This study was conducted to evaluate the potential antioxidant activity of lignin obtained from black liquor, a hazardous waste product generated during the extraction of palm oil. Antioxidant potential of the extracted lignin was evaluated by dissolving the extracted samples in 2 different solvent systems, namely, 2-methoxy ethanol and DMSO. Results revealed high percent inhibition of the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical in the lignin sample dissolved in 2-methoxy ethanol over DMSO (concentration range of 1-100 microg/ml). Lignin extracted in 2-methoxy ethanol exhibited higher inhibition percentage (at 50 microg/ml, 84.2%), whereas a concentration of 100 microg/ml was found to be effective in the case of the DMSO solvent (69.8%). Fourier transform infrared (FTIR) spectrometry revealed that the functional groups from the extracted lignin and commercial lignin were highly similar, indicating the purity of the lignin extracted from black liquor. These results provide a strong basis for further applications of lignin in the food industry and also illustrate an eco-friendly approach to utilize oil palm black liquor.
The present study was aimed to investigate the antioxidant and cytotoxicity activity against HCT-15 of fucoidan from Sargassum cinereum. Purification of fucoidan was done by DEAE cellulose and dialysis. Physicochemical characterization of fucoidan was analysed by calorimetric assay, FT-IR, HPLC and NMR. The extracted fucoidan contains 65.753% of fucose and 3.7±1.54% of sulphate respectively. HPLC results showed that the fucoidan contains the monosaccharide composition such as fucose, galactose, mannose and xylose. Antioxidant effect of fucoidan in Sargassum Cinereum was determined by DPPH. The maximum DPPH activity was found at the concentration of 100μg, where as the crude extract showed the scavenging activity was 63.58±0.56%. Cytotoxicity effect was done by MTT assay. Fucoidan extract caused about 50% of cell death after 24h of incubation with 75±0.9037μg/ml against HCT-15.
A sequential solvent extraction scheme was employed for the extraction of antioxidant compounds from kenaf (Hibiscus cannabinus L.) seeds. Yield of extracts varied widely among the solvents and was the highest for hexane extract (16.6% based on dry weight basis), while water extract exhibited the highest total phenolic content (18.78 mg GAE/g extract), total flavonoid content (2.49 mg RE/g extract), and antioxidant activities (p < 0.05). DPPH and hydroxyl radical scavenging, β-carotene bleaching, metal chelating activity, ferric thiocyanate and thiobarbituric acid reactive substances assays were employed to comprehensively assess the antioxidant potential of different solvent extracts prepared sequentially. Besides water, methanolic extract also exhibited high retardation towards the formation of hydroperoxides and thiobarbituric acid reactive substances in the total antioxidant activity tests (p < 0.05). As conclusion, water and methanol extracts of kenaf seed may potentially serve as new sources of antioxidants for food and nutraceutical applications.
The influence of both acidic and basic hydrolysis on the yield, total phenolic content and antioxidative capacity of methanolic extract of germinated brown rice (GBR) was studied. Total phenolic content (TPC), total flavonoid content (TFC), 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical cation scavenging, and ferric reducing antioxidant power (FRAP) tests were used for the measurement of antioxidant ability. There was a significant difference p < 0.05) in the TPC and DPPH radical scavenging assay results when comparing neutral with acidic and basic catalysed hydrolysis. The yield of the crude extract was slightly higher in acidic hydrolysis than in basic hydrolysis p > 0.05). The TPC and TFC were highest in acidic hydrolysis. A significant correlation was observed between ABTS radical cation scavenging and FRAP. The antioxidant activity measured using DPPH radical scavenging assay showed high activity in acidic hydrolysis, while the ABTS radical cationscavenging activity and FRAP showed the highest values in basic hydrolysis. The samples were further evaluated using HPLC to determine the individual phenolic concentrations in different hydrolytic media contributing to the antioxidant effects. This study revealed that acidic and basic hydrolysis can improve the yield, phenolic content, and antioxidant activity of germinated brown rice.
Two new xanthones, pyranocycloartobiloxanthone A (1) and dihydroartoindonesianin C (2), were isolated from the stem bark of Artocarpus obtusus Jarrett by chromatographic separation. Their structures were determined by using spectroscopic methods and comparison with known related compounds. Pyranocycloartobiloxanthone A (1) showed strong free radical scavenging activity by using DPPH assay as well as cytotoxicity towards K562, HL-60, and MCF7 cell lines.
A new xanthone, namely garcinexanthone G (1), along with eight known compounds, stigmasta-5,22-dien-3β-ol (2), stigmasta-5,22-dien-3-O-β-glucopyranoside (3), 3β-acetoxy-11α,12α-epoxyoleanan-28,13β-olide (4), 2,6-dimethoxy-p-benzoquinone (5), 1,3,5-trihydroxy-2-methoxyxanthone (6), 1,3,7-trihydroxyxanthone (7), kaempferol (8) and quercetin (9), were isolated from the stem bark of Garcinia atroviridis. Their structures were elucidated based on spectroscopic methods including nuclear magnetic resonance (NMR-1D and 2D), UV, IR, and mass spectrometry. All the isolated compounds were evaluated for their antioxidant properties based on the DPPH radical scavenging activities. Results showed that 1,3,7-trihydroxyxanthone and quercetin showed significant antioxidant activities with EC50 values of 16.20 and 12.68 μg/ml, respectively, as compared to the control, ascorbic acid (7.4 μg/ml).
The effects of ethanol concentration (0%-100%, v/v), solid-to-solvent ratio (1:10-1:60, w/v) and extraction time (30-180 min) on the extraction of polyphenols from agarwood (Aquilaria crassna) were examined. Total phenolic content (TPC), total flavonoid content (TFC) and total flavanol (TF) assays and HPLC-DAD were used for the determination and quantification of polyphenols, flavanol gallates (epigallocatechin gallate--EGCG and epicatechin gallate--ECG) and a benzophenone (iriflophenone 3-C-β-glucoside) from the crude polyphenol extract (CPE) of A. crassna. 2,2'-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was used to evaluate the antioxidant capacity of the CPE. Experimental results concluded that ethanol concentration and solid-to-solvent ratio had significant effects (p<0.05) on the yields of polyphenol and antioxidant capacity. Extraction time had an insignificant influence on the recovery of EGCG, ECG and iriflophenone 3-C-β-glucoside, as well as radical scavenging capacity from the CPE. The extraction parameters that exhibited maximum yields were 40% (v/v) ethanol, 1:60 (w/v) for 30 min where the TPC, TFC, TF, DPPH, EGCG, ECG and iriflophenone 3-C-β-glucoside levels achieved were 183.5 mg GAE/g DW, 249.0 mg QE/g DW, 4.9 mg CE/g DW, 93.7%, 29.1 mg EGCG/g DW, 44.3 mg ECG/g DW and 39.9 mg iriflophenone 3-C-β-glucoside/g DW respectively. The IC50 of the CPE was 24.6 mg/L.
Ultrasound-assisted extraction (UAE) with ethanol was used to extract the compounds responsible for the antioxidant activities of Misai Kucing (Orthosiphon stamineus). Response surface methodology (RSM) was used to optimize four independent variables: ethanol concentration (%), amplitude (%), duty cycle (W/s) and extraction time (min). Antioxidant compounds were determined by total phenolic content and total flavonoid content to be 1.4 g gallic acid equivalent/100 g DW and 45 g catechin equivalent/100 g DW, respectively. Antioxidant activities were evaluated using the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+) radical scavenging capacity assay and the 2,2-diphenyl-1-picrylhydrazyl (DPPH•) radical scavenging capacity assay to be 1,961.3 and 2,423.3 µmol Trolox Equivalent Antioxidant Capacity (TEAC)/100 g DW, respectively. Based on the optimal conditions, experimental values were reported to be close to the predicted value by RSM modeling (p>0.05), indicating the suitability of UAE for extracting the antioxidants of Misai Kucing. Rosmarinic acid, kaempferol-rutinoside and sinesetine were identified by high performance liquid chromatography-mass spectrometry.
A new series of gallic hydrazones containing an indole moiety was synthesized through the reaction of gallic hydrazide and different indole carboxaldehydes. Their antioxidant activities were determined on DPPH radical scavenging and inhibition of lipid peroxidation. The in-vitro cytotoxic activities of the compounds were evaluated against HCT-116 (human colon cancer cell line) and MCF-7 (estrogen-dependent human breast cancer cell line) by the MTT method. An attempt to correlate the biological results with their structural characteristics has been done. A limited positive structure activity relationship was found between cytotoxic and antioxidant activities.
Orthosiphon stamineus is considered an important traditional folk medicine. In this study ethanol and aqueous extracts of O. stamineus were evaluated in vitro for their antioxidant, antimicrobial as well as for their immunomodulatory properties on human peripheral blood mononuclear cells (PBMCs). The DPPH radical scavenging method was used for the determination of antioxidant activity, while the antibacterial efficacy was investigated by both disc diffusion method and Minimum Inhibitory Concentration (MIC) against four bacterial strains (Gram-positive and Gram-negative). Furthermore, the immunomodulatory potential of the extracts was investigated through the MTT assay. Aqueous extract of O. stamineus exhibited significant free radical scavenging activity with IC₅₀ 50 9.6 µg/mL, whereas the IC₅₀ for the ethanol extract was 21.4 µg/mL. The best antimicrobial activity was shown by the aqueous extract of O. stamineus against Staphylococcus aureus, with inhibition zone of 10.5 mm and MIC value 1.56 mg/mL. Moreover, the results observed from the MTT assay showed that both plant extracts stimulated the PBMCs proliferation in vitro in a concentration-dependent manner, but the aqueous extract has remarkable activity against PBMCs. These findings indicate that O. stamineus showed high antioxidant activity and may be considered as an immunomodulatory agent.
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, IC(50) 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, IC(50) 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.
The development of novel antioxidant compounds with high efficacy and low toxicity is of utmost importance in the medicine and food industries. Moreover, with increasing concerns about the safety of synthetic components, scientists are beginning to search for natural sources of antioxidants, especially essential oils (EOs). The combination of EOs may produce a higher scavenging profile than a single oil due to better chemical diversity in the mixture. Therefore, this exploratory study aims to assess the antioxidant activity of three EOs extracted from Cymbopogon flexuosus, Carum carvi, and Acorus calamus in individual and combined forms using the augmented-simplex design methodology. The in vitro antioxidant assays were performed using DPPH and ABTS radical scavenging approaches. The results of the Chromatography Gas-Mass spectrometry (CG-MS) characterization showed that citral (29.62%) and niral (27.32%) are the main components for C. flexuosus, while D-carvone (62.09%) and D-limonene (29.58%) are the most dominant substances in C. carvi. By contrast, β-asarone (69.11%) was identified as the principal component of A. calamus (30.2%). The individual EO exhibits variable scavenging activities against ABTS and DPPH radicals. These effects were enhanced through the mixture of the three EOs. The optimal antioxidant formulation consisted of 20% C. flexuosus, 53% C. carvi, and 27% A. calamus for DPPHIC50. Whereas 17% C. flexuosus, 43% C. carvi, and 40% A. calamus is the best combination leading to the highest scavenging activity against ABTS radical. These findings suggest a new research avenue for EOs combinations to be developed as novel natural formulations useful in food and biopharmaceutical products.
A study was conducted to compare secondary metabolites and antioxidant activity of Labisia pumila Benth (Kacip Fatimah) in response to two sources of fertilizer [i.e., organic (chicken dung; 10% N:10% P₂O₅:10% K₂O) and inorganic fertilizer (NPK green; 15% N, 15% P₂O₅, 15% K₂O)] under different N rates of 0, 90, 180 and 270 kg N/ha. The experiment was arranged in a randomized complete block design replicated three times. At the end of 15 weeks, it was observed that the application of organic fertilizer enhanced the production of total phenolics, flavonoids, ascorbic acid, saponin and gluthathione content in L. pumila, compared to the use of inorganic fertilizer. The nitrate content was also reduced under organic fertilization. The application of nitrogen at 90 kg N/ha improved the production of secondary metabolites in Labisia pumila. Higher rates in excess of 90 kg N/ha reduced the level of secondary metabolites and antioxidant activity of this herb. The DPPH and FRAP activity was also highest at 90 kg N/ha. The results indicated that the use of chicken dung can enhance the production of secondary metabolites and improve antioxidant activity of this herb.
In the present study, supercritical carbon dioxide (SC-CO(2)) extraction of seed oil from winter melon (Benincasa hispida) was investigated. The effects of process variables namely pressure (150-300 bar), temperature (40-50 °C) and dynamic extraction time (60-120 min) on crude extraction yield (CEY) were studied through response surface methodology (RSM). The SC-CO(2) extraction process was modified using ethanol (99.9%) as co-solvent. Perturbation plot revealed the significant effect of all process variables on the CEY. A central composite design (CCD) was used to optimize the process conditions to achieve maximum CEY. The optimum conditions were 244 bar pressure, 46 °C temperature and 97 min dynamic extraction time. Under these optimal conditions, the CEY was predicted to be 176.30 mg-extract/g-dried sample. The validation experiment results agreed with the predicted value. The antioxidant activity and fatty acid composition of crude oil obtained under optimized conditions were determined and compared with published results using Soxhlet extraction (SE) and ultrasound assisted extraction (UAE). It was found that the antioxidant activity of the extract obtained by SC-CO(2) extraction was strongly higher than those obtained by SE and UAE. Identification of fatty acid composition using gas chromatography (GC) showed that all the extracts were rich in unsaturated fatty acids with the most being linoleic acid. In contrast, the amount of saturated fatty acids extracted by SE was higher than that extracted under optimized SC-CO(2) extraction conditions.
The aim of the present study was to characterize the phenolic acids, flavonoids, and antioxidant properties of monofloral honey collected from five different districts in Bangladesh. A new high performance liquid chromatography (HPLC) equipped with a UV detector method was developed for the identification of the phenolic acids and flavonoids. A total of five different phenolic acids were identified, with the most abundant being caffeic acid, benzoic acid, gallic acid, followed by chlorogenic acid and trans-cinnamic acid. The flavonoids, kaempferol, and catechin were most abundant, followed by myricetin and naringenin. The mean moisture content, total sugar content, and color characteristics of the honey samples were 18.36 ± 0.95%, 67.40 ± 5.63 g/100 g, and 129.27 ± 34.66 mm Pfund, respectively. The mean total phenolic acids, total flavonoid content, and proline content were 199.20 ± 135.23, 46.73 ± 34.16, and 556.40 ± 376.86 mg/kg, respectively, while the mean FRAP values and DPPH radical scavenging activity were 327.30 ± 231.87 μM Fe (II)/100 g and 36.95 ± 20.53%, respectively. Among the different types of honey, kalijira exhibited the highest phenolics and antioxidant properties. Overall, our study confirms that all the investigated honey samples are good sources of phenolic acids and flavonoids with good antioxidant properties.
The phenolic acid and flavonoid contents of Malaysian Tualang, Gelam, and Borneo tropical honeys were compared to those of Manuka honey. Ferric reducing/antioxidant power assay (FRAP) and the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical-scavenging activities were also quantified. All honey extracts exhibited high phenolic contents (15.21 ± 0.51- 42.23 ± 0.64 mg/kg), flavonoid contents (11.52 ± 0.27- 25.31 ± 0.37 mg/kg), FRAP values (892.15 ± 4.97- 363.38 ± 10.57 μM Fe[II]/kg), and high IC₅₀ of DPPH radical-scavenging activities (5.24 ± 0.40- 17.51 ± 0.51 mg/mL). Total of 6 phenolic acids (gallic, syringic, benzoic, trans-cinnamic, p-coumaric, and caffeic acids) and 5 flavonoids (catechin, kaempferol, naringenin, luteolin, and apigenin) were identified. Among the Malaysian honey samples, Tualang honey had the highest contents of phenolics, and flavonoids, and DPPH radical-scavenging activities. We conclude that among Malaysian honey samples, Tualang honey is the richest in phenolic acids, and flavonoid compounds, which have strong free radical-scavenging activities.
The aim of the present study was to characterize the physical, biochemical and antioxidant properties of Algerian honey samples (n = 4). Physical parameters, such as pH, moisture content, electrical conductivity (EC), total dissolved solids (TDS), color intensity, total sugar and sucrose content were measured. Several biochemical and antioxidant tests were performed to determine the antioxidant properties of the honey samples. The mean pH was 3.84 ± 0.01, and moisture the content was 13.21 ± 0.16%. The mean EC was 0.636 ± 0.001, and the mean TDS was 316.92 ± 0.92. The mean color was 120.58 ± 0.64 mm Pfund, and the mean 5-hydroxymethylfurfural (HMF) content was 21.49 mg/kg. The mean total sugar and reducing sugar contents were 67.03 ± 0.68 g/mL and 64.72 ± 0.52 g/g, respectively. The mean sucrose content was 2.29 ± 0.65%. High mean values of phenolic (459.83 ± 1.92 mg gallic acid/kg), flavonoid (54.23 ± 0.62 mg catechin/kg), ascorbic acid (159.70 ± 0.78 mg/kg), AEAC (278.15 ± 4.34 mg/kg), protein (3381.83 ± 6.19 mg/kg) and proline (2131.47 ± 0.90) contents, as well as DPPH (39.57% ± 4.18) and FRAP activities [337.77 ± 1.01 µM Fe (II)/100 g], were also detected, indicating that Algerian honey has a high antioxidant potential. Strong positive correlations were found between flavonoid, proline and ascorbic acid contents and color intensity with DPPH and FRAP values. Thus, the present study revealed that Algerian honey is a good source of antioxidants.
This study was conducted to evaluate the effects of evaporation, gamma irradiation and temperature on the total polyphenols, flavonoids and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activities of Tualang honey samples (n = 14) following storage over three, six or twelve months. The mean polyphenol concentrations of the six gamma irradiated honey samples at three, six and twelve months, respectively, were 96.13%, 98.01% and 102.03% higher than the corresponding values of the eight non-gamma irradiated samples. Similarly, the mean values for flavonoids at three, six and twelve months were 111.52%, 114.81% and 110.04% higher, respectively, for the gamma irradiated samples. The mean values for DPPH radical-scavenging activities at three, six and twelve months were also 67.09%, 65.26% and 44.65% higher, respectively, for the gamma irradiated samples. These data indicate that all gamma irradiated honey samples had higher antioxidant potential following gamma irradiation, while evaporation and temperature had minor effects on antioxidant potential.
The Box-Behnken design was applied to optimize the extraction of pectin from Averrhoa bilimbi (ABP) using deep eutectic solvents (DES). The four variables of extraction were percentage of DES (X1), extraction time (X2), temperature (X3), and molar ratio of DES components (X4). The quadratic regression equation was established as a predicted model with R2 value of 0.9375. The optimal condition was X1 = 3.74% (w/v), X2 = 2.5 h, X3 = 80 °C, and X4 = 1:1. No significant difference between the predicted (14.70%) and experimental (14.44%) maximum yield of sample was noted. Characterization of physico-chemical properties characterization of ABP was performed. The main components of ABP were galacturonic acids, arabinoses, and xyloses. ABP also showed good functional properties such as water holding capacity (3.70 g/g), oil holding capacity (2.40 g/g), and foaming capacity (133.33%). The results also showed that ABP exhibited free radical scavenging activity (41.46%) and ferric reducing antioxidant power (1.15 mM).
A series of N-ethyl phthalimide esters 4(a-n) were synthesized and characterized by spectroscopic studies. Further, the molecular structure of majority of compounds were analysed by single crystal X-ray diffraction studies. The X-ray analysis revealed the importance of substituents on the crystal stability and molecular packing. All the synthesized compounds were tested for in vitro antioxidant activity by DPPH radical scavenging, FRAP and CUPRAC methods. Few of them have shown good antioxidant activity.