Physicochemical, Nutritional and Antioxidant Properties of Syzygium malaccense Extracted with Different Solvents

Background: Underutilized plants are nutritionally rich and contain variety of phytochemicals which need to be explored for their contribution to the improvement of human health and economic value.

Aim: To evaluate the physicochemical characteristics, nutrient, phytochemicals and antioxidant activity of S. malaccense grown in Nigeria.

Methodology: Fruit weight, yield, pH and nutritional composition of S. malaccense fruit were investigated using standard analytical methods. The samples were extracted with different solvents in order to analyze the phytochemical compounds and antioxidant activity. Different phytochemical assays were used to evaluate the polyphenolic contents of the fruit extracts. Antioxidant activity of the extracts were measured using 2,2-diphenyl‑1‑picrylhydrazyl (DPPH) and total antioxidant capacity (TAC) assays.

Results: The different part of the fruit exhibited significant differences (p<0.05) in their physicochemical characteristics. The flesh has a significant higher weight (104.6±19.57g) than the peel (25.85±4.838). The yield of the peel extract (11.315%) was higher than that of the flesh (6.231%) despite the higher weight of the flesh. The peel showed significant (P<0.05) lower value of moisture and higher contents of carbohydrates, proteins, fats, fibre, ash, dry matter and calorie than the flesh. The flesh had the highest concentration of minerals with Calcium as the predominant macro-element and Iron as the predominant trace mineral. The polyphenolic contents were higher in the peel. The phenolic, flavonoid and proanthocyanidin content of the acetone peel extract (10.917±0.01 mg GAE/g, 7.927±0.015 mg QE/g, 1.959±0.007 mg CE/g) was significantly (P <0.05) higher than other extracts while the aqueous flesh extract had the lowest values. All the solvent extracts showed great antioxidant activities with the acetone peel extract having the highest antioxidant activity based on DPPH and ethanol peel extract based on TAC assays with IC50 values of 133.339±1.87μg/ml and 31.189±6.55μg/ml, respectively. Polyphenolic contents were significantly correlated with antioxidant activity.

Conclusion: This study reveals that S. malaccense especially its peel contains abundant nutrients and polyphenolic compounds with high antioxidant activity that may impart health benefits when consumed.