IT'S a chance discovery so unexpected it defies belief and threatens to reignite debate about whether there is a scientific basis for thinking homeopathic medicines really work.
A team in South Korea has discovered a whole new dimension to just about the simplest chemical reaction in the book—what happens when you dissolve a substance in water and then add more water.
Conventional wisdom says that the dissolved molecules simply spread further and further apart as a solution is diluted. But two chemists have found that some do the opposite: they clump together, first as clusters of molecules, then as bigger aggregates of those clusters. Far from drifting apart from their neighbours, they got closer together.
The discovery has stunned chemists, and could provide the first scientific insight into how some homeopathic remedies work. Homeopaths repeatedly dilute medications, believing that the higher the dilution, the more potent the remedy becomes.
Some dilute to "infinity" until no molecules of the remedy remain. They believe that water holds a memory, or "imprint" of the active ingredient which is more potent than the ingredient itself. But others use less dilute solutions—often diluting a remedy six-fold. The Korean findings might at last go some way to reconciling the potency of these less dilute solutions with orthodox science.
German chemist Kurt Geckeler and his colleague Shashadhar Samal stumbled on the effect while investigating fullerenes at their lab in the Kwangju Institute of Science and Technology in South Korea. They found that the football-shaped buckyball molecules kept forming untidy aggregates in solution, and Geckler asked Samal to look for ways to control how these clumps formed.
What he discovered was a phenomenon new to chemistry. "When he diluted the solution, the size of the fullerene particles increased," says Geckeler. "It was completely counterintuitive," he says.
Further work showed it was no fluke. To make the otherwise insoluble buckyball dissolve in water, the chemists had mixed it with a circular sugar-like molecule called a cyclodextrin. When they did the same experiments with just cyclodextrin molecules, they found they behaved the same way. So did the organic molecule sodium guanosine monophosphate, DNA and plain old sodium chloride.
Dilution typically made the molecules cluster into aggregates 5 to 10 times as big as those in the original solutions. The growth wasn't linear, and it depended on the concentration of the original. "The history of the solution is important. The more dilute it starts, the larger the aggregates," says Geckeler. Also, it only worked in polar solvents like water, in which one end of the molecule has a pronounced positive charge while the other end is negative.
But the finding may provide a mechanism for how some homeopathic medicines work—something that has defied scientific explanation till now. Diluting a remedy may increase the size of the particles to the point when they become biologically active.
It also echoes the controversial claims of French immunologist Jacques Benveniste. In 1988, Benveniste claimed in a Nature paper that a solution that had once contained antibodies still activated human white blood cells. Benveniste claimed the solution still worked because it contained ghostly "imprints" in the water structure where the antibodies had been.
Other researchers failed to reproduce Benveniste's experiments, but homeopaths still believe he may have been onto something. Benveniste himself doesn't think the new findings explain his results because the solutions weren't dilute enough. "This [phenomenon] cannot apply to high dilution," he says.
Fred Pearce of University College London, who tried to repeat Benveniste's experiments, agrees. But it could offer some clues as to why other less dilute homeopathic remedies work, he says. Large clusters and aggregates might interact more easily with biological tissue.
Chemist Jan Enberts of the University of Groningen in the Netherlands is more cautious. "It's still a totally open question," he says. "To say the phenomenon has biological significance is pure speculation." But he has no doubt Samal and Geckeler have discovered something new. "It's surprising and worrying," he says.
The two chemists were at pains to double-check their astonishing results. Initially they had used the scattering of a laser to reveal the size and distribution of the dissolved particles. To check, they used a scanning electron microscope to photograph films of the solutions spread over slides. This, too, showed that dissolved substances cluster together as dilution increased.
"It doesn't prove homeopathy, but it's congruent with what we think and is very encouraging," says Peter Fisher, director of medical research at the Royal London Homeopathic Hospital. "The whole idea of high-dilution homeopathy hangs on the idea that water has properties which are not understood," he says. "The fact that the new effect happens with a variety of substances suggests it's the solvent that's responsible. It's in line with what many homeopaths say, that you can only make homeopathic medicines in polar solvents."
Geckeler and Samal are now anxious that other researchers follow up their work. "We want people to repeat it," says Geckeler. "If it's confirmed it will be groundbreaking".
From issue 2316 of New Scientist magazine, 10 November 2001, page 4