Antioxidant Activities and Polyphenolic Constituents of Bitter BeanParkia Speciosa

Abstract

Bitter bean (Parkia speciosa), also known as petai, is a popular non-timber forest product. Traditionally, its fruits are consumed as vegetables and herbal medicines in Malaysia. The present study aimed to evaluate the antioxidant activities of aqueous and ethanol extracts of P. speciosa empty pods using various antioxidant assays, as well as examining their polyphenolic constituent contents. Results showed that with the exception of superoxide radical scavenging activity, ethanol extracts possessed stronger DPPH and ABTS radical scavenging, anti-lipid peroxidation, metal chelating and reducing power activities than aqueous extracts. It was found to contain a higher level of total flavonoids and total phenols than aqueous extracts. The major polyphenolic constituents present in these extracts were gallic acid, catechin, ellagic acid, and quercetin. Although aqueous extracts contained a higher level in gallic acid, its catechin, ellagic acid, and quercetin contents were lower than ethanol extracts. Taken together, the higher amount of polyphenolic compounds present in ethanol extracts could have contributed to its stronger antioxidant activities than aqueous extracts; these results also provided the chemical basis for certain health benefits claimed of P. speciosa empty pods in folk medicine and as foods.

Stability and Antioxidant Activity of Food-Grade Phycocyanin Isolated fromSpirulina platensis

“…The ABTS scavenging activity was measured using spectrophotometric method with minor modifications. [31,32] Briefly, the ABTS stock solution was prepared by mixing ABTS (7 mM) and potassium persulfate (2.45 mM) in equal quantities. After being stored in the dark for 18 h, the stock solution was diluted with phosphate buffer saline (PBS) (0.02 M, pH 7.4) to a working solution yielding an absorbance of 0.70 ± 0.05 at 734 nm.…”

“…[41] The antioxidant activities of the food-grade phycocyanin solution were evaluated by the ABTS and DPPH methods, which are often used in the determination of the antioxidant abilities of natural compounds. [32,42] The ABTS radical-scavenging activity of phycocyanin solution at different concentrations is shown in Fig. 5A.…”

Bioactive compounds, food applications and health benefits of Parkia speciosa (stinky beans): a review

“…Phenols are ever-present bioactive compounds in plants and possess antioxidant activity responsible for good health. Plants are the origin of polyphenolic compounds [17]. It was deduced that phenolic compounds carry the major antioxidant substances.…”

“…So, it could be a promising remedy for certain human disease and disorder such as human gout and ischemia by their action of decreasing uric acid and superoxide concentrations in human tissues [25]. The flavonoid content of the pod methanolic extract is 5.28 mg RE/g DW [17] and the seeds contain 20.3 mg RE/g DW [16]. Scavenging or chelating processes are the mechanism behind their mode of action (Table 4).…”

Underutilised fruits: a review of phytochemistry and biological properties

“…In addition, other underutilised fruits species such as Parkia speciosa and Averrhoa bilimbi have also been widely reported by researchers to have various traditional remedial use. Parkia speciosa has been used for its diuretic and relaxing properties, treatment of high blood pressure, diabetes and has antibacterial effects on kidney, ureter and urinary bladder (Ko et al, 2014;Salma et al, 2006;Voon and Kueh, 1999) . Meanwhile, A. bilimbi is useful in treating fever, cold, coughs, itches, boils, beriberi, biliousness, inflammation of the rectum, internal haemorrhoids, hypertension, diabetes, syphilis and rheumatism (Khoo et al, 2016;Muhamad et al, 2014;Noor & Noriham, 2014;Salma et al, 2006).…”