<em>In Vitro</em> Free Radical Scavenging Activity of Methanol Extracts of Some Selected Medicinal Plants of Nepal

Research Article

Austin J Biotechnol Bioeng. 2015;2(1): 1035.

In Vitro Free Radical Scavenging Activity of Methanol Extracts of Some Selected Medicinal Plants of Nepal

Khaga Raj Sharma1,2*, Surya Kant Kalauni1, Suresh Awale3 and Yuba Raj Pokharel4*

1Central Department of Chemistry, Tribhuvan University, Nepal

2Birendra Multiple Campus Bharatpur, Chitwan, Nepal

3University of Toyama, Frontier Research Core for Life Science, Japan

4Facuty of Life Science and Biotechnology, South Asian University, India

*Corresponding author: Kalauni Surya Kant, Central Department of Chemistry, Tribhuvan University, Kirtipur, Kathmandu, Nepal.

Received: January 19, 2015; Accepted: February 11, 2015; Published: February 24, 2015

Abstract

Antioxidant potential of phenolic content from methanol extracts of fifteen selected medicinal plants of Nepal were analyzed by using 1,1-Diphenyl-2- Picrylhydrazyl (DPPH) scavenging assay, reducing power and total antioxidant capacity. Out of them Acacia catechu, Berberis aristata, Bauhinia variegata, Cleistocalyx operculatus, Shorea robusta, Bergenia ciliata, Phyllanthus emblica, Bombax ceiba, Lyonia ovalifolia, Bridelia retusa, Drymaria diandra, Euphorbia hirta, Callicarpa sp., Ziziphus mauritiana, and Scoparia dulcis showed potent antioxidant activity as compared with the IC50 value of the reference standard ascorbic acid. The total phenolic content was measured to be 95.80±3.6 mg GAE/gm in Ziziphus mauritiana and 169.35±0.2 mg GAE/gm in Acacia catechu. The total flavonoid content was measured to be 10.70±0.0 mg QE/ gm in Callicarpa sp. and 18.6±0.3 mg QE/gm in Acacia catechu. This study indicated medicinal plants in Nepal have strong antioxidant potential with high total phenolic and flavonoids content. The methanol extract of these plants may be a potent source of natural antioxidant and its use in the management of diseases associated with oxidative stress is justified. This study may provide the scientific basis for traditional use of those plants and may provide valuable information for further research.

Keywords: Medicinal plants; Antioxidant; DPPH; Plant extract free radical

Introduction

Nepal has significantly diverse ecosystems producing a wide range of unique and valuable medicinal plant resources. The Ayurvedic health care system depends solely on the use of these highly valued native medicinal plants [1]. The majority of Nepalese peoples are dependent on indigenous use of medicinal plants. Medicinal and aromatic plants play vital role in Nepalese livelihood health and socioeconomic prospects. The majority of Nepal’s population, especially tribal, ethnic groups and mountain people relies on traditional medical practices. In many cases this practice is transmitted orally from generation to generation and confined to them [2,3]. Very few systematic studies have been done on the medicinal plants of Nepal for their antioxidant and anticancer activities. Thus, in the present study, we collected and screened the Nepalese medicinal plants from different ecological regions of Nepal for the antioxidant activity leading to the isolation of active compounds. Oxidation induced by Reactive Oxygen Species (ROS) result in cell membrane disintegration, membrane protein damage and DNA mutation. The effect can further initiate or propagate the development of many diseases, such as cancer, liver injury, cardiovascular disease, tumour inflammation, hemorrhagic shock, atherosclerosis, diabetes, infertility, gastrointestinal, ulcerogenesis, asthma, rheumatism and neurodegenerative diseases [4-6]. Although the body possesses such defense mechanism, as enzymes and antioxidant nutrients, which arrest the damaging properties of ROS, continuous exposure to chemicals and contaminants may lead to an increase in the amount of free radicals in the body beyond its capacity to control them, and cause irreversible oxidative damage [7,8]. Oxidants are capable of stimulating cell division, which is a critical factor in mutagenesis when a cell with a damaged DNA stand divides, cell metabolism and duplication becomes deranged [9]. Thus, mutation can arise which in turn is an important factor in carcinogenesis. Cigarette smoking and chronic inflammation are of the major causes of cancer which have strong free radical components in their mechanism of action [10-12]. Some reports have indicated that people who smoke tend to have lower antioxidant levels than non-smokers and these smokers are at an increased risk for both cancer and cardiovascular disease [13]. It is generally assumed that frequent consumption of plant derived phytochemicals from vegetables; fruits, tea and herbs may contribute to shift the balance toward an adequate antioxidant status [14-16]. In this study we selected fifteen medicinal plants from different ecological regions of Nepal based on ethnobotanical applications. We found that these medicinal plants are the potent sources to isolate the pure antioxidant compound that could be used for management of different chronic illnesses.

Materials and Method

Plant materials

The plant samples were collected from different ecological regions of Nepal based on their ethnobotanical uses as shown in Figure 1 and Table 1. Dr. Rita Chhetry, Research Officer, National Herbarium and Plant Resources, Ministry of Forests and Soil Conservation, Godawari, Nepal identified the plants.