Solvent Selection Influences Grapefruit Flavonoid Extraction

Citrus flavonoids and their association with prevention of chronic diseases have been well documented. Due to structural variations, flavonoids have unique chemical properties; eventually their quantities vary with different extraction procedures. Earlier, reports on grapefruit flavonoids showed several disparities. This is possible due limited information on optimization of extraction procedures.  In present study, factors affecting the extraction of flavonoids such as solvent selection, centrifugal speed and temperature were investigated. Flavonoids were quantified using a high performance liquid chromatographic method. Flavonoids were eluted by a binary mobile phase with 0.03% phosphoric acid and acetonitrile and separated in 20 min. Among the five solvents examined, dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) have efficiently extracted five flavonoids such as narirutin, naringin, neohesperidin, didymin and poncirin. This may be due to higher polarity of DMSO and DMF compared to methanol (MeOH), ethanol (EtOH) and acetonitrile (ACN). Extracts of DMSO and DMF showed homogenous distribution of flavonoids, while MeOH, EtOH and ACN extracts showed significant variations in their distribution after centrifugation. Temperature and centrifugation speed did not have a significant increase in the flavonoid levels.