Elsevier

Food Chemistry

Volume 97, Issue 4, August 2006, Pages 654-660
Food Chemistry

Antioxidant activity of some algerian medicinal plants extracts containing phenolic compounds

https://doi.org/10.1016/j.foodchem.2005.04.028Get rights and content

Abstract

Phytochemicals are extensively found at different levels in many medicinal plants. This work had two objectives: the first, to evaluate the total phenolic or flavonoid contents of 11 Algerian medicinal plants and second, to determine whether these compounds have an antioxidant capacity toward free radical propagation. The polyphenolic extractions of the dried powdered samples have been performed using 70% ethanol. The total phenolic content, analyzed using Folin–Ciocalteu’s reagent, of the samples varied from 3.13 to 32.32 mg/g dry weight, expressed as gallic acid equivalents (GAE). The total flavonoid concentrations, detected using 2% aluminum chloride, varied from 1.62 to 13.12 mg rutin equivalents (RE)/g dry weight. To analyze the antioxidant activity, a common stable radical chromogen, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTSradical dot+), was used. The antioxidant activity measurement, expressed as Trolox equivalent antioxidant capacity (TEAC), ranged from 9.40 to 33.06 mM Trolox equivalents. With further data analysis it was found that there was a positive correlation between the total phenolic content of a given sample and its antioxidant activity, R2 = 0.7931, whereas the correlation between the total flavonoids and antioxidant activity was determined to be R2 = 0.7802. These results suggest that the level of antioxidant activity in these plants varies to a great extent. They also suggest that phenolics in these plants provide substantial antioxidant activity. Upon achievement of this survey, and using more samples, an extra benefit of these medicinal plants may be found. Flora of Algeria appears to be a rich and interesting source for supplementary ethnomedicinal and phytochemical studies.

Introduction

Herbs have been used in many domains including medicine, nutrition, flavoring, beverages, dyeing, repellents, fragrances, cosmetics, smoking, and other industrial purposes. Since the prehistoric era, herbs have been the basis for nearly all medicinal therapy until synthetic drugs were developed in the nineteenth century (Dahanukar et al., 2000, Exarchou et al., 2002).

The preservative effect of many plant spices and herbs suggests the presence of antioxidative and antimicrobial constituents in their tissues (Hirasa & Takemasa, 1998). Recently, interest has increased considerably in finding naturally occurring antioxidants for use in foods or medicinal materials to replace synthetic antioxidants, which are being restricted due to their carcinogenicity (Velioglu, Mazza, Gao, & Oomah, 1998).

Many medicinal plants contain large amounts of antioxidants such as polyphenols, which can play an important role in adsorbing and neutralizing free radicals, quenching singlet and triplet oxygen, or decomposing peroxides. Many of these phytochemicals possess significant antioxidant capacities that are associated with lower occurrence and lower mortality rates of several human diseases (Anderson et al., 2001).

It has been reported that there is an inverse relationship between the antioxidative status occurrence of human diseases (Rice-Evans, Sampson, Bramley, & Holloway, 1997). In addition, antioxidant compounds which are responsible for such antioxidants activity, could be isolated and then used as antioxidants for the prevention and treatment of free radical-related disorders (Middleton et al., 2000, Packer et al., 1999). Therefore, research to identify antioxidative compounds is an important issue. Although it remains unclear which of the compounds, of medical plants are the active ones, polyphenols recently have received increasing attention because of some interesting new findings regarding their biological activities. From pharmacological and therapeutic points of view, the antioxidant properties of polyphenols, such as free radical scavenging and inhibition of lipid peroxidation, are the most crucial. Even though a variety of herbs are known to be sources of phenolic compounds, studies isolating polyphenols and evaluating their antioxidative effects have rarely been carried out.

The choice of our investigated plants is based on two criteria: first, in this domain there is no study in Algeria that deals with these plants, and the second criterion is that these plants have ethnopharmacological data indicating their traditional utilization in the treatment of some abdomional diseases (Table 1). In addition, they have been proved to be efficient in the treatment of various cancerous lesions of the stomach, colon, rectum esophagus and liver. Furthermore, they have been described in treating hypertention and oedema, and as detoxicant, diuretic, anti-inflammatory, anti-pyretic and anti-purulent agents. Due to their traditional utilization and active components, these plants are also considered to be efficient for the treatment of free radical-related disorders.

The purpose of this study was to evaluate a variety of 11 medicinal plants that are of the same location and have grown in the same conditions. This evaluation is related to the total phenolic content and antioxidant activity to find out new potential sources of natural antioxidants.

Section snippets

Plant material

Eleven plants have been evaluated in this study, namely Artemisia campestres L, Artemisia herba halba, Artemisia arboresens L, Artemisia arvensis L, Juniperus oxycedrus L, Globularria alypum L, Oudneya africana, Thymeelaea hirsuta, Ruta monata L, Thapsia garganica and Teucrium polium L.

The medicinal plants were gathered in June 2002, from different places around the town of laghouat in the steppe region of Algeria. The various data (local name, medicinal uses, used parts of plant, method of

Total phenolic content

The amount of total phenolics varied in different plants and ranged from 3.1 to 32.3 mg GAE/g of dry material. The highest total phenolic levels have been detected in “Anthemis arvensis L”, “Artemisia campestris L” and “Globularia alypum L”, and the lowest in “Artemisia arboresens L” and “Ruta montana L” (Table 2).

It has been noted that amount of total phenolic compounds in Aseteraceae varieties is higher then the other families. The amount of total phenolic compounds in all tested plants was

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