Effect of extraction temperatures on tannin content and antioxidant activity of Quercus infectoria (Manjakani)

https://doi.org/10.1016/j.bcab.2019.101104Get rights and content

Abstract

This study was specifically aimed to investigate the effects of extraction temperatures on tannin and antioxidant activity; the interaction between these two responses towards the processing parameter chosen. The main bioactive compound; tannin was extracted from Quercus infectoria (Manjakani) galls using aqueous decoction method. Few different extraction temperatures were selected prior for the extraction of tannin from Q. infectoria galls optimally. The selected temperatures were at 50, 75 and 100 °C and the effects of these temperatures on tannin content and antioxidant activity were examined thoroughly. High Performance Liquid Chromatography (HPLC) was used to identify and quantify the active compounds mainly tannic acid found in Q. infectoria galls. Alternatively, DPPH radical scavenging assay was performed to analyse the antioxidant activity and trends affected from the extraction temperature. The results demonstrated that Q. infectoria aqueous extract gives the highest tannin concentration of 2233.82 ± 1.311 and highest antioxidant activity approximately at 93.422 ± 0.256% at the extraction temperature of 75 °C. The outcomes of this study illustrate that extraction temperatures gave significant effects on the response variables (tannin content and antioxidant activity) respectively and the interaction between these responses were considered.

Introduction

Concurrently, there are numerous studies being conducted on the potential of traditional plants on their biological activity and effects towards medicinal purposes. The biological activities correlated with these plants are basically related to the bioactive compounds present within these plants which notably able to exhibit physiological actions on human body (Mohemmadi, 2011). There are wide variety of bioactive compounds that have captured numerous researcher interest nowadays since a decade ago and they are tannins, saponins, alkaloids, flavonoids and phenolic compounds (Hill, 1952). However, the extraction of active compounds is highly reliant on various factors including type of extraction, extraction temperatures, solvent of extraction and concentration, particle size of medicinal plants and duration of extraction (Liyana-Pathirana and Shahidi, 2004; Nobre et al., 2005). These crucial factors will contribute to the efficiency of the bioactive compound extraction process based on its rate of extraction and quality of the extracted bioactive compounds. In this research, the extraction temperature is mainly the principle factor to be examined. Generally, extraction temperatures can potentially affect the chemical compositions and bioactivities of the plant extracts (Chen et al., 2016).

Quercus infectoria galls on the other hand have been widely used as folk medicine to treat wide range of illness including swelling, inflammation, teeth infection and oral cavity, acute diarrhea and bleeding (Galla, 1911; Kaur et al., 2008). Since ancient time, Asians have used this medicinal plant traditionally to treat inflammation diseases. While in Malaysia, this plant is widely known as Manjakani which has been extensively used as herbal drink to restore uterine wall elasticity among women after childbirth (Chopra et al., 1956). It was claimed that the high content of tannins present in this herbal plant is the main contributor to these biological actions. As being reported by researchers, high content of bioactive constituents such as tannins, gallic acid and syringic acid found in Q. infectoria galls have greatly induced the biological reactions exhibited by these compounds (Dar et al., 1956: Ikram and Nowshad, 1977; Hwang et al., 2000).

Tannins are widely distributed among all plants (Serrano et al., 2009; Manach et al., 2004). The galls of Q. infectoria contained specifically about 50–70% of tannins in composition besides about 2–4% of gallic acid and traces of ellagic acids (Evans, 2002). Since galls extract was found to be high content in polyphenols, it can pose a potent reducing power. Hence, when being tested chemically, the gall extracts able to exhibit a potent antioxidant activity (Kaur et al., 2008). A previous study also claimed that tannins from Q. infectoria galls whether aqueous, methanolic or ethanolic extract have high antioxidant activities consecutively (Ayub et al., 2015). Tannic acid is also a naturally occurring plant polyphenol, which are composed of a central glucose molecule which will derivatize at its hydroxyl groups with one or more galloyl residues (Gulcin et al., 2010).

Oxidative stress on the other hand is an important risk factor that would contribute to various chronic diseases. Free radicals and other reactive oxygen species are recognized as the possible agents related in the pathogenesis of sickness such as inflammatory arthropathies, asthma, Parkinson's and Alzheimer's disease, diabetes, cancers and also artheroclerosis. Besides that, these free radicals and reactive oxygen species are also responsible in human aging (Kanwar et al., 2009; Chiavaroli et al., 2011). As such, antioxidants can be defined as a substance potentially in delaying or inhibiting the oxidative damage to a target molecule (Yamagishi and Matsui, 2011). Antioxidants are defined as compound which able to inhibit or delay the oxidation of other molecules by its inhibition or propagation of oxidizing chain reactions (Velioglu et al., 1998). An antioxidant can actually trap free radicals which the compounds could be either phenolic acids, polyphenols or even flavonoids that has the ability to scavenge free radicals including peroxide, hyperoxide or lipid peroxyl. These antioxidant compounds will eventually inhibit the oxidative mechanism that leads to degenerative diseases (Wu et al., 2011). Hence, antioxidants are potentially able to protect human body from free radicals and the ROS (Reactive Oxygen Species) effects. Since ancient time, plants antioxidant has been greatly considered as a good alternative compared to modern medicines.

Since the extraction of bioactive compounds mainly tannins from Q. infectoria is highly crucial for numerous purposes. Considering factors that could affect the whole extraction process is beneficial for various purposes. Consecutively, the total extraction process of plants extracts is highly impacted from the crucial factors affecting the extraction process and that includes the extraction temperatures. In extracting the desired active compounds from the plant extract, it is crucial to screen for the best extraction temperatures beforehand in order to obtain a high quality of extracted compounds for diverse usage whether in pharmaceuticals, medicinal or other industries.

However, none of the evidence on scientific studies reported previously on performing different extraction temperatures effects on antioxidant activity and tannin content of Q. infectoria galls using decoction as its extraction method. Generally, active compounds from different plant extract requires extraction temperatures differently in which in the whole process, extraction temperature could affect the entire extraction process of desired active compounds. Hence, this present study primarily aimed to investigate the effects of extraction temperatures on the active compounds content (Tannin) extracted from Q. infectoria galls as well as to evaluate its antioxidant activity trends of the extracted active compound using DPPH free radicals scavenging assay.

Section snippets

Collection of plant material

The Quercus infectoria galls were purchased from a local herbal shop at Pasar Larkin, Johor Bahru and were sent to Food Laboratory at Institute of Bioproduct Development, Universiti Teknologi Malaysia, Skudai, Johor for further treatment.

Chemicals and reagents

2, 2-diphenyl-1-picrylhydrazyl (DPPH), Tannic Acid were purchased from Sigma-Aldrich (M) Sdn Bhd Chemicals.

Extraction of plant material

The raw material went for a pre-treatment process which includes cleaning and drying at 40 °C using a drying oven to remove excess water. The grinded

Results

Table 1 above shows the effects of extraction temperatures on concentration of tannic acid and its antioxidant activity. At minimum temperature of 50 °C, tannic acid is at its minimal amount which was around 1765 mg/g with approximately 91.9% of antioxidant activity. However, as the temperature increases to 75 °C, it can be illustrated that high amount of tannic acid has been acquired with as potentially high antioxidant activity at approximately 93.4%. However, both tannin content and

Discussion

Identification and quantification of tannic acid are performed by using High Performance Liquid Chromatography with UV detector was employed to identify and quantify tannic acid in Q. infectoria galls extract from different selection of extraction temperatures. The concentrations of tannic acid are determined by using the peak area from the calibration curves obtained as shown in Fig. 2 above.

The effects of extraction temperatures on phenolic compound mainly tannin found in Q. infectoria galls

Conclusion

Based on this present study, it can be deduced that extraction parameter plays a significant role in achieving optimal yet highly quality of the extracted bioactive compounds. Different plants comprise different active compounds which are responsible in exhibiting various human health benefits. Extraction temperatures are greatly important to properly distil out the active compounds from plant extracts. High temperatures may either boost up the amount of active compound extracted or degrades

Acknowledgments

Special thanks to the Universiti Teknologi Malaysia and Institute of Bioproduct Development for the research facilities provided.

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