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 thatthere was no significant difference in the
activity of the spice extracts (p > 0.05) against the test organisms (Streptococcus pneumoniaeand 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 multi-drug
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, fox
glove, garlic and ginger (Wainright, 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 (Gisleneet 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 andMyristicafragrans(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-BiskupandSaez, 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.