Nutrient Compositions, Antioxidant Activity, and Common Phenolics of Sonneratia apetala (Buch.-Ham.) Fruit

Fruits of Sonneratia apetala (Buch.-Ham.) are widely used as food and in treating various diseases in the tropical coastal areas. This study evaluated nutrient compositions in the pericarp and seed of this fruit. Each pericarp and seed was successively fractionated into n-hexane, diethyl ether, chloroform, ethyl acetate, and methanol. Polyphenols contents and antioxidant activities of different pericarp and seed fractions were measured in different in vitro methods and phenolic compounds were determined by HPLC. Carbohydrates, proteins, lipids, and ash contents were 29.6, 8.8, 2.8, and 25.5% of dry weight in pericarp, whereas 28.3, 11.5, 4.2, and 22.7% in seed, respectively. Among the mineral macro-elements, K content was the highest followed by Na, Ca, Mg, P, and S while in micro-elements, Fe was at the largest followed by Mn, Zn, and Cu. The methanol fraction of seed showed the highest polyphenols content (221.9 mg gallic acid equivalent/g fraction), 1,1-diphenyl-2-picrylhydrazyl (DPPH) (IC50 = 2.1 mu g/mL) and NO (IC50 = 490.8 mu g/mL) free radical scavenging. Similarly, methanol fraction of seed also attained very strong reducing power (OD = 1.67 at 100 mu g/mL), Fe2+ chelating and total antioxidant capacity. When subjected to high-performance liquid chromatogram analysis, six polyphenols namely caffeic acid, (+)-catechin, (-)-epicatechin, ellagic acid, gallic acid, and quercetin were detected and quantified as 88.1, 1459.3, 310.1, 616.9, 416.7, and 71.8 mg/100 g of methanol fraction of seed, respectively. Therefore, the fruit of S. apetala, especially its seeds could be of great use in preparation of functional foods and dietary supplements.