Effects of cobalt-60 gamma irradiation on microbial contaminants and phytochemical constituents of different medicinal plants
Medicinal plants have been utilized worldwide for many centuries to treat diseases and enhance human’s health since they are rich in phytochemical constituents. Nowadays, medicinal plants still play an important role in healthcare sectors across many countries include Europe and Southeast Asia....
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2020
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/97749/1/FPSK%28m%29%202020%2014%20-%20IR.1.pdf |
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| Summary: | Medicinal plants have been utilized worldwide for many centuries to treat
diseases and enhance human’s health since they are rich in phytochemical
constituents. Nowadays, medicinal plants still play an important role in
healthcare sectors across many countries include Europe and Southeast Asia.
Recently, medicinal plants such as Eurycoma longifolia, Ficus deltoidea and
Centella asiatica have been widely commercialized as herbal-based products in
Malaysia. However, high occurrence of microorganisms in medicinal plants can
cause hazards to the consumers and change the therapeutic effects. For this
reason, the study is focused on the effectiveness of cobalt-60 gamma irradiation
in reducing the microbial contaminants and preserving the phytochemical
constituents in common medicinal plants; Orthosiphon aristatus (Blume) Miq.,
Labisia pumila and Piper betle L. This study provides preliminary data on the
effectiveness of gamma irradiation as an efficient food sterilizer and provide
specific dosages to sterilize herbs in Malaysia.
The medicinal plants were processed as powder, individually packaged and
exposed to 0, 3, 6, 9 and 12 kGy cobalt-60 gamma irradiation at Malaysia
Nuclear Agency. The microbial contaminants present in non-irradiated and
irradiated medicinal plants were evaluated at 0, 3 and 6 months by conducting
the microbial enumeration tests; Total Aerobic Microbial Counts (TAMC) and
Total Yeast and Mold Counts (TYMC), bacterial identification using selective
media and 16S rRNA PCR amplification. The microbial enumeration tests results showed that the bacterial, yeast and mold loads were significantly reduced
after irradiation. There were significant changes (P < 0.05) observed in the
microbial counts after irradiation at 3 and 6 kGy, whereas no significant changes
(P > 0.05) observed after higher dosages. Interestingly, P. betle showed low
microbial loads (< 102 CFU/g) and no significant changes (P > 0.05) were
observed pre- and post- irradiation.
The identification results revealed the presence of bacteria from
Gammaproteobacteria and Clostridia classes in non-irradiated O. aristatus and
L. pumila, while bacteria from Bacilli class mostly isolated from irradiated
medicinal plants. Dose of 6 kGy was able to eliminate pathogenic Bacillus cereus
in O. aristatus, whereas 9 kGy was able to eliminate pathogenic B. cereus in L.
pumila. Interestingly, no pathogenic bacteria detected in P. betle pre- and postirradiation.
The data clearly showed that gamma irradiation dose is plantdependent
where irradiation at 6 and 9 kGy were needed to eliminate pathogenic
bacteria in O. aristatus and L. pumila, respectively. This highlights that specific
dosages are needed in eliminating pathogenic bacteria in different medicinal
plants. Meanwhile, P. betle is considered as a microbial low plant and gamma
irradiation seems not necessary to be applied on the plant. Concurrently, there
were no changes in the phytochemical contents of medicinal plants in which
constituents including saponins, tannins, steroids and triterpenes were detected
in both non-irradiated and irradiated medicinal plants. In conclusion, cobalt-60
gamma irradiation is effective in reducing the microbial contaminants in
medicinal plants and maintaining the phytochemical constituents. |
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