Qualitative Screening of Phytocompounds and Spectrophotometric Investigations of Two Pumpkin Species

Pumpkin (Cucurbita maxima) is a fruit packed with vitamins and nutrients beneficial to human health with numerous therapeutic uses including antiparasitic, antioxidant, it helps to lower bad cholesterol, as an adjuvant in weight loss, improves cancer prevention, etc. Pumpkin is rich in beta-carotene, and contains significant amounts of lutein and zeaxanthin, antioxidants that can considerably prevent cataracts and macular degeneration. Worldwide, five pumpkin species are grown for their edible fruit and seeds. This paper describes the qualitative screening of phytocompounds and the quantitative determination of the main bioactive compounds found in two pumpkin species: Valenciano and Waltham Butternut. The qualitative screening of phytochemicals was based on the visual change in color of aqueous extracts upon adding known reactants. This allowed a preliminary evaluation regarding the presence of different bioactive compounds such as saponins, alkaloids, tannins, flavonoids, etc. In order to determine the specific amount of different phytocompounds (e.g., total content of polyphenols, total content of flavonoids, etc.) UV-Vis spectra were recorded in triplicate at well-established wavelengths, thus obtaining an average absorbance. For example, a method widely applied for the determination of total polyphenolic content is the Folin–Ciocalteu (FC) reaction, which is basically an antioxidant analyses that relies on electron transfer that measures the reductive ability of a specific antioxidant. Briefly, the FC reaction involved mixing 1 mL diluted aqueous extract with 5 mL FC reagent and adding 4 mL Na2CO3 after 8 min After 60 min incubation at room temperature, we recorded the absorptions at 765 nm, which corresponds to the gallic acid curve calibration standard. Also, the antioxidant activity was recorded by using the DPPH method for both aqueous extracts.