Habtamu, Asmamaw (2017) Evaluation of the Antiplasmodial and Antimicrobial Properties of the Medicinal Plants Rumex nepalensis Spreng and Centella asiatica L. PhD thesis, Addis Ababa University.
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Abstract
Infectious diseases are the major health problems in the world particularly in developing countries. To combat this problem various drugs, antibiotics and vaccines have been developed through time, but these successes have been challenged by the emergence of drug resistant pathogens. In Ethiopia, most people use traditional medicinal plants which are the natural source of medicine to treat different diseases. However, traditional healers in this country apply medicinal plants to heal different infections without scientific prescription and optimization of the right doses. This study was conducted to investigate antiplasmodial, antibacterial, antifungal properties, evaluate acute toxicity and possibly isolate the active compounds of two widely used medicinal plants: Rumex nepalensis Spreng and Centella asiatica L. The two plants were collected from Dejen District, Northen part of Ethiopia, and air dried in shade. The specific plant parts (leaves, roots. aerial parts) were separately ground into powder. Each plant powder was soaked in water, methanol and hexane in separate Erlenmeyer flasks and placed on shaker of 120 rpm for 72 hours. The extracts were concentrated in rotary evaporator and by lyophilizer (aqueous extract). The crude extracts of water, methanol and hexane of the two plants were tested for antiplasmodial, antimicrobial activities, acute toxicity and screened for phytochemicals. The higher antimicrobial performing extract, methanol extracts of the roots of R. nepalensis and further fractionnated by solvent-solvent extraction (hexane, chloroform, ethanol, water and methanol) and these fractions were evaluated on pathogenic microorganisms (Plasmodium berghei, Esherchia coli, Pseudomonas aeruginosa, Shigella flexneri and Salmonella typhimurium, Klebsiella pneumonia, Candida albicans). Similarly the best fraction, ethanol fraction, was further fractionnated by column chromatography (CC) and tested for antiplasmodial and antimicrobial activities. Furthermore, column Chromatographic profiles of the roots of R. nepalensis were analyzed by thin layer chromatography (TLC). The crude methanol and hexane extracts of the root, the leaf extracts of R. nepalensis and the aerial parts of C. asiatica at the highest concentration of 5000 mg/kg BW was not toxic to the albino mice. Furthermore the phytochemical screening of the R. nepalensis revealed the presence of flavonoids, alkaloids, glycosides, triterpenoids, sterols, saponin and tannin. On the other hand, phytochemical screening of C. asiatica showed the presence of flavonoids, alkaloids, glycosides and saponin, triterpenoids and sterols but tannins were not clearly observed. CC and TLC profiles of ethanol fraction of the roots of R. nepalensis showed the presence of chrysophanol, emodin and 5 undefined compounds. The crude extracts of water, methanol and hexane of the two plants had shown suppression to Plasmodium berghei in vivo in mice. Particularly, the crude extracts of water, methanol and hexane of the roots of R. nepalensis had significantly higher day- 4 suppressive effect 52.00 %, 59.90 % and 39.30 % respectively than the negative control (2% DMSO). But all extracts had significantly lower day-4 suppressive level than the positive control, chloroquine in P. berghei infected albino mice. The ethanol fraction of the roots of R. nepalensis showed higher plasmodium percent suppression in vivo in albino mice (70.08 %) compared to water (54.31 %), chloroform (19.61 %) and methanol (10.27 %) suppression at 500 mg/kg body weight (BW). Similarly the mean survival time value of the mice administered with ethanol fraction was significantly higher than all extracts (water, chloroform and methanol) at 500 mg/kg BW and negative control, 2% DMSO treated mice. More specificaly the ethanol fraction of the roots of R. nepalensis fractionnated by column chromatography in ethyl acetate: methanol (1:1) v/v showed 73.66% plasmodium suppression in vivo in albino mice at 300 mg/kg BW. The re-fractionnated ethyl acetate: methanol fraction by column chromatography in methanol increased its suppression to 79.66% at 150 mg/kg BW. In the antimicrobial test, the ethanol fraction of the roots of R. nepalensis showed zone of inhibition for P. aeruginosa (19.33±0.33 mm), S. aureus (18.03±0.14 mm) and S. flexneri (12.77±0.15 mm) and S. typhimurium (8.33±0.33 mm) at 6 mg/well by using agar well diffusion method compared to the negative control (2% DMSO) which have no inhibition zone on the tested bacteria. However, the positive control (teteracyclin and chloramphenicol) significantly higher bacterial inhibition than ethanol fraction of the roots of R. nepalensis. From the result obtained it can be concluded that the five undefined compounds played a role in synergizing the atiplasmodial, antibacterial and antifungal activities of the roots of R. nepalensis. In conclusion this work has demonstrated the high potential of R. nepalensis and C. asiatica as sources for further exploitation of antiplasmodial, antibacterial and for use in herbal medicine.
| Item Type: | Thesis (PhD) |
|---|---|
| Uncontrolled Keywords: | antibacterial, antifungal, Plasmodium suppression, phytochemical screening, toxicity |
| Subjects: | Q Science > QH Natural history > QH301 Biology Q Science > QK Botany Q Science > QR Microbiology R Medicine > R Medicine (General) R Medicine > RA Public aspects of medicine > RA0421 Public health. Hygiene. Preventive Medicine |
| Divisions: | Africana |
| Depositing User: | Selom Ghislain |
| Date Deposited: | 16 Aug 2018 08:41 |
| Last Modified: | 16 Aug 2018 08:41 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/4908 |
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