Copolymers of acrylamide with the sodium salt of 2-acrylamido-2-methylpropane sulfonic acid-known as sulfonated polyacrylamide polymers-had been shown to produce very promising results in the enhancement of oil recovery, particularly in polymer flooding. The aim of this work is to develop an empirical model through the use of a design of experiments (DOE) approach for bulk viscosity of these copolymers as a function of polymer characteristics (i.e., sulfonation degree and molecular weight), oil reservoir conditions (i.e., temperature, formation brine salinity and hardness) and field operational variables (i.e., polymer concentration, shear rate and aging time). The data required for the non-linear regression analysis were generated from 120 planned experimental runs, which had used the Box-Behnken construct from the typical Response Surface Methodology (RSM) design. The data were collected during rheological experiments and the model that was constructed had been proven to be acceptable with the Adjusted R-Squared value of 0.9624. Apart from showing the polymer concentration as being the most important factor in the determination of polymer solution viscosity, the evaluation of the model terms as well as the Sobol sensitivity analysis had also shown a considerable interaction between the process parameters. As such, the proposed viscosity model can be suitably applied to the optimization of the polymer solution properties for the polymer flooding process and the prediction of the rheological data required for polymer flood simulators.
The effects of ethanol concentration (0-100%, v/v), extraction time (60-300 min) and extraction temperature (25-65°C) on the extraction of phenolic antioxidants from Andrographis paniculata was evaluated using single-factor experiments. The following complementary assays were used to screen the antioxidant properties of the crude extracts: total phenolic content (TPC), total flavonoid content (TFC), condensed tannin content (CTC), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical-scavenging capacity and 2,2’-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging capacity. The extraction conditions chosen had significant effects (p < 0.05) on the extraction of phenolic compounds and antioxidant capacity. The optimal conditions were 60% ethanol for 60 min at 65oC for phenolic compounds and at 25oC for antioxidant capacity. Strong negative significant (p < 0.05) correlations were observed between the phenolic compounds (TPC, TFC and CTC) and antioxidant capacity comprising ABTS (-0.924, -0.909, -0.887, respectively) and DPPH radical-scavenging capacities (-0.992, -0.938, -0.928, respectively) were determined under the influence of extraction temperature.
Pleurotus porrigens is a well-known edible, wild mushroom enjoyed as a delicacy by aborigines in Sabah and as source of income for the aborigines who collect and sell them at tamu (local market). This study aimed to evaluate the antioxidant activity in vitro and identify potent antioxidative components of aqueous extracts of P. porrigens. The antioxidant activities were evaluated using DPPH radical scavenging ability, ABTS radical cation inhibition activity, ferric reducing/antioxidant power, and total phenolic content. Activity-guided purifications based on DPPH radical scavenging ability resulted in 5 subfractions (SF). The highest DPPH radical scavenging ability was found in SF-III and SF-IV, but all were lower than butylated hydroxyanisole (BHA) and α-tocopherol. Analysis with high-performance liquid chromatography-diode array detectors found presence of ascorbic acid and (+)-catechin in SFs of P. porrigens, as well as some unidentified components that may have contributed to the radical scavenging ability. In conclusion, aqueous extract of P. porrigens possesses promising antioxidant activities, although they are lesser in their partially purified SFs. Nonetheless, P. porrigens could be promoted as an antioxidant-rich food as part of a normal diet that provides antioxidative benefit.
A simple and rapid gas chromatography (GC) method with flame ionization detector was developed for detection of isopropyl para-toluenesulphonate (IPTS) in palm-based isopropyl palmitate (IPP) and isopropyl myristate (IPM). The method involved spiking the IPP/IPM samples with IPTS and directly injecting the spiked samples into GC without undergoing clean-up steps. The calibration curves for IPTS showed good linearity with coefficient correlation of 0.9999 for six-point calibration from 0.5 to 50 μg mL(-1) and 0.9996 for six-point calibration from 0.5 to 200 μg mL(-1) . IPTS recoveries from IPP were 98.6-103.5% with relative standard deviation (RSD) of 0.40-2.80%, whereas recoveries from IPM were 97.0-107.2% with RSD of 0.42-4.21%. The identity of IPTS recovered from the isopropyl esters was confirmed by a GC-mass spectrometer detector. The method was successfully applied to the analyses of IPTS in commercial samples. It was found that there were IPTS in the range of 34.8-1303.0 μg g(-1) in the palm-based esters for some of the samples analysed.
Antioxidant properties of crude extract, partition extract, and fermented medium from Dendrobium sabin (DS) flower were investigated. The oven-dried DS flower was extracted using 100% methanol (w/v), 100% ethanol (w/v), and 100% water (w/v). The 100% methanolic crude extract showed the highest total phenolic content (40.33 ± mg GAE/g extract) and the best antioxidant properties as shown by DPPH, ABTS, and FRAP assays. A correlation relationship between antioxidant activity and total phenolic content showed that phenolic compounds were the dominant antioxidant components in this flower extract. The microbial fermentation on DS flower medium showed a potential in increasing the phenolic content and DPPH scavenging activity. The TPC of final fermented medium showed approximately 18% increment, while the DPPH of fermented medium increased significantly to approximately 80% at the end of the fermentation. Dendrobium sabin (DS) flower showed very good potential properties of antioxidant in crude extract and partition extract as well as better antioxidant activity in the flower fermented medium.
The antioxidant activity of fresh and dried plant extracts of Paederia foetida and Syzygium aqueum were studied using beta-carotene bleaching and the 2,2'-azinobis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) radical cation assay. The percentage of antioxidant activity for all extract samples using both assays was between 58 and 80%. The fresh samples of both plants had higher antioxidant activity than the dried samples. The results of the beta-carotene bleaching assay were correlated (R(2) = 0.9849) with those of the ABTS assay.
Papaya (Carica papaya L. cv. Hongkong) is an economically important fruit crop grown in Malaysia. During its ripening stages, (C. papaya L.) exhibits different physicochemical properties, antioxidant capacities, and sensory quality results. The objective of this study was to elucidate in detail the antioxidant capacity of C. papaya as determined by total phenol content (TPC), total flavonoid content (TFC), ferric reducing antioxidant power (FRAP),2,2-diphenyl-1-picrylhydrazyl (DPPH) and scavenging systemand (ABTS). The study also aimed to study physicochemical changes of papaya fruits based on measured pH, titratable acidity (TA), total soluble solids (TSS), moisture and fruit color at five different stages of ripening. The fruits were harvested at five different, stages RS1, RS2, RS3, RS4, and RS5 corresponding to 12, 14, 16, 18, and 20 weeks after anthesis, respectively. Significant differences were found at different stages of ripening. The pH of the fruit decreased significantly (P < 0.05), whereas TA, moisture, and TSS increased significantly (P < 0.05) during the ripening process. The redness (a*) and yellowness (b*) values of fruit color both increased significantly (P < 0.05), whereas
lightness (L*) varied. The total phenol content TPC, TFC, FRAP, DPPH and ABTS values increased significantly (P < 0.05) with the ripening process. Sensory evaluation based on the color, sweetness, sourness, flavor, and overall acceptance for the last three maturity stages was also performed. RS5 had a better score than RS3 or RS4. The results showed the important role of the ripening stage in increasing the antioxidant content of papaya fruits.
In this study, the effect of different solvent including ethanol, n-hexane and ethyl acetate on antioxidant
activity and total phenolic content (TPC) of winter melon (Benincasa hispida) seeds extract was investigated using conventional Soxhlet extraction (CSE). DPPH and ABTS scavenging activity and TPC results indicated that the seed extracts obtained using ethanol possessed the highest antioxidant activity and followed by ethyl acetate and n-hexane. By considering obtained results, it was clear that there was a high positive correlation between TPC and antioxidant activity. Linoleic acid forms a significant percentage of unsaturated fatty acids of the seed extract (60.6%). It is well known that essential fatty acids including linoleic acid and linolenic acid which are detected in extracts play important roles in preventing many disease and abnormal differentiation problems. B. hispida seeds are potential source of natural antioxidant compounds to replace synthetic antioxidants.
Plants that contain high amounts of polyphenolic compounds are potential candidates for natural antioxidant sources. Studies are on going in the search for new sources of antioxidants. Not much data are available on the antioxidant capacity of tropical herbs. With this in mind, 19 commonly consumed Malaysian herbs were analyzed for their polyphenolic content and antioxidant activities. A majority of these plants have never been studied before with regards to their polyphenolic content and antioxidant activities. The shoots of Anacardium occidentale, the shoots and fruits of Barringtonia racemosa, Pithecellobium jiringa and Parkia speciosa had high polyphenolic contents (> 150 microg gallic acid equivalents/mg dried plant) and antioxidant activities when measured using the ferric reducing antioxidant power (FRAP) (>1.2 mM) and Trolox equivalent antioxidant capacity (TEAC) assays (>2.4 mM). A strong correlation was observed between the two antioxidant assays (FRAP vs TEAC) implying that the plants could both scavenge free radicals and reduce oxidants. There was also a strong correlation between the antioxidant activities and polyphenolic content suggesting the observed antioxidant activities were contributed mainly by the polyphenolics in the plants.
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.
The genus Silene is renowned in Turkey for its traditional use as food and medicine. Currently, there are 138 species of Silene in Turkey, amongst which have been several studies for possible pharmacological potential and application in food industry. However, there is currently a paucity of data on Silene salsuginea Hub.-Mor. This study endeavours to access its antioxidant, enzyme inhibitory, and anti-inflammatory properties. Besides, reversed-phase high-performance liquid chromatography-diode array detector (RP-HPLC-DAD) was used to detect phenolic compounds, and molecular docking was performed to provide new insights for tested enzymes and phenolics. High amounts of apigenin (534 μg/g extract), ferulic acid (452 μg/g extract), p-coumaric acid (408 μg/g extract), and quercetin (336 μg/g extract) were detected in the methanol extract while rutin (506 μg/g extract) was most abundant in the aqueous extract. As for their biological properties, the methanol extract exhibited the best antioxidant effect in the DPPH and CUPRAC assays, and also the highest inhibition against tyrosinase. The aqueous extract was the least active enzyme inhibitor but showed the highest antioxidant efficacy in the ABTS, FRAP, and metal chelating assays. At a concentration of 15.6 μg/mL, the methanol extract resulted in a moderate decrease (25.1%) of NO production in lipopolysaccharide-stimulated cells. Among the phenolic compounds, epicatechin, (+)-catechin, and kaempferol showed the highest binding affinity towards the studied enzymes in silico. It can be concluded that extracts of S. salsuginea are a potential source of functional food ingredients but need further analytical experiments to explore its complexity of chemical compounds and pharmacological properties as well as using in vivo toxicity models to establish its maximum tolerated dose.
Coumarin sulfonates 4-43 were synthesized by reacting 3-hydroxy coumarin 1, 4-hydroxy coumarin 2and6-hydroxy coumarin 3 with different substituted sulfonyl chlorides and subjected to evaluate for their in vitro immunomodulatory potential. The compounds were investigated for their effect on oxidative burst activity of zymosan stimulated whole blood phagocytes using a luminol enhanced chemiluminescence technique. Ibuprofen was used as standard drug (IC50=54.2±9.2μM). Eleven compounds 6 (IC50=46.60±14.6μM), 8 (IC50=11.50±6.5μM), 15 (IC50=21.40±12.2μM), 19 (IC50=5.75±0.86μM), 22 (IC50=10.27±1.06μM), 23 (IC50=33.09±5.61μM), 24 (IC50=4.93±0.58μM), 25 (IC50=21.96±14.74μM), 29 (IC50=12.47±9.2μM), 35 (IC50=20.20±13.4μM) and 37 (IC50=14.47±5.02μM) out of forty demonstrated their potential suppressive effect on production of reactive oxygen species (ROS) as compared to ibuprofen. All the synthetic derivatives 4-43 were characterized by different available spectroscopic techniques such as 1H NMR, 13C NMR, EIMS and HRMS. CHN analysis was also performed.
Garcinia hombroniana (seashore mangosteen) in Malaysia is used to treat itching and as a protective medicine after child birth. This study was aimed to investigate the bioactive chemical constituents of the bark of G. hombroniana. Ethyl acetate and dichloromethane extracts of G. hombroniana yielded two new (1, 9) and thirteen known compounds which were characterized by the spectral techniques of NMR, UV, IR and EI/ESI-MS, and identified as; 2,3',4,5'-tetrahydroxy-6-methoxybenzophenone(1), 2,3',4,4'-tetrahydroxy-6-methoxybenzophenone (2), 2,3',4,6-tetrahydroxybenzophenone (3), 1,3,6,7-tetrahydroxyxanthone (4), 3,3',4',5,7-pentahydroxyflavone (5),3,3',5,5',7-pentahydroxyflavanone (6), 3,3',4',5,5',7-hexahydroxyflavone (7), 4',5,7-trihydroxyflavanone-7-rutinoside (8), 18(13→17)-abeo-3β-acetoxy-9α,13β-lanost-24E-en-26-oic acid (9), garcihombronane B (10), garcihombronane D (11), friedelan-3-one (12), lupeol (13), stigmasterol (14) and stigmasterol glucoside (15). In the in vitro cytotoxicity against MCF-7, DBTRG, U2OS and PC-3 cell lines, compounds 1 and 9 displayed good cytotoxic effects against DBTRG cancer cell lines. Compounds 1-8 were also found to possess significant antioxidant activities. Owing to these properties, this study can be further extended to explore more significant bioactive components of this plant.
A central composite design of response surface methodology (RSM) was employed to optimize the extraction time (X1: 266.4-393.6 min) and temperature (X2: 42.9-57.1°C) of Pleurotus ostreatus aqueous extract with high antioxidant activities, namely DPPH radical-scavenging activity, ABTS radical cation inhibition, and ferric reducing/antioxidant power, as well as total phenolic content (TPC). Results showed that the data were adequately fitted into four second-order polynomial models developed by RSM. The extraction time and temperature were found to have significant quadratic effects on antioxidant activities and TPC. The optimal extraction time and temperature were 282.3 min and 42.9°C (DPPH), 393.6 min and 42.9°C (ABTS), 340.4 min and 49.8°C (FRAP), and 347.6 min, 49.7°C (TPC), with corresponding yields of 53.32%, 73.20%, 37.14 mM Fe2+ equivalents/100 g, and 826.33 mg gallic acid equivalents/100 g, respectively. These experimental data were close to their predicted values. The establishment of such a model provides a good experimental basis for employing RSM to optimize the extraction time and temperature for high antioxidant activities from P. ostreatus.
The effect of room temperature ionic liquid (RTIL) on the formation of the fluorescence ternary complex oxalate-sodium morin-5-sulfonate (NaMSA)-Aluminium(III) has been studied. In weakly acidic medium and in the presence of RTIL, 1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6), total complex formation is achieved as compared with the formation of the binary complex of NaMSA-Aluminium(III). The fluorescence characteristics of the system allowed the establishment of a very sensitive method for the spectrofluorimetric determination of oxalate ion. The ternary complex formed its highest fluorescence signal at 513 nm and excitation at 420 nm. In these conditions, the method produces a detection limit of 0.57 ng mL(-1). The procedure has been satisfactorily applied to the determination of oxalate ion in a vegetal tissue (spinach leaves).
Clinacanthus nutans (Burm. F.) Lindau or locally known in Sabah, Malaysia as ‘Sabah Snake Grass’ has been ethnobotanically used to treat various diseases in Asian countries. This study was conducted to determine the total phenolics content (TPC), flavonoids content (TFC) and antioxidant activity of herbal teas developed from C. nutans leaves with different drying techniques (microwave-oven dried and freeze dried) and infusion time (1, 2, 5, 10, 15 and 20 min). Ferric reducing/antioxidant power (FRAP) assay, 2,2’-azino-bis(3-ethylbenzothiazoline- 6-sulphonic acid (ABTS) and 2, 2-diphenyl-1-pycryl-hydrazyl (DPPH) free radical scavenging assays were used to investigate the antioxidant capacity. The highest TPC of herbal tea was observed in 20 min infusion of unfermented microwave-oven dried leaves (177.80 ± 19.10 mg TAE/L), while the highest TFC was observed in 10 min infusion of fermented microwave-oven dried leaves (22.13 ± 1.53 mg CE/L). Short infusion times from 5 min to 15 min were able to extract high amount of phenolics compounds. Unfermented tea contained higher TPC content (P < 0.05) as compared to fermented tea, while, TFC showed no significant difference between both types. Freeze dried infusion shows no significant difference (P > 0.05) as compared to microwave-oven dried for TPC, TFC and antioxidant capacity. Moderate and low correlation was observed between TPC and FRAP values (r = 0.507) and between TFC and ABTS values (r = 0.256). Preparation of C. nutans herbal tea as potential natural antioxidant source can be used as a basic reference for future research on the dietary intake of these herbal teas.
The objective of this study was to evaluate the effects of solid-to-solvent ratio (1:5. 1:10, 1:15 and 1:20) on the extraction of phenolic compounds (TPC and TFC) and antioxidant capacity (ABTS and DPPH radical scavenging capacity) of P. niruri. Solid-to-solvent ratio showed a significant effect for both phenolic compounds (TPC and TFC) and antioxidant capacity (ABTS and DPPH radical scavenging capacity) with 1:20 was the condition for extracting the highest of phenolic compounds (TPC and TFC) with a value of 5788.7 mg GAE/100 g DW and 1906.5 mg CE/100 g DW, respectively and exhibited high antioxidant capacities (ABTS and DPPH radical scavenging capacities) with a value of 0.820 mM and 1.598 mM, respectively among the four levels studied. TPC was positively and significantly correlated with ABTS and DPPH (r=0.999 and r=0.999) under the effects of solid-to-solvent ratio as compared to TFC, positively and strongly correlated (r=0.865 and r=0.868) with ABTS and DPPH.
This study investigated the effects of different percentages of ethanol (0 - 100%), extraction times (1 - 5 h) and temperatures (25 - 60°C) on total phenolic content (TPC) and antioxidant activity (AA) of sapodilla pulp and peel. TPC was determined by Folin-Ciocalteu reagent method, while AA was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, 2,2-azino-bis-(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assay, ferric reducing antioxidant power (FRAP) assay and β-carotene bleaching (BCB) assay. Based on the optimal extraction conditions used, sapodilla pulp extract had TPC of 3.89 mg GAE/g, 63.20% of DPPH scavenging activity, 4.30% of ABTS scavenging activity, 19.17% of BCB activity, and FRAP value of 15.24 mg TE/g; while its peel extract had TPC of 9.23 mg GAE/g, 92.95% of DPPH scavenging activity, 5.36% of ABTS scavenging activity, 8.14% of BCB activity, and 27.85 mg TE/g (FRAP value). Using the optimal extraction conditions for sapodilla pulp (40% ethanol as extraction solvent that extracted at 60°C for 4 h) and sapodilla peel (80% ethanol and 2 h extraction time at 40°C), highest antioxidants can be extracted from the pulp and peel.
The study explored on the commonly available weed plant Commelina nudiflora which has potential in-vitro antioxidant and antimicrobial activity. The different polar solvents such as ethanol, chloroform, dichloromethane, hexane and aqueous were used for the soxhlet extraction. The extracts were identified pharmacologically as important bioactive compounds and their potential free radical scavenging activities, and antimicrobial properties were studied. C. nudiflora extracts were monitored on their in-vitro antioxidant ability by DPPH and ABTS radical scavenging assay. Aqueous extract shows significant free radical scavenging activity of 63.4 mg/GAE and 49.10 mg/g in DPPH and ABTS respectively. Furthermore, the aqueous crude extract was used in antibacterial studies, which shows the highest inhibitory activity against Pseudomonas aeruginosa, Escherichia coli and Salmonella typhi. Among all the extracts, aqueous extract of C. nudiflora has significant control over free radical scavenging activity and inhibition of the growth of food pathogenic bacteria. Also, the aqueous extract contains abundance of phenolics and flavonoids higher than other extracts. This study explored weed plant C. nudiflora as a potential source of antioxidant and antibacterial efficacy and identified various therapeutic value bioactive compounds from GC-MS analysis.