University of Khartoum

Agro-morphological, Biochemical, Antioxidant, Antityphoid and Molecular Characteristics of Selected Karkadeh (Hibiscus sabdariffa L.) Genotypes

Agro-morphological, Biochemical, Antioxidant, Antityphoid and Molecular Characteristics of Selected Karkadeh (Hibiscus sabdariffa L.) Genotypes

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Title: Agro-morphological, Biochemical, Antioxidant, Antityphoid and Molecular Characteristics of Selected Karkadeh (Hibiscus sabdariffa L.) Genotypes
Author: Nogud, Israa Salah Hamad
Abstract: An investigation was conducted, in the Demonstration Farm, Faculty of Agriculture, University of Khartoum (Shambat), in the autumn season of 2012 to assess the variation in agro-morphological characters, biochemical components, antioxidant capacity, antibacterial activity and molecular diversity in nineteen newly developed genotypes of Karkadeh. Significant differences (P ≤ 0.05) were obtained among genotypes in agro-morphological characters (plant height, number of branches per plant, number of fruits per branch and weight of 100-Seed). The proximate analysis indicated that the calyx contained 3 to 5.5 % moisture, 6.7 to 10 % ash, 6 to 14% crude fiber, 14 to 26% crude protein and 1.5 to 27.1 mg/g total saccharides. The highest total acidity of Karkadeh calyx was 16.47 %. The highest pH value of aqueous extract was 3.4. The highest value of total soluble solids (37.67 %) was detected in SHRHi-2 and the oxalate content ranged from 0.29 to 0.54%. In addition, the calyx was highly rich in minerals such as potassium, calcium and iron. Also, highly significant differences (P ≤ 0.01) were detected in phenols, anthocyanins, tannins, ascorbic acid and flavonoids contents among the evaluated genotypes using spectrophotometeric methods. The highest anthocyanin content was obtained in dark red genotype (SHRHi-17), whereas the white genotype (SHRHi-1) contained no anthocyanin. Determination of antioxidant activity of calyx methanolic extract, using DPPH and ABTS radical scavenging activity methods and propyl gallate and ascorbic acid as standard antioxidants, indicated high activity. For DPPH, highest scavenging activity (81.5%) was detected in SHRHi-9 with IC50 (0.33 mg/ml) whereas the lowest value (45.95%) was detected in SHRHi-1. With respect to ABTS method, the antioxidant activity ranged from 39.51% (SHRHi-1) to 88.1 % (SHRHi-9). Furthermore, the results obtained from anti-bacterial activity assay disc diffusion showed that the calyx extracts of Karkadeh had significant inhibitory effects on the test bacteria (Salmonella typhimurium). The widest zone of growth inhibition (25.3 mm) was produced by the extract of SHRHi-3. The chemical analysis showed that seed oil content ranged from 12.4 to 29.8 %. The major fatty acids identified in the oil were heptadecanoic acid (78.8%), cis- 10-heptadecenoic acid (72.6%), palmatic acid (77.23%), palmitoleic acid (76.26%) and caproic acid (77.6%). Application of iii Random Amplified Polymorphic DNA (RAPD) molecular markers revealed the presence of a wide genetic diversity among the studied nineteen genotypes of Karkadeh. The constructed dendrogram, based on Jaccardʼs similarity coefficients, differentiated the genotypes into six clusters. The closest genotypes (with 77% similarity) were SHRHi-4B and SHRHi-10, while the most distant ones (24% similarity) were SHRHi-6 and SHRHi-11. In conclusion, genotype SHRHi-9 showed high antioxidant capacity and had high amount of vitamin C and flavonoid contents. Thus, this genotype can be presented as an improved new cultivar or used in other breeding programmes for further improvement of these desirable compounds. Genotype SHRHi-3 which showed high antityphoid activity can be used as a natural herbal remedy for treating typhoid fever.
Description: 166 Pages
URI: http://khartoumspace.uofk.edu/123456789/26083


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