Fishes could use herbal
medicines like humans too
Asian herbs are popular in many parts of the world owing to ‘natural
origin’, low cost, and zero side effects. A recent study has found that it
benefits fishes too.
Tilapia fishes are cultured for food in many countries
including China, the Philippines, Taiwan, Indonesia, Thailand, India, and Bangladesh.
Significant numbers of fishes die in summer months due to infection
from a bacterium Entercoccus faecalis
in aquaculture farms leading to huge financial losses.
A group of scientists from Bangladesh found that feeding
fish with extracts of garlic and clove prevents death due to Entercoccus faecalis infection. This bacterium was resistant to most
available antibiotics and herbal medication could help prevent disease and death
in infected fishes, according to the study published in the journal Scientific Reports.
“A large number of herbs are effective against bacterial
diseases in humans. Therefore, we thought that screening medicinal plants
against fish pathogen may result in useful information and we, fortunately, got
it”, says Tofazzal Islam, Professor at the Department of Biotechnology, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh, who led the
study.
They collected tilapia fishes that looked ill from several
aquaculture farms in Ghazipur in Bangladesh. Fishes showed excess slime,
protruding opaque eyes, and swollen abdomen. The pelvic region had blood clots and
the tail fin seemed washed off. They swam erratic, were lethargic, and had a
decreased appetite. Since the cause of infection was unknown, the fishes were
brought to the lab where the disease-causing bacteria were isolated from the
skin, tail, gut, eye and brain.
After culturing on an artificial medium under controlled
conditions, the bacteria were identified to be Enterococcus faecalis. Subsequent tests revealed that they were
resistant to commercial antibiotics amoxicillin, ampicillin, cefradine,
cefuroxime, erythromycin and penicillin-G and mildly susceptible to
nitrofurantoin, azithromycin, gentamycin, levofloxacin, and vancomycin.
When healthy tilapia fishes were infected with the
bacterium, they died in less than 72 hours indicating that this bacterium was
highly virulent. Before exposing them to the bacterium, some fishes were
fed with herbal medicines and others were left untreated. Those that received
the herbal medication showed an average survival rate of approximately 70
percent compared to null in the infected untreated group. Commercial antibiotic azithromycin
exhibited a survival rate of about 75 percent, which was similar to that
bestowed by herbal medicines.
They selected garlic and clove after screening 23 different
herbs that included zinger, turmeric, onion, pomegranate, chilli, tamarind,
guava, and Indian gooseberry. “Our results suggest that medicinal plant extracts
could be used as a potential alternative to the synthetic antibiotics to
control fish diseases caused by Enterococcus
faecalis in aquaculture”, claim scientists in their paper. They emphasize
that mechanism of action of the plant crude extracts in preventing and fish
disease has to be elucidated.
“Bangladesh is ranked fourth in aquaculture in the world. We
are working now for elucidating the mode of action of crude extracts and also to
make a commercial formulation for the aquaculture industry. It would hugely
benefit the aquaculture industry in Bangladesh and other Asian countries as
natural herbs are safe and cost-effective”, exclaims Professor Islam.
The team consisted of Muntasir Rahman, Md Mahbubur Rahman,
Suzan Chandra Deb, Md Shahanoor Alam, Md Jahangir Alam, and Md Tofazzal Islam. This
study was done at the Bangabandhu Sheikh Mujibur Rahman Agricultural University,
Gazipur, and Shahjalal University of Science and Technology, Sylhet in Bangladesh.
Reference: Scientific Reports | 7: 3747 |
DOI:10.1038/s41598-017-03673-1
By Bhavya Khullar
No comments:
Post a Comment