Antibacterial effect of Ginger (Zingiber officinale) against Staphylococcus aureus

Medicinal plants are found to be useful as pharmaceuticals, nutraceuticals, cosmetics and food supplements.1 Plant derived products have been used for medicinal purposes for centuries. In traditional Indian medicine or Ayurveda, Zingiber officinale and many other herbs have been used as medicine.2 With an increase in the antibiotic-resistant strains of microorganisms, traditional plants are being investigated for their antibacterial and medicinal values. Traditional uses of plants have led to investigating their bioactive compounds, which have resulted in the detection of a significant number of therapeutic properties.1 Ginger has been used as medicine from Vedic period and is called 'mahaaushadhi' which means the great medicine.2 Ginger is easily available, universally acceptable and relatively inexpensive and well tolerated by Abstract This experimental study was carried out to determine the antibacterial effect of Crude Ginger Extract (CGE) and Ethanolic Ginger Extract (EGE) against standard strain of Staphylococcus aureus in the Department of Pharmacology and Therapeutics with the collaboration of Department of Microbiology, Mymensingh Medical College, Mymensingh from July 2016 to June 2017. The growth of Staphylococcus aureus started to be inhibited from 70% CGE incorporated media and complete inhibition of growth occurred at 100% CGE. In case of Ethanolic Extract, sensitivity was seen against Staphylococcus aureus using disc diffusion method. Zones of inhibition were 8, 13 and 19 mm at 25, 50 and 100 μg/10 μl respectively. The minimum inhibitory concentration (MIC) of EGE was assessed by broth dilution technique. The MIC of EGE was 400 μg/ml against Staphylococcus aureus. From the study it is clearly observed that there is definite antibacterial effect of crude ginger extract (CGE) and ethanolic ginger extract against Staphylococcus aureus. Further studies are required to detect and isolate the active ingredients present in the Ginger extract responsible for antibacterial effect.

most of the people.The ginger has been listed in'Generally Recognized as Safe' (GRAS) document of the US FDA. 2 Ginger (Zingiber officinale) belongs to Zingiberaceae family. 1 The Zingiberaceae plants are characterized by their tuberous or non-tuberous rhizomes, which have strong aromatic and medicinal properties. 3 The active ingredients of ginger are, phenolic compounds: shogaols and gingerols; Sesquiterpenes: bisapolene, zingiberene, sesquiphellandrene, curcurmene; others: 6-dehydrogingerdione, galanolactone, gingesulfonic acid, zingerone, geraniol, ginger glycolipids. 4 The active ingredients in ginger are thought to reside in its volatile oils, which comprise approximately 1-3% of its weight. 5 Ginger's active ingredients have a variety of physiologic effects. For example, the gingerols have antioxidant, antiinflammatory, anti-tumor, analgesic, sedative, antipyretic and antibacterial effects in vitro and in animals. 6,7 Active constituents of ginger inhibit multiplication of bacteria by membrane disruption. 8 Ginger is a strong antibacterial agent against Staphylococcus aureus. 6 Because of the increasing resistance of bacteria to antibiotics, herbal products are looking for new leads to develop better antibiotics.9 Therefore the aims of this study are to investigate the antibacterial effectiveness of crude paste and ethanolic ginger extract.

Preparation of crude ginger extract:
Ginger (1000 gm) was washed initially by distilled water and then by 95% ethanol and homogenized by using sterile mortar and pestle. Then it was sieved through double layer of sterile fine mesh cloth to make crude extract. This CGE was considered as 100% crude ginger extract.

Preparation of ethanolic ginger extract:
Ethanolic Ginger Extract was prepared by using 10 grams of the grounded ginger mixed with 200 ml of 95% ethanol and left in room temperature for 24 hours. After that it was filtered by using gauze pad to remove the large particle and then centrifuged at 3000 rpm for 10 minutes. Secondary filtration was done by filter paper to obtain a clear solution which was dried at 40°C in hot water bath and stored in the refrigerator until use. For preparation of parent solution, 1gm powder extract was mixed with 10 ml ethanol. Then it was filtered by gauze pad and centrifuged at 3000 rpm for 10 min and again filtered by filter paper. This solution was the source of preparing different concentrations of ethanolic ginger extract. The extract was stored at 4°C in refrigerator.

Calculation of concentration of different EGE Disc Diffusion solutions:
Powdered ginger extract 1gm in 10 ml ethanol. This solution was marked as Parent solution. 10

Antibacterial sensitivity test by disc diffusion method:
Antibacterial sensitivity test was performed by Modified Kirby-Bauer disc diffusion technique as following. After matching with 0.5 McFarland standards, a sterile cotton swab was dipped into bacterial suspension and streaked in three directions on the surface of Mueller-Hinton agar plates and then left for 5-10 minutes in room temperature. By using sterile forceps the blank paper discs (6 mm in diameter) were placed on the surface of the plates. Then with the help of micropipette 5µl amount of different concentrations of EGE were put over the blank discs and left for five minutes. Then the plates were incubated at 37°C for 24 hours. After that zone of inhibition for respective organisms were measured in mm by using ruler.

Determination of Minimum Inhibitory Concentration (MIC) of Ethanolic Ginger Extract (EGE) by broth dilution technique:
The minimum inhibitory concentration (MIC) is the concentration giving the least inhibitory activity and below which there is no further inhibition.
Stock EGE was prepared by mixing 1 gm of powdered ginger extract in 10 ml ethanol. With each 10 ml preparation except control-3 (set XII) 20 µl bacterial suspension was added after matching its opacity with that of 0.5 McFarland Standard. After matching the turbidity of bacterial suspension with 0.5 McFarland standards, 20 µl or one drop (0.02 m1) of bacterial suspension of Staphylococcus aureuswas separately added with each concentrations of working EGE in separate test tubes. These inoculum was also added to the controls (I and 2) except Control-3. The test tubes were marked set wise with black marker and were placed in the incubator at 37 0 C for 18 -24 hours. Then growth of test organism in each preparations of EGE were examined and compared against that of controls by matching their turbidity. The clear preparations were considered as no growth of bacteria and turbid ones, as growth of bacteria. The MIC was reported as lowest concentration of EGE required to prevent the visible growth of test organism.

Antibacterial sensitivity testing of ethanolic ginger extract
In case of Ethanolic extract in disc diffusion method sensitivity was seen against Staphylococcus aureus Zone of inhibition 8 mm at 25 µg/10 µl, 13 mm at 50 µg/10 µl and 19 mm at 100 µg/10 µl concentration (Figure 01). Table 04 shows that visible growth of Staphylococcus aureus was from Set-VII to Set-IX. And no growth was visible from Set-I to Set-VI. So, the MIC of EGE against Staphylococcus aureus was 400 µg/ml (Set-VI).

Conclusion
From this study it is clearly observed that there is definite antibacterial effects of ethanolic Ginger extract (EGE) against Staphylococcus aureus. The crude Ginger extract (CGE) also has its definite inhibitory effects against Staphylococcus aureus. Further studies are required to detect and isolate the active ingredients present in the Ginger extract responsible for antibacterial effect. Then their effects against the studied organism should be studied in vivo separately and their toxicity profiles should also be taken into account. Only then the Ginger extracts will fulfill the criteria for its therapeutic use. Until then ginger may be Mediscope 2020;7(1): 31-37 36