ANTIBACTERIAL ACTIVITY OF THYMUS VULGARIS AND MYRISTICA FRAGRANS ON STREPTOCOCCUS PNEUMONIAE AND PSEUDOMONAS AERUGINOSA

ABSTRACT

The aqueous and ethanolic extracts of the leaves of Thymus vulgaris (thyme) and the seeds of Myristica fragrans (nutmeg) were screened for their antibacterial activity and phytochemical constituents. The standard methods used to detect the phytochemicals present in the extracts revealed the presence of tannins, flavonoids, triterpenoids and phytosterols in all the extracts while steroids and amino acids were absent. The antibacterial evaluation of the spice extracts using agar plate-well diffusion and nutrient broth dilution techniques showed that there was no significant difference in the activity of the spice extracts (p > 0.05) against the test organisms (Streptococcus pneumoniae and Pseudomonas aeruginosa, clinical bacterial isolates). Ampiclox and chloramphenicol were used as control for the test organisms to provide approximate basis for the comparison of the activity of the extracts. The MIC and MBC was the same for all the extracts against S. pneumoniae, 6.25 mg/ml while 25 mg/ml for thyme extracts, and 50 mg/ml for nutmeg extracts against P. aeruginosa, showing the extracts to be bactericidal.

CHAPTER ONE

1.0 INTRODUCTION

The spread of drug-resistant pathogens is one of the most serious threats to public health in the 21st century.Although pharmacological industries have produced a number of new antibiotics in the last three decades, resistance to these drugs by microorganisms still remains. In general, bacteria have the genetic ability to transmit and acquire resistance to drugs, which are utilized as therapeutic agents (Cohen, 1992). Such a fact is a cause for concern, because of the number of patients in hospitals who have suppressed immunity, and due to new bacterial strains that are multidrug resistant. Consequently, new infections can occur in hospitals resulting in high mortality as observed by Montelli and Levy (1991).

The use of herbs as first medicines is a universal phenomenon. For a long period of time, plants have been a valuable source of natural products for maintaining human health, especially in the last decade, with more intensive studies for natural therapies. Most drugs of the past were substances with a particular therapeutic action extracted from plants. Thus, medicinal plants may be defined as any plant that can be put to culinary use such as onions, foxglove, garlic and ginger (Wainwright, 2001). More and more researchers find that food and their individual constituents perform similar fashion to modern drugs and sometimes better without the dreaded side effects (Serrentino, 1991).

Plant extracts have great potential as antimicrobial compounds against microorganisms (Gislene et al., 2000) and studies have reported that they can be used in the treatment of infectious diseases caused by resistant microbes.Thymus vulgaris (thyme) leaves and Myristica fragrans(nutmeg) seeds are plants parts that are widely used as spices for cooking especially for flavouring meats, soups and stews. They have also been reported to have medicinal uses and possess antimicrobial abilities(Stahl-Biskup and Saez, 2002; Cho et al., 2006; Narasimhan and Dhake, 2007).

Extracts of these spices were believed to have chemical components which are active against pathogenic microorganism. More people have continued to use these spices for a variety of culinary purposes in the absence of adequate toxicity data and proper understanding of their medicinal properties. Folk medicine practitioners believe that these herbs are non-toxic even though there is no scientific backing to support this claim. This study intends to investigate and provide adequate on the antibacterial properties and chemical constituents of thyme and nutmeg to determine whether they are beneficial or otherwise.

1.1 SIGNIFICANCE OF STUDY

Many antibiotics currently in use are either too expensive or possess undesirable side effects while some are no more effective due to bacterial resistance (Alper, 1998). Despite the remarkable progress in synthetic organic chemistry of the twentieth century, over 25% of prescribed medicines in industrialized countries are derived directly or indirectly from plants (Newman et al., 2000). Human disease management in Nigerian history also provides evidence of the relationship of plants and medicine (Ayandele and Adebiyi, 2007).

Thyme and nutmeg are spices widely employed in cooking in Nigeria. Researches have shown that both possess antibacterial capabilities but with the manner in which they are sold in market places, especially as thyme is processed and both spices are being exposed to prolong periods of sunlight, it is important to ascertain their efficacy. In the interest of public health, what is ingested is of great concern, the amount taken in is just as crucial and that they can help strengthen the immune system to resist deadly infections is a massive advantage.

1.2 AIM AND OBJECTIVES

The aim of this study is to evaluate the antibacterial activities of spices (thyme and nutmeg) especially as they serve culinary purposes. The objectives of this study are to;

i. Determine the effect of the spice extracts against test organisms (Streptococcus pneumonia and Pseudomonas aeruginosa).

ii. Compare the action of the aqueous and the ethanolic extracts of the spices.

iii. Determine whether the spice extracts are bactericidal or bacteriostatic.

1.3 SCOPE AND LIMITATION OF STUDY

This study was limited to the antibacterial effect of Thymus vulgaris leaves and Myristica fragrans seeds as well as the phytochemical screening of these spices was also conducted. The determination of the chemical constituents was qualitative for alkaloids, flavonoids, saponins, tannins, steroids, glycosides, triterpenoids, phytosterols, and amino acids. Their antibacterial activity was limited to the testing of the ethanolic and aqueous extracts of the thyme leaves and nutmeg seeds against Streptococcus pneumonia and Pseudomonas aeruginosa.