Efficacy and safety of 20 medicinal plants are tested

Six species, including Rhizophora mangle, show promising efficacy against conditions such as ulcers, inflammation and diabetes

By Karina Toledo

Agência FAPESP – An ongoing study at Universidade Estadual Paulista (Unesp) seeks to evaluate the safety and efficacy of extracts from 20 medicinal plants in the treatment of conditions such as ulcers, colitis, inflammatory intestinal disease, cancer, and diabetes and other chronic diseases.

In the first stage of the work, a Thematic Project coordinated by Wagner Vilegas, scientists extracted the active ingredients from the plant species. The molecules with activity against the above conditions were isolated, and their structure was characterized. Afterward, in vitro experiments and experiments with rodents were conducted to evaluate the therapeutic action and possible adverse effects of the molecules.

Based on these experiments, the researchers selected extracts of the six most promising species for deeper investigation. Serjania marginata and Machaerium hirtum extracts had gastroprotective, analgesic and anti-inflammatory activities, without mutagenic or toxic effects. Rhizophora mangle and Hymenaea stigonocarpa extracts had therapeutic potential for the treatment of inflammatory intestinal disease. The Myrcia bella and Bauhinia holophylla extracts showed promise for the treatment of diabetes.

“We intend to better investigate the mechanisms of action of the main active ingredients in these species. It would be interesting to discover mechanisms of action different from those found in medicines already being sold,” explained Vilegas, of Unesp’s São Vicente campus.

The study’s objective, according to Vilegas, is to broaden the options available in the National Register of Medicinal Plants of Interest to the National Health System (Renisus). Sponsored in 2009 by the Health Ministry, this list contains 71 plants with the potential to generate products of interest to the public health system.

According to the Ministry, the purpose of Renisus is to guide studies and research that can increase the number of phytotherapeutics available for use by the Brazilian peopel. Currently, derivatives of Espinheira santa (Maytenus ilicifolia Mart) are used for treating gastritis and ulcers, and guaco is used for colds and coughs.

“The problem is that some of the species listed by Renisus are found only in certain regions of the country, and there is not enough of the plant to serve the entire population. One must incorporate new therapeutic options into this list, but new studies are first needed to prove the efficacy and safety of the phytotherapeutics,” said Vilegas.

Another objective of the project, according to Vilegas, is to precisely study the effects of plants that are similar to those on the National Health System Register, such as the Pata-de-Vaca (Bauhinia forficata).

“B. forficata is already widely used for diabetes. We are studying a sister species, B. holophylla, which had very good results against diabetes in tests conducted in vitro and in vivo. It is also rich in flavonoids, which are antioxidant substances,” explained Vilegas.

Another plant that is widely used in traditional medicine and showed good performance in the laboratory is jurubeba (Solanum paniculatum). Rich in steroidal alkaloids, the species had significant effects on ulcers and other types of inflammation.

Terminalia catappa, popularly known as the tropical almond, showed intense antimicrobial and anti-ulcerative action and is an interesting alternative for treating stomach disease associated with the bacterium Helicobacter pylori. The safety tests, however, revealed that the plant’s active substances can induce mutations in cells.

“More studies will be necessary to discover whether there is a way to remove toxic molecules from the extract and reduce the possible side effects,” stated Vilegas.

There is also a need for additional studies of Crotalaria pallida, which is a potent immunomodulator but has high toxicity. “This species contains pyrrolidine alkaloids, which are toxic to the liver. This toxicity is why, for example, Symphytum officinale is no longer recommended,” explained Vilegas.

Regular supply

In the next stage of the study, scientists will evaluate whether there are seasonal or geographical changes in the extracts of the studied species. In particular, they will examine whether the quantity of the main active ingredients varies according to the location in which the plant is cultivated or the time at which the plant is harvested.

“We are harvesting fields of these species because, in order to produce standardized extracts, it is important to provide raw material for the production of phytotherapeutics in sufficient quantity throughout the year. If it is not possible to maintain a regular supply, it will not be feasible to transform them [these plants] into phytotherapeutic products,” explained Vilegas.

The study is being conducted under the auspices of the BIOTA-FAPESP Program and includes scientists from several Unesp units, in addition to partnerships with Universidade Estadual de Campinas (Unicamp), Universidade de São Paulo (USP), Universidade Estadual de Londrina (UEL), Universidade Federal