In Vivo Diuretic Activity and Anti-Hypertensive Potential of Hibiscus sabdariffa Extract by Inhibition of Angiotensin-Converting Enzyme and Hypertension Precursor Enzymes

Aqueous extracts of calyx from Hibiscus sabdariffa (HS) (roselle) are highly appreciated for their nutritional and therapeutic effects, especially as anti-hypertensive substances. This study aimed to evaluate their anti-hypertensive potential through an in vitro inhibition assay of angiotensin-converting enzyme (ACE) and hypertension precursor enzymes and to assess the in vivo diuretic activity of HS. Results showed that HS extract inhibited enzymes belonging to several classes, such as α-amylase, trypsin, chymotrypsin, xanthine oxidase, lipoxygenase, and angiotensin-converting enzyme. In particular, enzymatic kinetics of ACE indicated a competitive inhibition fashion of HS extract. Furthermore, the extracts showed remarkable diuretic and natriuretic effects at doses of 50 mg/kg/bw, 100 mg/kg/b.w, and 200 mg/kg.b.w. These activities can be explained by the high content of phenolic compounds and essential amino acids. Roselle could be a potential source of nutraceuticals and anti-hypertensive bioactive compounds.

Correction: Hibiscus sabdariffa: Genetic variability, seasonality and their impact on nutritional and antioxidant properties

[This corrects the article DOI: 10.1371/journal.pone.0261924.].

Modelling and optimisation of ultrasound-assisted extraction of roselle phenolic compounds using the surface response method

Extracts from Hibiscus sabdariffa L. (roselle) have been used traditionally as a food, in herbal medicine, in hot and cold beverages, as flavouring or coloring agent in the food industry. In vitro and in vivo studies and trials provide evidence, but roselle is poorly characterised phytochemically due to the extraction processes. The optimization of the extraction of phenolic compounds and their antioxidant activities is still a hot topic. In this study, the effect of solute/solvent ratio (33, 40 and 50 mg/mL), extraction temperature (40, 50 and 60 °C) and extraction time (30, 60 and 90 min) was evaluated through the content of phenolic compounds and antioxidant activity. A response surface methodology through a Box-Behnken design was applied and model fit, regression equations, analysis of variance and 3D response curve were developed. The results showed that TPC, TFC, DPPH and FRAP were significantly influenced by temperature, extraction time and solvent/solute ratio. Thus, TPC, TFC, DPPH and FRAP varied from 5.25 to 10.58 g GAE/100 g DW; 0.28 to 0.81 g QE/100 g DW; 0.24 to 0.70 mg/mL; 2.4 to 6.55 g AAE/100 g DW respectively. The optimal experimental condition (41.81 mg/mL; 52.35 °C and 57.77 min) showed a significant positive effect compared to conventional methods. The experimental values at this extraction condition show that this optimization model is technologically, financially and energetically viable as it requires a reasonable concentration, time and temperature.

Correlating the morphology of Anacardium occidentale L. fruits from 30 orchards with their physicochemical and nutritional properties

Cashew (Anacardium occidentale L.) is a cross-pollinating plant whose fruit consists of two parts, the nut, and the apple. This study aimed to carry out agro-morphological characteristics of cashew fruits to establish relationships with their physicochemical and nutritional properties. Thirty (30) cashew accessions fruits were sampled in different regions of Burkina Faso. The length, width, thickness, weight, yield, kernel output ratio (KOR), proximate composition, specific minerals, phenolic compounds, and anti-nutritional factors were assessed. Evaluations were made using standard methods. The results showed significant variations in agro-morphological, physicochemical and nutritional traits depending on the accessions and the organ. Also, the ratio of apple mass versus nut one was about 12.24 ± 1.24. Kernels are an important source of proteins, fat, total phenolic compounds, and flavonoids, with average contents of 22.84 ± 1.25 g/100 g, 51.65 ± 2.54 g/100 g, 9.78 ± 2.15 mg GAE/g, and 6.24 ± 12.15 mg QE/g, respectively. As for the apples, they contained substantial quantities of Potassium, Phosphorus, Chlorine, and Magnesium with contents of 611.24 ± 14.5 mg/100 g, 418.24 ± 16.47 mg/100 g, 332.24 ± 10.54 mg/100 g, and 224.95 ± 13.15 mg/100 g, respectively. Statistical analyses showed that mineral and phytate contents were positively correlated to cashew apples while phenolic compounds and tannins were strongly correlated with walnuts. Principal component analyses showed three groups of accessions based on apples and kernels characteristics. These data showed a direct relationship between cashew physicochemical, nutritional potentials, kernels, and apples' agro-morphological characteristics. These data constitute an important basis for the identification of cashew accessions with high nutritional and economic potential.

Tomato By-Products, a Source of Nutrients for the Prevention and Reduction of Malnutrition

Malnutrition is a global phenomenon that mainly affects children under five years old, the elderly and food insecure people. It can be linked to undernourishment or overnutrition. To prevent it, a healthy and balanced diet, rich in energy and micronutrients, is necessary. The objective of this study was to evaluate the nutritional composition and contribution of tomato by-products to prevent and reduce malnutrition. Thus, standard methods were used for proximate composition and bioactive compounds. Results showed that tomato by-products are rich in macronutrients and micronutrients capable of preventing undernutrition and reducing the incidence of the effects of overnutrition. The average carbohydrate, protein and lipid contents were 15.43%, 11.71% and 5.4% (DM) in peels and for seeds the contents were 58.75%, 15.4% and 22.2%, respectively. The average energy values were 280.47 kcal/100 g and 472.8 kcal/100 g DM for peels and seeds, respectively. The main minerals found were, in decreasing order, potassium, magnesium, sodium, iron and zinc. High contents of phenolic compounds, lycopene, β-carotene and vitamin C were also found in these by-products. They also presented important antioxidant activities. Due to their nutritional and bioactive compounds, tomato by-products may be included in functional food formulation programs to reduce the incidence of nutritional diseases.

Evaluation of the physicochemical parameters of edible oils sold in the three cities of Burkina Faso

The edible oil needs of African countries are met by imported or locally produced ones. Therefore, consumers are generally confronted with a choice of edible oils of poorly controlled quality. However, quality control of edible oils for local consumption is of high necessity. This study aimed to assess the quality of edible oils sold and consumed in some cities in Burkina Faso. Oil samples collected in the cities of Dédougou, Koudougou, and Nouna were used for several analyses. Oil samples from palm, refined and unrefined cottonseed, and groundnut were collected. Standard methods were used to assess the physicochemical quality parameters of the oils, including the peroxide value, water and volatile matter content, acid value, traces of soap, and mineral oil contents. The parameters varied significantly depending on the oil type, but not by the locality of origin. The peroxide indices had varied from 3.24 to 39.99 mEq O₂/kg oil. The acid indices varied from 0.22 mg KOH/g to 1.24 mg KOH/g. The water and volatile matter contents ranged from 0.04% to 0.88%. The test for traces of soap gave values ranging from 0 to 76 ppm. For the mineral oil test, four samples of cottonseed oil collected in Dedougou gave positive results. Compared to international reference standards, in particular the Codex Alimentarius standard, it may constitute a health risk for consumers. The poor storage, distribution, and marketing conditions of the oils could explain their poor quality. In order to provide consumers with quality oils, regular controls must be undertaken in the places where the oils are stored and/or marketed.

Hibiscus sabdariffa: Genetic variability, seasonality and their impact on nutritional and antioxidant properties

This study consisted of the physicochemical, phytochemical and antioxidant characterisation of two varieties of Hibiscus sabdariffa, to evaluate the influence of genetic and environmental factors on these parameters leading to an objective and rigorous classification of our extracts. To this end, calyxes and seeds of the red and white phenotypes were collected in Bobo-Dioulasso, Dano and Nouna respectively in December 2019 and 2020. Principal component analysis showed that physico-chemical and biochemical parameters could potentially be used to discriminate varieties. The calyxes of the sabdariffa variety showed the best physicochemical profile (total phenolics, flavonoids, ascorbic acid), pigments (anthocyanins, chlorophyll) and antioxidant activity (free radical scavenging and SOD activity) while the seeds showed the best carbohydrate, lipid and peroxidation inhibition content. In view of these results, the red phenotype has an interesting nutritional and therapeutic potential. It could therefore be interesting candidate in the pharmaceutical and food industries.