Elsevier

Carbohydrate Polymers

Volume 106, 15 June 2014, Pages 238-246
Carbohydrate Polymers

Optimization of polysaccharides from Zagros oak leaf using RSM: Antioxidant and antimicrobial activities

https://doi.org/10.1016/j.carbpol.2014.02.028Get rights and content

Highlights

  • Extraction of QBLP by ultrasonic extraction technique for the first time.

  • RSM with BBD was applied to optimize the extraction conditions for QBLP.

  • The optimum conditions were X1 205.8 W, X2 81.9 °C, X3 55.6 min, and X4 23.4.

  • QBLP showed good antioxidant and antimicrobial activities at 2.5–2.8 mg/mL.

Abstract

Ultrasonic assisted-extraction technique was applied to extract the polysaccharide from Zagros oak (Quercus brantii Lindl). The effects of four independent factors (ultrasonic power (X1: 150–300 W), extraction temperature (X2: 50–90 °C), extraction time (X3: 30–90 min), and the ratio of water to raw material (X4: 15–45)) on the extraction yield of polysaccharide from the leaves of Q. brantii Lindl (QBLP) were optimized using response surface methodology. The experimental data obtained were fitted to a second-order polynomial equation. The optimal extraction conditions for QBLP were determined as follows: X1: 205.8 W, X2: 81.9 °C, X3: 55.6 min and X4: 23.4. Under these optimal conditions, the experimental yield was 19.42 ± 0.53%, which was well matched with the value predicted by the model 19.61%. The results indicated that polysaccharide has strong scavenging activities in vitro on DPPH and hydroxyl radicals. In addition, the QBLP showed good antimicrobial activity at 1.5–2.5 mg/mL.

Introduction

A variety of extraction techniques have been employed for the separation of valuable compounds from the plant materials. Conventionally, polysaccharides are extracted by heating reflux extraction. Nowadays, various novel extraction techniques have been developed for the extraction of polysaccharides from natural plants. Compared with other advanced extraction methods such as supercritical fluid extraction, ion-pair extraction, enzymatic extraction and microwave-assisted extraction, the ultrasonic extraction is rapid, cheaper, and its operation is much easier (Chen et al., 2008, Li et al., 2005, Wang and Weller, 2006). The principles of ultrasonic treatment include thermal and mechanical effects and cavitation, which greatly facilitate mass transfer between immiscible phases through a super agitation (Vinatoru et al., 1997).

Quercus brantii, commonly known as oaks, belongs to the family Fagaceae. It is regarded as being a species well adapted to dry and low-temperature climates and is found in the mixed pine-oak forests in Zagros, Iran (Luna-José, Montalvo-Espinosa, & Rendón-Aguilar, 2003). Oaks have spirally arranged leaves, with lobate margins in many species. Q. brantii extract has been reported to have great hepatoprotective, anti-tumor and anti-aging activity, may be related to the antioxidant capacity of their constituents and effect on expression of CYP2E1 (Rivas-Arreola et al., 2011, Rocha-Guzmán et al., 2009). It has been also reported to have anti-inflammatory activity after oral or topical administration (Almeida, Fernandes, Lima, Costa, & Bahia, 2008).

Polysaccharides are polymeric carbohydrate molecules that can be extracted under appropriate conditions (Lin & Lai, 2009). Isolated polysaccharides from plentiful of plants are utilized to great extent in food processing, as: thickening or gel-setting agents; stabilizers for emulsions and dispersions; film-forming, coating substances to protect sensitive food from undesired change; and inert fillers to increase the proportion of indigestible ballast substances in a diet (Lai and Lin, 2004, Salazar-Montoya et al., 2002).

In recent years, ultrasonic-assisted extraction technique has been developed for the extraction of polysaccharides from natural plants (Zhong & Wang, 2010).

Some diseases such as cancer, atherosclerosis and rheumatoid, can be directly induced by oxygen-derived free radicals (radical dotOH), while the radical scavenging activity is one of the important functional properties for bioactive compounds (Yang, Zhao, Shi, & Yang, 2008). The radical scavenging activity and inhibition zone formation are often used to evaluate the capacity of antioxidant and antimicrobial compounds, respectively (Prior & Cao, 1999). Recent studies demonstrated many plant polysaccharides have great antioxidant activities and should be paid more attention to exploring them as novel potential antioxidants (Ramarahnam et al., 1995, Wang et al., 2012, Xu et al., 2009).

Response surface methodology (RSM) is a collection of empirical and mathematical techniques used to evaluate the interactions between multiple parameters and optimize processes (Zhong, Lin, Wang, & Zhou, 2012). This procedure reduces the number of experimental trials and overall cost (Myers & Montgomery, 2002).

To the best of our knowledge, there were no reports available in the literature regarding the optimization of ultrasonic-assisted extraction of polysaccharide from the leaves of Q. brantii by response surface methodology. In this work, the ultrasonic-assisted extraction variables (ultrasonic power, extraction temperature, extraction time and ratio of water to raw material) of polysaccharide (QBLP) (%) from the leaves of Q. brantii was firstly investigated and optimized using a BBD (4 factors and 3 levels). Antioxidant and antimicrobial activities of QBLP were investigated by various in vitro assays.

Section snippets

Materials

The leaves of Q. brantii were collected from Kermanshah province, Iran, washed, freeze-dried, and powdered for this study. All other chemicals and solvents used were of analytical grade and obtained from Merck Co., Germany.

Ultrasonic extraction of crude polysaccharides from Q. brantii leaves

The extraction of polysaccharides from Q. brantii leaf was conducted by the method of Pan et al. (2010) with some modifications. The powder of Q. brantii leaf was firstly extracted with 80% ethanol at 60 °C in a water bath to deactivate the endogenous enzymes and remove

Effect of ultrasonic power on extraction yield of QBLP

To investigate the influence of different ultrasonic powers on extraction yield of QBLP, extraction process was carried out using the different powers of 100, 125, 150, 175, 200, 225, 250, 275 and 300 W (Fig. 1a). The extraction temperature, extraction time and the ratio of water to the raw material were fixed at 70 °C, 60 min and 30, respectively. As shown in Fig. 1a, the maximum extraction yield of QBLP was observed when the ultrasonic power was 300 W. This was agreed closely with reports of

Conclusion

In this study, we had investigated an ultrasonic-assisted technique to extract polysaccharides from the oak (Q. brantii Lindl.) leaf via response surface methodology. Extraction temperature and ultrasonic power were the most important variables on the experimental yield of polysaccharides. A second-order using polynomial model was used to optimize polysaccharides extraction from Q. brantii leaf by ultrasonic-assisted method. The optimal extraction conditions were performed as following:

Acknowledgement

The author wishes to thank Ramin Agricultural and Natural Resources University for scientific and financial supports of this research (Project No: 922/60).

References (36)

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