolites (alkaloids, amino acids, antioxidants, cardiac glycosides, leucoanthocyanidins, flavonoids, phenols, sugars and triterpenes) were detected in all samples. The maximum production of extracellular TCG, TPC, TFC and TAA in cells suspensions were at 6-12 days; in contrast, intracellular content was relatively constant during the exponential grown phase (0 to 12-days). HPLC analysis detected one compound with retention time at 11.6 min; this compound was tentatively identified as dihydroquercetin, a flavonoid with anti-cancer properties. These results provide evidence on the utility of the in vitro cell cultures of T. peruviana for valuable pharmaceutical compounds production.

Development of a specialized high protein product for adaptive nutrition

The article is dedicated to the development of a multicomponent high-protein product for the nutrition of physically active individuals. The possibility to introduce flavoring fillers and a biologically active supplement in the milk and vegetable base of fermented whipped dessert has been established, and the expediency thereof has been justified. Based on a mathematical model, the possibility of preparing dessert systems with the specified optimum parameters has been confirmed. The influence of nondairy protein components on the improvement of functional and technological properties of multicomponent mixtures for desserts has been revealed. It has been demonstrated that the inclusion of desserts with specified optimum parameters in the diet will have a positive effect on increasing the body's adaptive capacity.

Study on chemical constituents from whole herbs of Sargassum fusiforme / 中草药

Objective: To study the chemical constituents of the whole herbs of Sargassum fusiforme. Methods: The chemical constituents from S. fusiforme were separated and purified by silica gel, MCI, ODS, Sephadex LH-20 gel column chromatographies, and preparative HPLC. Their structures were identified by analysis of NMR, MS, ORD, etc, and comparing physicochemical properties of compounds with references. Results: A total of 19 compounds were obtained from the 50% ethanol-H2O extract of S. fusiforme, and their structures were determined as lupenone (1), bauerenone (2), β-amyrenone (3), α-amyrenone (4), loliolide (5), isololiolide (6), (3S,5R,6S,7E)-5,6-epoxy-3-hydroxy-7-megastigmen-9-one (7), (R)-dehydrovomifoliol (8), 24-ethylcholesta-4,24 (28)-dien-3-one (9), fucosterol (10), 29-hydroperoxystigmasta-5,24 (28)-dien-3β-ol (11), 24-hydroperoxy-24-vinylcholesterol (12), saringosterol (13), (24R)-5,28-stigmastadiene-3β,24-diol-7-one (14), dihydroquercetin (15), aurantiamide acetate (16), dibutyl phthalate (17), glycerol monopalmitate (18), and methyl hexadecanoate (19). Conclusion: The compounds isolated from S. fusiforme were mainly identified as triterpenoids, sesquiterpenoids, highly oxidized sterols, alkaloids and so on. Compounds 1-4, 7-8 and 14-19 are isolated from S. fusiforme for the first time.

Effects of Dihydroquercetin on Hemorheology and Other Relevant Indexes in Local Cerebral Ischemic Injury Model Rats / 中国药房

OBJECTIVE： To observe the effects of dihydroquercetin （DHQ） on hemorheology and other relevant related indexes in local cerebral ischemic injury model rats. METHODS： SD rats were randomly divided into sham operation group， model group， nimodipine group （positive control， 20 mg/kg） and DHQ low-dose， medium-dose and high-dose groups （15， 30， 60 mg/kg）， with 10 rats in each group. Administration groups were given relevant medicine intragastrically， sham operation group and model group were given constant volume of 0.4％ Sodium carboxymethyl cellulose solution， once a day， for consecutive 14 d. After last administration， local cerebral ischemic injury model was induced by bilateral common carotid artery ligation in other groups except for sham operation group. After 24 h of cerebral ischemia， histopathological changes of brain tissue in rats of each group were observed； the levels of hemorheology indexes [whole blood viscosity （low， medium and high shear）， whole blood reduced viscosity （low， medium and high shear）， plasma viscosity]， erythrocyte parameters （hematocrit， EAI， DI， IR）， coagulation function indexes （APTT， PT， TT， FIB） were detected. RESULTS： Compared with sham operation group， the cells in the brain tissue of model group were loose， the gap was obvious， and the neurons around the ischemic area were damaged obviously； the levels of whole blood viscosity， whole blood reduced viscosity， plasma viscosity， hematocrit， EAI， IR and FIB were increased significantly， while the levels of DI， APTT， PT and TT were decreased or shortened significantly （P＜0.05 or P＜0.01）. Compared with model group， above symptoms of administration groups were improved to different extents， whole blood viscosity， plasma viscosity， EAI and IR of nimodipine group， whole blood viscosity and hematocrit of DHQ high-dose group， plasma viscosity and EAI of DHQ groups， and IR of DHQ medium-dose and high-dose groups were decreased significantly； DI， APTT， PT and TT of nimodipine group， DI， APTT and TT of DHQ groups and PT of DHQ high-dose group were increased or prolonged significantly （P＜0.05 or P＜0.01）. There was no statistical significance in other indexes among those groups （P＞0.05）. CONCLUSIONS： DHQ can protect against local cerebral ischemic injury model rats， the mechanism of which may be associated with improving hemorheology indexes and coagulation function disorder.

Isolation and Identification of Components in the Dihydroquercetin-Rich Extract from Larch Wood (Larix olgensis Henry)

Background: The finding that antioxidant dihydroquercetin (DHQ) present in high content in the wood of Dahurian larch (Larix gmelinii Rupr.) which distributes mainly in Khingan Mountains led to the development and manufacture of a DHQ-rich extract, Lavitol (a trade name). Whether the composition of DHQ-rich extract from L. olgensis Henry, a great resource of Larch species distributed in Changbai Mountain in China, is same or similar with trade DHQ product becomes an interesting question. Aims: To isolate and identify the components in the DHQ-rich extract from larch wood (L. olgensis). Methodology: Compounds were isolated from a DHQ-rich extract (91% purity) of L. olgensis through polyamide and Sephadex LH-20 column chromatography, and their structures were elucidated based on 1H-NMR, 13C-NMR, MS and CD data analysis. Thin layer chromatography (TLC) was applied to quickly identify the components in the extract. Results: Five compounds were isolated from the extract, the main one was (2R,3R)-dihydroquercetin (1), four minor components were identified as (2R,3R)-aromadendrin (2), quercetin (3), 3,5,7-trihydroxychromone (4) and (2R,3R)-3'-O-methyl-taxifolin (5). Polyamide and silica gel TLC were developed to identify these components in the extract, and the results indicated that three batches of DHQ-rich extracts contained the same components. Conclusion: Except for the presence of trace impurities 4 and 5, DHQ-rich extracts from L. olgensis contained (2R,3R)-DHQ (1) and two minor impurities 2 and 3, which were similar with the composition of trade DHQ-rich extract from Dahurian larch (L. gmelinii). Further quantification of these impurities in DHQ-rich extract from L. olgensis by HPLC analysis need to be done in the future.

Ethyl Acetate-soluble Chemical Constituents from the Leaves of Callicarpa kwangtungensis Chun / 中国药学杂志

OBJECTIVE: To study the chemical ethyl acetate-soluble constituents of the leaves of Callicarpa kwangtungensis Chun. METHODS: The compounds were isolated and purified by column chromatography using silica gel, Sephadex LH-20, ODS and MPLC. The structures of the compounds were identified according to their physicochemical properties and spectroscopic methods. RESULTS: Thirteen compounds were isolated and identified as 5,7,2’,6’-tetrahydroxyflavone(1), 2,3-dehydrosilychristin(2), silychristin A(3), dihydroquercetin(4), syringaresinol(5), medioresinol(6),(7R,8S)-3,5’-dimethoxy-4’,7-epoxy-8,3’-neolignane -5,9,9’-triol(7),(2S,3R)-methyl-7-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-3-(hydroxymethyl)-2,3-dihydrobenzofuran-5-carboxylate(8), curcasinlignan B(9), vanillin(10), 19α-hydroxyursolic acid(11), 2α,3β,19α,23-tetrahydroxy-12-ene-28-oleanolic acid(12), and euscaphic acid(13). CONCLUSION: All these compounds were isolated from this plant for the first time.

Dihydroquercetin ameliorates alcoholic liver steatosis through P2x7R-NLRP3 inflammasome pathway / 中国药理学与毒理学杂志

OBJECTIVE Dihydroquercetin(TAX)is the most abundant dihydroflavone found in on-ions,milk thistle and Douglas fir bark.We investigated whether TAX could inhibit the lipid accumulation in alcoholic liver steatosis in vivo and in vitro.METHODS An in vivo model was established by intragas-trically treating mice with ethanol,and an in vitro model was created by treating HepG2 cells with etha-nol.RESULTS TAX regulated Sterol Regulatory Element-binding Protein-1(SREBP1)and Acetyl CoA Carboxylase (ACC) expression via elevating Liver Kinase B1 (LKB1)/ AMP-activated Kinase (AMPK) phosphorylation. Also, TAX upregulated SIRT1 expression, which suppressed by ethanal intake. Suppression of Purinergic 2X7 receptor (P2x7R), nucleotide-binding oligomerization domain-like re-ceptor protein 3(NLRP3)and Cysteine protease-1(caspase-1)cleavage by TAX resulted in the inhibi-tion of Interleukin-1β(IL-1β) production and release. Additionally, TAX reduced lipogenesis and pro-moted lipid oxidation via the regulation of AMPK and ACC in ethanol-treated steatotic HepG2 cell.TAX downregulated IL-1β cleavage response to Lipopolysaccharides (LPS) plus adenosine triphosphate(ATP) stimulation in HepG2 cells. P2x7R deficiency attenuated lipid accumulation with increasing AMPK activity and decreasing SREBP1 expression in ethanol-treated HepG2 cells.CONCLUSION Our data showed that TAX exhibited the inhibitory properties on lipogenesis and hepatoprotective ca-pacity,indicating that TAX has therapeutic potential for preventing alcoholic liver steatosis.

Antioxidation effect of dihydroquercetin pretreatment in isolatedrat hearts during myocardial ischemia reperfusion injury / 中国药理学通报

Aim To investigate the protective effects of dihydroquercetin(DDQ) against myocardial ischemis reperfusion injury(MIRI) in rats.Methods Male Sprague-Dawley rats were randomly divided into 4 groups(n=10):normal,control,I/R model, and I/R model+DDQ(5,10 mg·L-1).This study used an isolated Langendorff rat heart model.The left ventricu-lar developed pressure(LVDP),heart rate(HR) and the maximum rise and fall rate of the left ventricular pressure(±dp/dtmax) were monitored and documented using a physiological recorder.The levels of lactate dehydrogenase(LDH) and creatine kinase(CK) were analyzed using enzyme-linked immunosorbent assay(ELISA).Infarct size was measured using 2,3,5-triphenyltetrazolium chloride staining.The levels of superoxide dismutase(SOD) and malondialdehyde(MDA), as well as the ratio of glutathione/glutathione disulfide(GSH/GSSG) were measured via ELISA.HE staining was used to observe the pathological changes of myocardial tissue.Results Compared with the I/R model group, the I/R model+DDQ groups raised hemodynamic parameters, SOD level, and GSH/GSSG ratio;and reduced the amount of CK, LDH, MDA levels.Moreover, the I/R model+DDQ groups had lower infarct size and pathological changes in myocardial tissue than I/R model group.Conclusion DDQ exertes cardioprotective effects against I/R via improving the oxygen free radical scavenging ability, the inhibition of oxygen free radical and reducing lipid peroxidation.

Phenolic acids from seed coats of Glycine max / 中草药

Objective: To study the phenolic acids from the seed coats of Glycine max. Methods: The chemical constituents in the acid water extract from the seed coats of G. max were isolated and purified by chromatographic methods, including macroporous resin, silica gel, ODS, Sephadex LH-20, Toyopearl HW-40, and MCI columns, as well as semi-preparation HPLC. The structures of the isolated compounds were elucidated based on physicochemical properties and spectroscopies, such as ESI-MS, 1H-NMR, and 13C-NMR. Results: Eleven compounds were obtained from the acid water extract and identified as cyanidin-3-O-glucoside (1), methyl caffeate (2), 3-methoxy-4, 5-dihydroxy methyl benzoate (3), protocatechuic acid methyl ester (4), protocatechuic acid ethyl ester (5), 3-methoxy-4-hydroxy benzoic acid (6), 3-methoxy gallic acid (7), dihydroquercetin (8), protocatechuic acid (9), protocateuic acid anhydrite (10), and epicatechin (11). Conclusion: Compounds 2-10 are isolated from the plants in Glycine Wild. for the first time.