Houseplant has many medicinal properties (4/6/98)The beneficial effects of the aloe vera plant were recorded long ago in the writings of Hippocrates, yet only in recent times have we begun to understand the true healing properties of this magnificent plant.
According to Wendell D. Winters, PhD, associate professor of microbiology at The University of Texas Health Science Center at San Antonio, extracts from the aloe plant, applied topically, can relieve pain and act as an anti-inflammatory.
"What is there in aloe that makes it work?" asks Dr. Winters. "This has been the subject of our international cooperative investigations for over 14 years.
"It all started when three South Texas friends familiar with aloe's actions, Ray Benevides, Jim Fuentes and Jesus Garza, said that minor cuts, insects stings and wounds healed more quickly when aloe was used on the skin," says Dr. Winters. "Since I'm a microbiologist, this piqued my curiosity. These men have volunteered their assistance throughout the years and their cooperation has contributed to helping prove that aloe definitely helps promote healing.
"In our initial studies, we found the rate of growth in normal human cells - skin cells or epithelial cells - could be increased as much as 50 percent with crude extracts of aloe," says Dr. Winters. "As it turned out, no one had done this previously."
This paper, published in the early eighties, has been quoted several thousand times.
The scientists then tried aloe on all different types of human and animal tumor cells and found it had little or no effect. However, a counterpart study determined that commercial aloe, available at markets, was toxic for both normal human cells and human tumor cells.
"This was undoubtedly due to the material put into aloe to preserve it - the fillers - not the aloe itself," says Dr. Winters. "aloe, fresh from the plant, promotes growth of normal cells; it doesn't kill normal cells. Even fresh aloe that has been freeze-dried maintains many of its good properties. It appears to expedite wound healing, apparently due to increased collagen activity."
In 1991, Dr. Winters was chairman of a world conference held in Seoul, Korea, where scientists from 17 countries presented scientific data for the first time about various species of aloe. "Once all the species had been tested only three were found to be commonly used worldwide in folk or traditional medicines, although there are about 600 known species," says Dr. Winters. "Aloe barbadensis Miller, grown mostly in the southwestern part of the United States including South Texas, and in Florida, has proven to be the most beneficial."
The three aloe species commonly used for folk medicine purposes share five major common polypeptides (a compound of low molecular weight that yields two or more amino acids when split).
"All three species contained substances with properties similar to that described by my friends so many years before - they all promoted healing, were immune-reactive and could be anti-microbial," says Dr. Winters.
The other 597 species are mainly decorative, although a few do have limited anti-microbial and growth-healing qualities.
"Our next question was, how do we make this available for everyone? We found that there were many varieties of aloe in the valley and that they hybridized naturally with each other, which made them less desirable," says Dr. Winters. "In cooperation with scientists from the Texas A&M extension station, who had done a comparison of the agricultural factors influencing the growth of all aloes in the valley, studies were made to determine why there were changes in bioactivities when aloe is obtained from different places."
Dr. Winters realized that no one had previously compared the different aloe species, so his international team of scientists took young, adolescent and mature plants and looked at the whole leaf, the gel, the roots, the stems and the stalks, searching for the richest source of aloe's medicinal substances. Using biochemical and biological analyses, they found certain materials with healing properties in the whole leaf and in the gel, some in the root, but very little in the stem. In the root, age didn't matter - it could be an immature, an adolescent or a mature plant. Overall, mature plants proved to be the best source of bioactive substances.
Reference specimens of the medicinal aloes from Africa and the Pacific Rim were acquired and grown in Texas. After comparisons were made, it was found that almost all those aloes have properties that will increase healing and cell growth; however, they differed in terms of their ability to stimulate immune responses.
Like many natural products, when purified, aloe doesn't work very well. "We can't totally purify aloe," says Dr. Winters. "In the philosophy of folk medicine one thing interacts with another - like the yin and yang in Chinese traditional medicine - one thing balances here and another must balance there. This means a minimum level of interactive components are essential to achieve the desired bioeffects, i.e., on wound healing.
"Using substances extracted from medicinal aloes, we first found that aloe stimulates human lymphocytes in the test tube," he continues. "In other words, aloe could stimulate your immune system and your lymphocytes to combat infection and promote healing. Unfortunately, further testing determined it would take too large a quantity of these aloe substances for this to do much good compared to other immune cell stimulators.
"In our recent experiments, we found that aloe contained powerful red blood cell hemagglutinins (antibodies that cause clumping)," Dr. Winters says. "Furthermore, cell agglutinins were also detected. So we devised an inhibition of binding assays with known sugars to try to identify the nature of the aloe agglutinin. We found that there is only one sugar that
worked well and this is a sugar that some human tumor cells and human and animal viruses share on their surface.
"Through exchanges of information, Pacific Rim scientists have used aloe to treat athlete's foot and other surface fungi," says Dr. Winters. "aloe also has proven to inhibit in vitro infection with certain other viruses, particularly of the herpes group."
Working with Dr. John Heggers at the Shriner's Burn Institute in Galveston, Dr. Winters tested wound healing with aloe in animal models. "We identified aloe hemagglutinins effective in wound healing activity - incisional wounds, bites and insect stings. One must be quick to apply fresh aloe after insect stings for it to work. aloe doesn't appear to help stings of the sting ray or jelly fish, though - they carry a different toxin," says Dr. Winters.
"A word of caution - several deaths have now been attributed to ingesting or being injected with aloe. Some people were using aloe as a purgative for weight reduction. They found it worked and they took more and more to cleanse their bodies. They took too much," Dr. Winters says. "There has been an element of toxicity in aloe fed to animals.
"Based on present evidence, aloe should only be used topically on humans," he says. "Eat it with caution. In our studies of hypersensitivity to aloe substances, up to 20 percent of the normal volunteer study group had a reaction to some aloe extracts. More men than women had reactions, for some reason. So there is something vigorously immuno-reactive in aloe and we have to investigate further."
What does the future hold for aloe?
"Dr. Yushu Huo and I are investigating several Chinese traditional medicines," says Dr. Winters. Dr. Huo is a visiting professor from China who is past director of the World Health Organization's Chinese Traditional Medicine Reference Laboratory and is now a member of the Chinese Food and Drug Administration panels.
"We are especially interested in aloe substances that are anti-viral. While aloe has proven to be anti-microbial, we don't yet know how good it is going to be," says Dr. Winters. "The Chinese have used aloe as part of some treatments for skin disorders. We are attempting to merge the best of Pacific Rim traditional medicines with Eastern-type medicine.
"I'm looking forward to a very interesting future for phytotherapeutics (plant therapy)," Dr. Winters concludes, smiling.
Contact: Jan Elkins, (210) 567-2570