https://repositorium.sdum.uminho.pt/bitstream/1822/16850/1/pp.pdf

Extraction of antioxidant phenolic compounds from spent coffee grounds

Psidium guajava (guava) is well known tropic tree which is abundantly grown for fruit. Many countries have a long history of using guava for medicinal purposes. This plant finds applications for the treatment of diarrhea, dysentery, gastroenteritis, hypertension, diabetes, caries and pain relief and for improvement in locomotors coordination. Its leaf’s extract is being used as a medicine in cough, diarrhea, and oral ulcers and in some swollen gums wound. Its fruit is rich in vitamins A, C, iron, phosphorus and calcium and minerals. It contains high content of organic and inorganic compounds like secondary metabolites e.g. antioxidants, polyphenols, antiviral compounds, anti-inflammatory compounds. The phenolic compounds in guava help to cure cancerous cells and prevent skin aging before time. The presence of terpenes, caryophyllene oxide and p-selinene produces relaxation effects. Guava leaves contain many compounds which act as fungistatic and bacteriostatic agents. Guava has a high content of important antioxidants and has radio-protective ability. Quercetin is considered as most active antioxidant in the guava leaves and is responsible for its spasmolytic activity. Its ethyl acetate extract can stop the germ infection and thymus production. Guava possesses anti-viral, anti-inflammatory, anti-plaque and anti-mutagenic activities. Guava extract shows antinociceptive activity and is also effective in liver damage inflammation and serum production. Ethanolic extract of guava can increase the sperm quality as well as quantity and can be used for the treatment of infertile males.

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The phytochemistry and medicinal value of Psidium guajava (guava)

A novel high throughput method based on the DPPH dry reagent array for determination of antioxidant activity.

A systematic review on COVID-19 pandemic with special emphasis on curative potentials of Nigeria based medicinal plants

In this study, three types of solvent extracts from two cultivars of papaya fruit (Hongkong and Eksotika) were used to examine the effects of extraction solvent on total phenolics content (TPC), total flavonoids content (TFC) and antioxidant activity by ferric reducing antioxidant power (FRAP), 1,1-diphenyl-2-picryl hydrazyl radical scavenging (DPPH) and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) were determined spectrophotometrically Results showed that extraction solvent had significant effects on TPC, TFC, and antioxidant activity of methanol and acetone extract The highest content of TPC, TFC and antioxidant activity (FRAP, DPPH and ABTS) were found in 50% methanol and 50% acetone extracts The TPC varied for both cultivars (Hongkong and Eksotika) from 1635 to 4665, 6750 to 2338 mg gallic acid/100 g fresh weight, and TFC were between 1940 and 3617, 3981 and 2104 mg quercetin/100 g fresh weight and antioxidant activity (FRAP from 12484 to 9023, 19059 to 15998 mg Trolox equivalents/100 g fresh weight), DPPH were between 4782 and 2872%, 7456 and 3857%) and (ABTS from 5734 to 3149% and 6906 to 3484%), respectively The largest amount of TPC and TFC which leads to more effective radical scavenging effect was shown by 50% methanol extract Moreover, amount of phenolic compounds and antioxidant activities increased in methanol and acetone extract Therefore, a positive correlation occurred between antioxidant activity and phenolics compound Methanol 50% and acetone 50% solvent showed the greatest capability in extracting antioxidants and inhibiting the free radicals produced It was concluded that extraction solvent play important roles on the phenolics compounds and their antioxidant activity of papaya fruit extract

	 

	Key words: Papaya, extraction solvent, antioxidant activity, phenolic compound

https://www.academicjournals.org/article/article1386586217_Addai et al.pdf

Effect of extraction solvents on the phenolic content and antioxidant properties of two papaya cultivars

The effect of commonly used techniques and solvents in the antioxidant activities of pink-flesh guava fruit were studied. The extraction techniques compared were homogenization, shaking, sonication, magnetic stirring, and maceration for 1, 2, and 3 days. The solvent systems used were methanol, ethanol, and acetone at three different concentrations (50%, 70%, and 100%) and with 100% distilled water. The antioxidant activity of the fruit was evaluated using Folin–Ciocalteu index, ferric-reducing antioxidant power assay, and 1,1-diphenyl-2-picrylhydrazyl free radical-scavenging capacity. Ultrasonic and homogenization were the best techniques to extract the antioxidant from guava fruit. Homogenization technique was found to be the most convenient exhaustive and time-saving extraction technique. Results showed that the extracting solvent significantly (P < 0.05) altered the antioxidant property estimations of pink-flesh guava fruit. Pure solvents were inefficient extraction media for antioxidant. Enhanced extraction yields were obtained from solvent containing higher water concentrations and 50% acetone is a recommended solvent for extracting antioxidants compounds from pink-flesh guava fruit. High correlations between phenolic compositions and antioxidant activities of pink-flesh guava extracts were observed. High levels of antioxidant activities were detected in pink-flesh guava, indicating that the fruit may serve as an excellent dietary source of natural antioxidants.

Antioxidant Activity of Pink-Flesh Guava (Psidium guajava L.): Effect of Extraction Techniques and Solvents

This article determines ascorbic acid, total phenolic content and the antioxidant capacity of whole fruit, flesh, and skin fractions of two varieties of pink guava widely produced in Malaysia (semenyih and sungkai). They were analysed and specific flavonoid compounds (apigenin, isorhamentin, kaempferol, luteolin, myricetin, and quercetin) were determined. Ascorbic acid, total phenolic content and antioxidant capacity was found to be higher in semenyih than in sungkai, mainly in the skin fraction. The predominant flavonoid in all pink guava fractions was kaempferol, with sungkai flesh having the highest kaempferol content. The pink guava represents an important source of antioxidant flavonoid compounds that may have health benefits.

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Flavonoid profile and antioxidant activity of pink guava

The Bougainvillea glabra bract was extracted using three ratios of methanolic solvents at 50%, 70% and 100%. In this study, the methanolic extracts of B. glabra bract were evaluated for antioxidant properties and quantification of phenolics and flavanoids. Methanol at 100% was the highest extraction efficiency among three other methanolic with yield value of 38%. The content of phenolics and flavonoids of B. glabra bracts in methanol 100% were 63.92±0.90 GAE mg/100g and 249.53±26.20 QE mg/100g respectively. The antioxidant activity was measured using three different bioassays namely, DPPH, ABTS and FRAP. The results were expressed as mg Trolox equivalent per 100 g where Trolox is a vitamin E analog. Among these methanol extracts, highest antioxidant capacity was observed in the pure methanol concentration. Positive correlation was observed in B. glabra bract between DPPH assay and TPC, r2=1.00. The methanol extract at 100% was rich in polyphenolics, which indicating that the B. glabra bract has the potent...

Determination of antioxidant activities, total phenolic and flavanoid contents in Bougainvillea glabra bracts at various methanol concentrations

Backhousia citriodora commonly known as lemon myrtle belongs to Myrtaceae family. This species is an evergreen tree which can grow up to 30 meters. Lemon myrtle is highly aromatic, having an exquisite flavour and aroma of a blend of lemongrass, lime and lemon. The leaf and flowers are used in tea blends and beverages, dairy, biscuits, breads, confectionery, pasta, syrups, liqueurs, flavoured oils, dipping and simmer sauces. In our study, the chemical composition and antioxidant properties of the lemon myrtle volatile oil obtained via hydro distillation were investigated. Examination by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) analysis showed that the volatile oil obtained from the leaves was made up predominantly neral (39.57%) and geranial (52.43%). Linalool (0.37%), citronellal (0.15%), E-isocitral (2.47%), geraniol (0.66%), ethyl geranate (0.13%), caryophyllene (0.08%) and spathulenol (0.09%) were the other component present in significant amounts. For the stem part, similarly the major components also are neral (36.76%) and geranial (56.30%). Other minor components found in stem oil were 6-methyl-5-hepten-2-one (0.13%), linolool (0.24%), citronellal (0.09%), trans-paramentha-2,8-dien-1-ol (0.39%), E-isocitral (0.92%), (3Z)-hexenyl-(3Z)-hexenoate (0.22%), 8-hydroxy-neo-menthol (1.17%), (E)-α-Damascene 0.70%), spathulenol (0.17%) and globulol (0.14%). The obtained volatile oils were screen for the antioxidant properties by using DPPH (1,2-diphenyl-2-picryl-hydrazyl) radical scavenging assay and xanthine/xanthine oxidase superoxide scavenging assay. Our study indicated both the lemon myrtle leaf and stem volatile oil showed high antioxidant properties. DPPH scavenging activity for both the leaf and stem parts are 83.72% and 84.46% respectively. As for the xanthine/ xanthine oxidase superoxide scavenging assay, both the lemon myrtle leaf and stem volatile oil showed high superoxide scavenging activity, which are 83.72% and 84.46% respectively.

Chemical Composition and Antioxidant Properties of Backhousia Citriodora Volatile Oil

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Vimala Subramaniam

Papers

Antioxidant Activity of Pink-Flesh Guava (Psidium guajava L.): Effect of Extraction Techniques and Solvents

Flavonoid profile and antioxidant activity of pink guava

Determination of antioxidant activities, total phenolic and flavanoid contents in Bougainvillea glabra bracts at various methanol concentrations

Chemical Composition and Antioxidant Properties of Backhousia Citriodora Volatile Oil

Chemical Composition and Antioxidant Properties of Volatile Oil