Rice chemist uses buckyballs to reinvent ‘antibiotic of last resort’

Rice
chemist uses buckyballs to reinvent ‘antibiotic of last resort’
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BY JADE BOYD
Rice News Staff

Rice University chemists hope a new
variant of vancomycin that contains buckyballs — tiny cage-shaped molecules
of pure carbon — could become the world’s first targeted antibiotic,
creating a new line of defense against bioweapons like anthrax.

Vancomycin, which entered clinical
service 40 years ago, is the antibiotic of last resort, given only when all
others fail. Unfortunately, vancomycin-resistant strains of bacteria have appeared
in recent years.

In an effort to reinvigorate the
antibiotic, researchers have created vancomycin conjugates — pairs of vancomycin
molecules joined by an intermediate molecule that acts as a bridge — some
of which have proven more effective at killing resistant bacteria.

Rice Chemistry Professor Lon Wilson
decided to create a buckyball-vancomycin conjugate following years of work developing
biochemical targeting mechanisms for buckyballs, spherical cages containing
60 carbon molecules. By linking antibodies to a buckyball with anticancer drugs
attached to it, Wilson and two of his graduate students, Tatiana Zakharian and
Jared Ashcroft, are creating targeted compounds that will bind only with certain
cells, like those found in melanoma tumors, for example.

“Having the ability to target
antibiotics to attack specific bacterial antigens opens the door for treatments
that simply aren’t available today,” said Wilson. “For example,
we believe it’s feasible to create a C60-vancomycin conjugate that attaches
to anthrax while it is still in the spore form.”

Weaponized anthrax is delivered in
spores, a dormant form in which the disease is encased in a rugged shell. Once
the spore finds its way into a living host, it germinates and becomes active.

Wilson said vancomycin can attack
anthrax only after it germinates. However, having the ability to affix the antibiotic
to a spore could enable the drug to knock the disease out when it tries to emerge
from hibernation, before it has a chance to spread throughout the body and release
its toxins.

A postdoctoral fellow in Wilson’s
lab, Andrey Mirakyan, recently presented preliminary results of the work at
this spring’s American Chemical Society annual meeting, and the researchers
expect to publish their findings soon.

This research was sponsored by the
Welch Foundation.