Antimicrobial Activities of Garlic and Ginger Extracts
CHAPTER ONE
OBJECTIVE OF STUDY
The objective of this study is to explain the antimicrobial activities of garlic and ginger extracts.
CHAPTER TWO
LITERATURE REVIEW
Underground stem (rhizome) of Zingiber officinale (Ginger) has been used as a medicine in Asian, Indian, and Arabic herbal traditions since ancient times (Altman and Marcussen, 2001). It has been used extensively for more than 2500 years in China for headache, nausea, and colds (Grant and Lutz, 2000) and in Mediterranean (Sharma and Clark, 1988) and Western parts in herbal medicine practice for the treatment of arthritis, rheumatological conditions and muscular discomfort (Bordia et al., 1997, Langner et al., 1998).
During the thirteenth and fourteenth centuries, next to pepper, ginger was the commonest and most precious of spices, costing nearly seven scrolling per pound, or about the price of a sheep (Watt, 1872; Mahindru, 1982). The literature also indicates that ginger preserved in syrup (called Green Ginger) was also imported to the Western World during the middle ages and was regarded as a delicacy of the choicest kind. In Africa, ginger is regarded as auspicious, which is absolutely necessary to the Savaras tribe for their religious and marriage functions (Mahindru, 1982).
During the Middle Ages and until the end of the nineteenth century English tavern keepers used to have ground ginger in constant supply for thirsty customer to sprinkle on top of their beer or ale and then stir into the drink with a red-hot poker (Rosengarten, 1969). The Western herbalists and naturalists knew the great qualities of ginger as confirmed by the well-known British herbalist John Gerad. He writes in his herbal (1577) that “ginger is right good with meat in sauces,” and says that this spice is “of an eating and digesting quality (Parry, 1969).
History of ginger in India
In olden India, ginger was not important as a spice, but it was named as mahabheshaj, mahaoushadhi, literally meaning the great cure, the great remedy. For the ancient Indian, ginger was the God given universal remedy for a number of ailments. That may be the reason why ginger found a prime place in the ancient Ayurvedic texts of Charaka (Charaka samhita) and Susruth (Sushrutha samhita). In Ashtangahridyam of Vagbhatt (a very important ancient Ayurvedic text), ginger is recommended along with other herbs for the cure of elephantiasis, gout, extenuating the juices, and purifying the skin from all spots arising from scorbutic acidities. Ginger is also recommended when exotic faculties were impaired due to indigestion.
Rabbi Benjamin Tudella, who travelled between 1159 and 1173 A.D and gave an account of ginger cultivated on the west coast of India. Tudella gave a vivid description of the place and trade in spices as well as cultivation of spices in and around the port of Quilon in the State of Kerala (Mahindru, 1982). Marco polo (A.D. 1298), in his famous travelogue, writes “good ginger also grows here in known by the name of Quilon ginger. Another traveller, Friar Odoric (A.D. 1322), writes. Quilon is at the extremity of pepper forests towards the south. Ginger is grown here, better than anywhere else in the world and huge quantities.
Linschotten (1596) presented a very interesting description of the spices. He observed that ginger grew in many parts of India, but the best and the most exported grew on the coast of Malabar.
Ridley (1912) gave a detailed description about ginger and turmeric practices prevalent in nineteenth-century India. Buchanan (1807) made many references on the cultivation of various spices, including ginger, during the journey to south India. Later on ginger cultivation spread from Kerala to various others parts of India, mainly to Bengal and North-eastern states.
CHAPTER THREE
METHODOLOGY
Preparation of Extracts
In order to prepare fresh garlic (Allium sativum) extract, fresh garlic was purchased from the local market, deskinned and was washed with 0.2% mercuric chloride solution for 3-4 times and then washed 5-6 times in sterile distilled water. About 100g of this washed garlic was mashed in sterile mortar and pestle and sieved through sterile muslin cloth to obtain the extract. From this 0.5, 1.0, 2.0, 4.0, 7.0 and 10.0 per cent of the extract was prepared. Fresh extract was prepared at each time of the experiment.
The fresh extract of ginger (Zingiber officinale) was prepared as described for the preparation of garlic.
Bacterial Cultures
The standard culture of Listeria monocytogenes (MTCC-657) was obtained from the Institute of Microbial Technology, Chandigarh and Escherichia coli (V517) was obtained from the Department of Veterinary Microbiology, College of Veterinary and Animal Sciences, Mannuthy, Thrissur. These isolates were maintained in Nutrient agar media.
In order to test each isolate, it was subcultured in Brain Heart Infusion broth (Hi-Media, Mumbai) and was incubated at 37°C for overnight. The serial dilution of the culture was made in sterile normal saline solution (NSS). All overnight cultures were standardized using the MacFarland turbidity standard using sterile normal saline. The count of the serially diluted samples was also estimated by pour plate method. The count per ml of the samples was estimated by multiplying the mean count of each dilution with the dilution factor. The dilution with a count of 105 organisms per ml was selected for the estimation of antibacterial effect of ginger and garlic extract.
Estimation of Inhibitory Effect
The sterile brain heart infusion broth (9ml) each was transferred into fourteen tubes, with 1ml each of the inoculums containing 6.6 x 105 of Listeria monocytogenes. One ml of each concentration of the garlic extract were added in duplicate tubes containing the inoculums. Two of the tubes were kept as control without the addition of the extract. The optical density (OD) of both the experimental and control tubes were determined by spectrophotometer at 620 nm. Then the control and experimental tubes were incubated at 37°C for 24 hours. At the end of the incubation period, the OD of each tube was determined as before. The experiment with the extract at the above concentration was repeated six times. The difference between the final and initial readings was calculated and interpreted as the growth of bacteria whereas the comparison of the final readings with the control reading depicted the inhibitory effect of the spices on bacterial cultures.
Inhibitory effect on Escherichia coli was determined as in case of Listeria monocytogenes but the initial inoculum contained 7.2 x 105 cfu/ml.
CHAPTER FOUR
RESULTS AND DISCUSSION
The antibacterial effect of ginger (Zingiber officinale) and garlic (Allium sativum) extract on Escherichia coli and Listeria monocytogenes was determined invitro by spectrophotometer method.
The effect of these spice extracts at varying concentrations on E.coli is shown in Table I. From the table, it may be observed that the inhibitory effect of garlic and ginger extract increases with the increase in the concentration of the extracts. Similar observation was also reported by Ural et al. The inhibitory effect of ginger extract was much higher at all concentrations as compared to garlic extract on the organism. The antibacterial effect of ginger extract at 0.5, 1.0 and 2.0% level was significantly (p<0.05) higher than that of garlic extract on E. coli. The observation of the study also indicate that the inhibitory effect of Allicin (active principle of garlic) on Gram positive bacteria was more as compared to Gram negative bacteria. Both the extracts were found to produce bacteriostatic effect at all concentrations.
The MIC of the garlic and ginger extracts on E. coli is shown in Fig. 1. The MIC required for the inhibition of 80% growth of the organism was 9.1 and 8.7 per cent of garlic and ginger extract, respectively. In a study, it was observed that garlic at different concentrations (25%, 50%, 75% and 100%) had good antibacterial action against a number of E. coli serogroups, whereas ginger had only moderate antibacterial action. Aqueous extracts of ginger had no significant antibacterial effect on E. coli. The per cent of garlic extract required to produce 80% inhibition of the organism observed in the study was much higher than that recorded in another study, where it was observed that 4% of the extract produced the above effect. This may be attributed to the difference in the strain of E. coli used in both studies and also the difference in the variety of garlic used in the above studies. While some workers observed that the antimicrobial activity of clove on E. coli was more than other spices like ginger, garlic, mustard, amla, aloe vera and saffron, another worker reported that turmeric had more antibacterial effect on E. coli than ginger, cinnamon, clove and asafoetida.
The inhibitory effect of these spice extracts at varying concentration on Listeria monocytogenes is shown in Table-2. Both ginger and garlic extracts have bacteriostatic effect on the organism. The inhibitory effect of garlic extract at 0.5 per cent level was significant (P≤0.5) as compared to the effect of ginger. Increase in concentration of extracts inhibit the growth of bacteria, which is indicated by the reduction in OD value. The above observation of the study was in accordance with the findings of some workers, while in another study, it was observed that the essential oil of ginger extracted by hydrodistillation had the highest efficiency against L. monocytogenes, with a minimum concentration of inhibition being 6.25 µg/ml.
CHAPTER FIVE
CONCLUSION
Garlic and ginger extracts produced bacteriostatic effect against Escherichia coli and Listeria monocytogenes invitro. Both the spices exhibited more inhibitory effect against Gram positive organism as compared to Gram negative. Hence, both the spices provide a potential for their use as natural preservatives in food.
There are several advantages for the use of spices (that derived from plant origins) as dietary supplement or alternative medicine manifested by reduction the chance for developing antibiotic-resistant bacteria that resulted from the frequent use of antibiotics (misuse, abuse), beside decreasing the cost of treatment (drug administration) and also minimizes the development of adverse drug reactions.
RECOMMENDATION
It is recommended for further in the future studies that should focus more on other advantages of spices especially the clinical applications in order to obtain low cost treatment and also prevention of recurrent infection.
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