Purple sweet potatoes (Ipomoea batatas (L.) genotype) in Southern Africa have a phytonutritional composition and antioxidant properties that can increase incomes and improve nutrition. This study compared the phytonutrient composition and antioxidant properties of four purple-colour sweet potato genotypes (local Purple-purple, ‘2019-1-1’, and USA genotypes, ‘08-21P’ and ‘16-283P’). These purple sweet potato genotypes were characterised by UPLC/QTOF/MS and 16 phenolic compounds were identified. Purple-purple (very dark purple) showed the highest concentration of cyanidins and peonidin derivatives. Chlorogenic acid derivatives were highest in the genotype ‘16-283P’. ‘Puple-purple’ and ‘16-283P’ displayed the strongest antioxidant power and scavenging activities. Diaffeoylquinic acid isomer 1 was identified as the marker candidate for distinguishing the four purple sweet potato genotypes. Southern Africa’s highest-protein sweet potato genotypes are Purple-purple (28.81 g/100 g) and ‘08-21 P’ (24.31 g/100 g). A 13.65 g portion of ‘2019-1-1′ would meet the Recommended Dietary Allowance (RDA) for iron for men, while 25.59 g would meet the RDA for children, and 30.72 g would meet the RDA for women. The sweet potato root of genotype ‘2019-1-1′ provides 31.43 g of Zn per day for children and 22.86 g for adults. The roots of local cultivar Purple-purple can be used as functional food ingredients.

Baby spinach is becoming increasingly popular as a salad ingredient and needs high fertiliser rates to grow well and attain higher-quality leaves (dark green leaves). Chemical fertilisers, especially nitrogen (N), boost yields. There are many risks associated with nitrogen fertilisation. Additionally, spinach contains phenolic compounds and carotenoids. Nitrogen fertilisation affects growth, development, yield and metabolites. This study examined the impact of lower concentrations of N (0, 30, 60, 90, 120, 150 mg/L) on yield and colour properties [light intensity (L*) colour coordinates, unique for green colour (a*) and yellow colour (b*)], as well as the impact of varying N concentrations on the total phenolic content and p-coumaric acid, quercetin, ferulic acid, kaempferol, lutein, zeaxanthin, β-carotene and antioxidant activities in the baby spinach varieties ‘Acadia’, ‘Crosstrek’ and ‘Traverse’, and it was established that N fertilisation improves phytochemical bioaccessibility and antioxidant activity. In a split strip plot design, three baby spinach varieties were treated with different N concentrations, including 0, 30, 60, 90, 120 and 150 mg/L. For 40 days, three baby spinach varieties were grown on soilless Mikskaar Professional substrate 300. During both seasons, ’Crosstrek’ had the highest fresh mass (921.4 g/m², 856.3 g/m²) at 120 mg/L N, while ‘Traverse’ had the highest fresh mass at 554.8 g/m² and at 564.3 g/m² at 90 mg/L N and did not differ significantly from 90 to 150 mg/L N during either season. During both seasons, ‘Acadia’ at 90 mg/L N increased fresh mass to 599 g/m² and 557.9 g/m². The variety × N supply interaction significantly affected the leaf colour; chlorophyll content across seasons; the levels of bioactive compounds, p-coumaric acid, quercetin, ferulic acid, kaempferol, lutein, zeaxanthin and β-carotene in spinach varieties; the in vitro bioaccessibility; and the antioxidant activity. Varietal differences influenced the bioaccessibility of phenolic compounds and carotenoid components. The appropriate N levels can be used during plant cultivation to optimise the bioaccessibility of this spinach variety. Thus, fertilising ‘Traverse’ with 90 mg/N mL increased the in vitro bioaccessibility of β-carotene (35.2%), p-coumaric acid (7.13%), quercetin (8.29%) and ferulic acid (1.92%) without compromising the yield.

Sweet potatoes (Ipomoea batatas) are highly profitable, contribute to food security, and their leaves rich in phytonutrients. This study examined the optimal leaf harvesting stage by harvesting newly formed leaves (leaves 1 to 5) to achieve the highest concentration of carotenoids, phenolic compounds, antioxidant properties and mineral content. Leaves of five purple-fleshed sweet potato genotypes ‘2019-11-2’ and ‘2019-1-1’, ‘Purple-purple’, and from the USA ‘08-21P’ and ‘16-283P’ were harvested based on tuber life cycle [vegetative 8 weeks after planting (VS-8WAP), tuber initiation (TIS-12WAP), and tuber maturation phases (TMS-16WAP)]. At the 8WAP stage, leaves of genotype ‘2019-11-2’ had the highest concentrations of cyanidin-caffeoyl-sophoroside-glucoside (17.64 mg/kg), cyanidin-caffeoyl-feruloyl-sophoroside-glucoside (41.51 mg/kg), peonidin-caffeoyl-hydroxybenzoyl-sophoriside-glucoside (45.25 mg/kg), and peonidin caffeoyl-feruloyl-sophoriside-glucoside (24.47 mg/kg), as well as antioxidant scavenging activity. In contrast, ‘Purple-purple’ harvested at TIS-12WAP showed the highest concentration of caffeoylquinic acid derivatives. Zeaxanthin, lutein, all trans-β-carotene, and cis-β-carotene are the most abundant carotenoids in genotype ‘08-21P’ at VS-8WAP. As a result, local genotypes ‘2019-11-2’ harvested at 8WAP and ‘Purple-purple’ harvested at 12WAP are potential sources of anthocyanins and caffeoylquinic acid derivatives. Conversely, USA’s genotype ‘08-21P’ at the VS-8WAP stage is an excellent source of carotenoids. The leaves of USA’s ‘08-21P’ genotype and the local ‘2019-11-2’ genotype at TMS-16WAP exhibited the highest content of Fe and Mn, respectively. The study identified the optimal leaf stage for consumption of leaves and for use as a functional ingredient.

This study examined the impact of fermentation using Lactiplantibacillus plantarum (L75) and Bifidobacterium longum (BF) on the total soluble solids (TSS), pH, TA, LAB survival, color properties, ascorbic acid content, total phenolic content (TPC), carotenoid components, and antioxidant properties of smoothies made from melon varieties (Cantaloupe, Honeydew, and Watermelon) separately with pumpkin leaves (Cucurbita moschata and Cucurbita pepo). For all smoothies, pH (r = −0.74) and TSS (r = −0.79) were inversely and strongly correlated with LAB counts, while LAB counts were positively correlated with TA (r = 0.87). Fermentation time (24 to 72 h) significantly (p < 0.05) decreased the TSS (%), pH, and color properties of all smoothies fermented with L75 or BF, while TA increased. Fermenting Cantaloupe melon and C pepo leaves with L75 (CMCL75) for 24 h increased the ascorbic acid content to 3.8 mg/100 mL. The sensory panel scores were highest for Watermelon and C. moschata or C. pepo fermented with L75 or BF for 24 h. TPC concentration was highest in CMCL75 (70.76 mg of gallic acid per 100 mL) after 24 h. C. pepo leaves and Cantaloupe fermented with L75 (CPCL75) showed the highest concentration of total carotenoids (70.38 mg/100 mL), lutein (2.53 µg/100 mL), cis β-carotene (25.43 µg/100 mL), and trans β-carotene (620.37 µg/100 mL). In contrast, CMCL75 showed the highest concentration of zeaxanthin (0.70 mg/100 mL). This study demonstrated the potential of fermenting Cantaloupe and pumpkin leaves together with the L75 strain to produce non-dairy functional products.

The emergence and spread of drug-recalcitrant Plasmodium falciparum parasites threaten to reverse the gains made in the fight against malaria. Urgent measures need to be taken to curb this impending challenge. The higher plant-derived sesquiterpene, quinoline alkaloids, and naphthoquinone natural product classes of compounds have previously served as phenomenal chemical scaffolds from which integral antimalarial drugs were developed. Historical successes serve as an inspiration for the continued investigation of plant-derived natural products compounds in search of novel molecular templates from which new antimalarial drugs could be developed. The aim of this study was to identify potential chemical scaffolds for malaria drug discovery following analysis of historical data on phytochemicals screened in vitro against P. falciparum. To identify these novel scaffolds, we queried an in-house manually curated database of plant-derived natural product compounds and their in vitro biological data. Natural products were assigned to different structural classes using NPClassifier. To identify the most promising chemical scaffolds, we then correlated natural compound class with bioactivity and other data, namely (i) potency, (ii) resistance index, (iii) selectivity index and (iv) physicochemical properties. We used an unbiased scoring system to rank the different natural product classes based on the assessment of their bioactivity data. From this analysis we identified the top-ranked natural product pathway as the alkaloids. The top three ranked super classes identified were (i) pseudoalkaloids, (ii) naphthalenes and (iii) tyrosine alkaloids and the top five ranked classes (i) quassinoids (of super class triterpenoids), (ii) steroidal alkaloids (of super class pseudoalkaloids) (iii) cycloeudesmane sesquiterpenoids (of super class triterpenoids) (iv) isoquinoline alkaloids (of super class tyrosine alkaloids) and (v) naphthoquinones (of super class naphthalenes). Launched chemical space of these identified classes of compounds was, by and large, distinct from that of ‘legacy’ antimalarial drugs. Our study was able to identify chemical scaffolds with acceptable biological properties that are structurally different from current and previously used antimalarial drugs. These molecules have the potential to be developed into new antimalarial drugs.