Chemical Composition, Antibacterial and Antimutagenic Activities of Essential Oil from (Tunisian) Cyperus rotundus

Journal of Essential Oil Research: JEOR, Nov/Dec 2005 by Kilani, Soumaya, Abdelwahed, Afef, Ammar, Ribai Ben, Hayder, Nawel, Et al

Abstract

Essential oil from the tubers of Cyperus ratundus, obtained by steam distillation, was analyzed by GC and GC/MS. In total, 33 compounds were identified. The oil was characterized by its high content of sesquiterpenes with cyperene (30.9%) being major. The antibacterial activity of oil from tubers of Cyperus rotundus, showed more important activity against Gram-positive bacteria specially Staphylococcus aureus than Gram-negative bacteria. The antimutagenic activity was tested by the "SOS Chromotest" and the "Ames" test. C. rotundas oil acted as an antimutagen against Aflatoxin B1 in both Salmonella strains (TA100 and TA98) and Escherichia coli strain (PQ37) and against nifuroxazide in Escherichia coli strain (PQ37), where its mutagenicity is not expressed. The highest rates of AFB1 mutagenesis inhibition tested by Ames assay, ranged from about 82.56% for TA100 strain to 85.47% for TA98 strain at the same dose of 50 µg AFB1 per plate. Whereas, the mutagenic effect of respectively nifuroxazide and AFBl (50 µg/assay) were reduced by aproximately 58.19% and 81.67% when tested by the SOS chromotest assay.

Key Word Index

Cyperus wtundus, Cyperaceae, essential oil composition, antibacterial activity, mutagenicity, antimutagenicity, SOS chromotest, Ames test.

Introduction

Cyperus rotuncliis L., a sedge of the family Cyperaceae, was collected in the region of Monastir situated in the center of Tunisia in June 2003. It is widely distributed in the Mediterranean basin areas. This plant, which grows naturally in tropical, subtropical and temperate regions, is widespread in northeast, center and south (Gabes) of Tunisia (1).

The tuberal part of C, rotuncliis is one of the oldest known medicinal plants used for the treatment of dysmenorrhoea and menstrual irregularities. It was also used as analgesic, sedative, antispasmodic and to relieve diarrhea (2). Cyperus rotundus has been widely investigated by several authors (3,4). It is a medicinal plant appearing among Indian, Chinese and Japanese traditional drugs that are used against spasms, stomach disorders and anti-inflammatory diseases (5,6).

Other pharmacological investigations indicated that C. rotundus had remarkable hypotensive, anti-inflammatory and antipyretic effects. Previous phytochemical studies showed that the major chemical components of this herb were essential oil, flavonoids, sesquiterpenes and cardiac glycosides (7).

In this study, we report on the composition analysis of essential oil from C. rotundus tubers, its antibacterial and antimutagenic activities using two tests of genotoxicity: the "SOS chromotest" and the "Ames test."

The Aines test was further more chosen as it is a wellknown reference test that proved suitable in many similar investigations (8-11). Whereas the SOS chromotest is a widely used assay for genotoxic/antigenotoxic activity (12) that has been used for testing extracts from medicinal plants (13,14). The SOS chromotest and the Ames test detect genotoxicity by different mechanisms and thus complement each other.

Experimental

Chemicals: O-Nitrophenyl-β-D-galactopyranoside (ONPG) and P-nitrophenyl phosphate (PNPP) were purchased from Sigma, Germany. The positive mutagens Aflatoxin B1 (AFB1) and nifuroxazide were purchased from Sigma, Aldrich USA.

Plant material: Tubers parts of C. rotundas were harvested in the region of Monastir in the center of Tunisia, in June 2003. Botanical identification was carried out by Pr Chaieb (Department of Botany, faculty of Sciences, University of Sfax, Tunisia), according to the flora of Tunisia (1). A voucher specimen (CP-06.03) has been deposited in the Herbarium of the Laboratory of Pharmacognosy, Faculty of Pharmacy of Monastir, Tunisia.

Oil isolation: The oil was isolated from 100 g of the tubers parts by hydrodistillation for 2 h in 500 mL of distilled water, using the apparatus described in the 9th edition of the French Pharmacopeia cited by Bruneton (15). They were kept in vials covered with aluminium foil at 4°C (to prevent the negative effect of light, especially direct sunlight).

Oil analysis: The composition of the oil was investigated by GC and GC/MS. GC analysis was performed with chromatograph HP5890 equipped with a flame ionization detector (HP5 30 m x 0.25 mm fused silica capillary column, film thickness 0.25 µm). Injector and detector temperature were set at 240°C and 280°C, respectively. The oven temperature program was 50°C for 3 min, then 50°-280°C at 9°C /min, and 280°C for 3 min. Nitrogen was employed as carrier gas at a flow rate of 1 mL/min. The volume injected was 0.1 µL, of oil diluted in hexane (10%). The percentage composition of the oils was recorded from the GC peak areas without using any correction factors.

The sample was analyzed by GC/MS using a HP5972/A mass spectrometer recording at 70 eV at the same conditions as described above in GC analysis. The identification of compounds was performed by comparison of retention indexes (determined relatively to the retention times of a series of n-alkanes) with those of authentic standards of a mass spectra library (Wiley 275.1) (16).