Antimicrobial and anti-Quorum Sensing activities of selected medicinal plants of Ethiopia: Implication for development of potent antimicrobial agents.

BACKGROUND: Traditional medicinal plants have been used as an alternative medicine in many parts of the world, including Ethiopia. There are many documented scientific reports on antimicrobial activities of the same. To our knowledge, however, there is no report on the anti-Quorum Sensing (Quorum Quenching, QQ) potential of traditional Ethiopian medicinal plants. As many of the opportunistic pathogenic bacteria depend on Quorum Sensing (QS) systems to coordinate their virulence expression, interference with QS could be a novel approach to control bacterial infections. Thus, the aim of this study was to evaluate selected medicinal plants from Ethiopia for their antimicrobial activities against bacterial and fungal pathogens; and to assess the interference of these plant extracts with QS of bacteria. METHODS: Antimicrobial activities of plant extracts (oil, resins and crude extracts) were evaluated following standard agar diffusion technique. The minimum inhibitory concentrations (MIC) of potent extracts were determined using 96 well micro-titer plates and optical densities were measured using an ELISA Microplate reader. Interference with Quorum Sensing activities of extracts was determined using the recently established E. coli based reporter strain AI1-QQ.1 and signaling molecule N-(ß-ketocaproyl)-L-homoserine lactone (3-oxo-C6-HSL). RESULTS: Petroleum ether extract of seed of Nigella sativa exhibited the highest activity against both the laboratory isolated Bacillus cereus [inhibition zone (IZ), 44 ± 0.31 mm] and B. cereus ATCC 10987 (IZ, 40 ± 2.33 mm). Similarly, oil extract from mature ripe fruit husk of Aframomum corrorima and mature unripe fruit of A. corrorima revealed promising activities against Candida albicans ATCC 90028 (IZ, 35 ± 1.52 mm) and Staphylococcus aureus DSM 346 (IZ, 25 ± 1.32 mm), respectively. Antimicrobial activities of oil extract from husk of A. corrorima and petroleum ether extract of seed of N. sativa were significantly higher than that of the control antibiotic [Gentamycin sulfate, (IZ, 25-30 mm)]. The lowest MIC value (12.5 mg/mL) was recorded for oil from husk of A. corrorima against Pseudomonas aeruginosa. Of the total eighteen extracts evaluated, two of the extracts [Methanol extract of root of Albiza schimperiana (ASRM) and petroleum ether extract of seed of Justica schimperiana (JSSP)] interfered with cell-cell communication most likely by interacting with the signaling molecules. CONCLUSION: Traditional medicinal plants from Ethiopia are potential source of alternative medicine for the local community and scientific research in search for alternative drugs to halt challenges associated with the emerging antimicrobial resistance. Furthermore, the Quorum Quenching activities observed in two of the plant extracts calls for more comprehensive evaluation of medicinal plants for the control of many bacterial processes and phenotypic behaviors such as pathogenicity, swarming, and biofilm formation. Being the first assessment of its kind on the potential application of Ethiopian traditional medicinal plants for interference in microbial cell-cell communication (anti-Quorum Sensing activities), the detailed chemistry of the active compounds and possible mechanism(s) of actions of the bio-molecules responsible for the observed interference were not addressed in the current study. Thus, further evaluation for the nature of those active compounds (bio-molecules) and detailed mechanism(s) of their interaction with microbial processes are recommended.

Household food insecurity and mental distress among pregnant women in Southwestern Ethiopia: a cross sectional study design.

BACKGROUND: There are compelling theoretical and empirical reasons that link household food insecurity to mental distress in the setting where both problems are common. However, little is known about their association during pregnancy in Ethiopia. METHODS: A cross-sectional study was conducted to examine the association of household food insecurity with mental distress during pregnancy. Six hundred and forty-two pregnant women were recruited from 11 health centers and one hospital. Probability proportional to size (PPS) and consecutive sampling techniques were employed to recruit study subjects until the desired sample size was obtained. The Self Reporting Questionnaire (SRQ-20) was used to measure mental distress and a 9-item Household Food Insecurity Access Scale was used to measure food security status. Descriptive and inferential statistics were computed accordingly. Multivariate logistic regression was used to estimate the effect of food insecurity on mental distress. RESULTS: Fifty eight of the respondents (9%) were moderately food insecure and 144 of the respondents (22.4%) had mental distress. Food insecurity was also associated with mental distress. Pregnant women living in food insecure households were 4 times more likely to have mental distress than their counterparts (COR = 3.77, 95% CI: 2.17, 6.55). After controlling for confounders, a multivariate logistic regression model supported a link between food insecurity and mental distress (AOR = 4.15, 95% CI: 1.67, 10.32). CONCLUSION: The study found a significant association between food insecurity and mental distress. However, the mechanism by which food insecurity is associated with mental distress is not clear. Further investigation is therefore needed to understand either how food insecurity during pregnancy leads to mental distress or weather mental distress is a contributing factor in the development of food insecurity.

In vitro evaluation of antileishmanial activity and toxicity of essential oils of Artemisia absinthium and Echinops kebericho.

Potential toxicity, costs, and drug-resistant pathogens necessitate the development of new antileishmanial agents. Medicinal and aromatic plants constitute a major source of natural organic compounds. In this study, essential oils of Artemisia absinthium L. and Echinops kebericho Mesfin were investigated by GC and GC/MS analyses. Isolated oils were screened for antileishmanial activity against two Leishmania strains (L. aethiopica and L. donovani), and toxicity on the human monocytic leukemia (THP-1) cell line and red blood cells in vitro. GC/MS Analysis revealed 65 compounds (93.74%) for Artemisia absinthium and 43 compounds (92.85%) for Echinops kebericho oil. The oils contained the oxygenated monoterpene camphor (27.40%) and the sesquiterpene lactone dehydrocostus lactone (41.83%) as major constituents, respectively. Both oils showed activity against promastigote (MIC 0.0097-0.1565 µl/ml) and axenic amastigote forms (EC(50) 0.24-42.00 nl/ml) of both leishmania species. Weak hemolytic effect was observed for both oils, showing a slightly decreased selectivity index (SI 0.8-19.2) against the THP-1 cell line. Among the two oils tested, E. kebericho exerted strong antileishmanial activity that was even higher than that of amphotericin B with significant cytotoxicity. This study, therefore, demonstrated the potential use of both oils as source of novel agents for the treatment of leishmaniasis.

Essential-oil composition, antileishmanial, and toxicity study of Artemisia abyssinica and Satureja punctata ssp. punctata from Ethiopia.

Essential oils of Artemisia abyssinica and Satureja punctata ssp. punctata from Ethiopia were analyzed by GC and GC/MS, and screened for leishmanicidal activity against promastigote and axenic amastigotes of Leishmania donovani and L. aethiopica, including toxicity studies on human monocytic leukemia cells (THP-1) and erythrocytes in vitro. GC/MS of A. abyssinica oil revealed 67 compounds (99.94%) with the major constituents yomogi alcohol (38.47%), artemisyl acetate (24.88%), and artemisia alcohol (6.70%), and oxygenated monoterpenes (84.00%) as the dominant group. The oil of S. punctata contained 67 compounds (99.49%) with the main constituents geranial (27.62%), neral (21.72%), alpha-bisabolol (13.62%), and (E)-nerolidol (4.82%), of which oxygenated mono- and sesquiterpenes (58.39 and 26.91%, resp.) showed highest abundance. Both oils showed effect on promastigotes (MIC 76.5 to 312.5 nl/ml) and amastigotes (EC(50) 4.06 to 131.00 nl/ml) of L. donovani and L. aethiopica, and varying toxicities on THP-1 cells (CC(50) 0.013 to 350 nl/ml with selectivity index between 0.001 and 28) and erythrocytes (with LC(50) 0.35 to 1.52 microl/ml). S. punctata oil exerted highest activity against both Leishmania sp. and toxicity. The revealed antileishmanial activities support further isolation and investigation of oil constituents for in vitro/in vivo evaluation.

Molluscicidal effect of Achyranthes aspera L. (Amaranthaceae) aqueous extract on adult snails of Biomphalaria pfeifferi and Lymnaea natalensis.

BACKGROUND: Intestinal schistosomiasis caused by Schistosoma mansoni is a wide spread disease in most parts of Ethiopian highlands. Snail control is one major strategy in schistosomiasis control. The use of molluscicidal plant products is becoming interesting due to their environmental friendliness, accessibility and easy application. This research is aimed to evaluate the molluscicidal effect of Achyranthes aspera on Biomphalaria pfeifferi and Lymnaea natalensis snails, which are of great medical and veterinary importance in Ethiopia. METHODS: Adult B. pfeifferi snails were exposed to the various concentrations of A. aspera aqueous leaf extract for 24, 48 and 72 h. Similarly, adult L. natalensis snails were exposed to the extract for 24 h. Mortality data were analyzed using probit regression model. Phytochemical content of the plant was analyzed using standard screening methods. RESULTS: The plant's molluscicidal effect on the two snail species was demonstrated. The 24 h LC50 and LC90 values against L. natalensis were 69.5 and 93.9 ppm respectively. In the 24, 48 and 72 h exposure of B. pfeifferi, the LC50 values were 72.4, 69.9, 64.7 ppm and the LC90 were 96.5, 93.8, 92.8 ppm, respectively. The phytochemical screening tests indicated presence of saponins. CONCLUSION: From the findings of this study, A. aspera has a molluscicidal potential. The result provides a useful foundation for further in-depth studies to ensure its wider applicability in different water bodies and evaluate its toxic effects on non-target species.

Constituents, antileishmanial activity and toxicity profile of volatile oil from berries of Croton macrostachyus.

The chemical composition of the volatile oil from berries of Croton macrostachyus Hochst. ex Del. was determined by GC and GC/MS. The oil was tested for its in vitro antileishmanial activity on two Leishmania strains, and its toxicity on the human monocytic leukemia (THP-1) cell line and erythrocytes from sheep blood. The main constituents of the oil were benzyl benzoate (51.8%), linalool (10.1%), gamma-muurolene (9.3%), (E,E)-alpha-farnesene (3.2%), delta-cadinene (2.8%) and alpha-curcumene (2.7%). The oil was effective against L. donovani and L. aethiopica promastigotes (MIC = 0.08 microL/mL and 0.16 microL/mL, respectively) and axenic amastigote stages (EC50 = 20.00 nL/mL and 6.66 nL/mL, respectively). The CC50 value for the oil was 10.00 nL/mL on THP-1 cells with selectivity index values of 0.5 for L. donovani and 1.5 for L. aethiopica. The median lethal concentration (LC50) of the oil was 2.45 microL/mL. Thus the observed high efficacy and moderate toxicity of the volatile oil from C. macrostachyus, makes the plant a promising source of new lead compounds in the search for safe and effective antileishmanial drugs.