Análise qualitativa da presença de alcaloides em espécies conhecidas popularmente como boldo

Abstract

Boldo has long been popularly used for the treatment of gastrointestinal and liver disorders, among others, and is easily found in nature and often cultivated by the population. However, there are several different plant species and genera that share the common name "boldo", as “boldo-do-chile” (Peumus boldus), “falso-boldo’ (Plectranthus barbatus) and “boldo-miúdo” (Plectranthus ornatus). It is important to distinguish between them due to their unique characteristics in terms of active compounds and therapeutic applications, in order to avoid inefficacy or potential toxicity in treatments. Unlike boldo-do-chile, whose main active compound is boldine (an alkaloid), plants of the Plectranthus genus do not produce detectable amounts of alkaloids, with their main chemical constituents being diterpenoids, such as forskolin. In this study, a literature review was conducted on species known as boldo and colorimetric phytochemical analysis of some boldo samples collected in Uberlândia, aiming to investigate the presence of alkaloids. A total of four plant samples were collected, from which three leaf extracts and one stem extract were prepared. Additionally, dried boldo-do-chile leaves from four herbal stores, a capsule-based herbal medicine, and a tincture were acquired. Extracts were prepared by acid-base extractions and analysis of alkaloid content using thin-layer chromatography (TLC) with Dragendorff’s colorimetric reagent. All extracts from collected species showed negative results for alkaloids, whereas the commercial leaf samples tested positive with varying degrees of intensity. The boldo-do-chile capsule-based herbal product showed a positive result, while the liquid tincture did not indicate the presence of alkaloids. These results indicate that alkaloids are indeed present in the dried leaves and capsule-based product, suggesting the presence of boldine and making it likely that these are products derived from Peumus boldus. As for the other samples analyzed, it is not possible to definitively state whether the negative results truly indicate the absence of alkaloids, due to the detection limits of the method used. However, under the evaluated methodology, no presence of alkaloids was observed. Seasonality and low compound concentration may be factors that justify the absence of these substances.