Response Surface Optimized Ultrasonic Assisted Extraction of Total Flavonoids from Walnut Leaves and In Vitro Antibacterial Activities

Jingjing Fu,Han Wu,Yuanda Song,Haifang Xiao,Aydin Berenjian,Shaoxuan Yu

doi:10.3844/ajbbsp.2017.176.188

Abstract

In this paper, the optimum extraction conditions of total flavonoids extracted from walnut leaves subjected to Ultrasonic Assisted Extraction (UAE) were optimized by Response Surface Methodology (RSM). The mathematical model showed the high coefficient of measurement (R2 = 0.9938) which indicated that this model could be used to guide the response surface methodology. The optimum extraction parameters for extracting flavonoids from walnut leaves determined in this study were extraction temperature 47.73°C, extraction time 30.79 min, ethanol concentration 72.89% (v/v). Under the optimal extraction conditions, the flavonoids yield was about 3.5315%. Statistical analysis of the results showed that extraction temperature, extraction time and ethanol concentration significantly affected the extraction yield of total flavonoids. In addition, the antibacterial activity assays of the flavonoids were carried out and it was demonstrated that the total flavonoids extracted at the optimum conditions had pronounced antibacterial effects against the four bacterial species. Therefore, this study suggested that walnut leaves are promising resources with antibacterial properties for the development of phytomedicines.

Highlights

Walnut (Juglans regia L.), which belongs to the Juglandaceae family, is a local deciduous tree in northwestern Chain (2012; Moser, 2012)
The results indicated that the flavonoids obtained from walnut leaves have antibacterial activity at 100mg/mL−1 and the bacterial inhibition ring of flavonoids was measured
Response Surface Methodology (RSM) was applied in optimizing the total flavonoids compounds extraction from walnut leaves and it was showed that the Ultrasonic Assisted Extraction (UAE) is a valid method for obtaining flavonoids from walnut leaves

Summary

Introduction

Walnut (Juglans regia L.), which belongs to the Juglandaceae family, is a local deciduous tree in northwestern Chain (2012; Moser, 2012). Walnut leaves are known to possess many biological properties and are available in abundant amounts (Derebecka et al, 2012). They have been used as a traditional medicine in China and have shown various health benefits for the treatment of skin inflammations, venous insufficiency and ulcers (Cheniany et al, 2013). Researches in pharmacology and therapeutics have shown that walnut leaves have hypoglycemic, antioxidative, antimicrobial and antihypertensive effects (Gîrzu et al, 1988). It is well known that certain chemicals produced by plants are naturally toxic to bacteria and fungi. Various medicinal plant extracts containing flavonoids are reported to have antimicrobial activity (Basile et al, 1999)

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Conclusion