Co-Ingestion of Natal Plums (Carissa macrocarpa) and Marula Nuts (Sclerocarya birrea) in a Snack Bar and Its Effect on Phenolic Compounds and Bioactivities

Abstract

This study investigated the effect of co-ingesting Natal plums (Carissa macrocarpa) and Marula nuts (Sclerocarya birrea) on the bioaccessibility and uptake of anthocyanins, antioxidant capacity, and the ability to inhibit α-glucosidase. A Natal plum–Marula nut bar was made by mixing the raw nuts and the fruit pulp in a ratio 1:1 (v/v). The cyanidin-3-O-sambubioside (Cy-3-Sa) and cyanidin-3-O-glucoside content (Cy-3-G) were quantified using the ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS). Inclusion of Natal plum in the Marula nut bar increased the Cy-3-Sa, Cy-3-G content, antioxidants capacity and α-glucosidase inhibition compared to ingesting Marula nut separately at the internal phase. Adding Natal plum to the Marula nut bar increased bioaccessibility of Cy-3-Sa, Cy-3-G, quercetin, coumaric acid, syringic acid and ferulic acid to 80.2% and 71.9%, 98.7%, 95.2%, 51.9% and 89.3%, respectively, compared to ingesting the Natal plum fruit or nut separately.

Antioxidant Activities of Co-Encapsulated Natal Plum (Carissa macrocarpa) Juice Inoculated with Ltp. plantarum 75 in Different Biopolymeric Matrices after In Vitro Digestion

“…Similarly, a strong positive correlation between FRAP and TPC, TPC and anthocyanins has been observed previously by Seke et al [ 2 ] and Manhivi et al [ 41 ]. The antioxidant power (FRAP) also showed a positive correlation with all phenolic compounds identified in the Natal plum juice.…”

“…However, the changes that occur during gastrointestinal digestion can alter the chemical structure of the phenolic components, resulting in varying antioxidant capabilities[40]. A strong positive correlation exists between TPC and FRAP (r = 0.95), TAC and FRAP (r = 0.94), Cy-3-Sa (r = 0.93), syringic acid (0.85), and ellagic acid (0.74), which was significant at p < 0.01 (Figure5).Similarly, a strong positive correlation between FRAP and TPC, TPC and anthocyanins has been observed previously by Seke et al[2] and Manhivi et al[41]. The antioxidant power (FRAP) also showed a positive correlation with all phenolic compounds identified in the Natal plum juice.…”

A systematic review of the inhibitory effect of extracts from edible parts of nuts on α-glucosidase activity

“…Surprisingly more than 66% of the studies did not provide details on the type or source of enzyme, 53,56–61,63,64,66 with some requiring a search through secondary or even tertiary citations to ascertain that the yeast enzyme had been used, and 5 of 15 studies did not provide the amount/concentration of enzyme that was used. 18,58,60,61,66 Almost half of the studies were lacking some or all details on the enzyme assay, including pH, buffer, incubation time and temperature, and concentration/amount of enzyme added; each of which affects enzyme activity and inhibition, 17,18,55,58,60,61,66 and in three studies, the method of detection or endpoint, used to calculate enzyme activity/inhibition, was not specified.…”

“…Also, the absence of acarbose as a positive control in eight studies complicates the comparison between various nut extracts. 53,55–57,59,60,66 Due to the small number of included studies for rat enzyme inhibition, it is difficult to determine whether compounds in nut extracts are effective inhibitors of mammalian α-glucosidase.…”

“…Full texts of all articles were obtained to retrieve detailed study characteristics. A total of 15 papers met all inclusion criteria; 17,18,[53][54][55][56][57][58][59][60][61][62][63][64][65] 10 studies examined the inhibitory effect on α-glucosidase activity of polyphenol-rich extracts, four studies examined the effects of isolated protein/ peptides and one study used nuts extracted in hot water with no further extraction applied (Tables 1 and 2). Of the included studies, no studies reported the effect of nut extracts on human α-glucosidase, two studies examined rat α-glucosidase activity (Table 1), and 13 articles used α-glucosidase from yeast (Table 2).…”