Late night reading:
~ 07/1988
Chinese Herbs Screened for Anti-HIV Activity
Two researchers, one at the University of California at
Davis and the other at the Chinese University of Hong Kong, have
screened 27 herbs used in traditional Chinese medicine for treat-
ing infections. Five of the herbs almost completely stopped HIV
in laboratory cells; six others also showed significant activity
(see lists below). The scientists published this work in the
journal Antiviral Research earlier this year.
The first step in the study was to select the herbs. The
researchers used a computerized database of traditional Chinese
medicinal herbs, compiled at the Chinese University of Hong Kong,
to select the 27 herbs to test. Many others would also be
appropriate for the same screening.
Then crude extracts were prepared by boiling "under reflux",
meaning that special apparatus was used to condense and recircu-
late vapors. After further purification steps, the researchers
ran tests to find the greatest concentration of each extract
which was not toxic to the cells and did not inhibit their
growth.
Then each of the 27 herbs was assayed by adding HIV to the
cell cultures in the presence of the largest nontoxic concentra-
tion of the extract. Every assay was repeated three times. To
be considered as showing anti-HIV activity, every one of the
three assays had to reduce the percent of infected cells by at
least three standard deviations from the average value in control
assays (which were done in quadruplicate).
For example, the herb which did best, Viola yedoensis,
reduced the percentage of infected cells from 12.8 to zero in the
first assay, from 3.8 to .4 in the second, and from 21.5 to
extract not toxic to the cells.
The five best herbs were Arctium lappa L., Viola yedoensis,
Andrographis paniculata, Lithospermum erythrorhizon, and Alter-
nanthera philoxeroides. The other six which also passed the test
in all three assays were Epimedium grandiflorum, Lonicera japon-
ica, Woodwardia unigemmata, Senecio scandens, Coptis chinensis,
and Prunella vulgaris.
The researchers studied one herb, Viola yedoensis, in
greater depth. They found that it did not kill or inactivate HIV
on direct exposure, did not induce interferon production by the
cells, and did not inhibit herpes or other viruses against which
it was tested. The mechanism of action against HIV is unknown.
Comments
The fact that a drug stops HIV infection in the laboratory
does not mean that it will work in people. And in this experi-
ment, the concentrations of herbal extracts tested -- the maximum
concentration which did not harm the cells which the HIV was
infecting -- was probably much higher than could be achieved in
the body. Presumably blood levels were not measured because of
the many obvious difficulties of conducting any human experimen-
tation. If the researchers had set out to run human trials,
their project would not have happened at all.
Yet despite this caution in interpreting the results, it
seems clear that a medicine long used in humans and which almost
completely stops infection of cells by HIV at a concentration
harmless to the cells deserves a closer look. How will this
research be carried out?
The authors stated in their paper that they do not have the
expertise or facilities to isolate and identify the anti-HIV
compounds. Drug companies could do this work. But even if one
took an interest -- and few of even the largest pharmaceutical
companies have any antiviral program -- it would take years to
isolate the chemicals, learn how to manufacture and use them, and
get them approved as drugs.
The alternative, of course, is to test the herbs themselves,
with the help of herbalists familiar with them. Such a trial
might be done through a community-based research organization
such as New York's Community Research Initiative. That way the
trial would meet all legal standards for protection of patients,
and also meet scientific standards of good study design and data
collection and analysis, so that the results would be credible.
In practice it will take a long time to get any such study
going, because there are so few organizations now doing
community-based trials, and so many candidate drugs to test.
Meanwhile people are likely to try some of the herbs on their
own; most if not all of those mentioned above are widely avail-
able. Anyone trying herbs should at least check with herbalists,
physicians, or other experts about dosage, precautions, and any
other information on how to use them safely. Even though herbs
are "natural", they are medicines and must be used appropriately.
For More Information
For more information on screening the herbs for anti-HIV
activity, see R. Shihman Chang and H. W. Yeung, "Inhibition Of
Growth Of Human Immunodeficiency Virus By Crude Extracts OF
Chinese Medicinal Herbs", Antiviral Research, 9 (1988), pages
163-176.
Note that we have only reviewed the article here. We have
not interviewed the authors, or herbalists or other experts. We
hope that others, perhaps an organization of herbalists or of
persons interested in AIDS treatments, will look further into
these potential treatments. We do not know of anyone following
up these leads at this time. |
