Mineral elements analysis and total flavonoids content in the fresh leaves from two varieties of Hibiscus sabdariffa L. consumed as vegetable in Lubumbashi (DR Congo)

Abstract

Fresh leaves of sorrel (Hibiscus sabdariffa L.) are among the most consumed vegetables in the Lubumbashi in the Democratic Republic of Congo (DR Congo). According to the literature, this vegetable shows the chemical variability depending on the culture area. Two varieties of this species, cultivated and consumed in Lubumbashi have not yet been studied for their micronutrient content, of which fruits and vegetables are the main sources. This study investigated the mineral and total flavonoid content of fresh leaves from red and green varieties of H. sabdariffa L., consumed as a vegetable in the aforementioned city. Fresh leaves of red and green variety of H. sabdariffa were purchased in 10 main markets of the Lubumbashi city. Gravimetric and spectrophotometric methods were used for analyzes of water, mineral and total flavonoids content. Three of the major mineral elements (Na, Ca, Mg) and several trace elements (Cu, Zn, Fe, Mn, Se, Co, Cr) were found in both varieties in elevated quantity in leaves of red variety. These latter were marked by a high content of iron (7 mg/100 g of fresh material) and Manganese (600 µg/100 g of fresh material). Total flavonoids quantification revealed that the leaves of red variety have a high value (28.2 ± 0.3 mg Quercetin Equivalent per g of extract) in total flavonoids compared to the leaves of green variety. Fresh leaves of the red variety of H. Sabdariffa consumed in Lubumbashi could be a source of iron for adults and manganese for children.

The Effects of Foliar Application of Some Selected Phytohormones on the Proximate, Phytochemical, and Mineral Compositions of Roselle (Hibiscus Sabdariffa L.) Leaves

“…For example, the current calcium requirement by a male adult between 19 to 65 years of age is about 1000mg according to FAO and WHO (2001), and the calcium content of the leaves of H. sabdariffa treated with 20 % CW was 193.20 mg per 100 g. Therefore, an adult will comfortably have a daily dose of his required calcium by consuming 500 g of the aforementioned. This can be further corroborated by the work of Shakalenga et al (2021) which confirmed that H. sabdariffa cultivated in Lubumbashi, Congo are highly rich in essential minerals and flavonoids. Overall, the single treatment of 20 % CW has the best nutritional status been highest in most of the phytochemicals, minerals, protein, fibre, chlorophyll and vitamin c.…”

“…In some regions in China, H. sabdariffa is cultivated mainly for its medicinal properties while in some part of Africa, specifically in the West, the leaves and seeds of H. sabdariffa are cultivated mainly for use in meals (Da-Costa-Rocha, 2014;Boukerche et al, 2023). For example, in Lubumbashi area of Congo, the leaves of H. sabdariffa is the economic important part of the plant as it is consumed as vegetable (Shakalenga et al, 2021). Also, in Nigeria, the calyces are processed and consumed as beverages or tea, while the seeds are processed as seasoning, popularly called "Dadawa" in the Northern part of Nigeria (Borrás-Linares et al, 2015;Daudu et al, 2015;Hinojosa-Gómez et al, 2018).…”