Defence mechanism
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City scientists prepare strong antibiotics out of discarded placenta.
Srabanti Basu reports
New formulation: Bhattacharyya (right) and Chakraborty (Picture by Anirban Bose) |
It is the tissue, which connects a mother and her child before birth. During delivery, it comes out of the mother’s body and is usually thrown away as a waste. But to some drug manufacturers, it is of tremendous importance as the medicines prepared from it help in wound healing. Doctors prescribe it for skin diseases, burn injuries, chronic urinary tract infection and even in post-surgical dressings.
Though the placental extract, as doctors call it, works well against a range of medical problems, nobody knew for sure how it works. Recently Dr Debasish Bhattacharyya and Piyali Datta Chakraborty of the Indian Institute of Chemical Biology (IICB), Calcutta, have got some clues to unravel the mystery. Bhattacharyya and his colleague have studied the properties a formulation prepared from the placental extract.
The drug resists growth of common bacteria and fungi that make the wounds messy, says Bhattacharyya. He mixed the drug along with bacterial or fungal food and let the bugs grow on it. The bugs did not grow even after three days, whereas normally they take only six hours to have a full-fledged growth.
The bacteria against which Bhattacharyya tested the drug included Escherichia coli (which causes urinary tract infection), Staphylococcus aureus (responsible for skin and other infections) and Pseudumonous aeuruginosa (which invades the wound and turns it septic). He also tested the efficacy of the drug against fungi like Saccharomyces cerevisiae and Candida albicans. The former also makes wounds septic, whereas the later is responsible for severe skin diseases.
Bhattacharyya and his team found that the drug inhibited growth of all these bacteria and fungi. Some of the bacterial samples used in the tests were isolated from patients admitted at the state-run hospitals in the city. “This shows that the extract is effective not only on lab-grown bacteria, but also on those that affect patients at the clinics,” says Bhattacharyya. Some of the varieties used by the IICB team can withstand common antibiotics like ampicillin or chloramphenicol. Bhattacharyya has reported their findings in a recent issue of the journal Current Science, givint details of the placental extract’s capacity to prevent even the growth of those antibiotic-resistant organisms.
The IICB team has found out what makes the bacteria susceptible to the placental extract. They purified the components of the drug by a high-precision purification method and tested each component for the anti-bacterial and anti-fungal properties. They identified some short DNA molecules which inhibited the growth of bacteria and fungi.
“These DNA fragments inhibit duplication of DNA molecules before cell division and thus do not allow the bacteria to divide and multiply from two to four, four to eight and so on,” explains Bhattacharyya. In the normal bacterial or fungal cells, two strands of DNA molecule exist together. Before cell division, these strands get separated and the DNA molecule is duplicated. The short DNA fragments present in the placental extract bind with the separated DNA strands and prevent their duplication.
Apart from resisting bacterial growth, the extract boosts the capacity of our immune system. The researchers got a small protein from the placental extract which is similar to fibronectin, a protein present in blood. Fibronectin represents a group of proteins, rather than a single one. The members of the group are a part of the body’s defence system and help fight invaders. “Since the protein we identified has similar structure to one of the members of fibronectin family, there is every possibility that it can charge up our defence system and play similar roles,” says Bhattacharyya.
The protein probably binds with some other proteins present on the cell surface. These proteins then interact, forming a network, and the cells stay together.
The IICB team also identified a small molecule, known as NADPH, in the placental extract. Like fibronectin, this molecule is abundant in blood cells and plays a key role in destroying foreign bacteria. Probably the presence of all the three compounds makes the placental extract a good wound-healer. According to the IICB team, efficiency of the extract as a wound-healer is independent of mother’s age.
The drug that Bhattacharyya and his team worked on is manufactured by the drug company Albert David Limited, Kolkata (ADLK). “It is a licensed drug available only under prescription and not over the counter,” says Dr Subhasree Bhattacharyya, Medical Advisor, ADLK. “We collect placenta from state-run hospitals and the medicine is extracted from it.” The IICB team tries to avoid using the placenta of aborted foetuses as they pose a risk of infection.
The use of placental extract as a drug is not new. It was used in traditional Chinese medicine around 4,000 years ago. Even now in some tribal communities, women use placental extract as a health-booster after childbirth. As a mainstream medicine, the extract made its debut in 1950s. Prof. V. P. Filatop, a Russian opthalmologist and the pioneer of corneal transplants, used it for preservation of corneal tissues. He also used the extract to treat corneal ulcer.
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