Determination of antioxidant activity of lichen Cetraria islandica (L) Ach

https://doi.org/10.1016/S0378-8741(01)00396-8Get rights and content

Abstract

The study was aimed at evaluating the antioxidant activity of aqueous extract of C. islandica. The antioxidant activity, reducing power, superoxide anion radical scavenging and free radical scavenging activities were studied. The antioxidant activity increased with the increasing amount of extracts (from 50 to 500 μg) added to linoleic acid emulsion. About 50, 100, 250, and 500 μg of aqueous extract of C. islandica showed higher antioxidant activity than 500 μg of α-tocopherol. The samples showed 96, 99, 100, and 100% inhibition on peroxidation of linoleic acid, respectively. On the other hand, the 500 μg of α-tocopherol showed 77% inhibition on peroxidation on linoleic acid emulsion. Like antioxidant activity, the reducing power, superoxide anion radical scavenging and free radical scavenging activities of C. islandica depends on concentration and increasing with increased amount of sample. The results obtained in the present study indicate that C. islandica is a potential source of natural antioxidant.

Introduction

Oxygen is present in the atmosphere as a stable triplet biradical (3O2) in the ground state and a vital component for the survival of the human. Once inhaled, it undergoes a gradual reduction process and ultimately gets metabolized into water. In this process, a small amount of reactive intermediates, such as superoxide anion radicals (O2radical dot), hydroxyl radicals (OHradical dot), nonfree radical species (such as H2O2), and the single oxygent (1O2) are formed (Sies, 1993). Those reactive intermediates are collectively termed as reactive oxygen species (ROS) (Halliwell, 1995, Sato et al., 1996, Squadriato and Peyor, 1998, Yildirim et al., 2000). These primary derivatives of oxygen play an important role in mediating ROS-related effects (Halliwell and Gutteridge, 1989). ROS can easily initiate the peroxidation of the membrane lipids, leading to the accumulation of lipid peroxides. The peroxidation products by themselves and their secondary oxidation products, such as malondialdehyde (MDA) and 4-hidroxinonenal (4-HNE) are highly reactive; they react with biological substrates, such as protein, amines, and deoxyribonucleic acid (DNA) (Kehrer, 1993).

In living organisms various ROS can be formed by different ways. In normal aerobic respiration, stimulated polymorphonuclear leukocytes and macrophages, and peroxisomes appear to be the main endogenous sources of most of the oxidants produced by cells. Exogenous sources of free radicals include tobacco smoke, ionizing radiation, certain pollutants, organic solvents and pesticides. (Halliwell and Gutteridge, 1989, Halliwell, 1994, Davies, 1994, Robinson et al., 1997, Yildirim et al., 2000).

Most living species have an efficient defense systems to protect themselves against the oxidative stress induced by ROS (Sato et al., 1996). Recent investigations have shown that the antioxidant properties of plants could be correlated with oxidative stress defense and different human diseases including cancer, atherosclerosis, and the aging processes (Stajner et al., 1998, Sanchez-Moreno et al., 1999, Malencic et al., 2000).

Antioxidants can interfere with the oxidation process by reacting with free radicals, chelating free catalytic metals and also by acting as oxygen scavengers. Phenolic antioxidants functions are free radical terminators and sometimes also metal chelators (Shahidi and Wanasundara, 1992, Sanchez-Moreno et al., 1999). Thus, antioxidant defense systems have co-evolved with aerobic metabolism to counteract oxidative damage from ROS.

The antioxidants may be used to preserve food quality from oxidative deterioration of lipid. Therefore, antioxidants play a very important role in the food industry. Synthetic antioxidants, such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and tert-butylhydroquinone (TBHQ) are widely used in the food industry, but BHA and BHT have suspected of being responsible for liver damage and carcinogenesis (Grice, 1986, Wichi, 1988). Therefore, the development and utilization of more effective antioxidants of natural origin are desired.

Lichens have been used for medicinal purposes throughout the ages and some, such as C. islandica, Lobaria pulmonaria and Cladonia speres were reputed to be effective in the treatment of pulmonary tuberculosis (Vartia, 1973). Lichen species are very common in Turkey. Especially, C. islandica is one of the most common lichen species, which grows in west regions of Turkey (Dülger et al., 1998). Some lichen species are used as stomachic and antidiabetic drug in Turkish folk medicine (Baytop, 1999). C. islandica is well known in Turkish folk medicine and used for treatment of diseases such as hemorrhoids, bronchitis, dysentery and tuberculosis (Dülger et al., 1998). In addition, this lichen species has been used as hemostatic drug (Baytop, 1999).

Many scientists have investigated the chemical composition of the lichen C. islandica beginning from the XIX century till today. However, so far the nature of the lichen has not been elucidated exactly (Stepanenko et al., 1997). In addition to this, there are some pharmaceutical studies about composition of this lichen species. Protolichesterinic acid isolated from C. islandica has in-vitro inhibitory effects on arachidonate 5-lipoxygenase. Protolichesterinic acid, α-methylene-γ-lactone, fumarprotocetric acid and β-orcinol depsidone are considered to be the major biologically active secondary metabolites in the lichen C. islandica (Ogmundsdottir et al., 1998). Several lichen metabolities of C. islandica exhibited highest antimiyobacterial activity (Ingolfsdottir et al., 1998). Aliphatic α-methylene-γ-lactone isolated from the lichen C. islandica were found to be potent inhibitors of the DNA polymerase activity of human immunodeficiency virus-1 reverse transcriptase (HIV-1 RT) (Pengsuparp et al., 1995). However, there is no information about antioxidant activity of aqueous extract of lichen C. islandica. In our investigation, we wanted to describe the antioxidant effects of C. islandica and to compare their antioxidant effects with those commonly used as food antioxidants, such as BHT, BHA, and α-tocopherol. In addition to this, the components responsible for the antioxidative ability of C. islandica are currently unclear. Hence, it is suggested that further work could be performed on the isolation and identification of the antioxidative components in C. islandica.

The aim of the present study was to investigate the antioxidant properties of C. islandica in order to evaluate its medicinal value and to point to an easily accessible source of natural antioxidants that could be used as a possible food supplement or in the pharmaceutical industry.

Section snippets

Chemicals

Ammonium thiocyanate was purchased from E. Merck. Ferrous chloride, polyoxyethylenesorbitan monolaurate (Tween-20), α-tocopherol, 1,1-diphenyl-2-picryl-hydrazyl (DPPH.), nicotinamide adenine dinucleotide (NADH), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), quercetin and trichloracetic acid (TCA) were purchased from Sigma Chemical Co. All other unlabeled chemicals and reagents were analytical grade.

Lichen material

The lichen C. islandica was collected in Oltu, Erzurum regions of Turkey and

Results and discussion

C. islandica (L) Ach. demonstrated effective antioxidant activity at all concentrations (Fig. 1). The antioxidant activity of C. islandica was determined by the thiocyanate method. The effects of various amounts of aqueous extract of C. islandica (from 50 to 500 μg) on peroxidation of linoleic acid emulsion are shown in Fig. 1. All concentrations of aqueous extract of C. islandica showed higher antioxidant activities than that 500 μg of α-tocopherol and had 96, 99, 100 and 100% inhibition on

Conclusion

Aqueous extract of C. islandica showed strong antioxidant activity, reducing power, DPPH radical and superoxide anion scavenging activities when compared with different standards such as α-tocopherol, BHA, BHT, and quercetin. The results of this study show that aqueous extract of C. islandica can be of use as an easily accessible source of natural antioxidants and as a possible food supplement or in pharmaceutical industry. However, the components responsible for the antioxidative activity of

References (35)

  • H.C Grice

    Safety evaluation of butylated hydroxytoluene (BHT) in the liver, lung and gastrointestinal tract

    Food and Chemical Toxicology

    (1986)
  • B Halliwell

    Free radicals, antioxidants and human disease: curiosity, cause or consequence

    Lancet

    (1994)
  • B Halliwell

    How to characterize an antioxidant: an update?

    Biochemistry Society Symphosium

    (1995)
  • B Halliwell et al.
  • T Hatano et al.

    Effect of interaction of tannins with co-existing substances. VI. Effects of tannins and related polyphenols on superoxide anion radical and on DPPH radical

    Chemical and Pharmaceutical Bulletin

    (1989)
  • J.P Kehrer

    Free radicals as mediators of tissue injury and disease

    CRC Critical Reviews in Toxicology

    (1993)
  • Dj Malencic et al.

    Screening for antioxidant properties of Salvia reflexa hornem

    Phytotherapy Research

    (2000)
  • Cited by (445)

    View all citing articles on Scopus
    View full text