The broad spectrum of bioactive properties of phenolic extracts: a prospective study in three different plants

Natural resources like plants are currently used all over developed and under developed countries of the world as traditional home remedies and are promising agents for drug discovery as they play crucial role in traditional medicine. The use of plants for medicinal purpose usually varies from country to country and region to region because their use depends on the history, culture, philosophy and personal attitudes of the users (Ahmad et al., 2015). The use of plants and plant products as drugs predates the written human history (Hayta et al., 2014). Plants are a very important resource for traditional drugs and around 80% of the population of the planet use plants for the treatment of many diseases and traditional herbal medicine accounts for 30-50% of the total medicinal consumption in China. In North America, Europe and other well-developed regions over 50% of the population have used traditional preparations at least once (Dos Santos Reinaldo et al., 2015). Medicinal plants have been used over years for multiple purposes, and have increasingly attract the interest of researchers in order to evaluate their contribution to health maintenance and disease’s prevention (Murray, 2004). Recently between 50,000 and 70,000 species of plants are known and are being used in the development of modern drugs. Plants were the main therapeutic agents used by humans from the 19th century, and their role in medicine is always topical (Hayta et al., 2014). The studies of medicinal plants are rapidly increasing due to the search for new active molecules, and to improve the production of plants or bioactive molecules for the pharmaceutical industries (Rates, 2001). Several studies have been reported, but numerous active compounds directly responsible for the observed bioactive properties remain unknown, while in other cases the mechanism of action is not fully understood. According to the WHO 25% of all modern medicines including both western and traditional medicine have been extracted from plants, while 75% of new drugs against infective diseases that have arrived between 1981 and 2002 originated from natural sources, it was reported that the world market for herbal medicines stood at over US $60 billion per year and is growing steadily (Bedoya et al., 2009). Traditional medicine has an important economic impact in the 21st century as it is used worldwide, taking advantage on the low cost, accessibility, flexibility and diversity of medicinal plants (Balunas & Kinghorn, 2005).

Medicinal plants have received great attention in the last years because of their richness in bioactive compounds responsible for different biological activities. In the present study, hydroethanolic extracts of Hypericum androseamum L., Equisetum giganteum L. and Tilia platyphyllos Scop., were chemically characterized in terms of phenolic composition and evaluated for their antioxidant, antitumor and anti-inflammatory properties. All three medicinal plants displayed antioxidant activity as free radical scavengers but mainly as lipid peroxidation inhibitors. The extracts were also effective in inhibiting nitric oxide production, as an indicator of the anti-inflammatory potential, displayed antitumor properties in breast carcinoma (MCF-7), non-small cell lung cancer (NCI-H460), cervical carcinoma (HeLa) and hepatocellular carcinoma (HepG2) cell lines and, up to the maximal tested concentration, did not show any cytotoxic effects for non-tumor cells. 5-O-Caffeoylquinic acid and 3-O-caffeoylquinic acid were the most abundant phenolic compounds identified in the H. androsaemum extract, and might be responsible for the observed bioactivity. Protocatechuic acid and epicatechin were most abundant in the T. platyphyllos extract, while kaempferol-O-glucoside-O-rutinoside was the most abundant phenolic compound in the E. giganteum extract. The results showed that these medicinal plants displayed very interesting bioactivities, which are related with phenolic composition and quantity. However, it would be interesting to evaluate the in vivo efficacy of these plant extracts, as also their mechanisms of action, in order to establish real therapeutic doses.