Mohammad Dolatabadi; Zeynab Raftani Amiri; Reza Esmaeilzadeh kenari
Abstract
Introduction: In recent years, much attention has been focused on agricultural wastes especially those containing phenolic compounds with natural antioxidant properties. One of these sources is the green husks of walnuts. The contents of phenolic compounds of plants are influenced under various factors ...
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Introduction: In recent years, much attention has been focused on agricultural wastes especially those containing phenolic compounds with natural antioxidant properties. One of these sources is the green husks of walnuts. The contents of phenolic compounds of plants are influenced under various factors including genetic factors, agricultural varieties and the species, climate and extraction procedures. Extraction is the first step for researchers who work on plants. Traditional extraction techniques with solvent such as water have disadvantages such as time consuming process, solvent consumption and high labor work. So the need to develop and use new extraction techniques, including combination of ultrasound bath and microwave devices, has provided valuable results. This method increases the mass transfer rate of the cell wall and intracellular compounds more rapidly transported out of the cell. In the ultrasound method to create cavitation in the extraction process and with collapse of bubbles and mechanical effects on the cell wall and most influential into the cell solvent improves the mass transfer. Extraction process performed by ultrasound process was used to facilitate the release of the intracellular content. These two methods can increase extraction efficiency within a shorter time and using less solvent, increasing the amount of extracted compounds are less damaging to the environment. Three different weather conditions for walnut production in northern Iran and different methods for extraction and measurement of phenolic compounds were adapted to find the best area and the most efficient extraction method.
Materials and methods: Three areas were selected from north parts of Iran including Bandar Gaz with mild climate, Shahrood with semi-arid climate and Hezarjerib region with mountainous climate located in the Alborz Mountain chains in which walnut is one of their major products. Walnuts randomly were picked by hand without any damage to their husks from a few walnut trees in a random garden in each region. The selected walnut trees were almost similar and were about 35 to 40 years old. In the selected areas, it is not conventional to use pesticides or chemicals and toppings for walnut trees. Walnuts collected were transported to the lab in cold conditions (8 to 10° C) and after cleaning the walnuts, green husks were separated and kept at -18 °C. Solvent extraction of phenolic compounds was carried out by choosing ethanol - water in a ratio of (1-1) by soaking, ultrasound and microwave methods at different times. The amount of phenolic compounds was measured using a spectrophotometer device with the aid of using the Folin Ciocalteau reagent, and antioxidant properties were measured using DPPH free radical scavenging and regenerative power of Iron III.
Results and discussion: This research was carried out on a factorial design (334) with three replications with Duncan's test for comparison of averages at the 95% confidence level. Comparing the extraction methods (soaking, microwave and ultrasound) showed that the most efficient method was ultrasound method at 30 minutes and the highest phenolic compounds in walnut green husk was for Hezarjerib area. In addition to the savings in time of extraction and safety in this method, the extraction of phenolic compounds is preferred to the other two methods. The results showed that the antioxidant properties were increased with increase in the amount of phenolic compounds. The results of this study also revealed that the walnuts green husks from Hezarjerib had the highest antioxidant properties followed by temperate region (Bandargaz) and semi-arid region (Shahrood).
Hossein Jooyandeh; Vahid Samavati
Abstract
Introduction: Accumulation of free radicals could lead to permanent oxidative destruction of organisms by attacking macromolecules and organelles of the body, thus causing organism aging, fatigue and degenerative diseases. Therefore, discovering and developing safe and non-toxic natural antioxidants ...
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Introduction: Accumulation of free radicals could lead to permanent oxidative destruction of organisms by attacking macromolecules and organelles of the body, thus causing organism aging, fatigue and degenerative diseases. Therefore, discovering and developing safe and non-toxic natural antioxidants has been an interesting topic in recent decades. Compared to synthetic antioxidants, extracts from plant resources usually have quite stable constructions and great antioxidant activities, and can easily be absorbed without dangerous immunoreactions. Many antioxidant compounds, naturally occurring from plant sources, have been identified as free radicals or active oxygen scavengers. Malva neglecta (MN), which is known as Panirak/Tooleh in Iran is an annual and herbaceous plant. The leaves and flowers of MN are used in traditional phytotheraphy and in treatment of cough, respiratory system and digestive system problems. The objective of this study was to optimize process conditions of extraction in order to obtain the highest yield from crude extract of MN leaves and identify its antioxidant properties. Materials and methods: Three-variable-three-level Box-Behnken design-response surface methodology (BBD-RSM) with five replications at central point was used to optimize the extracting parameters of crude extract from the MN leaves including extraction time (1-8 h), extraction temperature (50-100°C), and the water/solid ratio (3-30). The ability of extracted materials to scavenge the free radicals of DPPH, OH and super oxide was also evaluated by chemical analysis. Results and Discussion: All three independent variables effected the yield of crude extract of MN leaves. The extraction yield of MN crude extract significantly increased from 5.90% to 8.01% with extraction time varying from 1 h to 6 h. However, the yield was not altered meaningfully, as the extraction time was increased from 6 h up to 8 h. This may be due to degradation of the polysaccharides because of the extended extraction time. The extraction process was performed with temperatures from 50 °C to 100 °C, with the other extraction variables such as ratio of water to raw material and extraction time fixed at 13 ml/g and 3.5 h, respectively. The extraction yield of crude extract increased with increasing extraction temperature and peaked at 7.89 at 100 °C. Different ratios of water to raw material have considerable effect on extraction yield. In this study, we used ratios of water to raw material from 3 to 30 ml/g, with fixed parameters (extraction time and extraction temperature at 3.5 h and 75 °C, respectively). Extraction yield increased noticeably from 6.10 to 8.10 with ratio of water to material varying from 3 ml/g to 24 ml/g. As extraction time, at the higher experimental levels, as the ratio of water to raw material was increased (from 24 up to 30 ml/g) the yield of crude extract was not changed considerably. Under the appropriate condition of ratio of water to raw material, the crude extract molecules can swell thoroughly, and more compounds could dissolve in water to improve extraction yield. The determination coefficient (R2 = 0.9897) suggested that the model was valid, implying that 98.97% of the variation could be explained by the fitted model. The adjusted determination coefficient was used to evaluate the correlation between the experimental values and predicted values, and the outcome (R2Adj= 0.9794) suggested that the correlation was significant. The f-value (1.49) for “the lack of fit” indicated that the “lack of fit” was not significant relative to the pure error (p > 0.05). The CV for yield of MN leaves was 0.64%, which defined a good reliability of the experimental values. The adequate precision value 21.61 and PRESS 0.42 for our model indicated an appropriate model could be designed. On multiple regression analysis, the quadratic polynomial equation for the independent variables and response variable expressed as follows: Y =7.82 + 1.025X1 + 3.241667X2 + 2.031X3 + 0.525X1X2 - 0.7X1X3 + 0.675X2X3 – 0.206X12 – 0.21833X22 Where, Y is extraction yield (%); X1, extraction time (h); X2, extraction temperature; and X3, ratio of water to raw material (ml/g) Statistical analysis of the results showed that the optimal conditions for higher extraction yield were extraction time: 6 h, extraction temperature: 90oC, and the ratio of water to raw material: 19. Under these conditions, the experimental yield was 9.22% ± 0.47%, which well matched the predicted value (9.18%), under these conditions; the experimental yield was 9.18%. Furthermore, results obtained from chemical analysis showed that DPPH, OH and super oxide scavenging of MN crude extract increased rapidly with increasing of its concentration. DPPH scavenging rate of the crude extract was more than BHT standard (89% vs. 78%) at their maximum equivalent concentration (300 ppm). Furthermore, OH and super oxide scavenging ability of MN crude extract (87% and 91%, respectively) were significantly more than ascorbic acid standard solutions (74% and 81%, respectively) at their highest experimental concentrations (150 ppm). Based on our results, components extracted from Malva neglecta leaves may introduce as an antioxidant and free radical scavenger. This study could help food industries to add a new source of hydrocolloid with certain functionality as an alternative additive in different foods, cosmetic and pharmaceutical products.
Somayeh Rezai Erami; Seyed Mahdi Jafari; Morteza Khomeiri; Houman Bayat
Abstract
The aim of this study is extraction of phenolic compounds from walnut leaves of touyserkani variety with two extraction methods (traditional method and with microwave assisted extraction (MAE)) and evaluation of their antioxidant activity. Total Phenolic contents and antioxidant properties of aqueous, ...
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The aim of this study is extraction of phenolic compounds from walnut leaves of touyserkani variety with two extraction methods (traditional method and with microwave assisted extraction (MAE)) and evaluation of their antioxidant activity. Total Phenolic contents and antioxidant properties of aqueous, methanol (80%) and ethanol (50%) extracts in different times was determined. At the next stage, effect of methanol extract on retarding of oxidation of soy oil was assessed. All of extracts showed antioxidant activity in a concentration-dependent way. In MAE, methanol extract had highest total phenol whose content is 89.15 ± 0.25 mg/g. the ethanol extract presented highest activity in radical-scavenging activity (EC50 = 27.90 µg/ml), reducing power assay (EC50 = 93.26 µg/ml) and antioxidant activity assay (EC50=68.23 µg/ml). Also extract at 1000 ppm could control oxidation of soy oil and this extract was effective than all of synthesis antioxidant in retarding oil oxidation Hence we can present walnut leaves as a potential source of phenolic compounds and natural antioxidant.
