**2. General overview**

*Mikania glomerata* Sprengel and *M*. *laevigata* Schultz Bip. ex Baker, commonly known as guaco, are medicinal species used to treat several inflammatory and allergic conditions, particularly in the respiratory system due to their bronchodilator properties (Gasparetto et al., 2010).

Both species grow in the same regions and have similar morphological characteristics, which make them hard to distinguish. The leaves are similar, and both species have the characteristic odor of coumarin. The main difference between the species is the flowering period, which occurs in January for *Mikania glomerata* and September for *M. laevigata*. Therefore, humans use these plants without distinction (Lima, 2003; Ritter & Miotto, 2005).

An similar chemical profile has also been described for these plants (Oliveira, 1986; Lima & Biasi, 2002). Therefore, detailed studies of their morphological and anatomical features are necessary to allow botanical identification and quality control of these medicinal species in the absence of another way to make the distinction.

In folk medicine, these plants have a long history of use by rainforest inhabitants, especially by native peoples in South American, who have an ancient tradition of using guaco for the treatment of several diseases. Amazonian tribes have used the crushed leaf topically on skin eruptions and on snakebites. They also consume teas made from the leaves and/or stems against snake venom and to cure fevers, stomach disorders and rheumatism. South American tribes also believe that the aroma of the freshly crushed leaves left around sleeping areas keeps snakes away (Napimoga & Yatsuda, 2010).

In recent decades, guaco has been used as a home and commercial remedy. In popular medicine, the leaves have been widely used due to their tonic, antipyretic, balsamic, antiophidic, appetite stimulant, neuralgia, antispasmodic, expectorant, and antimalarial properties and for the treatment of rheumatism, eczema, influenza, asthma and sore throat. Guaco can be used as infusion and decoction, but it is most commonly used in the commercialization of crude extracts for medicinal purposes (Coimbra, 1942; Lucas, 1942; Neves & Sá, 1991; Ruppelt et al., 1991; Galvani & Barreneche, 1994; Alice et al., 1995; Matos, 2000; Souza & Felfili, 2006; Botsaris, 2007).

Because of the therapeutic effects attributed to guaco species, syrups and oral solutions are widely used by the South American population and have been distributed in free government phytotherapy programs (Gasparetto et al., 2010). These preparations have been used as an effective natural bronchodilator, expectorant and cough suppressant in treatment of respiratory problems such as bronchitis, pleurisy, cold, flu, coughs and asthma, and sore throats, laryngitis and fever (Napimoga & Yatsuda, 2010).
