The Folin-Ciocalteau (F-C) method of assay is the simplest method available for the measurement of phenolic content in products. It is a development of Folin Denis reagent used in the early 19th century for the determination of tyrosine in proteins [1]. F-C reagent can be prepared by dissolving 100 g sodium tungstate (VI) dihydrate and 25 g sodium molybdate (VI) dihydrate with 700 ml distilled water, 100 ml concentrated hydrochloric acid, and 50 ml of 85% phosphoric acid to which is added 150 g of lithium sulphate hydrate. This reagent is very stable if protected from reductants and even when diluted if protected from light. For many years now, the F-C method of assay has been in use as a measure of polyphenol in natural products, and the basic mechanism is an oxidation/ reduction reaction with the phenolic group being oxidized and the metal ion reduced. Chemistry controlling the reaction with Folin-Ciocalteau reagentFolin-Ciocalteau phenol reagent consists of a mixture of the heteropoly acids, phosphomolybdic and phosphotungstic acids in which the molybdenum and the tungsten are in the 6+ oxidation state. On reaction with a reductant, the molybdenum blue and the tungsten blue are formed and the mean oxidation state of the metals is between 5 and 6. Na 2 WO 4 /Na 2 MO 4 yellow⇒ (Phenol-MoW 11 O 40 ) -4 blue Mo +6 (yellow) + e -1 ⇒ Mo +5 (blue) Mo +5 + e -1 ⇒ Mo +4 (blue) ØOH ⇒ ØO • + H +1The above reaction is slow at acidic pH and faster when basic. It is very sensitive, precise but lack specificity. Singleton and Rossi [2] further improved the method with a molybdotungstophosphoric heteropolyanion reagent that reduced polyphenols more specifically with the λ max for the product at 765 nm.To achieve meaningful, reliable and predictable results, some conditions such as proper volume ratio, optimal reaction time, and temperature for colour development, standard optical density, and use of a particular reference-standard polyphenol are required.The improved method F-C reagent can be used by two principal procedures for the measurement of polyphenolic content i.e. as dual reagent [2,3] and as single reagent [4,5].
Four plants (Amphimas pterocaroides, Harungana madagascariensis, Myrianthus arboreus, and Cussonia barteri) that are commonly used in Cameroon for the management or reversal of anaemia were screened for their phytochemical content and antioxidant potential. Four extracts (methanolic, hydro-ethanolic, aqueous, and hydrolysed) from each of the plants were prepared and analysed. Qualitative phytochemical tests were used to detect the presence of alkaloids, tannins, saponins, flavonoids, glycosides and phenols, while three quantitative methods; Folin, Ferric Reducing Antioxidant Power (FRAP) and diphenyl-1, 2-picryl hydrazyl (DPPH) were used to determine the antioxidant potential of these extracts. With the exception of the extracts of Cussonia barteri (negative for triterpenes and phenols) and the aqueous extract of Harungana madagascariensis (negative result for cardiac glycosides and glycosides), all other extracts contained the phytochemicals tested. The highest antioxidant activities were observed in the hydrolysed extracts of each plant, while the aqueous extract showed the least activity irrespective of the method used. The presence of active phytochemical substances with antioxidant activities may provide substantial basis for the use of these plants in ethnomedicine.
Oxidation of LDL has been suggested to be an initial step in the development of atherosclerosis. This research work deals with the evaluation of antioxidant potential of Plectranthus glandulosus leaves extracts and fractions as well as its protective effects against human LDL oxidation. A preliminary quantitative phytochemical screening was carried out. Antioxidant potential was evaluated employing in vitro hydrogen peroxide, nitric oxide scavenging assays and TAOC test. The human LDL oxidation induced by CuSO4 inhibition test was also performed. Plectranthus glandulosus leaves exhibited the presence of 18.3% of saponines, 25.6% of terpenoids and 36.2% of flavonoids. EAF exhibited highest hydrogen peroxide and nitric oxide scavenger activity (IC50 13.63µg/ml and 24.59 µg/ml respectively). Ascorbic acid exhibited an IC50 value of 15.39µg/ml in hydrogen peroxide assay and 22.96 µg/ml in nitric oxide scavenging activity. EAF exhibited a higher TAOC (optical density 0.186±0.00) than that of ascorbic acid (0.162±0.001) at the concentration of 25µg/ml while at 200µg/ml N-BUTF exhibited a higher optical density (1.261±0.001) than that of ascorbic acid (1.065±0.001). EAF lengthened the lag time of the CD formation up to 150mins at the concentration 1mg/ml. TBARS formation inhibition at the concentration 0.5mg/ml, were no significant different between n-butanol (68.55%) ethyl acetate fraction (68.21%) and quercetin 67.69%). Plectranthus glandulosus is a promising prospect as an anti-atherosclerotic agent and needs a detailed study to establish the same. Key words: Plecthrantus glandulosus; oxidation; LDL; atherosclerosis, antioxidant.
We evaluated the qualitative chemical composition and tested the antiulcer actions on cold/restraint stress ulcers, the healing effect on chronic acetic acid-induced gastric ulcers, and thein vivoandin vitroantioxidant capacity ofOcimum suaveextract. Triterpenes, flavonoids, sugars, phenols, sterols, and multiple bonds were among the phytochemicals detected. The extract (250–500 mg/kg) dose-dependently inhibited the formation of gastric ulcers induced by cold/restraint stress (52.30%–83.10%). The prophylactic actions were associated with significant increases in gastric mucus production. There was significant histological healing of chronic ulcers following 14-day treatment withO. suaveextract (250–500 mg/kg). We also evaluated the efficacy ofO. suaveextract in cold/restraint-induced oxidative stress in rat stomach tissue.O. suave(500 mg/kg) ameliorated the decreased levels of reduced glutathione from 0.85 (control group) to 2.08 nmol/g tissue. The levels of SOD and catalase were also improved in rats treated withO. suaveextract. The extract had a high phenol content (899.87 mg phenol/g catechin equivalent),in vitroDPPH radical scavenging activity (89.29%), and FRAP (antioxidant capacity) (212.64 mg/g catechin equivalent). The cytoprotective and ulcer healing effects of the extract are attributed to enhanced mucus production and the antioxidant properties which may likely be associated with the high presence of flavonoids and polyphenols.
The present work concerns the anti-inflammatory activity of chemical constituents isolated from the roots of Echinops gracilis. The anti-inflammatory activity of the ethyl acetate extract as well as compounds 1, 2, and 3 were evaluated using inhibition of protein denaturation and antiproteinase methods. Structural elucidation was achieved through analysis of NMR spectra (1H and 13C, 1H1H COSY, HSQC, HMBC) and literature survey. Seven compounds were identified as erythrinasinate (1), vogelate (2), ferulic acid (3), p-coumaric acid (4), ursolic acid (5), oleanolic acid (6), and quercetin (7). All the isolated compounds were reported for the first time from this plant. Ethyl acetate extract showed potent inhibitory activity against protein denaturation (IC50 = 125.54 µg/mL). Erythrinasinate (1) and vogelate (2) showed a significant anti-inflammatory activity with an IC50 value of 469.43 and 413.71 µg/mL, respectively. The results obtained from the ethyl acetate extract can justify the use of E. gracilis roots in traditional medicine for the treatment of rheumatism.
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