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Agronomy

Small and powerful

Researchers verify protective effects of a Brazilian mushroom

miguel boyayanShitake cultivated in the field, on eucalyptus trunksmiguel boyayan

Fleshy and soft to the touch, the Agaricus blazei fungus, the Murill Mushroom known popularly in Brazil as the mushroom of the Sun, stimulates the immune system and works like a powerful collaborator in the treatment of hepatitis C, to the extent that it improves the appetites of the patients, who usually lose a lot of weight. It also diminishes the side effects of the antiviral medicines, like fatigue and muscle pains. Furthermore, it is an excellent source of proteins and vitamins.

Every 100 grams of the dehydrated mushroom contains 35 grams of proteins, besides iron, phosphorus, calcium, and vitamins of the B complex. These were some of the conclusions reached by the team of researchers coordinated by Professor Augusto Ferreira da Eira, from the Plant Production Department of the School of Agronomic Sciences of the São Paulo State University (Unesp) of Botucatu, after four and a half years of studies. They also found that many of the results publicized by the media for Agaricus blazei, like the reduction of tumors, are only achieved with the concentrated extract of the fungus, and not with pills and teas.

The study of the medicinal properties of A. blazei, and also of Lentinula edodes, the mushroom known as shitake, was one of the objectives of the research. The growing demand from producers for techniques that guarantee better results in the cultivation of these mushrooms also served as an incentive. Funded by FAPESP, the project now has results for farming, mainly of the A. blazei, which are being passed on to the producers, who are concentrated in the São Paulo cities of Sorocaba and Piedade and in the western part of the state (Boituva, Conchas, Lençóis Paulista, Marília and others).

Traditional consumption
Like other mushrooms of the same genus, A. blazei looks like an umbrella. It originates from the mountain regions of the Atlantic Rain Forest in the south of the state of São Paulo. In the 1970’s, it was taken to Japan, where its medicinal properties began to be studied. On the other hand, shitake took the opposite route. It was brought from Asia by the Japanese and Chinese, and was acclimatized to Brazilian conditions. Although it is the second most consumed mushroom in the world, with about 14% of the market, it is still far behind the unbeatable leader, Agaricus bisporus, the famous mushroom that originates from France, with over 50%.

There are, in the world, about 10,000 known species of mushrooms, according to some specialists, of which 700 are edible, 50 toxic, and from 50 to 200 used in medicinal practices. Among the Asians, the tradition of the medical consumption of mushrooms goes back many years, as is attested by reports dated from almost 2,000 years ago. And they are the biggest consumers of the Brazilian product, according to data from the Ministry of Development, Industry and Foreign Trade. In the first quarter of this year alone, of the 6,243 kilos (kg) of dry A. blazei exported, in the amount of US$ 557,901.00 (US$ 89.36 the kilo), almost the whole, or 6,223 kg, had Japan for a destination. In 2003, of the 20,072 kg sold, 19,368 went to the Japanese market.

In the last few years, A. blazei has become very well known, because of popular reports about the benefits brought about by tea made with this mushroom, which is said to be responsible for the recovery and the improvement in the clinical conditions of patients with cancerous tumors, when administered together with the conventional treatments like radiotherapy and chemotherapy. “We went into the research to see what is the truth and what is a lie, in the reports spread abroad by the media”, Augusto says.

Taking part in the project were researchers linked to several areas, such as biotechnology, immunology, pathology, biochemistry, and agronomy, adding up, by the reckoning of the coordinator, to about 80 professionals, split into seven teams. The first task for the researchers involved in the project, which started in 1999, consisted of verifying whether the fungus that was to be studied was precisely the A. blazei. To do so, strains were chosen from the states of São Paulo, Paraná, Rio de Janeiro, Minas Gerais, and Rio Grande do Sul.

The analysis, carried out by Brazilian mycologists (experts in mushrooms), with others from Israel taking part, resulted in the proposition that the Brazilian strains should be identified as Agaricus blazei (Murr.) ss. Heinem, or as a new species, called Agaricus brasiliensis, because they are really different from the strains found in Florida, United States, and described by mycologist William Murrill in 1945. The study that identifies the Brazilian species, headed up by Solomon Wasser, from the University of Haifa, in Israel, was published in 2003 in the International Journal of Medicinal Mushrooms and is awaiting the opinion of other mycologists.

In parallel with this work, the mushrooms obtained in several situations of cultivation were sent to the other teams. The group responsible for the biochemical characterization, coordinated by Professor Edson Rodrigues Filho, from the Chemistry Department of the Federal University of São Carlos (UFSCar), analyzed several substances in apolar extracts (fatty acids, which are present in mushrooms) and also in polar ones (which are soluble in water, like proteins and amino acids). “In the case of A. blazei’s apolar extracts, several substances were detected, including linoleic acid, described in the scientific literature as having anticarcinogenic properties for animals”, Augusto says.

To find out at what stage of the mushroom linoleic acid is most present, several strains were looked into, picked in their young stage, characterized by the closed top of the mushroom, known as the cap, and at the stage at which it is now fully open. According to Augusto, the market prefers the whiter, closed mushroom for consumption. “But it is not always the young mushroom that contains more active ingredients”, he adds.

Cell protection
Carried out by Ana Paula Terezan, a student for a master’s degree at the Chemistry Department of UFSCar, the tests indicated that in some strains the linoleic acid, for example, is more concentrated in the open stage, while in others this happens in the young stage. The variations were related to the lineage and to the material used as covering, where they are cultivated, which can be turf, schist, or a mixture of earth and charcoal.

Another team, coordinated by Lúcia Regina Ribeiro, from the Pathology Department of the School of Medicine at Unesp in Botucatu, assessed the efficiency of the aqueous extracts of A. blazei and shitake in rats, against tumors and other chemically induced cell damage. This study had the objective of assessing whether the much proclaimed medicinal properties of the mushroom taken in the form of juices or teas really had any foundation. The experiments showed that the aqueous extracts protect against genetic alterations in the cells. “When the mushrooms were ground and incorporated into the feed, the benefit was the nonappearance of tumors”, Augusto says.

The researches also threw new light on the form of extraction and the daily dosage indicated for the mushrooms. Some producers recommend the consumption, on a daily basis, of up to 40 grams of dehydrated A. blazei, in an aqueous infusion of 1 liter, at a temperature of 100°C and boiled during from one to two hours.

Data obtained by the team coordinated by Ramon Kaneno, from the Microbiology and Immunology Department of UNESP’s Biosciences Institute, run totally counter to these recommendations. “The tests showed that aqueous extracts of A. blazei obtained by boiling curtailed the survival of mice suffering from cancerous tumors, compared with treatment with juices, probably for their hepatotoxic effects”, Augusto reports. As a result of these results, the researchers are studying far smaller doses than the 40 grams in powder form or in the form of juice.

According to Augusto, almost everything that is said about reducing the progression of tumors, enhancing the survival of the patients, and even contributing towards a regression of the tumors was not corroborated with the taking of teas (hot infusions). These effects can only be observed when concentrated fraction of A. blazei are used, in which the active ingredients are to be found present in more strength. “In fractions soluble in ammonium oxalate (ATF extract), the researchers from the area of immunology observed that the tumors stopped proliferating. They did not regress, but they stagnated at a given point”, he reports.

“About 80% of the concentrated extracts (ATF) are made up of betaglycans (polysaccharides), which really do have an effect of controlling tumors. He stresses that the propaganda targeting the consumer uses scientific results that were obtained with concentrated extracts, which does not correspond to the products that are on sale, in the form of pills, for example. “In spite of the mushroom of the sun being known by this name for a long time, a businessman entered a request to register the brand”, Augusto says. The case recalls the case of cupuassu, a typical fruit from the Amazon, the registration of which was canceled in Japan (please see Pesquisa Fapesp nº 98).

Augusto reminds us that A. blazei has an effect in neutralizing free radicals (molecules linked to the process of cell degeneration) and works as an important assistant in some kinds of treatment, such as chemotherapy, because it eliminates, in part, the side effects. As to radiotherapy, tests by the team coordinated by Professor Alzira Teruio Yida-Satake, from the Dermatology and Radiotherapy Department of Unesp’s School of Medicine in Botucatu, showed that the teas from some strains are modifiers of the radiation responses.

If they are taken before radiation, they do not interfere with the treatment. However, the same tea administered after the radiation makes the individual resistant to radiotherapy. The radioprotective effect was also observed with the juices administered both before and after radiation. Accordingly, the treatment may not have the desired effect, if tea is taken after radiation, or juice before or after.

When the thematic project was now in the final stage, Milena Costa Menezes, who is studying for a master’s degree under the supervision of Carlos Antônio Caramori, from the School of Medicine at Unesp, in Botucatu, began to assess the influence of the dietary supplementation with the mushroom on the evolution of the nutritional state and of the treatment of hepatitis C in patients at the university outpatients department.

During six months, a mixture of six different strains was administered, in powder form, to five sufferers from this disease. The study accompanied the patients at the beginning of the antiviral treatment, without the use of the mushroom, and after the administration of the new preparation. The control group was given the same antiviral treatment. The results indicated that the group in the experiment showed an improvement in all the reported side effects – in a comparison with the control group – after the first month of treatment with the medicine.

Alternated temperatures
The other part of the research, which deals with the technology for cultivation, has also made a lot of headway. Before the project started, the producers who cultivated A. blazei would employ the same technology used to grow French mushrooms. However, the mushroom that is native to Brazil needs alternation in the temperature to give fruit (ten to 14 days of heat, followed by three to five days of cold, and, once again, the same period of heat). To reach this conclusion, the conditions for cultivating them in the field were reproduced, in greenhouses adapted inside containers. All the variables were controlled by a computer program developed by the researchers.

For A. blazei, besides choosing selected strains, the most favorable compost for cultivation has to be chosen. Grass, sugarcane bagasse, meal, dung, and other agro-industrial wastes are some of the substrates used to inoculate the “seed” of the fungus. At this stage, it remains in a humid atmosphere, which is reminiscent of a moldy room, which exhales a peculiar smell of sweet almond. Reproduction takes with tiny little filaments (hyphae) extracted from the cap of the mushroom. To start with, A. blazei used to be cultivated only in unprotected beds in the field, which is why is was known as the mushroom of the sun. But even in the open, it is cultivated with a covering of grass, and does not get any light. In the case of shitake, cultivation is done on tree trunks, an ancient and rustic method, but widely practiced for calling for a low investment.

The results of the project suggest that there is still a large field for research into shitakes and A. blazei, even though several answers have already been found. The next stage, in the plans of Professor Augusto, is to turn the focus to the active ingredients concentrated in the extracts, and to correlate the intensity of the medicinal effects with the time they are picked, the substrate, and the climate.

The project
Edible and Medicinal Mushrooms: Technology for Cultivating, Biochemical Characterization, and Protective Effects of the Agaricus blazei Murrill (mushroom of the sun) and Lentinula edodes (Berk.) Pegler (shitake) mushrooms (nº 98/07726-5); Modality Thematic Project; Coordinator
Augusto Ferreira da Eira – Unesp in Botucatu; Investment R$ 542,578.00 and US$ 261,003.00

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