Use of garlic and ginger as a natural supplement is considered healthy choice for the treatment of cardiovascular diseases [19
], hypertension [21
], diabetes [22
]. Alzheimer's disease [23
], inflammation, thrombosis [25
] and even for cancer [26
]. Recently ginger was also reported for treatment of nonalcoholic fatty liver diseases, [27
]. With the increasing awareness of population toward natural therapies, spices can be considered as obvious alternate medication [28
In the present study antibacterial effect of garlic and ginger was evaluated by disc diffusion method. The results indicated that different extracts of spices have broad spectrum antibacterial activity with variable degree of sensitivity of tested bacterial species toward these extracts. The controls did not show any antimicrobial activity. The data presented in Table
shows that garlic aqueous extract exhibited highest antibacterial activity against all tested bacteria except E. coli
. Garlic methanol extract was least effective against all tested bacteria. The antimicrobial activity shown by garlic extracts in this study agrees with the findings of others [13
Antibacterial activity of spices extracts measured as diameter (mm) of zone of inhibition
The results given in Table
show that ginger methanol and ethanol extracts are more effective against all tested bacterial strains than ginger aqueous extracts. E. coli
were also more susceptible to the ginger extracts. E. coli
showed maximum susceptibility to the ginger ethanol extracts while Shigella
showed maximum susceptibility to both ginger methanol and ethanol extract. The results of antimicrobial effect of ginger in the study are in accordance with most of the reports published regarding ginger antimicrobial activity [32
]. The antibacterial activities of the extracts are expected perhaps due to the compounds like flavonoids and volatile oil which were dissolved in organic solvents. It is reported that sesquiterpenoids are the main component of ginger which attributes its antibacterial activity [35
]. The results obtained in our study corroborate with the report of Roy et al [37
], which explains that bioactive compounds of ginger rendering antimicrobial activity are volatile in nature and antimicrobial activity of ginger extract decreases upon storage. In addition to water, methanol and ethanol were also used for extract preparation as de Boer et al [38
] has reported that bioactive compounds show better solubility in water miscible organic solvents.
The order of antibacterial activity of different garlic and ginger extracts against tested clinical isolates of pathogenic bacteria was as follow: 1) E. coli, GiEE> GiME> GaAE> GiAE> GaME> GaE; 2) P. aeruginosa, GaAE> GiEE> GiME> GaEE> GiAE>GaME; 3) Bacillus subtilis, GaAE> GiEE> GaEE> GiAE>GaME> GiME; 4) Shigella, GiEE, GiME> GaEE> aAE> GiAE> GaME; 5) S.aureus, GaAE> GiME> GiEE, GiAE> GaEE> GaME; 6) K. pneumoniae, GaAE> GaEE> GiME> GiEE, GiAE, GaME; 7) S.epidermidis, GaAE> GiEE> GiAE> GiME> GaEE> GaME; 8) S.typhi, GaAE> GiME> GiEE> GiAE> GaEE> GaME.
The minimum inhibitory concentration (MIC) was determined by making the dilutions of different extracts of garlic and ginger ranging from 100
mg/ml to 0.01
mg/ml. The MIC values of different garlic and ginger extracts are summarized in Figure and respectively. The results showed that MIC of different extracts of garlic and ginger against bacterial strains ranged from 0.05
mg/ml to 1.0
mg/ml. The data in Figure indicated that all tested strains were susceptible to garlic aqueous, methanol and ethanol extract but most effective was garlic aqueous extract. From all MIC values of different garlic extracts, lowest MIC values for E. coli, P. aeruginosa, B. subtilis, S. aureus, K. pneumoniae, S. epidermidis
and S. typhi
mg/ml and 0.02
mg/ml respectively with garlic aqueous extract except Shigella
which showed lowest MIC value (0.07
mg/ml) with garlic methanol extract. Ethanol and methanol extract of ginger had lower MIC in comparison to the ginger aqueous extract against tested bacterial strains (Figure ). In case of different ginger extracts, the lowest MIC value for E. coli
mg/ml), P. aeruginosa
mg/ml), B. subtilis
mg/ml) and S. epidermidis
mg/ml) was observed with ginger methanol extract while for S. aureus
mg/ml), K. pneumoniae
mg/ml) and S. typhi
mg/ml) was observed with ginger ethanol extract. The ginger methanol and ethanol extract showed lowest and same MIC value for Shigella
Minimum inhibitory concentration (MIC) of different garlic extracts against tested bacterial isolates.
Minimum inhibitory concentration (MIC) of different ginger extracts against tested bacterial isolates.
The decreasing susceptibility of tested pathogenic bacteria was observed in this order: S.epidermidis>S.aureus>B. subtilis>P. aeruginosa>K. pneumoniae=S.typhi>E. coli=Shigella.
It was interesting to note that clinical isolates, both Gram negative and Gram positive bacteria were sensitive to all tested extracts of garlic and ginger but Gram positive bacteria were more sensitive than Gram negative bacteria. This result is in accordance with the findings of Chandarana [39
]; Onyeagba [40
] and de-Souza [41
It is established in the study that spices reduce and inhibit the growth of food pathogens therefore the use of spices would decrease the chances of food poisoning and increase the food shelf life. Several socioeconomic factors are major cause of miserable health condition of poor people of Pakistan which includes; poverty, unhygienic conditions, overcrowding, contamination of food /water by poor sanitary practices, limited awareness of seriousness of foodborne diseases and importance of hygiene. While living in such conditions, use of spices (garlic/ginger) in diet can reduce the risk of food contamination, protect the consumer from different foodborne diseases, improve their health status and combat with the foodborne diseases by using small quantity of spices (garlic/ginger) in diet. In this study heat effect on antimicrobial activity of garlic and ginger was not checked as it is already reported that antimicrobial activity of garlic is affected by heating at 100°C for 30–60 minutes [42
]. Therefore, it is recommended to use garlic and ginger in different raw forms like pickle, garlic/ginger bread, curry powder, sauces, raw juices and without extensive cooking.
In conclusion, the results of present study have provided the justification for therapeutic potential of spices. The practice of using spices as supplementary or alternative medicine in developing countries like Pakistan will not reduce only the clinical burden of drug resistance development but also the side effects and cost of the treatment with allopathic medicine. Further clinical evaluation of spices in in vivo experiments is required to be carried for low cost treatment with few side effects and for prevention of recurrent infection.