Proximate Nutritional Analysis, Phytochemical Screening and Antioxidant Properties of Aqueous Extract of Neptunia oleracea Leaves

Neptunia oleracea also known as water mimosa is widely consumed by people worldwide including Malaysia. This plant was claimed able to treat several diseases such as epileptic convulsion, syphilis, jaundice, and bloody diarrhea. Moreover, it has been reported to possess antimicrobial, antioxidant, and anti-ulcer properties that benefit human health. Hence, this study investigates the content of macronutrients, micronutrients, phytochemical constituents, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant properties in the aqueous leaf extract of this plant. The study found that N. oleracea leaves were possessed with high fiber (52%), moisture (23.33%), fat (5.33%), protein (5.25%), carbohydrate (6.42%), ash (7.67%), and mineral content with a sequence of Potassium > Calcium > Sodium > Phosphorus. A positive result of tannins, steroids, phenols, and flavonoids were detected. High values of TPC and TFC which were 136.19 ± 0.62 mg GAE/g and 829.17 ± 19.09 mg GAE/g of dry weight respectively were obtained. Meanwhile, the hydrogen peroxide scavenging activity of the plant extract produced an IC50 of 70.09 µg/mL. The presence of a high content of polyphenolic compounds may reflect the antioxidant properties of this plant. In conclusion, the aqueous extract of N. oleracea leaves showed the presence of various phytochemical constituents and has a high content of TPC and TFC which may be derived from its nutritional content.  Hence, consumption of N. oleracea leaves is useful for human health and disease prevention.