Total phenolic compounds and flavonoids in Madeira Island Fruits

Ferreira, Joana O.; Costa, Denise; Castilho, Maria Conceição; Sanches-Silva, Ana; Albuquerque, T.G.; Ramos, Fernando; Costa, H.S.

http://hdl.handle.net/10400.18/3314

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Authors

Ferreira, Joana O.

Costa, Denise

Castilho, Maria Conceição

Abstract(s)

Madeira Island is a prime location for the production of some exotic and tropical fruits, such as Cattley guava (Psidium cattleianum Sabine), rose apple (Syzygium jambos L.) and Surinam cherry (Eugenia uniflora L.). They all have distinct antioxidant characteristics that are still scarcely studied. The extracts of these fruits were evaluated regarding their total phenolic compounds (TPC) and total flavonoids content. The TPC assay relies on the transfer of electrons from phenolic compounds to phosphomolybdic/phosphotungstic acid complexes in alkaline medium. These are determined spectrophotometrically at 765 nm. The content of total flavonoids was also measured, spectrophotometrically, by using the aluminium chloride colorimetric assay. TPC results are given in gallic acid equivalents (GAE) per 100 g and the results of total flavonoids in epicatechin equivalents (ECE) per 100 g. Phenolic compounds are considered to be antioxidants, scavengers of free radicals, metal chelators, antimutagens, and signalling agents and flavonoids act on several different synergistic pathways as both antioxidant and anti-inflammatory. Therefore, the consumption of fruits with high content on these compounds is important. The following order was found for TPC content in the analysed fruits: Rose apple (36.1 mg GAE/100 g) < Surinam cherry (57.9 mg GAE/100 g) < Cattle guava (109 mg GAE/100 g). Regarding flavonoids content the following order was found: Surinam cherry (37.2 mg ECE /100 g) < Cattle guava (72.4 mg ECE /100 g) < Rose apple (168.9 mg ECE /100 g). Cattle guava presented about 3 times more phenolics than rose apple, but rose apple contained about 4.5 times more flavonoids than Surinam cherry. Some properties like antioxidant activity of Madeira island fruits remain uncharacterized, therefore these studies are very important to provide information to the population about the health benefits of their consumption.