Effects of acid hydrolysis on the free radical scavenging capacity and inhibitory activity of the angiotensin converting enzyme of phenolic compounds of two varieties of jamaica (Hibiscus sabdariffa)

Bananas are an essential source of staple food and fruit worldwide and are widely regarded as the world’s largest fruit crop, with more than 100 million tons total annual production. Banana peel, a by-product that represents about 40% of the entire banana’s weight, and pulp are rich in bioactive compounds and have a high antioxidant capacity. As the production of polyphenols in fruit and vegetables is highly dependent on environmental conditions, genetic factors, and the level of maturity, this study aims to characterize six Australian banana cultivars in various stages of ripening for their phenolic compounds using the liquid chromatography-electrospray ionization quadrupole time of flight mass spectrometry (LC-ESI-QTOF-MS/MS), polyphenols quantification with the high-performance liquid chromatography coupled with photodiode array detector (HPLC-PDA), and their antioxidant capacity. All bananas were analysed for total polyphenols content (TPC), total flavonoids content (TFC), and total tannin content (TTC) and their antioxidant activities. Ripe Ducasse peel and pulp contained the highest amounts of total polyphenols content (1.32 and 1.28 mg gallic acid equivalent (GAE) per gram of sample), total tannin contents (3.34 mg catechin equivalent (CE) per gram of sample), and free radical scavenging capacity (106.67 mg ascorbic acid equivalent (AAE) per g of sample). In contrast, ripe Plantain peel had the greatest total flavonoids (0.03 mg quercetin equivalent (QE) per g of sample). On the other hand, unripe Ladyfinger pulp possessed the highest total antioxidant activity (1.03 mg AAE/g of sample). There was a positive correlation between flavonoids and antioxidant activities. By using LC-ESI-QTOF-MS/MS, a total of 24 phenolic compounds were tentatively characterized in this research, including six phenolic acids, 13 flavonoids, and five other polyphenols. Quantification of phenolic compounds by the high-performance liquid chromatography coupled with photodiode array detector (HPLC-PDA) revealed a higher content of phenolic acids. These findings confirmed that banana peel and pulp have considerable antioxidant activity and can be employed in human food and animal feed for variant health enhancement uses.

The feasibility and the effect of acid or alkali hydrolysis in microwave-assisted extraction as well as the antibacterial activity of the resulting extracts were studied to select appropriate phenols extraction method. The results demonstrated that acid hydrolysis was suitable for the extraction of phenols from Geranium sibiricum and hydrochloric acid (HCl) hydrolysis do not only performed the highest effectiveness, but also enhanced its antibacterial capacity. After the process was optimized, the total phenols content, yields of corilagin and geraniin were increased by 28.60, 53.80 and 35.65%, respectively, as compared to only 20% in microwave-assisted extraction (MAE). Scanning electron microscopy (SEM) was employed to verify the destructive effects of the methods, the results represented that HCl hydrolysis in MAE method had dramatic destructiveness on cell wall. Thus, HCl hydrolysis in MAE provides an efficient and rapid approach for the natural products extraction and the research also provides a valuable nature resource for healthy food industry. Key words: Phenols, Hydrolysis method, Microwave-assisted extraction, Geranium sibiricum Linne, Antibacterial activity.

Spices have long been used to improve food flavor, due to their appealing fragrance and sensory attributes. Nowadays, spices-based bioactives, particularly phenolic compounds, have gained attention due to their wide range of significant effects in biological systems. The present study was conducted to characterize the 12 widely used spices (allspice, black cardamom, black cumin, black pepper, cardamom, cinnamon, clove, cumin, fennel, nutmeg, star-anise, and turmeric) for their phenolics with the liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS2), polyphenols estimation, and their antioxidant potential. Total phenolics, total flavonoids, and total tannin content and their antioxidant activities were estimated in all spices. Clove and allspice had the highest value of total polyphenol content (215.14 and 40.49 mg gallic acid equivalent (GAE) per g of sample), while clove and turmeric had the highest total flavonoids (5.59 mg quercetin equivalent (QE) per g of sample) and total tannin contents (23.58 mg catechin equivalent (CE) per g of sample), respectively. On the other hand, black cumin and black pepper had the highest phosphomolybdate activity (15.61 and 15.43 mg ascorbic acid equivalent (AAE) per g of sample), while clove was almost identified with highest free radical scavenging capacity. A positive correlation was observed among phenolic compounds and antioxidant activities. In this quest, a total of 79 phenolic compounds were tentatively characterized by using LC-ESI-QTOF-MS2 including 26 phenolic acids, 33 flavonoids, 16 other polyphenols, and 4 lignans. The high-performance liquid chromatography coupled with photodiode array detector (HPLC-PDA) quantification of phenolic compounds exhibited higher phenolic acids. These results provided us some valuable information that spices have powerful antioxidant potential that can be further used in human food and animal feed as a supplement for different health promoting applications.

In this study, the polyphenols composition and antioxidant properties of 12 blue highland barley varieties planted on the Qinghai-Tibet Plateau area were measured. The contents of the free, bound and total phenolic acids varied between 166.20–237.60, 170.10–240.75 and 336.29–453.94 mg of gallic acid equivalents per 100 g of dry weight (DW) blue highland barley grains, while the free and bound phenolic acids accounted for 50.09% and 49.91% of the total phenolic acids, respectively. The contents of the free, bound and total flavones varied among 20.61–25.59, 14.91–22.38 and 37.91–47.98 mg of catechin equivalents per 100 g of dry weight (DW) of blue highland barley grains, while the free and bound flavones accounted for 55.90% and 44.10% of the total flavones, respectively. The prominent phenolic compounds in the blue hulless barley grains were gallic acid, benzoic acid, syringic acid, 4-coumaric acid, naringenin, hesperidin, rutin, (+)-catechin and quercetin. Among these, protocatechuic acid, chlorogenic acid and (+)-catechin were the major phenolic compounds in the free phenolics extract. The most abundant bound phenolics were gallic acid, benzoic acid, syringic acid, 4-coumaric acid, benzoic acid, dimethoxybenzoic acid, naringenin, hesperidin, quercetin and rutin. The average contribution of the bound phenolic extract to the DPPH• free radical scavenging capacity was higher than 86%, that of free phenolic extract to the ABTS•+ free radical scavenging capacity was higher than 79%, and that of free phenolic (53%) to the FRAP antioxidant activity was equivalent to that of the bound phenol extract (47%). In addition, the planting environment exerts a very important influence on the polyphenol composition, content and antioxidant activity of blue highland barley. The correlation analysis showed that 2,4-hydroxybenzoic acid and protocatechuic acid were the main contributors to the DPPH• and ABTS•+ free radical scavenging capacity in the free phenolic extract, while chlorogenic acid, vanillic acid, ferulic acid and quercetin were the main contributors to the free radical scavenging capacity in the bound phenol extract. The study results show that the blue highland barley grains have rich phenolic compounds and high antioxidant activity, as well as significant varietal differences. The free and bound phenolic extracts in the blue hulless barley grains have an equivalent proportion in the total phenol, and co-exist in two forms. They can be used as a potential valuable source of natural antioxidants, and can aid in enhancing the development and daily consumption of foods relating to blue highland barley.

Physicochemical composition, antioxidant and anti-proliferative capacity of a lilly pilly (Syzygium paniculatum) extract

Microalgae are a developing novel source of carbohydrates, phenolic compounds, carotenoids and proteins. In this study, in vitro digestion and colonic fermentation were conducted to examine the total phenolic content and potential antioxidant activity of four microalgal species (Chlorella sp., Spirulina sp., Dunaliella sp., and Isochrysis sp.). The bioaccessibility of targeted phenolic compounds and the short-chain fatty acid (SCFA) production were also estimated. Particularly, Spirulina sp. exhibited the highest total phenolic content (TPC) and free radical scavenging (2,2'-diphenyl-1-picrylhydrazyl, DPPH) capacity after gastrointestinal digestion of 7.93 mg gallic acid equivalents (GAE) per g and 2.35 mg Trolox equivalents (TE) per g. Meanwhile, it had the highest total flavonoid content (TFC) of 1.07 quercetin equivalents (QE) per g after 8 h of colonic fermentation. Dunaliella sp. and Isochrysis sp. showed comparable ferric reducing antioxidant power (FRAP) of 4.96 and 4.45 mg QE per g after 4 h of faecal reaction, respectively. p-hydroxybenzoic and caffeic acid almost completely decomposed after the intestine and fermented in the colon with the gut microflora. In Dunaliella sp. and Isochrysis sp., these phenolic acids were found in the colonic fermented residual, probably due to the presence of dietary fibre and the interactions with other components. All four species reached the highest values of SCFA production after 16 h, except Spirulina sp., which displayed the most increased total SCFA production after 8 h of fermentation. It is proposed that Spirulina sp. could be more beneficial to gut health.

Antioxidant and Free Radical Scavenging Capacity of Extensively Used Medicinal Plants in Sri Lanka

The effect of sulfuric acid hydrolysis on the Pickering emulsifying capacity of Tartary buckwheat flour (TBF) rich in starch was evaluated for the first time. The results indicate that the sulfuric acid concentration and hydrolysis time had a significant impact on the Pickering emulsifying capacity of acid-hydrolyzed Tartary buckwheat flour (HTBF). A low sulfuric acid concentration (1-2 mol/L) could reduce the particle size of HTBF, but it also decreased the Pickering emulsifying ability. At a sulfuric acid concentration of 3 mol/L, appropriate treatment time (2 and 3 days) led to particle aggregation but significantly improved wettability, thereby resulting in a rapid enhancement in emulsifying capacity. Under these conditions, the obtained HTBF (HTBF-D2-C3 and HTBF-D3-C3) could stabilize medium-chain triglyceride (MCT)-based Pickering high-internal-phase emulsions (HIPEs) with an oil-phase volume fraction of 80% at the addition amounts (c) of ≥1.0% and ≥1.5%, respectively. Its performance was significantly superior to that of TBF (c ≥ 2.0%). Furthermore, at the same addition amount, the droplet size of HIPEs constructed by HTBF-D3-C3 was smaller than that of HTBF-D2-C3, and its gel strength and microrheological performance were also superior to those of HTBF-D2-C3, which was attributed to the higher wettability of HTBF-D3-C3. The findings of this study can facilitate the in-depth application of Tartary buckwheat and provide references for the development of novel Pickering emulsifiers.

Lentil (Lens culinaris M.) is a legume widely consumed worldwide. It is rich in bioactive compounds, including polyphenolic compounds that contribute to positive health benefits. This study aimed to determine the phenolic content and antioxidant activity of black, red, green, and brown whole lentils. Towards this end, the lentils' phenolic compounds were evaluated regarding their total phenolic content (TPC), total flavonoid content (TFC), total tannin content (TTC), total condensed tannin (TCT), total proanthocyanin content (TPAC), total anthocyanin content (TAC). For the antioxidant activity 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), hydroxyl radical scavenging activity (•OH-RSA), ferrous ion chelating activity (FICA), reducing power assay (RPA) and phosphomolybdate (PMA) assay were accessed. To identify individual phenolic compounds, liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS2) was used. The results showed that green lentils exhibited the highest TPC (0.96 mg gallic acid equivalents (GAE)/g) whereas red lentils presented the highest TFC (0.06 mg quercetin equivalents (QE)/g). Black lentils were noted with the highest TCT (0.03 mg catechin equivalents (CE)/g), TPAC (0.009 mg cyanidin chloride equivalents (CCE)/g), and TAC (3.32 mg/100 g) contents. While the greatest TTC (2.05 mg tannic acid equivalents (TAE)/g) was observed in the brown lentil. Regarding the total antioxidant capacity, red lentils (4.01 mg ascorbic acid equivalents (AAE)/g) presented the greatest activity, whereas the lowest was found in the brown samples (2.31 mg AAE/g). The LC-ESI-QTOF-MS2 tentatively identified a total of 22 phenolic compounds, containing 6 phenolic acids, 13 flavonoids, 2 lignans, and 1 other polyphenol. The relationships among phenolic compounds by Venn Diagram showed a high number of overlapping compounds in brown and red lentils (6.7%), and a low number of overlapping compounds between the green, brown, and black lentils (2.6%). Flavonoids were the most abundant phenolic compound within the studied whole lentils, with the brown lentils being the richest in phenolic compounds, especially flavonoids. This study emphasized a comprehensive understanding of the antioxidant potential of lentils and disclosed the phenolic distribution across various lentil samples. This may increase interest in the development of functional food products, nutraceutical ingredients, and pharmaceutical applications with lentils.

Reactive oxygen species (ROS) such as superoxide anions, hydrogen peroxide, and hydroxyl, nitric oxide radicals, play an important role in oxidative stress related to the pathogenesis of various important diseases. Active (or reactive) oxygen species and free radical-mediated reactions are involved in degenerative or pathological processes. Antioxidants act as a major defense against radical mediated toxicity by protectingagainst the damages caused by free radicals. Antioxidant-based drugs/formulations for the prevention and treatment of complex diseases like atherosclerosis, stroke, diabetes, Alzheimer’s disease, and cancer have appeared during the last three decades. This has attracted a great deal of research interest in natural antioxidants. Flavonoids and phenolic compounds widely distributed in plants which have been reported toexert multiple biological effect, including antioxidant, free radical scavenging abilities, anti-inflammatory and anticarcinogenic activities. Recently there has been an upsurge of interest in the therapeutic potentials of medicinal plants as antioxidants in reducing such free radical induced tissue injury. The aim of the present investigation was to evaluate in vitro antioxidant and free radicals scavenging effect of two edibleweeds. Certain weeds are nutritious and eaten as foods or vegetables. In the present study two weeds namely Chenopodium album and Vitis trifolia have been screened for their antioxidant potential by using various in vitro methods. Aqueous leaf extract Chenopodium album and methanolic fruit extract of Vitis trifolia exhibit significant reducing power and free radical scavenging effect on DPPH, hydroxyl, superoxide, hydrogen peroxide radicals. The extracts also inhibit nitric oxide production. All theseantioxidant activities were concentration dependent which were compared with standard antioxidants such as BHA, α-tocopherol and ascorbic acid. In addition, total phenolic and total flavonoids contents were determined as gallic acid and catechin equivalents respectively. From the results, C. album leaf extract was found to contain 0.94 % total phenolic contents (gallic acid equivalent) and 0.27 % total flavonoid contents (catechin equivalent). Whereas V. trifolia fruit extract was found to contain1.23 % phenolic compounds as gallic acid equivalent (GAE) and 0.38 % flavonoid content as catechin equivalent (CE).

The aim of this study was to find out phytochemical classes present in various extracts of Stylochiton borumensis and to determine the total phenolic, flavonoids and tannins content in different plant extracts. Total phenols, flavonoids and tannins content was determined by folin-ciocalteu assay, aluminum chloride colorimetric assay and ferric chloride colorimetric assay respectively. Different extracts of S. Borumensis showed the presence of alkaloids, sterols/ triterpenoid, flavonoids, tannins and coumarins. The phenolic, flavonoids and tannins contents of plant extracts using gallic acid (Y= 0.0007x + 0.1078, r² = 0.9997), quercetin (Y= 0.0007x + 0.053, r²= 0.9984) and tannic acid (Y= 0.0009x + 0.043) as standards. The total phenolic content ranged from 460 to 530 mg/g gallic acid equivalent in leaves and from 240 to 520 mg/1 gallic acid equivalent in roots. The total flavonoids content was ranged from 140.870 to 360.750 mg/1 quercetin equivalent in leaves and from 138.678 to 357.670 mg/1 quercetin equivalent in roots. The total tannins contents ranged from 210 to 300 mg/l tannic acid equivalent in leaves and 190 to 270 mg/1 tannic acid equivalent in roots. The study showed significant amount of gallic acid, quercetin and tannic acid equivalents were present in S.Borumensis extracts which may responsible for valuable pharmacological property of the plant.

In this study, 17 commercial honey samples from Morocco were analyzed. Four samples did not meet the international physicochemical standards due to high hydroxymethylfurfural content and low diastase activity. Phenol content varied from 163.82 mg gallic acid equivalent (GAE)/kg in citrus honey to 923.70 mg (GAE)/kg in thyme honey from Rachidia; flavonoid content ranged from 4.26 mg quercetin equivalent (QE)/kg in citrus honey to 139.62 mg QE/kg in black cumin honey. Black cumin honey had the highest peroxyl scavenging activity; oregano (from Zaraphyt) and thyme honeys (from Rachidia) had the highest ABTS (2,2′-azino-bis[3-ethylbenzothiazoline-6-sulphonic acid]) scavenging activity; and thyme honey (Saouira) had the highest NO scavenging capacity. The antioxidant activity of Moroccan honeys was correlated with the phenol, flavonoid, and melanoidin contents. Dark honeys had higher antioxidant activity than light honeys. Samples with high sodium levels had lower free radical scavenging activity. On the other hand, calcium and magnesium increased the ABTS and peroxyl scavenging capacity, respectively, of honey samples. According to cluster and discriminant analyses, the honey samples were grouped in three clusters with respect to the phenol, flavonoid, melanoidin, proline, mineral and sugar contents, and free radical scavenging capacity.

Extraction of phenolic compounds from bean seed coats by acetic acid was evaluated and compared to conventional extraction with 80% methanol. Total phenols, flavonoids and free radical scavenging capacity were determined by colorimetric methods. Furthermore, qualitative flavonoid characterization was performed via HPLC diode array. The acetic acid extract contained 73.4 ± 7 mg/g of sample expressed as gallic acid equivalents (GAE), and 41.3 ± 4 mg/g as catechin equivalents (CE). The acetic acid extract (at 1 mg/mL) showed over 89% efficiency to scavenge the 1,1 diphenyl-2-picrylhydrazil (DPPH) radical (EC50 = 6.13 mg extract/mg standard). Gallic acid, delphinidin-3-glycoside, petunidinglycoside, petunidin, malvidin-3-glycoside, myricetin-glycoside, quercitin-glycoside, saponin (β-g), and 3-hydroxy-5, 7-megastigmadien-9-one were identified in both extracts. Additionally, kaempferol-3-glycoside was found in the acetic acid extract. Sequential acetic acid extractions indicated that the antiradical activity was about 90% in DPPH radical scavenging within the first 8 h of extraction, when compared to a 24 h extraction. In general, acetic acid offered a faster and more efficient approach for the extraction of phenolic

The Amhara region of Ethiopia is endowed with honey of diverse varieties and qualities. However, there is a lack of information on its secondary metabolite content and antioxidant nature. For this study, 47 fresh honey samples were collected from seven administrative zones throughout three provinces in the Amhara National Regional State, Ethiopia. The honey samples’ restorative nature was evaluated by the quantitative determination of phenolic content and antioxidant capabilities using standard colorimetric methods. The finding showed that the mean values of total polyphenol content based on gallic acid equivalent (GAE) ranged from 17.03 to 42.04 mg GAE per 100 g of honey. The mean value of the entire flavonoid content using catechin equivalent (CE) was from 3.20 to 7.40 mg CE, and when using quercetin equivalent (QE), it ranged from 1.67 to 5.08 mg QE, per 100 g of honey sample. The ascorbic acid equivalent antioxidant content (AEAC) of the honey samples – ranged from 16.23 to 26.5 9 mg AEAC per 100 g of the honey samples. The percent antioxidant activities (% AA) of the honey samples—ranged from 23.74 to 40.11%. There was a strong positive correlation between phenolic content and antioxidant properties. Amber-colored honey enjoyed the highest value on the stated parameters based on the samples’ colors, while the white-colored samples registered the least value. Based on the findings, it is concluded that the region’s honey has a magnificent therapeutic nature. Using the principal component analysis (PCA) model, the top three principal components described 96.63% of the total variations. The linear discriminant analysis (LDA) model has an average of 68.1% discriminant power. The LDA model was cross-validated by the leave-one-out cross-validation approach, and 70.21% of it clustered adequately. In the biplot analysis, honey sample distribution based on their color clustered better than the geographic origin and climate factors.

In vitro screening of Mexican arnica (Heterotheca inuloides Cass.) inhibitory activity of the angiotensin converting enzyme as a hypotensive mechanism