In vitro antioxidant activities of Stevia rebaudiana leaves and callus

Leaf extract of Stevia rebaudiana promotes effects on certain physiological systems such as the cardiovascular and renal and influences hypertension and hyperglycemia. Since these activities may be correlated with the presence of antioxidant compounds, leaf and callus extracts of Stevia rebaudiana were evaluated for their total phenols, flavonoids content and total antioxidant capacity. Total phenols and flavonoids were analyzed according to the Folin–Ciocalteu method and total antioxidant activity of water and methanolic extracts of stevia leaves and callus was assessed by ferric reducing/antioxidant power (FRAP) assay as well as 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The total phenolic compounds were found to be 25.18 mg/g for stevia leaves and 35.86 mg/g for callus on dry weight basis. The flavonoids content was found to be 21.73 and 31.99 mg/g in the leaf and callus, respectively. The total antioxidant activity was expressed as mg equivalent of gallic acid, ascorbic acid, BHA and trolox per gram on dry weight basis. Total antioxidant activity found was ranged from 9.66 to 38.24 mg and 11.03 to 36.40 mg equivalent to different standards in water and methanolic extract of stevia leaves, respectively. In case of stevia callus, it was found to be 9.44 to 37.36 mg for water extract and 10.14 to 34.37 mg equivalent to standards for methanolic extract. The concentrations required for 50% inhibition (IC₅₀) of DPPH radicals were 11.04, 41.04 and 57.14 μg/mL for gallic acid, trolox and butylated hydroxyanisole (BHA), respectively. The percent inhibition of DPPH radical of various extracts of stevia leaves and callus found were ranged from 33.17% to 56.82%. The highest percent of inhibition was observed in methanolic extract of callus.     

Phenolic and antioxidant composition of cider

Forty-four Asturian ciders were analysed for total phenolic content, phenolic profiles, and antioxidant capacity by the FRAP and the DPPH radical assays. The Folin index of ciders ranged between 446 and 1180 mg gallic acid/L. The phenolic profile of Asturian cider is mainly constituted by phenolic acids, flavan-3-ols, volatile phenols and dihydrochalcones. The methods to determine the antioxidant activity of ciders were optimised in terms of suitable reaction times, within-day and between-day repeatability. Thus, time courses of ciders in the DPPH and the FRAP assays were performed. Mean values for antioxidant activity of cider, expressed in ascorbic acid equivalents were 2.9 mM (as determined by the DPPH assay). When the FRAP assay was used, the antioxidant capacity of cider increased with the reaction time from 3.8 mM (4 min) to 5.4 mM (40 min). Multivariate approaches based on phenolic composition can be useful to predict the antioxidant capacity of cider. Folin index and flavanols and hydrocaffeic acid contents were the best predictors for antioxidant activity.     

Characterization of phenolics,betacyanins and antioxidant activities of the seed,leaf, sprout,flower and stalk extracts of three Amaranthus species

Hydrophilic extracts from different parts including leaves, stalks, seeds, flowers and sprouts of 3 Amaranthus species (Amaranthus hypochondriacus, Amaranthus caudatus and Amaranthus cruentus) were characterized for their phytochemical profiles including the phenolics and betacyanins by UHPLC and LC–ESI–MS, and their antioxidant activities by FRAP and ORAC assays. The main betacyanins in Amaranthus samples were identified to be amaranthine and isoamaranthine. Eleven phenolic compounds (gallic acid, protocatechuic acid, chlorogenic acid, gentistic acid, 2,4-dihydroxybenzoic acid, ferulic acid, salicylic acid, rutin, ellagic acid, kaempferol-3-rutinoside and quercetin) were identified in the extracts of different parts of Amaranthus. The total phenolic content (TPC) ranged from 1.04 to 14.94 mg GAE/g DW; the total flavonoid content (TFC) ranged from 0.27 to 11.40 mg CAE/g DW; while the total betalain content (TBC) ranged from 0.07 to 20.93 mg/100 g DW. FRAP values ranged from 0.63 to 62.21 μmol AAE/g DW and ORAC ranged from 30.67 to 451.37 μmol TE/g DW. The leaves of Amaranthus showed the highest TPC, TFC, TBC, FRAP and ORAC values; while the seeds and stalks the lowest. There was a strong correlation between TPC, TBC, TFC and the antioxidant activity. The result suggests that all parts of the Amaranthus plant can be a good source of antioxidants.     

Effects of cooking on in vitro sinigrin bioaccessibility,total phenols,antioxidant and antimutagenic activity of cauliflower (Brassica oleraceae L. var. Botrytis)

Cauliflower (Brassica oleraceae L. var. Botrytis) is a good source of bioactive compounds, such as glucosinolates, phenolic compounds and vitamins. In this study, the effects of some processes (i.e. boiling, steaming) on the sinigrin bioaccessibility as a major glucosinolate found in cruciferous vegetables after in vitro digestion, also in vitro antimutagenic activities, total phenols and total antioxidant capacities of cauliflower were determined. The sinigrin content was reduced by approximately 9.6% and 29.1% in steamed and boiled cauliflower (p > 0.05), respectively. After in vitro simulated digestion, sinigrin content was decreased by 26.4% in raw samples, increased by 29.5% and 114.7% in steamed and boiled samples, respectively. In all samples, mutagenic effect to Salmonella typhimurium TA 100 was not seen. When samples were steamed, phenol content was increased by 14.83%. After boiling total phenol content of cauliflower was decreased by 1.8%. Total antioxidant capacities (TAC) measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3 ethylbenzothiazoline-6-sulfonic acid) (ABTS) methods were increased by 47% and 39%, respectively (p < 0.05) in steamed samples and decreased by 8% and 7% with boiling, respectively (p > 0.05). TAC in raw sample of cauliflower, which was investigated in phosphomolybdenum assays, was determined as 18.7 mg ascorbic acid equivalents (AAE)/100 g. In all cases, the highest antioxidant activity was determined in the steamed samples, while the lowest antioxidant activity was in boiled samples.     

Antioxidant activity of Potentilla fulgens: An alpine plant of western Himalaya

Antioxidant activities of the methanol extract, fractions and isolated compounds from the roots of Potentilla fulgens Lodd. were evaluated by three in vitro experiments, namely, ABTS, DPPH, and FRAP assays. PF-2 was characterized as a new biflavanoid and designated as Potifulgene on the basis of NMR and mass spectrum, whereas PF-1 was identified as epicatechin. The activities of aqueous methanolic extract and fractions could be correlated with their respective total phenolic content and compared with standard natural antioxidants such as quercetin, vitamin C and pyrogallol. The root powder of the plant was extracted with methanol/water (80:20) by cold extraction and its extract was further partitioned with ethyl acetate, butanol and water fractions. Among the three fractions (ethyl acetate, butanol and water fraction) and the total aqueous methanolic extract, the butanol fraction exhibited good scavenging response measured in terms of TEAC (mM Trolox equivalent/mg extract). The butanol fraction was found to possess strong antioxidant activity (2.54 ± 0.69, 2.41 ± 0.53, 3.57 ± 0.05 mM Trolox equivalent/mg extract) with ABTS, DPPH and FRAP assays, respectively. The chemical composition of extracts, studied in terms of total polyphenol content (TPC), was found in the range of 20.61 ± 0.38 to 33.28 ± 0.11 mg/g gallic acid equivalent. A significant correlation was observed between total polyphenolics and antioxidant activity, indicating participation of phenolics in antioxidant activities of extract and fractions. The antioxidant activity of new biflavanoid (Potifulgene) was found to be higher, i.e. 6.85 ± 0.38, 4.24 ± 0.41, 5.35 ± 0.53 than that of epicatechin, 2.13 ± 0.05, 1.50 ± 0.02, 1.57 ± 0.03 with ABTS, DPPH and FRAP assays.     

Effect of extraction solvents on the phenolic compounds and antioxidant activities of bunga kantan (Etlingera elatior Jack.) inflorescence

In the present study, we investigated the effect of methanol, acetone (50%, 90% and 100%, v/v) and distilled water on the extractability of some of the antioxidant compounds (total phenols, tannins, flavonoids, anthocyanins) of bunga kantan inflorescence (Etlingera elatior Jack.). The antioxidant activity of each individual extract was also evaluated through DPPH (2,2-diphenyl-1-pic-rylhydrazyl) radical scavenging activity and ferric reducing antioxidant power (FRAP) assay. Of all the solvents employed, 50% acetone extract showed highest amount of total phenols (687.0 mg GAE/100 g) and total flavonoids (1431 mg QE/100 g), while 50% methanol extract showed maximum (5.9 mg c-3-gE/100 g) recovery for anthocyanins. Tannin extractability was found to be highest with 100% methanol (467.8 mg CE/100 g). The results obtained suggest the use of bunga kantan inflorescence as a potential source of natural antioxidants for food and nutraceutical applications.     

Changes in phenolic antioxidants during chuño production (traditional Andean freeze and sun-dried potato)

Total antioxidant capacity (TAC), total phenolic compounds (TPH), total flavonoids (TF) and the amounts of individual phenolic compounds were assessed in Bolivian potato cultivars (various Solanum species) before, during and after the traditional freezing and sun-drying of potatoes known as chuños. The TAC of chuños ranged from 0.4 to 2.7 μmol Trolox equivalents/g dry matter using 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) and from 0.7 to 3.0 according to the ferric reduction antioxidant power (FRAP). The values of TAC obtained using FRAP were about 70% lower after freeze-drying while they remained essentially constant when measured using ABTS. High-performance liquid chromatography showed the presence of epicatechin, chlorogenic acid, gallic acid, syringaldehyde and protocatechuic acid in both potato and chuño samples although the values were lower in the chuño samples. The results suggest that the antioxidant capacity and the content of individual phenolics are somewhat decreased but far from eliminated during the process. Chuño can therefore still be considered an important source of antioxidants in the diet.     

Effect of solvents in extracting polyphenols and antioxidants of selected raw vegetables

Thirty-seven raw vegetables were extracted using four solvent systems: 70% acetone, 70% ethanol, 70% methanol, and distilled water. The extracts were tested for their total phenolic content, total flavonoid content and antioxidant activities (using diphenylpicryl-hydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays). The results revealed the effect of different extracting solvents in altering the quantitative analyses of all vegetables and 70% acetone was identified as the most efficient solvent for extracting polyphenolic antioxidants from the vegetables. The highest total phenolic content and total flavonoid content were obtained from 70% acetone extract of Portulaca oleracea (138.2 ± 2.1 mg GAE/g dw basis) and 70% methanol extract of Cosmos caudatus (27.7 ± 1.0 mg QE/g dw basis), respectively. The 70% acetone extract of Etlingera elatior with moderate amount of total phenolic content exhibited the highest antioxidant activity in both assays. The correlation analyses within 37 different extracts of each solvent extraction demonstrated weak to moderate relationships between all the studied parameters. The highest r value of 0.7139 (p < 0.001) was determined between total phenolic contents and FRAP values of the 70% methanol extracts. Meanwhile, a wide range of correlation coefficients was derived from correlation analyses within four different extracts of each vegetable, with the highest relationship between total phenolic contents and FRAP values for the extracts of Coriandrum sativum (r = 0.9998, p < 0.001).     

Antioxidant activity and phenolic content of fresh and dry nuts with or without the seed coat

Total antioxidant activities based on ABTS free radical scavenging activity and phenolic content of fresh or dry hazelnuts, walnuts and pistachios assayed with their seed coats changed between 3063 and 11,076 μmol trolox equivalents/100 g d.w. and 256 and 755 mg gallic acid equivalents/100 g d.w., respectively. The walnuts used in this study showed the highest antioxidant activity, followed by pistachios and hazelnuts. The removal of seed coat reduced the total antioxidant activity of hazelnuts, walnuts and pistachios almost 36, 90 and 55%, respectively. The total antioxidant activities of investigated fresh and dry nuts are not considerably different. However, phenolic content and antioxidant activity in hydrophilic and ethanolic fractions obtained by successive extraction of nuts showed some variation. The antioxidant activity in 1-serving portion of fresh or dry walnuts is equivalent to that in almost 2-serving portions of black tea, and 1.2–1.7-serving portions of green and Earl Grey tea. One-serving portions of dry hazelnuts and fresh or dry pistachios contained antioxidant activity equivalent to that in 0.7–1-serving portions of black tea. The antioxidant activity measurements correlated with phenolic content (r² = 0.70). This study showed the potential of using fresh or dry nuts to develop functional foods with high antioxidant activity.     

Antioxidant activity of methanolic extract of emblica fruit (Phyllanthus emblica L.) from six regions in China

The phenolic contents of methanolic extracts of emblica (Phyllanthus emblica L.) fruit from six regions in China were measured in this work. The antioxidant activities of these extracts were also evaluated. Total phenolic content was ranged from 81.5 to 120.9 mg gallic acid equivalents (GAE)/g and the flavonoid content was varied from 20.3 to 38.7 mg quecetin equivalents (QE)/g, while proanthocyanidin content was ranged from 3.7 to 18.7 mg catechin equivalents (CE)/g. Among all the methanolic extracts analyzed, the Huizhou sample exhibited a significantly higher phenolic content than other samples (P<0.05). The antioxidant activities were evaluated by in vitro experiments using scavenging assays of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, hydroxyl radicals, and superoxide anion radicals, chelating ability of ferrous ion, reducing power, and inhibition capability of Fe (II)-induced lipid peroxidation, respectively. The Huizhou sample was found to have the strongest antioxidant activities in scavenging DPPH radicals, superoxide anion radicals, and had the highest reducing power, while the Chuxiong sample showed the best performance in chelating iron and inhibiting lipid peroxidation. Furthermore, the Chuxiong sample exhibited a stronger inhibition activity of the hydroxyl radicals compared with other samples. The high correlation coefficient was existed between the phenolic content and superoxide anion radical scavenging activity, but no significant correlation was found between the former and hydroxyl radical scavenging activity. Methanolic extracts of emblica fruit from some selected regions exhibited stronger antioxidant activities compared to those of the commercial compounds (quercetin and BHA). It might be considered as a potential plant source of antioxidants.     

Polyphenols,vitamin C and antioxidant activity in wines from Rosa canina L. and Rosa rugosa Thunb.

The purpose of this study was to determine the concentration of biologically active compounds (polyphenols and l-ascorbic acid) in Rosa canina L. and Rosa rugosa Thunb. wines. The antioxidant capacity and antimutagenicity of the wines were also investigated. Aged and young wines contained phenolics levels of 2786–3456 and 3389–3990 mg/L GAE, respectively. The final concentrations of ascorbic acid were 1200 for Rosa rugosa Thunb. and 600 mg/L for Rosa canina L. R. rugosa and R. canina wines revealed high antioxidant activity in different assays (with ABTS, DPPH, and DMPD radicals). Expressed in terms of Trolox equivalent antioxidant capacity (TEAC), the activity ranged from 8 to 13.5 mM. Significant differences were found between the tested wines terms of their reactivity against the ABTS and DMPD radicals. The wines inhibited in vitro N-methyl-N′-nitro-nitrosoguanidine (MNNG) and the number of induced His⁺ revertants increased in a dose-dependent manner by 16–48% in Salmonella Typhimurium TA98 and 12–52% in Salmonella Typhimurium TA100. Wines from dog rose (Rosa canina L.) showed a greater ability to reduce mutations.     

Bioactive compound composition of pomegranate fruits removed during thinning

Thinning consists of reducing fruit load at immature stage and thus allowing remaining fruits to develop to their maximum size and quality. The waste material produced during this farming practice was characterised in 9 pomegranate cultivars, by evaluating: weight, size, maturity index, pH, organic acids and sugars profiles, contents of minerals, punicalagin, and ellagic acid, total polyphenols and antioxidant activity. Citric and quinic were the main organic acids. Potassium was the predominant mineral, reaching up to 11 g kg⁻¹ dry weight (dw). Total polyphenol content ranged from 777 to 1660 g GAE kg⁻¹ dw, α-punicalagin from 101 to 195 and β-punicalagin from 80.1 to 111 g kg⁻¹ dw. The antioxidant activity was assessed by three methods and its values varied from 2923 to 4486 for ABTS, from 3153 to 4685 for FRAP, and from 2075 to 2934 mmol Trolox kg⁻¹ dw for DPPH. Pomegranate thinning fruits, especially sour-sweet cultivars, are rich in bioactive compounds, with a potential use in the food, chemical and pharmaceutical industries.     

Antioxidant capacity of underutilized Malaysian Canarium odontophyllum (dabai) Miq. fruit

This study aimed to evaluate the antioxidant capacities of various parts of the dabai (Canarium odontophyllum Miq.) fruit. The antioxidant capacities of C. odontophyllum were evaluated using a β-carotene bleaching assay, ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assays. Total phenolic content of the dabai fruit was estimated using the Folin–Ciocalteu method. The antioxidant capacities ranked in the following order: skin > flesh + skin > flesh > kernel. Our findings show that a high correlation exists between total phenolic content and total antioxidant activity. This indicates that phenolic compounds could be the major contributors to the antioxidant capacity of C. odontophyllum fruit. Therefore, dabai fruit, especially the skin, can be recommended as a major source of natural antioxidants.     

Radical scavenging,antioxidant and metal chelating activities of Annona cherimola Mill. (cherimoya) peel and pulp in relation to their total phenolic and total flavonoid contents

This study aimed to evaluate the total phenolic and flavonoid content, radical scavenging activity (by DPPH and ABTS tests) and antioxidant capacity (by β-carotene bleaching test) of Annona cherimola (cherimoya) fruits cultivated in Italy for human consumption. The metal chelating activity and ferric reducing power were also determined. A. cherimola peel and pulp were characterized by a total phenolic content of 14.6 and 12.6 mg chlorogenic acid equivalents/100 g fresh weight, respectively. A similar trend was observed with flavonoid content. Both extracts exhibited high antioxidant activity through different mechanisms of action. In particular, peel extract demonstrated the strongest free radical scavenging activity with an IC₅₀ value of 57.7 μg/mL. The same extract was more effective in preventing β-carotene oxidation (IC₅₀ value of 63.5 μg/mL after 60 min) and showed higher chelating ability (IC₅₀ value of 79.6 μg/mL) than pulp extract. This work demonstrated the high quality of cherimoya fruits cultivated in Italy, and recommends the peel of this fruit product that may be of interest from a functional point of view as a major source of natural antioxidants.     

Bioactive compounds and antioxidant activity of gamma irradiated sun dried apricots (Prunus armeniaca L.)

The phenolics from both control and irradiated (3.0 kGy) dried apricots of Halman variety were identified and quantified by HPLC method using external standards. HPLC analysis revealed the presence of seventeen phenolic acids and eight flavonoids in dried apricots. Among the phenolic acids, ten were hydroxybenzoic acid derivatives (HBA), six hydroxycinnamic acid derivatives (HCA) and the one was present as ellagic acid. The most abundant flavonoids present in dried apricots were apigenin followed by quercetin and catechin. The results of the antioxidant activity as determined by DPPH radical scavenging, ferric reducing ability power (FRAP) and β-carotene bleaching assay revealed significant (p ≤ 0.05) decrease in EC₅₀ values and corresponding increase in antioxidant profile and activity due to irradiation, in addition to its effect in overcoming quarantine barriers. Irradiation decreased the EC₅₀ values by 19.1%, 13.6%, and 16.1% respectively with respect to control for DPPH, FRAP and β-carotene assays.     

Characterization,bioactive compounds and antioxidant potential of three Brazilian fruits

With the objective of stimulating the cultivation and consumption of native Brazilian fruits, the physicochemical composition and antioxidant potential of three native species, namely the araticu-do-mato (Rollinia sylvatica A. St.-Hil.), pindo palm (Butia capitata (Mart.) Becc.) and mandacaru-de-três-quinas (Cereus hildmannianus K. Schum.) were determined in this study. The pindo palm fruit stood out because of its elevated carotenoid content (39.6 μg/g) and greater antioxidant capacity (26 μM trolox/g of fresh sample) by the ABTS (2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic) method, although by the DPPH (2,2-diphenyl-1-picrylhydrazyl) method, the pindo palm fruit (3847.5 g of fresh sample/g DPPH) and mandacaru-de-três-quinas fruit (3249.8 g of fresh sample/g DPPH) were considered to have the same antioxidant potential with no difference between them. The mandacaru-de-três-quinas fruit also showed the highest total phenolic compound content (1337.3 mg/100 g). Although the araticu-do-mato presented the highest vitamin C content (0.32 mg/g), it did not differ statistically from the mandacaru-de-três-quinas fruit (0.25 mg/g); on the other hand, it was considered to be equal to the pindo palm fruit (0.23 mg/g). The araticu-do-mato also showed the best result for the TSS/TTA (total soluble solids/total titratable acidity) ratio (41.92), thus it was adequate for in natura consumption and for processing as well.     

Antioxidant Activities and Total Phenolic Content of Aqueous Extract of Pleurotus ostreatus (Cultivated Oyster Mushroom)

Pleurotus ostreatus better known as oyster mushroom is widely cultivated and consumed as food in Malaysia. The present study aims to assess the antioxidative potential and total phenolic content of P. ostreatus aqueous extract. The antioxidant activities were evaluated against DPPH and ABTS radical-scavenging activity, ferric-reducing antioxidant power (FRAP) and β-carotene-linoleate bleaching assay, and the Folin-Ciocalteu method for total phenolic content (TPC). The DPPH and ABTS radical-scavenging activity was found to be 63.20% and 87.29% respectively; antioxidant activity using FRAP at 1.45 mM FE/100g and β-carotenelinoleate bleaching assay was 83.51%, while the TPC was found to be 798.55 mg GAE/100g. These antioxidant activities were compared to synthetic antioxidant, BHA and ascorbic acid. Ascorbic acid showed highest scavenging effects on DPPH and ABTS radical, followed by P. ostreatus and BHA (at maximum safety limit). The ferric reducing power of P. ostreatus was significantly higher than BHA and ascorbic acid. The antioxidant activity as assessed in β-carotene-linoleate bleaching assay was found to be higher in BHA compared to P. ostreatus. The aqueous extract of P. ostreatus was found to respond differently in antioxidant assays. The antioxidative activity of the aqueous extract of P. ostreatus correlated with its total phenolic content. Generally, the antioxidant activities of P. ostreatus' aqueous extract are comparable to that of BHA and ascorbic acid to a certain extent.     

Phenolic compounds and antioxidant activity of Spanish commercial grape juices

Evaluation of the antioxidant activity of components of the diet is important in order to establish healthy consumption patterns. Data are reported here on the antioxidant activity (FRAP and ABTS), of 20 commercial grape juices and 10 typical Spanish wines and on their content of total phenolic compounds, anthocyanins, flavonoids and 10 individual phenolic compounds (flavanols, benzoic acids and cinnamic acids, measured by HPLC-UV). Red grape juices had a significantly higher (p < 0.05) concentration of total phenols (1177 vs. 744 mg gallic acid/L), flavonoids (98 vs. 63 mg catechin/L) and a higher antioxidant activity (9.16 vs. 2.83 meq Trolox/L) in comparison to white grape juices. In comparison to the white wines, white grape juices contained more total phenols (744 vs. 286 mg gallic acid/L) and flavonoids (63 vs. 29 mg catechin/L) and evidenced higher antioxidant activity (p < 0.05). In comparison to the red wines, a lower content of total phenols (286 vs. 2358 mg gallic acid/L) and flavonoids (228 vs. 29 mg catechin/L) and an absence of anthocyanins were observed in the white wines, which are therefore less antioxidant. Although a two-fold higher concentration of antioxidant compounds was found in red wines than in red grape juices, the latter may be a good option for all age groups because of the absence of alcohol and the potentially beneficial health effects of their phenolic composition and elevated antioxidant activity.     

Antioxidant activity and phenolic content in three lupin species

Total phenolic compounds, phenolic acids and flavonoid contents and antioxidant activities were measured in extracts from seeds of Lupinus albus, Lupinus luteus and Lupinus angustifolius cultivars. The total phenolic compound contents varied from 491.51 to 731.14 mg/100 g d.m. for cvs. Butan (L. albus) and Parys (L. luteus), respectively. Protocatechuic acid was the most abundant in seeds of yellow lupin (up to 73.60 mg/kg d.m.), whereas p-hydroxybenzoic acid in narrow-leaf lupin (about 43 mg/kg d.m.). The HPLC (high performance liquid chromatography) analysis revealed two dominant flavonoid compounds, which were identified by HPLC/MSⁿ to be apigenin-6,8-di-C-β-glucopyranoside and apigenin 7-O-β-apiofuranosyl-6,8-di-C-β-glucopyranoside. The highest content of the apigenin glycosides was recorded in yellow lupin while the lowest in white lupin. A positive correlation between the content of the analyzed compounds and the antioxidant activity measured by 2,2′-diphenyl-1-picrylhydrazyl (DPPH) method was established, but no such relation was found using the radical-trapping antioxidant parameter (TRAP) method. Modification of the peroxyl radical-trapping potential of lupin extracts by formation of phenoxyl radicals is suggested.     

Nutritional composition and antioxidant properties of Canarium odontophyllum Miq. (dabai) fruits

The present study sought to determine the nutritional composition and antioxidant properties of Canarium odontophyllum Miq. (dabai) fruits from different districts in Malaysia, namely Kanowit, Sarikei, Kapit and Song in Sarawak. Two varieties of the fruits were investigated. Lipid (21.16 ± 4.71 to 25.76 ± 3.03 g/100 g FW) was the major macronutrient in dabai fruits, while the predominant minerals were calcium, sodium and potassium. The fruit protein was rich in aspartic and glutamic acids which accounted for 45–49% of total amino acids. Purple dabai fruits from Kapit were found to contain the highest total phenolic levels, flavonoids and anthocyanin contents (p < 0.01) and to exhibit the most significant antioxidant activities (p < 0.01), using trolox equivalent antioxidant capacity (TEAC) and ferric reducing ability (FRAP) assays. Antioxidant activities were highly correlated with total phenolic and flavonoid contents of dabai fruits.