In vitro and in vivo studies of natural products: A challenge for their valuation. The case study of chamomile (Matricaria recutita L.)

Medicinal plant research is universally on the rise. Researchers, as well as the general public, recognize that natural products, predominantly those derived from plants, may exhibit health benefits. The tendency is to consider natural products as non-toxic and presenting fewer side effects than those used by conventional medicine. However, information concerning the real human health benefits of natural products is yet seldom available, which is a drawback for their possible valuation. Chamomile is one of the most widely used medicinal plants and its sesquiterpenic-related products are an example of this informative weakness. Several health benefits have been claimed for chamomile extracts and for a large number of sesquiterpenic compounds known to occur in chamomile. However, a deep knowledge concerning the compounds responsible for each specific effect, as well as the mechanisms behind them has not been stated, or, if it exists, is dispersed in literature. Thus, this review comprises a deep survey on the reported potential health benefits of chamomile-related sesquiterpenic compounds, and takes into account the models used for their evaluation: in vitro or in vivo. In spite of the relevance of the in vitro and animal studies reported in literature, where the data obtained are very promising concerning the potential health benefits of chamomile-related sesquiterpenic compounds, their extension to human trials is essential. Several aspects related to this actual challenge are discussed.

Focus on medicinal plant research has being increasing all over the world. People are turning to natural products; predominantly those derived from plants for their health care, due to the growing recognition that these natural products are mainly non-toxic, have lesser side effects than synthetic drugs, and are accessible at affordable prices (Milner, 1999; Chandrasekaran et al., 2010). In traditional medicine, plant formulations and combined extracts of plants are used for the treatment of a wide variety of diseases (Ansarullah et al., 2009). This therapeutic approach, although considered to be an alternative to conventional medicine, is still ignored by medical practice due to the lack of suitable scientific and clinical evidence (Fontanarosa and Lundberg, 1998; Yuan and Lin, 2000).