Abstract
Guava (Psidium guajava L.) is one of the most important tropical fruits belonging to the genus Psidium and the Myrtaceae family and claim to have phenolic compounds that have been reported to possess strong antioxidant activity. This study was aimed to evaluate the bioactive constituents in guava cultivars at different ripening stages by HPLC. The five guava cultivars were selected at different ripening stages and the bioactive components were analysed by high-pressure liquid chromatography. The quantification of bioactive compounds revealed that the highest amount of bioactive compounds was found in cultivar Safeda at the unripe stage, while a minimum amount was found in ripe Apple Colour guava cultivar. The six bioactive compounds were quantified in the range of gallic acid (9.46-63.08 mg/100 g), quercetin (0.11-2.51 mg/100 g), myrcetin (0.09-0.034 mg/100 g), ascorbic acid (7.45-75.07 mg/100 g), apegenin (0.01-0.032 mg/100 g) and lycopene (0.34-0.92 mg/100 g). The exploratory evaluation of guava samples was performed through Principal Component Analysis (PCA), the bioactive compounds, lycopene, myricetin, and quercetin are dominant variables on this PC1 (61.52%) (Scores better than 0.7), thereby causing greater variability among these samples. The second principal component (PC2) represents 16.54% of the total variance and the ascorbic acid, gallic acid and apeginin (score better than 0.7), are the dominant variables on this PC.
Highlights
It is known that plants are a rich source of secondary metabolites like flavonoids, carotenoids, alkaloids, terpenoids and tannins and they have been implicated in several therapeutic methodologies
The comparative efficiency of the solvents was estimated from the total peak areas of the High-performance liquid chromatography (HPLC) chromatograms obtained
The maximum extraction of the bioactive compound was observed in acetonitrile: water (10:90 v/v), which was proved to be a most efficient combination for polyphenol, three flavonoids, ascorbic acid and carotenoid present in all the samples
Summary
It is known that plants are a rich source of secondary metabolites like flavonoids, carotenoids, alkaloids, terpenoids and tannins and they have been implicated in several therapeutic methodologies. The guava tree has been distributed through many countries as a result of its capacity to grow in tropical and subtropical conditions (Morton, 1987). Compounds such as carotenoids and flavonoids have already been recognised as either inhibitor of oxidative stress or compounds that reduce oxidative stress (Sies and Stahl, 1995) because they can act with antioxidants that are able to inactivate free radicals and their action (Halliwell, 1996; Devasagayam et al, 2004). Carotenoids are abundant in fruits and vegetables but are usually masked by green-coloured chlorophyll. HPLC columns offer high resolving power and numerous papers have been published on the HPLC separation of carotenoids (Rodriguez-Amaya, 2015). A few of these papers included quantification, and discrepancies continue to exist in the reported quantitative data
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