Antimicrobial activity, phytochemical analysis and toxicity test of Cosmos caudatus Kunth extract
The uses of natural products in the elimination of microorganism contaminations in food have increased nowadays. In this study, air-dried leaf methanolic extract of Cosmos caudatus Kunth was used. The antimicrobial activity of C. caudatus extract and time-kill curve analysis was evaluated agai...
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| Format: | Thesis |
| Language: | English |
| Published: |
2015
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/71266/1/IB%202015%2034%20IR.pdf |
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| Summary: | The uses of natural products in the elimination of microorganism contaminations in
food have increased nowadays. In this study, air-dried leaf methanolic extract of
Cosmos caudatus Kunth was used. The antimicrobial activity of C. caudatus extract
and time-kill curve analysis was evaluated against foodborne pathogens. The stability
of extract at different pH and temperature also were evaluated. The identification and
quantification of bioactive compounds were conducted using LC-MS/MS and HPLC.
Three representative microorganisms were observed under transmission electron
microscope (TEM). The effect of C. caudatus extract on natural microflora in selected
food materials and its sensory acceptability were tested at different concentrations of
extract for different exposure time. The toxicity level of extract was assessed using
Artemia salina spp. Results showed that all tested foodborne pathogens were
susceptible to C. caudatus extract at different range of MIC value from 6.25 to 50.00
mg/ml. Time-kill curve study shows that all tested foodborne pathogens can be killed
by the extract with different time-killing curve. Generally, the antimicrobial activities
of C. caudatus extract were not significantly affected on tested pH and temperatures.
LC-MS/MS analysis identified the presence of rutin, quercetin 3-O-glucoside,
quercetin 3-O-arabinoside, quercetin 3-O-rhamnoside and quercetin. HPLC analysis
showed the highest concentration was quercetin rhamnoside (29.66 mg/g). All the
identified active compounds proved possess antimicrobial activities. TEM observation
showed changing on the pathogen cells’s structure. Generally the significant reduction
of natural microflora in raw food materials were started at 0.05% of C. caudatus extract
for 10 min of exposure time, and the sensory acceptability at this concentration and
time were accepted by the panellists. The toxicity study demonstrated that C. caudatus
extract was not toxic to A. salina (LC50 = 3.54 mg/ml). In conclusion, C. caudatus
extract exhibits antimicrobial activities, thus can be developed as natural sanitizer for
washing raw food materials. |
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