Antioxidant properties of Phyllanthus amarus extracts as affected by different drying methods

Recycling of osmotic solutions in microwave-osmotic dehydration: product quality and potential for creation of a novel product

BACKGROUND

Despite osmotic dehydration being a cost effective process for moisture removal, the cost implications of making, regenerating, and properly disposing of the spent osmotic solutions contributes greatly to the economic feasibility of the drying operation. The potential for recycling of osmotic solutions and their use for creation of a novel product was explored using microwave-osmotic dehydration under continuous flow spray (MWODS) conditions.

RESULTS

Identical runs were repeated 10 times to determine the progressive physical and compositional effects of the thermal treatment and leaching from the cranberry samples. The microbiological stability and constant drying performance indicated that MWODS would be well suited for employing recycled solutions. While the anthocyanin content of the solution never approached that of cranberry juice concentrate, it is demonstrated that the spent syrup can infuse these health positive components into another product (apple).

CONCLUSION

This study found that re-using osmotic solutions is a viable option to reduce cost in future MWODS applications, with no detriment to product quality and potential to use the spent solution for novel products. © 2015 Society of Chemical Industry.

Variation of the Phytochemical Constituents and Antioxidant Activities of Zingiber officinale var. rubrum Theilade Associated with Different Drying Methods and Polyphenol Oxidase Activity

The effects of different drying methods (freeze drying, vacuum oven drying, and shade drying) on the phytochemical constituents associated with the antioxidant activities of Z. officinale var. rubrum Theilade were evaluated to determine the optimal drying process for these rhizomes. Total flavonoid content (TFC), total phenolic content (TPC), and polyphenol oxidase (PPO) activity were measured using the spectrophotometric method. Individual phenolic acids and flavonoids, 6- and 8-gingerol and shogaol were identified by ultra-high performance liquid chromatography method. Ferric reducing antioxidant potential (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays were used for the evaluation of antioxidant activities. The highest reduction in moisture content was observed after freeze drying (82.97%), followed by vacuum oven drying (80.43%) and shade drying (72.65%). The highest TPC, TFC, and 6- and 8-shogaol contents were observed in samples dried by the vacuum oven drying method compared to other drying methods. The highest content of 6- and 8-gingerol was observed after freeze drying, followed by vacuum oven drying and shade drying methods. Fresh samples had the highest PPO activity and lowest content of flavonoid and phenolic acid compounds compared to dried samples. Rhizomes dried by the vacuum oven drying method represent the highest DPPH (52.9%) and FRAP activities (566.5 μM of Fe (II)/g DM), followed by freeze drying (48.3% and 527.1 μM of Fe (II)/g DM, respectively) and shade drying methods (37.64% and 471.8 μM of Fe (II)/g DM, respectively) with IC50 values of 27.2, 29.1, and 34.8 μg/mL, respectively. Negative and significant correlations were observed between PPO and antioxidant activity of rhizomes. Vacuum oven dried rhizomes can be utilized as an ingredient for the development of value-added food products as they contain high contents of phytochemicals with valuable antioxidant potential.

Comparison of different drying methods on Chinese ginger (Zingiber officinale Roscoe): Changes in volatiles, chemical profile, antioxidant properties, and microstructure

Nowadays, food industry is facing challenges in preserving better quality of fruit and vegetable products after processing. Recently, many attentions have been drawn to ginger rhizome processing due to its numerous health promoting properties. In our study, ginger rhizome slices were subjected to air-drying (AD), freeze drying (FD), infrared drying (IR), microwave drying (MD) and intermittent microwave & convective drying (IM&CD). Quality attributes of the dried samples were compared in terms of volatile compounds, 6, 8, 10-gingerols, 6-shogaol, antioxidant activities and microstructure. Results showed that AD and IR were good drying methods to preserve volatiles. FD, IR and IM&CD led to higher retention of gingerols, TPC, TFC and better antioxidant activities. However, FD and IR had relative high energy consumption and drying time. Therefore, considering about the quality retention and energy consumption, IM&CD would be very promising for thermo sensitive material.

Comparison of different drying methods on the physical properties, bioactive compounds and antioxidant activity of raspberry powders

BACKGROUND

Dehydration has been considered as one of the traditional but most effective techniques for perishable fruits. Raspberry powders obtained after dehydration can be added as ingredients into food formulations such as bakery and dairy products. In this study, raspberry powders obtained by hot air drying (HAD), infrared radiation drying (IRD), hot air and explosion puffing drying (HA-EPD), infrared radiation and microwave vacuum drying (IR-MVD) and freeze drying (FD) were compared on physical properties, bioactive compounds and antioxidant activity.

RESULTS

Drying techniques affected the physical properties, bioactive compounds and antioxidant activity of raspberry powders greatly. FD led to significantly higher (P < 0.05) values of water solubility (45.26%), soluble solid (63.46%), hygroscopicity (18.06%), color parameters and anthocyanin retention (60.70%) of raspberry powder compared with other drying methods. However, thermal drying techniques, especially combined drying methods, were superior to FD in final total polyphenol content, total flavonoid content and antioxidant activity. The combined drying methods, especially IR-MVD, showed the highest total polyphenol content (123.22 g GAE kg(-1) dw) and total flavonoid content (0.30 g CAE kg(-1) dw). Additionally, IR-MVD performed better in antioxidant activity retention.

CONCLUSION

Overall, combined drying methods, especially IR-MVD, were found to result in better quality of raspberry powders among the thermal drying techniques. IR-MVD could be recommended for use in the drying industry because of its advantages in time saving and nutrient retention.

Effects of drying methods on contents of bioactive compounds and antioxidant activities of black chokeberries (Aronia melanocarpa)

Optimal drying techniques for maintaining high levels of bioactive compounds and antioxidant activities in black chokeberries were investigated. Effects of 3 drying methods on total bioactive compound contents and in vitro antioxidant activities in 80% ethanol extracts were evaluated. Fresh black chokeberries were dried using sun-drying, freeze-drying, and oven-drying. Highest amounts of total polyphenols, flavonoids, and anthocyanins were detected in freeze-dried black chokeberry extracts after sun and oven-drying. 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS), and superoxide anion scavenging activities in black chokeberry extracts were also evaluated. Freeze-dried berries produced strongest antioxidant activities. Freeze-drying was the optimal drying method for maintaining high levels of bioactive compounds in 80% ethanol extracts of dried black chokeberries.

Effect of Initial Temperature Treatment on Phytochemicals and Antioxidant Activity of Azadirachta indica A. Juss

The present study was undertaken to evaluate the effect of initial temperature treatment on phytochemical and antioxidant potential of commercially important plant Azadirachta indica A. Juss. The leaves were differentially treated after harvest at temperatures 4, -20, and 110 °C and at room temperature, separately. It was found that a quick drying process at 110 °C followed by air-drying helped in maximum retention of bioactive compounds and antioxidant activity, which was significantly higher than other processing methods. Correlation analysis revealed that total phenolic content (TPC) and total flavonoid content (TFC) can be a measure to assess the antioxidant potential using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays. Nitric oxide scavenging assay (NOSA) was insignificantly related to DPPH and FRAP. Also, FRAP and DPPH can be a predictive assay for each other, but not with NOSA. Thus, a quick drying process at 110 °C using an oven can be a cost-effective venture, especially in developing countries, for retaining the nutritive value and antioxidant activity of A. indica.

Fourier transform infrared spectroscopy (FTIR) analysis, chlorophyll content and antioxidant properties of native and defatted foliage of green leafy vegetables

FTIR analysis for five selected green leafy vegetables (GLVs) viz., Hibiscus cannabinus L., (kenaf), H. sabdariffa L., (roselle), Basella alba L., (vine spinach), B. rubra L. (malabar spinach) and Rumex vesicarius L., (sorrel) confirmed the presence of free alcohol, intermolecular bonded alcohol, intramolecular bonded alcohol, alkane, aromatic compounds, imine or oxime or ketone or alkene, phenol and amine stretching. The chlorophyll content was higher in native leaves of B. alba (2.96 g/kg) than defatted samples (1.11 g/kg). Total phenolic content (TPC) in H. sabdariffa native methanol extractives is more (17.6 g/kg) than defatted leaves (9.67 g/kg). Native B. rubra methanol extractives exhibited highest total flavonoid content (TFC) (21.59 g/kg), while that of R. vesicarius was lowest (3.21 g/kg). In general, antioxidant activities showed a significant reduction in retention of antioxidants in both native and defatted GLVs samples of ethanol and methanol extractives. Methanol extractives showed significantly stronger antioxidant activity probably due to greater solubility of phenolics and destruction of cellular components.

Effect of different drying methods on chlorophyll, ascorbic acid and antioxidant compounds retention of leaves of Hibiscus sabdariffa L

BACKGROUND

Use of the indigenous, easily accessible leafy vegetable roselle (Hibiscus sabdariffa L.) for value addition is gaining impetus as its nutritive and nutraceutical compounds are exposed by investigations. Being a perishable, storage is challenging, hence different methods of drying have been an attractive alternative for its postharvest usage in foods without much compromising its quality and antioxidant potential.

RESULTS

Room- and freeze-dried samples were found to have best quality in terms of colour, total flavonoid content (18.53 ± 2.39 and 18.66 ± 1.06 g kg(-1) respectively), total phenolic content (17.76 ± 1.93 and 18.91 ± 0.48 g kg(-1)), chlorophyll content (1.59 ± 0.001 and 1.55 ± 0.001 g kg(-1)) and ascorbic acid content (11.11 ± 1.04 and 8.92 ± 0.94 g kg(-1)) compared with those subjected to infrared, crossflow, microwave, oven or sun drying. Samples treated by room and freeze drying retained maximum antioxidant potential as shown by the phosphomolybdate method and the 2,2-diphenyl-1-picrylhydrazyl free radical-scavenging activity and ferric-reducing antioxidant power assays. Cold water and hot water extracts showed significantly higher total phenolic content and total antioxidant activity owing to the greater solubility of phenolics and destruction of cellular components in polar solvents than in organic solvents.

CONCLUSION

The data obtained show the potential for retaining quality parameters of roselle leaf under suitable drying methods.

Relationship Between Metabolites Composition and Biological Activities of Phyllanthus niruri Extracts Prepared by Different Drying Methods and Solvents Extraction

The study investigated the changes in the metabolite, antioxidant and α-glucosidase inhibitory activities of Phyllanthus niruri after three drying treatments: air, freeze and oven dryings. Water extracts and extracts obtained using different solvent ratios of ethanol and methanol (50, 70, 80 and 100%) were compared. The relationships among the antioxidant, α-glucosidase inhibitory activity and metabolite levels of the extracts were evaluated using partial least-square analysis (PLS). The solvent selectivity was assessed based on the phytochemical constituents present in the extract and their concentrations quantitatively analyzed using high performance liquid chromatography. The freeze-dried P. niruri samples that were extracted with the mixture of ethanol or methanol with low ratio of water showed higher biological activity values compared with the other extracts. The PLS results for the ethanolic with different ratio and water extracts demonstrated that phenolic acids (chlorogenic acid and ellagic acid) and flavonoids were highly linked to strong α-glucosidase inhibitory and antioxidant activities.

Evaluation of Antioxidant Activity and Acute Toxicity of Clausena excavata Leaves Extract

Clausena excavata (Lour.), locally known as “Kemantu hitam,” is a common plant in Malaysian folklore medicine. This study evaluated the antioxidant properties of the solvent extracts of C. excavata leaves and determined the acute toxicity of methanolic extract C. excavata (MECE) leaves in Sprague-Dawley rats. Harvested leaves were dried and subjected to solvent extraction using petroleum ether, chloroform, ethyl acetate and methanol in succession. The antioxidant activity of each extract was determined using the ferric-reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picryl dihydrazyl (DPPH) radical scavenging activity. The total phenolic content (TPC) and total flavonoids content (TFC) were estimated by Folin-Ciocalteu and ethanolic aluminium chloride method, respectively. The chloroform extract was found to be highest in flavonoid content, while the methanolic extract showed the highest TPC and antioxidant activity. There was no mortality in rats treated with MECE leaves even at a high dose of 5000 mg/kg body weight. However, the MECE leaves produced mild to moderate pathological changes in the liver and kidneys, shown by mild degenerative changes and leucocyte infiltration. The extract did not affect the haematological parameters or relative weights of the liver or kidneys. Overall, the MECE leaves have potent antioxidant activity and are presumed safe to be used orally as health-promoting product at low to moderate doses.

Preparation of Au and Ag nanoparticles using Artemisia annua and their in vitro antibacterial and tyrosinase inhibitory activities

This work describes a plant-mediated approach to the preparation of metal nanoparticles using leaf extract of Artemisia annua (A. annua), an ethno-medicinal plant widely found in Asia, which was used as reducing and stabilizing agent. A. annua is used in traditional Chinese medicine to alleviate fever. Au and Ag nanoparticles were prepared using a one-step aqueous method at room temperature without any toxic chemicals. The formation of Au and Ag nanoparticles was monitored by UV-vis spectroscopy. Synthesized nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetric analysis (TGA). TEM analysis of Au nanoparticles showed that they had triangular and spherical shapes with sizes ranging from 15 to 40 nm. The silver nanoparticles were predominantly spherical and uniformly sized (30-50 nm). The Au and Ag nanoparticles produced showed significant tyrosinase inhibitory and antibacterial effects. These results suggest that the synthesized nanoparticles provide good alternatives in varied medical and industrial applications.

Effects of Different Drying Methods and Storage Time on Free Radical Scavenging Activity and Total Phenolic Content of Cosmos Caudatus

The present study was conducted to determine the effect of air (AD), oven (OD) and freeze drying (FD) on the free radical scavenging activity and total phenolic content (TPC) of Cosmos caudatus and the effect of storage time by the comparison with a fresh sample (FS). Among the three drying methods that were used, AD resulted in the highest free radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) (IC50 = 0.0223 mg/mL) and total phenolic content (27.4 g GAE/100 g), whereas OD produced the lowest scavenging activity and TPC value. After three months of storage, the dried samples showed a high and consistent free radical scavenging activity when compared to stored fresh material. The drying methods could preserve the quality of C. caudatus during storage and the stability of its bioactive components can be maintained.

Condensed tannins from Ficus virens as tyrosinase inhibitors: structure, inhibitory activity and molecular mechanism

Condensed tannins from Ficus virens leaves, fruit, and stem bark were isolated and their structures characterized by 13C nuclear magnetic resonance spectrometry, high performance liquid chromatography electrospray ionization mass spectrometry, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The results showed that the leaves, fruit, and stem bark condensed tannins were complex mixtures of homo- and heteropolymers of B-type procyanidins and prodelphinidins with degrees of polymerization up to hexamer, dodecamer, and pentadecamer, respectively. Antityrosinase activities of the condensed tannins were studied. The results indicated that the condensed tannins were potent tyrosinase inhibitors. The concentrations for the leaves, fruit, and stem bark condensed tannins leading to 50% enzyme activity were determined to be 131.67, 99.89, and 106.22 μg/ml on monophenolase activity, and 128.42, 43.07, and 74.27 μg/ml on diphenolase activity. The inhibition mechanism, type, and constants of the condensed tannins on the diphenolase activity were further investigated. The results indicated that the condensed tannins were reversible and mixed type inhibitors. Fluorescence quenching, copper interacting, and molecular docking techniques were utilized to unravel the molecular mechanisms of the inhibition. The results showed that the hydroxyl group on the B ring of the condensed tannins could chelate the dicopper irons of the enzyme. Moreover, the condensed tannins could reduce the enzyme product o-quinones into colourless compounds. These results would contribute to the development and design of antityrosinase agents.

Structure characterization of proanthocyanidins from Caryota ochlandra Hance and their bioactivities

Proanthocyanidins (PAs) from Caryota ochlandra fruit pericarp and fruit flesh were characterized by (13)C nuclear magnetic resonance, high performance liquid chromatography-electrospray ionization mass spectrometry, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry techniques. The fruit pericarp and flesh PAs were complex mixtures of homo- and heteropolymers of B-type procyanidins and prodelphinidins both with degrees of polymerization up to dodecamer. Their antioxidant and antityrosinase activities were investigated. The fruit pericarp PAs exhibited potent antioxidant activity with IC50 values of 142.86 ± 1.53 and 80.51 ± 0.4 μg/ml for DPPH and ABTS free-radical scavenging assays; with FRAP value of 373.09 ± 5.02 mg ascorbic acid equivalent/g dry weight. Furthermore, the fruit pericarp PAs had antityrosinase activity while the fruit flesh PAs could be oxidized by tyrosinase. The structure and antioxidant activities of the C. ochlandra fruit PAs together with their effects on tyrosinase activity would lay scientific foundation for their utilization in food and nutrition industry.

Comparison of flavonoids, phenolic acids, and antioxidant activity of explosion-puffed and sun-dried jujubes (Ziziphus jujuba Mill.)

The goal of the present study was to investigate the effect of explosion puffing and sun-drying on individual phenolic acids in four forms (free, esters, glycosides, and insoluble-bound), flavonoids, total phenolic content (TPC), and their antioxidant activity on jujube samples. Phenolic compounds were identified and quantified using high-performance liquid chromatography. Antioxidant capacity of jujube samples was evaluated by 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity and total reducing power. The results showed that all samples significantly differed in their phenolic contents, phenolic acid and flavonoid composition, and antioxidant activities. The explosion-puffed jujubes had the highest total gallic, p-hydroxybenzoic, vanillic, p-coumaric, ferulic acids, and rutin contents. Also, explosion-puffed jujubes contained a higher level of total phenolics and antioxidant activity than their counterparts. Among phenolic acid fractions in four forms, each form of phenolic acids in explosion-puffed jujubes had the most abundant content, followed by fresh and sun-dried jujubes. The glycosided and insoluble-bound phenolic acid fractions for each sample represented the highest TPC and the strongest antioxidant activity. The results indicated explosion puffing was a good choice for jujube processing.

Antioxidant, antityrosinase, anticholinesterase, and nitric oxide inhibition activities of three malaysian macaranga species

The methanol extracts of three Macaranga species (M. denticulata, M. pruinosa, and M. gigantea) were screened to evaluate their total phenolic contents and activities as cholinesterase inhibitors, nitric oxide (NO) production inhibitors, tyrosinase inhibitors, and antioxidants. The bark of M. denticulata showed the highest total phenolic content (2682 mg gallic acid equivalent (GAE)/100 g) and free radical scavenging activity (IC₅₀ = 0.063 mg/mL). All of the samples inhibited linoleic acid peroxidation by greater than 80%, with the leaves of M. gigantea exhibiting the highest inhibition of 92.21%. Most of the samples exhibited significant antioxidant potential. The bark of M. denticulata and the leaves of both M. pruinosa and M. gigantea exhibited greater than 50% tyrosinase inhibition, with the bark of M. denticulata having the highest percentage of inhibition (68.7%). The bark and leaves of M. denticulata exhibited greater than 50% inhibition (73.82% and 54.50%, resp.) of the acetylcholinesterase enzyme (AChE), while none of the samples showed any significant inhibition of butyrylcholinesterase (BChE). Only the bark of M. denticulata and M. gigantea displayed greater than 50% inhibition of nitric oxide production in cells (81.79% and 56.51%, resp.). These bioactivities indicate that some Macaranga spp. have therapeutic potential in medicinal research.

Antioxidative and anticholinesterase activity of Cyphomandra betacea fruit

Cyphomandra betacea is one of the underutilized fruits which can be found in tropical and subtropical countries. This study was conducted to determine the antioxidant activity and phytochemical contents in different parts (i.e., flesh and peel) of the fruits. Antioxidants were analyzed using DPPH and ABTS free radical scavenging assays as well as FRAP assay. Anticholinesterase activity was determined using enzymatic assay using acetyl cholinesterase enzyme. For 80% methanol extract, the peel of the fruit displayed higher antioxidant activity in both FRAP and ABTS free radical scavenging assays while the flesh displayed higher antioxidant activity in the DPPH assay. Total phenolic and total flavonoid content were higher in the peel with the values of 4.89 ± 0.04 mg gallic acid equivalent (GAE)/g and 3.36 ± 0.01 mg rutin equivalent (RU)/g, respectively. Total anthocyanin and carotenoid content were higher in the flesh of the fruit with the values of 4.15 ± 0.04 mg/100 g and 25.13 ± 0.35 mg/100 g. The anticholinesterase was also higher in the peel of C. betacea. The same trends of phytochemicals, antioxidant, and anticholinesterase were also observed in the distilled water extracts. These findings suggested that C. betacea has a potential as natural antioxidant-rich nutraceutical products.

Antioxidant Activity and Phenolic Content of Streblus asper Leaves from Various Drying Methods

Aqueous and ethanol extracts of oven and freeze-dried Streblus asper leaves were investigated using DPPH assay. The presence of phenolic compounds and flavonoids in the extracts, which were detected by Folin and colorimetric assays, respectively, may be responsible for the antioxidant activities of S. asper. The different drying treatments resulted in significant differences (p < 0.05) in the antioxidant properties as well as the phenolic and flavonoid contents of the S. asper extracts. Freeze-dried S. asper leaf extracts exhibited high DPPH radical scavenging activity ranging from 69.48% ± 0.03% to 89.25% ± 0.01% at concentrations ranging from 0 to 1 mg/mL, significantly higher compared with the oven-dried extracts which were in the range of 68.56% ± 0.01% to 86.68% ± 0.01%. Generally, the 70% ethanol extract of the freeze-dried samples exhibited higher phenolic and flavonoid content than the aqueous extract, with values of 302.85 ± 0.03 mg GAE/g and 22.70 ± 0.02 mg QE/g compared with 226.8 ± 0.03 mg GAE/g and 15.38 ± 0.05 mg QE/g, respectively. This study showed that S. asper leaf extracts contain a number of health promoting bioactive compounds, such as phenolic compounds, and are potential sources of natural antioxidants.

Cosmos caudatus as a potential source of polyphenolic compounds: optimisation of oven drying conditions and characterisation of its functional properties

The aim of the study was to analyze the influence of oven thermal processing of Cosmos caudatus on the total polyphenolic content (TPC) and antioxidant capacity (DPPH) of two different solvent extracts (80% methanol, and 80% ethanol). Sonication was used to extract bioactive compounds from this herb. The results showed that the optimised conditions for the oven drying method for 80% methanol and 80% ethanol were 44.5 °C for 4 h with an IC₅₀ of 0.045 mg/mL and 43.12 °C for 4.05 h with an IC₅₀ of 0.055 mg/mL, respectively. The predicted values for TPC under the optimised conditions for 80% methanol and 80% ethanol were 16.5 and15.8 mg GAE/100 g DW, respectively. The results obtained from this study demonstrate that Cosmos caudatus can be used as a potential source of antioxidants for food and medicinal applications.

Optimal binary solvent extraction system for phenolic antioxidants from mengkudu (Morinda citrifolia) fruit

Antioxidants have been widely used in the food industry to enhance product quality by preventing oxidation of susceptible substances. This work was carried out to maximise the recovery of total phenolic content (TPC), total flavonoid content (TFC), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical-scavenging capacity and 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging capacity from Morinda citrifolia fruit via modification of the ethanol concentration, extraction time and extraction temperature at minimal processing cost. The optimised conditions yielded values of 881.57 ± 17.74 mg GAE/100 g DW for TPC, 552.53 ± 34.16 mg CE/100 g DW for TFC, 799.20 ± 2.97 µmol TEAC/100 g DW for ABTS and 2,317.01 ± 18.13 µmol TEAC/100 g DW for DPPH were 75% ethanol, 40 min of time and 57 °C. The four responses did not differ significantly (p > 0.05) from predicted values, indicating that models obtained are suitable to the optimisation of extraction conditions for phenolics from M. citrifolia. The relative amounts of flavonoids were 0.784 ± 0.01 mg quercetin/g of extract and 1.021 ± 0.04 mg rutin/g of extract. On the basis of the results obtained, M. citrifolia extract can be used as a valuable bioactive source of natural antioxidants.

Sensory characteristics of antioxidant extracts from Uruguayan native plants: influence of deodorization by steam distillation

Polyphenolic-rich antioxidant extracts from native plants have potential applications as ingredients in functional foods; however, their intense characteristic flavour is a major limitation to their application. In this context, the aim of the present work was to evaluate the influence of steam distillation on the sensory and physicochemical characteristics of extracts of five native Uruguayan plants (Acca sellowiana, Achyrocline satureioides, Aloysia gratisima, Baccharis trimera and Mikania guaco). Aqueous extracts from the five native plants were obtained. Steam distillation was used to produce two types of deodorized extracts: extracts from deodorized leaves and extracts deodorized after the extraction. The extracts were characterized in terms of their total polyphenolic content and antioxidant activity (using 2,2-diphenyl-1-picryl-hydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid methods). A trained assessor panel evaluated characteristic odour, characteristic flavour, bitterness and astringency of the extracts. The total polyphenolic content of the extracts ranged from 112.4 to 974.4 mg/100 mL, whereas their antioxidant capacity ranged from 9.6 to 1008.7 mg vitamin C equivalents/100 mL, depending on the type of extract and the method being considered. Steam distillation was effective in reducing the characteristic odour and flavour of the extracts, without causing large changes in their polyphenolic content and antioxidant activity. In general, in terms of sensory characteristics, steam distillation performed on the extracts gave better results than when performed on the leaves; whereas the opposite trend was found for polyphenolic content and antioxidant activity. Results suggested that steam distillation could be a promising low-cost procedure for the production of antioxidant extracts for food products.

Evaluation of antioxidant activity and characterization of phenolic constituents of Phyllanthus amarus root

The antioxidant property of the 70% aqueous ethanol extract of Phyllanthus amarus roots and its ether-soluble, ethyl acetate-soluble, and aqueous fractions were investigated by various in vitro assays. The root extracts showed higher DPPH, hydroxyl, superoxide, and nitric oxide radical scavenging and reducing power activity. Among all the samples, the ethyl acetate-soluble fraction demonstrated highest radical scavenging activity and total phenolics content. Twenty-eight different phenolic compounds were identified by LCMS/MS analysis of the ethyl acetate-soluble fraction. The majority of the compounds were found to exist as their glycosides, and many of these were gallic acid derivatives. Free epicatechin and gallic acid were also identified in the ethyl acetate-soluble fraction. The present investigation suggested that P. amarus root is a potent antioxidant and can be used for the prevention of diseases related to oxidative stress.

Fucoxanthin content and antioxidant properties of Undaria pinnatifida

This study investigated the fucoxanthin content of New Zealand (NZ) Undaria pinnatifida harvested from two locations in the Marlborough Sounds, New Zealand across its growing season. Fucoxanthin content and antioxidant properties of processed New Zealand U. pinnatifida and commercial wakame from Japan and Korea were further compared. Results showed that U. pinnatifida harvested from Port Underwood had higher fucoxanthin content in the blade compared to Pelorus Sound. The sporophyll also contained a significant amount of fucoxanthin throughout the harvest season, although lower than in the blade. Two antioxidant measurement methods, DPPH and CUPRAC, were utilised to measure antioxidant activities. Processed NZ U. pinnatifida had a lower fucoxanthin content and antioxidant activity than freeze-dried Undaria. Fucoxanthin content and antioxidant activities of NZ processed U. pinnatifida were not significantly different from other commercial samples from Japan and Korea. In conclusion, U. pinnatifida in New Zealand has a great potential to be a food and nutraceutical resource.

Effect of drying of jujubes ( Ziziphus jujuba Mill.) on the contents of sugars, organic acids, α-tocopherol, β-carotene, and phenolic compounds

This study investigated the changes in sugars, organic acids, α-tocopherol, β-carotene, phenolic profiles, total phenolic content (TPC), and antioxidant capacity of jujube fruits after four drying treatments (sun-, oven-, microwave- and freeze-drying). Sugar, organic acid, phenolic compounds, α-tocopherol, and β-carotene were qualitatived and quantitatived by high-performance liquid chromatography. The TPC and antioxidant activity of jujube samples were evaluated using the Folin-Ciocalteau method and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity, respectively. Freeze-drying resulted in jujubes with higher antioxidant activity and was also a good choice for the preparation of β-carotene from jujubes for the food industry. Microwave-dried jujubes had a higher content of protocatechuic acid, catechin, and epicatechin and maintained the same antioxidant capacity with the freeze-dried jujubes. The combination of microwave- and freeze-drying may be an efficient alternative with shorter processing time and, consequently, less impact on the nutritional value of the jujube.

Assessment of in vitro antioxidant, antibacterial and immune activation potentials of aqueous and ethanol extracts of Phyllanthus niruri

BACKGROUND

Recently much attention has been paid to biologically active plants because of their low production cost and fewer adverse effects compared with chemical drugs. In the present investigation the bioactivity of Phyllanthus niruri ethanol and aqueous extracts was evaluated in vitro.

RESULTS

The ethanol extract of P. niruri showed a high level of flavonoid content (123.9 ± 0.002 mg g⁻¹), while the aqueous extract showed the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH; IC₅₀ 6.85 ± 1.80 µmol L⁻¹) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS; 46.44 ± 0.53 µmol L⁻¹) free radical scavenging activities with high phenol content (376 ± 0.02 mg g⁻¹) and elevated levels of ferric reducing antioxidant power (FRAP; 23 883 ± 0.019 mmol g⁻¹) with excellent antibacterial activity against Staphylococcus aureus (20 mm inhibition zone) and Streptococcus agalactiae (12 mm inhibition zone), respectively, in addition to the best immune activation potential of human peripheral blood mononuclear cells (450.5%).

CONCLUSIONS

It is clear from our results that both extracts of P. niruri has excellent bioactivity roles via elevated levels of antibacterial, antioxidant and percentage of peripheral blood mononuclear cell proliferation, which could lead to the development of medications for clinical use.

Acute toxicity evaluation, antibacterial, antioxidant and immunomodulatory effects of Melastoma malabathricum

Melastoma malabathricum (MM) is a well-known plant in Malaysian traditional medicine, locally known as senduduk. Its ethanol and aqueous extracts have been used in the present investigation to study the immunomodulatory role on human peripheral blood mononuclear cell (PBMC), and the DPPH, ABTS and FRAP free radical scavenging activities were also measured. Total flavonoids and total phenolic contents were assayed and the antibacterial effect was tested against four species of bacteria; two Gram-positive (Staphylococcus aureus and Streptococcus agalactiae) and two Gram-negative (Escherichia coli and Klebsilla pneumonia). The tests were carried out using the disc diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods. Moreover, the acute toxicity was evaluated in vivo on the ethanol extract of MM to establish its safety when administered orally. In our results, both extracts of MM showed abilities to scavenge DPPH and ABTS free radicals, IC₅₀ values: (11.599 ± 0.84, 10.573 ± 0.58 µmol/L) and (62.657 ± 0.78, 63.939 ± 0.48 µmol/L) for ethanol and aqueous extracts respectively. Indeed the ethanol extract evidenced high phenolic content (384.33 ± 0.005 mg/g), flavonoids contents (85.8 ± 0.009 mg/g) and ferric reducing antioxidant power (33,590 ± 0.038 mmol/g), with high activity against S. aureus and S. agalactiae (11 ± 0.3 and 12 ± 0.6 mm inhibition zones). Likewise, the percentage of peripheral blood mononuclear cells (PBMC) viability was increased in response to MM, IC₅₀ values (1.781 ± 1.2 and 6.545 ± 0.93 µg/mL) for ethanol and aqueous extracts, respectively. In addition, our results showed that the MM extract is safe even at a high dose of 5,000 mg/kg and has no oral toxicity. These findings suggest the excellent medicinal bioactivity of MM and explain the popularity of this plant in the folk medicine as a remedy for different illnesses.

Phyllanthus amarus: ethnomedicinal uses, phytochemistry and pharmacology: a review

ETHNOPHARMACOLOGICAL RELEVANCE

Phyllanthus amarus Schum. & Thonn. belongs to the family Euphorbiaceae is a small herb well known for its medicinal properties and widely used worldwide. P. amarus is an important plant of Indian Ayurvedic system of medicine which is used in the problems of stomach, genitourinary system, liver, kidney and spleen. It is bitter, astringent, stomachic, diuretic, febrifuge and antiseptic. The whole plant is used in gonorrhea, menorrhagia and other genital affections. It is useful in gastropathy, diarrhoea, dysentery, intermittent fevers, ophthalmopathy, scabies, ulcers and wounds.

MATERIALS AND METHODS

The present review covers a literature across from 1980 to 2011. Some information collected from traditional Ayurvedic texts and published literature on ethanomedicinal uses of Phyllanthus amarus in different countries worldwide.

RESULTS

Phytochemical studies have shown the presence of many valuable compounds such as lignans, flavonoids, hydrolysable tannins (ellagitannins), polyphenols, triterpenes, sterols and alkaloids. The extracts and the compounds isolated from P. amarus show a wide spectrum of pharmacological activities including antiviral, antibacterial, antiplasmodial, anti-inflammatory, antimalarial, antimicrobial, anticancer, antidiabetic, hypolipidemic, antioxidant, hepatoprotective nephroprotective and diurectic properties.

CONCLUSION

The present review summarizes information concerning the morphology, ecology, ethnopharmacology, phytochemistry, biological activities, clinical applications and toxicological reports of P. amarus. This review aims at gathering the research work undertaken till date on this plant in order to provide sufficient baseline information for future works and commercial exploitation.

Determination of polyphenols and free radical scavenging activity of Tephrosia purpurea linn leaves (Leguminosae)

BACKGROUND

Leaves of Tephrosia purpurea Linn. (sarpankh), belonging to the family Leguminaceae, are used for the treatment of jaundice and are also claimed to be effective in many other diseases. This research work was undertaken to investigate the in vitro antioxidant activity of aqueous and ethanolic extracts of the leaves.

METHOD

The therapeutic effects of tannins and flavonoids can be largely attributed to their antioxidant properties. So, the quantitative determinations were undertaken. All the methods are based on UV-spectrophotometric determination.

RESULT

The total phenolic content of aqueous and ethanolic extracts showed the content values of 9.44 ± 0.22% w/w and 18.44 ± 0.13% w/w, respectively, and total flavonoid estimation of aqueous and ethanolic extracts showed the content values of 0.91 ± 0.08% w/w and 1.56 ± 0.12%w/w, respectively, for quercetin and 1.85 ± 0.08% w/w and 2.54 ± 0.12% w/w, respectively, for rutin. Further investigations were carried out for in vitro antioxidant activity and radical scavenging activity by calculating its percentage inhibition by means of IC(50)values, all the extracts' concentrations were adjusted to fall under the linearity range and here many reference standards like tannic acid, gallic acid, quercetin, ascorbic acid were taken for the method suitability.

CONCLUSION

The results revealed that leaves of this plant have antioxidant potential. The results also show the ethanolic extract to be more potent than the aqueous decoction which is claimed traditionally. In conclusion, T. purpurea Linn. (Leguminosae) leaves possess the antioxidant substance which may be responsible for the treatment of jaundice and other oxidative stress-related diseases.