University of Khartoum

Taxonomical Revision of Indigenous Species Belonging to the Family Onagraceae and Phytochemical and Biological Activity Evaluation of Ludwigia erecta (L.) H.Hara

Taxonomical Revision of Indigenous Species Belonging to the Family Onagraceae and Phytochemical and Biological Activity Evaluation of Ludwigia erecta (L.) H.Hara

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Title: Taxonomical Revision of Indigenous Species Belonging to the Family Onagraceae and Phytochemical and Biological Activity Evaluation of Ludwigia erecta (L.) H.Hara
Author: Elhaj, Maheda Gaafer Mohammed Khier
Abstract: The study provides taxonomical revision of the family Onagraceae, including six species belonging to two genera; these are: Epilobium hirsutum L., Ludwigia adscenoens (L.) H.Hara, L. erecta (L.) H.Hara, L. leptocarpa (Nutt.) H.Hara, L. octovalvis (Jacq) P.H. Raven and L. perennis L. Moreover, the biological activity including antimicrobial, antigiardial, antimalarial, antitumor and antioxidant activities and phytochemistry of root, stem, leaf, flower and fruit of L. erecta were evaluated. Dried powdered plant samples were subjected separately to sequential extraction using hexane and mixture of methanol: chloroform (1:1, v/v) as solvents. Dried extracts were then dissolved in 1% DMSO (dimethyl sulfoxide) for different biological assays. Extracts were evaluated for their effectiveness, at different concentrations (two-fold dilution), against four bacterial species including Gram negative (Escherichia coli and Pseudomonas aeruginosa) and Gram positive (Staphylococccus aureus and Bacillus subtilis) bacteria as well as two fungal species (Aspergillus niger and Candida albicans) using the disc diffusion and microdilution methods. Antimalarial and antigiardial activities were determined by the microplate assay against the K1 parasite strain of Plasmodium falciparum and Giardia lamblia, respectively. The cytotoxicity of extracts on three cancerous cell lines; human breast carcinoma (MCF7 and MDA-MB231) and human colon adenocarcinoma (HT29 and HCT116) cell lines in addition to one normal Vero cell line (EAhy926) was established by colorimetric measurement of cell viability. The antioxidant potential of extracts was determined on the basis of their scavenging activity of the stable 1, 1-diphenyl-2-picryl hydrazyl (DPPH) free radical. Phytochemical study was performed by using different chromatographic techniques including Thin Layer Chromatography (TLC) and Gas chromatography/mass spectrometry (GC/MS) techniques. Standard methods were used for quantitative estimation of phenols. The present study showed descriptive morphological studies for the six species. Their nomenclature, morphology, phenological data, distribution and uses are given along with key to the species. Three species of the plants (L. adscenoens (L.) H.Hara., L. erecta (L.) H.Hara and L. perennis L) were updated to their new names. Chemotaxonomical study (on the leaf, flower and fruit) of L. erecta, L. leptocarpa and E. hirsutum) suggested that phenols, flavonoids, terpenes and alkaloids could be considered as chemotaxonomical markers. Data indicated also the strong chemical affinity of L. erecta and L. leptocarpa and therefore supporting their closer relationship as two species belonging to same genus and enforced the taxonomical position of E. hirsutum in different genus. Results of antimicrobial activity revealed that the highest antibacterial activity was obtained from the methanol: chloroform extracts of the stem and flower against B. subtilis with MIC value of 0.625 mg/mL followed by the same extract of flower against P. aeruginosa and E. coli with MIC value of 1.25 mg/mL. Hexane extract of the fruit displayed the best antifungal activity against C. albicans and A. niger with MIC value of 10 mg/mL. All methanol: chloroform extracts possessed antigiardial activity and the ranking order of extracts with high antigiardial activity in term of IC50 values was the root (41.60 μg/mL) > fruit (109.89 μg/mL) > stem (168.47 μg/mL) > leaf (212.26 μg/mL). The same extracts exhibited weak antimalarial activity (IC50> 320µg/mL). Results of antioxidant activity showed that the fruit (IC50 50 µg/mL), stem (IC50 75 µg/mL) and leaf (IC50 75 µg/mL) possessed very good DPPH radical scavenging activity (higher than the standard control (IC50 77 µg/mL)). All extracts of different parts of J. erecta were virtually non-toxic against Vero cells with IC50 value ranged from 169 to 9800 µg/mL and only the flower extract demonstrated moderate antitumor effect against MDA-MB231 cell lines with IC50 value 30.5 ± 2.9 µg/mL. Phytochemical screening revealed that extracts were rich in secondary metabolites. The fruit exhibited the highest phenolic (3671.50 ±0.63 mg gallic acid eq./L), flavonoids (3928 ± 0.74 mg quercetin eq./L) and tannins (48.66 ±0.14 mg tannic acid eq./L) contents. GC-MS analysis of hexane extracts showed that fatty acids presented the main fractions of the root and fruit. The stem was marked with high presence of Dimethyl sulfoxonium formyl methylide. The leaf and fruit were characterized by the high proportion of l-(+)-Ascorbic acid and 2, 6-dihexadecanoate. Different types of sterols were also identified in the hexane extracts of the four organs where β-Sitosterol was the most prominent compound found in highest concentration (16.50%) in the leaf. In conclusion, the results showed the potentiality of phenols, flavonoids, terpenes and alkaloids as chemotaxonomical markers for the classification of species belong to the family Onagraceae and the results also demonstrated the potential of J. erecta to exert beneficial antimicrobial, antigiardial and antioxidant effect and thus, could be a natural source for bioactive agents.
URI: http://khartoumspace.uofk.edu/123456789/25682


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