Researchers from São Paulo and Santa Catarina have discovered new ways of exploiting medicinal plants and are thereby contributing towards avoiding the extinction of a few species, as a result of a wide-ranging study carried out over four years in the Atlantic Rain Forest in the Ribeira Valley, in the southeast of São Paulo. Supported both by interviews with local inhabitants and by chemical analyses and tests on laboratory animals, they demonstrated that three plants can be used instead of espineira-santa (Maytenus ilicifolia) – the target for predatory gathering that started 20 years ago, when the Medicine Center (Ceme), a now extinct body of the Ministry of Health, attested the effectiveness of this species against ulcers, gastritis, indigestion and arthritis, as part of a research program into Brazilian medicinal plants.
The scientists from the São Paulo State University (Unesp) and the Federal University of Santa Catarina (UFSC) also showed that a climbing plant known as taiuiá (Wilbrandia ebracteata) can be used to treat ulcers and digestive problems, as the inhabitants in the region already knew.
The taiuiá is from the same family as the chayote (Sechium edule) – its foliage is similar, with leaves spread out and tendrils, extensions look like springs and bind the plant to others. However, unlike what the inhabitants of the Ribeira Valley think, the best part of the plant to be exploited is not the root – actually a kind of differentiated stem, called a rhizome -, which has toxic effects, but the leaf, which has the same pharmacological action without the toxicity, as the laboratory tests showed. “Selling the rhizome kills the plant off, but not the leaves”, explains Luiz Claudio Di Stasi, from Unesp’s Biosciences Institute in Botucatu. “We showed new ways of economic exploitation and have collaborated towards the conservation of this species”.
Collectors and faith healers
Along with Maurício Sedrez dos Reis, from the Center for Agrarian Sciences at the UFSC, Di Stasi coordinated ten biologists and eight agronomists who, between 1996 and 2000, interviewed 200 residents in the three towns of the Ribeira Valley (Eldorado, Sete Barras and Jacupiranga) in some way involved with medicinal plants – they were users, collectors or faith healers who had lived ten years in the area.
As a result, the researchers published in the March/April issue of the Phytomedicine magazine the evidence of the safety of using leaf extracts and the risks of using the roots of the taiuiá. Also in March, in the Fitoterapia magazine, they presented a preliminary survey of the 290 medicines made with 114 species of plants, suitable for 628 medicinal uses. In the book Medicinal Plants in the Amazon and in the Atlantic Rain Forest, which is to come out this month from Unesp’s publishers, Di Stasi and Clélia Hiruma-Lima, also from Botucatu, compare the plant diversity of the two ecosystems and show the similarities between the popular uses.
However, the proof that the three plants studied – Maytenus aquifolium, Sorocea bomplandii and Zolernia ilicifolia – may substitute the original Maytenus ilicifolia, for showing similar pharmacological action, was published in the November-December 2002 issue of the Journal of Ethnopharmacology. Called adulterations, although popularly they have the same name as the plant for which they are mistaken, these species are also trees with pointed leaves and serrated edges. It is only at the time they come into flower, which happens once a year, is it possible to distinguish between the species. The chemical analyses and the tests with mice suggest that the action against the gastric lesions of the adulterated versions comes from the existence of substances that are more common in these species, like the flavonoids, probably for increasing the factors that protect the organism or for their antioxidant activity.
“We tested a strategy of action for the Atlantic Rain Forest ecosystem, to study products from the forest that are potentially useful as medicines, and to associate the interest in improving the quality of life of the population of the Ribeira Valley with preservation of the environment”, says Di Stasi, who has been working in the region since 1986. The researchers developed a comprehensive approach, which began with interviews with the local inhabitants, went on to pharmacological, toxicological and quality control tests, and followed on to the impact of the exploitation of these resources on the Atlantic Rain Forest, with some indications as to the strategy for sustainable management and the rational exploitation of natural resources.
Peppers against ulcers
After cataloging the knowledge of the residents of the Ribeira Valley, following the indications of plants in popular use and with commercial value, the researchers selected ten species with an activity against ulcers that is higher than the equivalent doses of cimetidine, omeprazole and carbenoxolone – the drugs most used in the treatment of lesions in the digestive apparatus. In his post-doctoral studies, carried out with finance from the National Council for Scientific and Technological Development (CNPq) , at the School of Pharmacy of the University of Granada, in Spain, Di Stasi is taking care of the pharmacological characterization of natural substances, like flavonoids and paepalantine, on the digestive tract, in collaboration with Wagner Vilegas, from the Chemistry Institute of Unesp in Araraquara, who analyzes the plants from the chemical point of view.
Among the species studied, a group of peppers from the piperaceae family stands out, which not only has a prolonged pharmacological action with an intense analgesic activity proven in the laboratory, but also represents an alternative for the exploitation of the Atlantic Rain Forest, for containing essential oils for the cosmetics and food industries.
Studies are more advanced with Piper cernuum, whose basic chemical composition, pharmacological action and biological cycle (how it grows and reproduces), including the best time for picking – essential information for the sustained handling of the species in the forest – are already known. “The multiple use of forest resources”, comments Di Stasi, “makes it possible to reduce the exploitation of certain species, such as the hearts of palm tree and the Maytenus ilicifolia, reduces the risks of extinction and of environmental imbalance, at the same time that it guarantees the sustainable exploitation of forest resources by the inhabitants of the region”.
For the local town halls and organizations, such as the Association of Extractors and Producers of Medicinal Plants of the Ribeira Valley (Aepam in the Portuguese acronym), the researchers drew up the standardization chart for the plant extracts, with the chemical and physical characterization of each species and of the tests on laboratory animals, which indicate the benefic activities and the limits of toxicity. As Di Stasi points out: “We always try to turn the results of our work into something useful locally”.
Ethnopharmacological Study of the Atlantic Tropical Forest (SP) and the Pharmacochemcial Triage of Native Species with an Analgesic and Antiulcerogenic Activity; Modality Young Researcher Support Program;
Coordinator Luiz Claudio Di Stasi – Unesp; Investment R$ 67,048.93