Pharmacognosy

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Browsing Pharmacognosy by Author "Asres, Kaleab (PhD)"

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    Ethnopharmacological Survey of Medicinal Plants among the Hamer Ethnic Group, Hamer Woreda, South Omo Zone, SNNPR, Ethiopia and Evaluation of a Selected Plant for its Antimalarial Activity
    (Addis Ababa University, 2012-07) Paulos, Biniam; Asres, Kaleab (PhD); Gedif, Teferi (PhD)
    Health seeking behaviour of people around the globe will be affected by different socio-cultural and economical factors. People in Ethiopia, particularly tribal people have long history of using medicinal plants as a major component of their traditional medical practices over many centuries to satisfy their health care needs. The transfer of this sort of knowledge from generation to generation is mainly effected by words of mouth. Cross-sectional survey was conducted to document ethnopharmacological information of the Hamer semi pastoralists by using semi structured questionnaires administered to eight traditional healers/key informants and one thousand six hundred household (HH) respondents supplemented by eight focus group discussions (FGDs). The majority (84%) of HH respondents were males, 94.4% of whom suffered illnesses in the last two weeks recall period and had taken action. The prevalence of the use of traditional medicine among the Hamer community was found to be very common as indicated by FGD participants, key informants and HH respondents. HH respondents reported that traditional medical practices are their first choice when family members get sick. Females’ preference of traditional medical practices was higher than males. The main reasons for the preference of the community members to traditional medical practices include its effectiveness, low cost and ease of availability. A total of sixty medicinal plants were reported and collected along with their local names, indication(s), parts used and method of preparations. The health seeking behavior of the Hamer ethnic group is affected by different socioeconomic and cultural factors. There is also a strong indication for traditional medical practices and use of plant materials to treat various ailments and health problems among the study population. Therefore, due attention should be given to these traditional medical practices. The ethnopharmacological survey part of this study revealed that Aloe otallensis Baker., an indigenous Ethiopian plant, was among the most widely used medicinal plants by the members of the Hamer Ethnic Group. The plant is used for the treatment of malaria and wound healing. Malaria, a diseases caused by protozoan parasites is a major obstacle to the socioeconomic xii development of several developing countries including Ethiopia. The phytoconstituents of A. otallensis studied by thin layer chromatography (TLC) and its antimalarial and antioxidant activities were assessed by in vivo four day Plasmodium berghei suppressive test and 1,1- diphenyl-2-picrylhydrazyl (DPPH) assay, respectively. The study revealed the presence of picataloside (2,8-O,O-di (β-D-glucopyranosyl)-1,2,8-trihydroxy-3-methylnaphtalene) in the exudate of A. otallensis, which was isolated from the plant for the first time. The study further showed that the leaf exudate of the plant possesses maximum antimalarial activity (60.7% suppression) at a dose of 300 mg/kg. Similarly, at a dose of 100 mg/kg the isolated compound suppressed P. berghei parasites by 47.9%. Both the exudate and the isolated compound displayed comparable radical scavenging activity possessing IC50 value of 26.9 and 26.2 μg/ml, respectively in DPPH assay. The results of the present study do seem to justify the traditional use of A. ottalensis for the treatment of malaria.
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    Screening for antimicrobial and anti inflammatory activities and, formulation studies on the extracts of selected medicinal plants topically applied in Ethiopia
    (Addis Ababa University, 2014-02) Taddese, Samuel; Gebre-Mariam, Tsige (Professor); Asres, Kaleab (PhD)
    In an attempt to integrate traditionally used herbal products into modern topical formulation, extracts of the leaves of Maesa lanceolata (Myrsinaceae), Osyris quadripartita Decn. (Santalaceae), Steganotaenia araliacea Hochst ExA. Rich (Apiaceae), Cadaba farinosa (Capparidaceae) and; the aerial parts of Plantago lanceolata (Plantagonaceae) and Alachemilla pedata A. Rich (Rasaceae) have been screened for their antibacterial and antifungal activities. All hydroalcoholic extracts, except C. farinosa and S. araliacea were active against E. coli. And, all extracts had activities against S. aureus and P. aeroginosa. Similarly, screeneing of the total extracts against Candida albicans and Trichophyton mentagrophytes indicated that all extracts, except P. lanceolata on both strains and C. farinosa on T. mentagrophytes, were active. But none of the extracts tested displayed activity against Aspergillus niger. The antimicrobial activities of A. pedata and M. lanceolata were higher than those plants tested and hence, further works have been undertaken on these plants. In an attempt to localize the active ingredients, successive fractionation with petroleum ether, chloroform, acetone and methanol have been carried out. The antimicrobial activity study of the various fractions revealed that the antimicrobial effect of A. pedata was because of the non-polar components (petroleum ether fraction) and that of M. lanceolata, the activities were distributed among the various fractions. The action against T. mentagrophytes of the latter was entirely because of the polar compounds present in the methanol extract. To assess the clinical utility of these plants, MICs were determined. Accordingly, the results for A. pedata were 5 mg/ml against S. aureus and E. coli and, 10 mg/ml for C. albicans using agarwell diffusion technique. The MIC of this plant extract using agar dilution technique on the same bacteria was 0.125 mg/ml. Similarly; the MIC of M. lanceolata was 1.25 mg/ml against the abovementioned bacteria and, 0.625 mg/ml against fungi using agar-well diffusion technique. And, using dilution technique, the result was 1.25 mg/ml for bacteria and 0.0625 mg/ml for fungi. Anti-inflammatory activities and semi-quantitative standardization works were also conducted and it was found that M. lanceolata has significant anti-inflammatory activity at 100 mg/kg and 750mg/kg with better activity at 100 mg/kg. Similarly, A. pedata has also displayed antiinflammatory activity, even though the effect was less than M. lanceolata. The water extractive values were 4.66 and 5.24% (W/W) for A. pedata and M. lanceolata, respectively. Successive extractive values using petroleum ether, chloroform, acetone, methanol and water were (3.20, 4.56), (3.38, 4.36), 1.28, 0.56), (5.38, 6.52), (4.60, 6.64) for A. pedata and M. lanceolata, respectively. Ash value determination and TLC-fingerprinting were also conducted as part of the standardization work. Ointments and creams were formulated using the hadroalcoholic extracts of A. pedata and M. lanceolata. Study on the in vitro performances of the proposed formulations indicated that releases from hydrophilic bases were better and polyethylene glycol-based preparations were superior in activity than formulations prepared with hydrophobic bases. Furthermore, the in vitro performances of the formulated topical dosage forms were comparable to the activity of locally available marketed antimicrobial products.
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    Studies on Antimalarial Activity of the Leaf Constituent of Otostegia Integrifolia Benth. (Lamiacea) Against Plasmodium Berghei in Mice
    (Addis Ababa University, 2012-08) Endale, Abyot; Asres, Kaleab (PhD); Bisrat, Daniel(PhD)
    Medicinal plants play an important role in the treatment of malaria especially in developing countries where resources are limited. A continued search for other effective, safe and cheap plant-based antimalarial agents thus becomes imperative in the face of these difficulties. The leaves of Otostegia integrifolia Benth. are used traditionally as malarial remedy in Northern Ethiopia. This study was aimed to investigate the antimalarial potentials of the crude leaf extract, solvent fractions as well as isolated compound(s) in vivo in Plasmodium berghei infected mice to give scientific proof to the ethnobotanical claims. Leaves of O. integrifolia were collected and dried under the shade. The dried plant material was pulverized and extracted with 80% methanol. The dried crude extract was then further fractionated with different solvents. Both the crude extract and fractions were evaluated for their antimalarial activity in vivo, in 4-day suppressive assays against P. berghei in mice. Column chromatography was used to isolate compound/s from the most active fraction. The isolated compound was evaluated for its antimalarial activity in vivo, in 4-day suppressive assay against P. berghei and its structure elucidated using spectroscopic methods (MS and NMR). Preliminary phytochemical screening was performed using standard procedure. Acute and sub-acute toxicity studies of the crude extract were carried out in Swiss albino mice prior to antimalarial activity tests. No sign of toxicity was observed up on administration of the 80% methanol extract of the plant up to the highest dose (5000 mg/kg) given. Preliminary phytochemical screening showed the presence of saponins, flavonoids and other phenolic compounds in the hydroalcoholic leaf extract. The hydroalcoholic leaf extract (200, 400 and 600 mg/kg/day) and solvent fractions (200, 400 and 600 mg/kg/day) exhibited significant (P<0.01) antimalarial activity compared to the negative control group in four day suppression test with a considerable mean survival time. The highest parasite suppression (80.52%) was observed at 600 mg/kg /day for the crude extract, while the ethyl acetate fraction was found to be the most active among the solvent fractions and showed highest suppression (60.15%) at 600 mg/kg/day. The isolated compound also showed significant antimalarial (P<0.001) activity at the tested doses (25, 50 and 100 mg/kg/day) with chemosuppression of 50.13, 65.58, and 73.16%, respectively. Structural elucidation revealed that the isolated compound is a labdane type diterpenoid, 15,16-epoxy-3α,9α-dihydroxy-labda-13(16),14-diene. The crude extract, solvent fractions and the isolated compound possess considerable antiplasmodial activities which justify the use in ethnomedicine and can be exploited in the control of malaria.
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