DFT Studies on the Antiradical Potential of Phenolic Compounds

Phenolic compounds are a class of hazardous substances for human.To study the antiradical potential of a series of phenolic compounds from the aspect of position and substituent type,phenol,o⁃dihydroxybenzene(ODB),m⁃dihydroxybenzene(MDB),p⁃dihydroxybenzene(PDB),paranitrophenol(PNP),and o⁃chlorophenol(OCP)were selected as typical targets.In addition,to elucidate the degradation discrepancy of phenolic compounds,quantum chemical calculations(QCCs)were obtained using the B3LYP method along with a 6-311G(d,p)basis set.Calculations indicate that phenol,ODB,MDB,and PDB,with electron⁃donating groups,exhibited high antiradical potential,while PNP and OCP,with electron⁃withdrawing groups,exhibited low antiradical potential.The chemical indices calculations show that para⁃compounds and ortho⁃compounds had high antiradical ability.Moreover,phenol,ODB,MDB,and PDB possessed higher bond dissociation enthalpy(BDE)and lower adiabatic ionization potential(AIP)values compared with those of OCP and PNP.Medium effects,even in vacuo,were also taken into account to reveal the antiradical ability of phenolic compounds.

A Comparative Study on Antiradical and Antimicrobial Properties of Red Grapes Extracts Obtained from Different <i>Vitis vinifera</i>Varieties

The present work is devoted to the study of antiradical and antimicrobial activities of phenolic compounds extracted from different grapevine varieties grown in the Bekaa plane-Lebanon. The amount of phenolic compounds in selected grape extracts was determined by the Folin-Ciocalteau method. Phenolic composition was specified by high performance liquid chromatography. Free radical scavenging activity was examined by using the (2,2’-diphenyl-1-picrylhy-drazyl) DPPH assay. The potential antimicrobial activity was studied using a new quantitative method developed during this work. This activity was tested against several microbial pathogens, including a Gram-positive strain (Listeria monocytogenes), two Gram-negative strains (Escherichia coli and Salmonella arizonae) and a fungal strain (Candida albicans). According to the results of the present screening study, a great variability in the composition of phenolic com-pounds in red grape extracts was detected. All phenolic compounds extracts, demonstrated important scavenging properties and antimicrobial effect against bacterial and fungal strains. Yet, a different response degree was noticed depending on the tested microorganism and the phenolic composition of grape extracts. Antimicrobial activity was more effective against Gram-positive than Gram-negative and yeast strains. Furthermore, our results highlighted a significant role of synergistic effect between various phenolic compounds in the free radical scavenging and antimicrobial activities.

Phytochemical Study and Evaluation of the Antiradical Activity of Extracts of Oleaginous Seeds of Panda oleosa and Isolona hexaloba from Gabon

Our study focused on phytochemical tests and evaluation of the anti-free radical activity of seed extracts of two oleaginous plants from Gabon used in traditional medicine or as condiments: Panda oleosa and Isolona hexaloba. The extraction was carried out by maceration with solvents of increasing polarity: cyclohexane, trichloroethylene, acetone, ethanol and finally distilled water. The total yields of the extracts are about 69.50% for Panda oleosa and 34.28% for Isolona hexaloba. The phytochemical tests carried out on the extracts of the seeds of Panda and Isolona highlight in both seeds the presence of alkaloids, polyphenols, triterpenes, carotenoids, reducing compounds, flavonoids, total sugars, coumarins, anthraquinones, free quinones, free anthracene derivatives, and terpenoids. Isolona seeds also contain leucoanthocyanins, sterols, cardiac glycosides and saponins. Phytochemical tests revealed the absence of tannins and mucilage in both seeds. The free radical scavenging activity was measured by scavenging the free radical cation of 2,2’-azino-bis[3-ethylbenzothiazoline-6-sulfonic acid] (ABTS-+) with gallic acid as the reference antioxidant. The results of the free radical scavenging activity of the aqueous and ethanolic extracts of both seeds showed that the aqueous extracts were more active than the ethanolic extracts. The IC50s of the aqueous and ethanolic extracts of Panda seeds are 40 and 60 μg·mL-1 respectively, and those of the aqueous and ethanolic extracts of Isolona are 37.5 and 95 μg·mL-1 respectively. Gallic acid, the reference antioxidant (IC50 = 0.37 μg·mL-1) is about 10 times more active than the aqueous extracts of both seeds, 16 times more active than the ethanolic extract of Panda and 25 times more active than the ethanolic extract of Isolena.

Phytochemical Analysis and Antioxidant Activity of Crocus speciosus Leaves

The numerous studies indicate leaves of plants are a rich source of bioactive compounds that can be a valuable source of compounds used in the pharmaceutical and cosmetic industries.Aim of this study was to investigate the chemical composition and the antioxidant property of Crocus speciosus leaves.Primary phytochemical screening of C.speciosus leaves revealed the presence of some following compound categories such as phenolic compounds,aminoacids,saponins,proteins,tannins,triterpenoids,glycosides,polysaccharides.The total flavonoids and phenolic compounds content were determined spectrophotometrically and by HPLC-DAD and HPLC-MS.Antiradical activity was determined by ABTS radical-cation scavenging method,spectrophotometrically.The total amount of flavonoids in C.speciosus leaves was 1.07±0.02 mg RE/g(p<0.05),the total amount of phenolic compounds was 0.41±0.01 mg GAE/g(p<0.05).By HPLC-DAD-MS analysis the presence of the mangiferin,chlorogenic acid,isoorientin,kaempferol,hyperoside,and isoquercitin was established for the first time in Crocus leaves.The antiradical activity of C.speciosus leaves extracts was 150.08±4.5μmol/g(p<0.05)and its was mainly attributed to phenolic compounds content.The high amounts of flavonoids and antiradical activity in C.speciosus leaves suggests promising phytochemical and pharmacological study of this Crocus species.

Solvent-solvent fractionations of Combretum erythrophyllum(Burch.) leave extract: Studies of their antibacterial, antifungal, antioxidant and cytotoxicity potentials

Objective: To evaluate the biological activities of Combretum erythrophyllum(C. erythrophyllum) leaf extracts against infectious diseases' pathogenesis and their cytotoxicity potentials. Methods: Powdered leaf material(300 g) of C. erythrophyllum was extracted(1:10 w/v) using acetone to obtain the crude extract. Liquid-liquid fractionation was performed on the crude acetone extract(30 g) using solvents of different polarity. The bioautographic method was used to detect the inhibition of bacterial and fungal growth by active compounds present in the crude and fractions. The extracts were then tested on bacterial strains: Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa; fungal strains: Candida albicans(C. albicans), Cryptococcus neoformans, and Aspergillus fumigatus, by microtitre dilution method for MIC determination. Results: The extracts MIC values ranged between 0.08–2.50 mg/m L against the tested pathogens. Water fraction had the highest activity against bacteria strains, while the fungal assay revealed crude acetone extract and ethyl acetate fraction to be active against C. albicans(1.25 mg/m L), dichloromethane extract against C. albicans and Aspergillus fumigatus(0.16 mg/m L). Extract fractions showed a good antioxidant activity via DPPH, ABTS and hydroxyl radical scavenging assays, in the order: ethyl acetate > water > acetone > dichloromethane > hexane. The toxicity level of crude extract and fractions evaluated in Vero monkey kidney cells ranged from 34–223 μg/m L, while doxorubicin(IC_(50) = 7.19 μg/m L) served as the positive control. Conclusions: It can be concluded that the extracts of C. erythrophyllum are safe for medicinal use in folk medicine for treating infectious and stress related diseases.

Antioxidants from Syrah Grapes (<i>Vitis vinifera L</i>.<i>cv</i>. <i>Syrah</i>). Extraction Process through Optimization by Response Surface Methodology

In this work, optimization of phenolic compounds (PC) and monomeric anthocyanins (MA) extraction from Syrah (Sy) wine grapes (Vitis vinifera L. cv. Syrah) using response surface methodology was conducted. The comparisons between two extraction mixtures, Acetone/Water (A/W) as well as Methanol/Water (M/W) and the effects of three critical variables, Extraction Time (between 8 and 88 h), Extraction Temperature (between 1℃ and 35℃) and Solvent Content (between 63% and 97%), on Phenolic Compounds Yield (PCY), Monomeric Anthocyanins Yield (MAY) and the DPPH Free Radical Inhibition Potential (DFRIP) were studied. The highest PCY was obtained in 63% A/W solvent content after 88 h incubation at 35℃. The highest MAY was acquired in 97% M/W solvent content after 8 h incubation at 17℃. The highest DFRIP of the extract was attained using 97% A/W solvent content after 16 h incubation at 35℃. The low cost of this process, on economic and environmental levels, could lead to interesting applications on an industrial scale. It could be used to obtain bioactive phytochemicals from direct material or byproducts for either therapeutic or nutritional purposes.

Chemical Characterization and Anti-Radical Activity of Fruits and Vegetables Commonly Consumed in Brazzaville

The objective of this study was to analyze ten (10) species of edible vegetables and nine (9) fruit commonly found in Congo (Brazzaville) in order to determine their total polyphenol content (TPC) and total flavonoid content (TFC), and their antiradical activity by the method of 1,1-diphenyl-2-picrylhydrazyl (DPPH). The results obtained showed that the highest TPC and TFC were found, on the one hand, in the extracts of four species of vegetables, i.e. Ipomoea batatas L. (536.02 ± 0.01 mg of GAE/100 g DW;486.46 ± 0.10 mg of QtE/100 g DW), Cucurbita pepo (533.60 ± 0.05 mg of GAE/100 g DW;303.72 ± 0 mg of QtE/100 g DW), Hibiscus sabdariffa (421.02 ± 0.015 mg of GAE/100 g DW;243.49 ± 0.10 mg of QtE/100 g DW), Solanum negrum 1 (412.10 ± 0.05 mg of GAE/100 g DW;292.10 ± 0.14 mg of QtE/100 g of DW) and, on the other hand, in the extracts of two species of fruit, i.e. Chrysophyllum lacourtianum (532.79 ± 0.19 mg of GAE/100 g of DW;380.55 ± 0.10 mg of QtE/100 g of DW) and seeds of Aframomum alboviolaceum (469.38 ± 0.28 mg of GAE/100 g DW;107.27 ± 0.10 mg of QtE/100 g DW). The lowest TPC and TFC were obtained with the extracts of Brassica campestris and of Spinacia oleracea, respectively 97.78 ± 0.17 GAE mg/100 g DW and 27.52 ± 0.10 QtE mg/100 g DW. The extract of the Saba senegalensis pulp had the lowest TPC and TFC. In addition, the highest antiradical activity was observed with extracts from vegetables and fruit with high TPC and TFC. The results indicate that these vegetables and fruit could be potential sources of the phenolic compounds and the biomolecules having several biological activities. Thus, their consumption might be an alternative in the prevention of chronic diseases.

Detection of Puerarin from Pueraria Mirifica Tuber and Its Formulated Cosmetic Products

Pueraria mirifica(PM)has traditionally been used to relieve postmenopausal symptoms.Recently,its extract has been developed into various cosmetic products to promote skin rejuvenation and youthfulness.This study investigated the phytochemicals of PM tuber and compared between the tuber flesh and its outer peel.Puerarin which is one of the major isoflavones and being considered as the marker compound was used to determine the presence of PM extract in local cosmetic products.Puerarin could be ionized by a mass spectrometer at both negative and positive modes.The peak ionized at the negative mode showed to have a narrower peak width(0.2 min)and higher signal-to-noise ratio(30)for pueararin(1 mg/L).The results also found PM extract contained many C-and O-glycosylated isoflavones,especially from its peel extract.This explains the peel extract showed to have four times higher antiradical activity than those of flesh extract.Puerarin from the cosmetic products was recovered via successive methanolic sonication and followed by liquid-liquid extraction using ethyl acetate.Puerarin was successfully partitioned from the highly complex chemical mixture of cosmetic products with the recovery ranged from 89.1%to 115%.Hence,isoflavones was found to be higher at the outer peels than its tuber flesh.A simple and reliable method has been developed to analyse the presence of PM extract in cosmetic products based on the detection of puerarin after successive extraction via methanolic sonication and ethyl acetate partition.