Kusari S.,TU Dortmund |
Tatsimo S.J.N.,University of Maroua |
Zuhlke S.,TU Dortmund |
Talontsi F.M.,TU Dortmund |
And 2 more authors.
Angewandte Chemie - International Edition | Year: 2014
We have independently investigated the source of tramadol, a synthetic analgesic largely used for treating moderate to severe pain in humans, recently found in the roots of the Cameroonian medicinal plant, Nauclea latifolia. We found tramadol and its three major mammalian metabolites (O-desmethyltramadol, N-desmethyltramadol, and 4-hydroxycyclohexyltramadol) in the roots of N. latifolia and five other plant species, and also in soil and local water bodies only in the Far North region of Cameroon. The off-label administration of tramadol to cattle in this region leads to cross-contamination of the soil and water through feces and urine containing parent tramadol as well as tramadol metabolites produced in the animals. These compounds can then be absorbed by the plant roots and also leached into the local water supplies. The presence of tramadol in roots is, thus, due to an anthropogenic contamination with the synthetic compound. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
News Article | October 30, 2015
Tramadol, a synthetic opioid component of the painkiller tramal, was surprisingly identified in 2013 as a natural product of Sarcocephalus latifolia, a tree found in Cameroon. Scientists from Germany and Cameroon now refute this finding in the journal Angewandte Chemie. By determination of the 14C content, for example, they established that the tramadol found in plants is in fact anthropogenic and introduced by off-label use of the drug. Serious health and environmental problems may occur as a consequence. In Northern Cameroon, tramadol is used less as a pain reliever or antidepressant but rather as a doping agent to allow both animals and humans to work in temperatures above 40 °C during the dry season. Contaminated soil and water samples were therefore not surprising. Or does tramadol come from trees? A team headed by Michael Spiteller has now conclusively answered this question. By using the radiocarbon method usually used for age determination, the researchers proved that the tramadol in Cameroon's environment is of synthetic origin. If the tramadol had recently been produced by a plant, it would mirror the current 14C content in our atmosphere. Industrially produced organic molecules made from fossil-fuel-derived starting materials contain no 14C because it has long since decayed. The tramadol found in the environmental samples investigated was free of 14C and is therefore unambiguously synthetic. A further piece of evidence is that the Sarcocephalus latifolius plants that the researchers grew from seeds from a botanical collection contained no tramadol. However, if the plants were grown with tramadol-containing water, the plants took up the drug without metabolizing it further. In order to evaluate the persistence of tramadol in the environment and the extent of its misuse, Spiteller and his co-workers from the TU Dortmund and the University of Maroua (Cameroon) tested the tramadol content of soils, groundwater, surface water, and well water, as well as S. latifolius. In some cases, these tests revealed alarmingly high concentrations, even in plants other than S. latifolia. High concentrations of tramadol and one of its powerful metabolites were found in public wells. "We found particularly high levels of contamination in the dry season when water levels were low in a river bed in downtown Maroua in North Cameroon," says Spiteller. "This area is inhabited by many homeless people, who use the contaminated water for drinking." "Now that we have provided unambiguous proof that the environment in Cameroon is significantly contaminated with synthetic tramadol, urgent measures must be taken to reduce the off-label use of tramadol," states Spiteller. This requires the prohibition of street-market sales of prescription drugs. "In addition, further research is needed to assess the long-term side effects of tramadol in humans, animals, and the environment." Explore further: An analgesic molecule discovered in its natural state in Africa More information: Souvik Kusari et al. Synthetic Origin of Tramadol in the Environment, Angewandte Chemie International Edition (2015). DOI: 10.1002/anie.201508646
Mune Mune M.A.,University of Maroua |
Minka S.R.,University of Yaounde I |
Mbome I.L.,Food and Nutrition Research Center
Food Chemistry | Year: 2014
Response surface methodology (RSM) was used for modelisation and optimisation of protein extraction parameters in order to obtain a protein concentrate with high functional properties. A central composite rotatable design of experiments was used to investigate the effects of two factors, namely pH and NaCl concentration, on six responses: water solubility index (WSI), water absorption capacity (WAC), oil holding capacity (OHC), emulsifying activity (EA), emulsifying stability (ES) and foam ability (FA). The results of analysis of variance (ANOVA) and correlation showed that the second-order polynomial model was appropriate to fit experimental data. The optimum condition was: pH 8.43 and NaCl concentration 0.25 M, and under this condition WSI was ≥17.20%, WAC ≥ 383.62%, OHC ≥ 1.75 g/g, EA ≥ 0.15, ES ≥ 19.76 min and FA ≥ 66.30%. The suitability of the model employed was confirmed by the agreement between the experimental and predicted values for functional properties. © 2014 Elsevier Ltd. All rights reserved.
Thomas B.B.,University of Yaounde I |
Saleh M.,University of Yaounde I |
Saleh M.,University of Maroua |
Kofane T.C.,University of Yaounde I
General Relativity and Gravitation | Year: 2012
We investigate thermodynamics and phase transition of the Reissner-Nordström black hole surrounded by quintessence. Using thermodynamical laws of black holes, we derive the expressions of some thermodynamics quantities for the Reissner-Nordström black hole surrounded by quintessence. The variations of the temperature and heat capacity with the entropy were plotted for different values of the state parameter related to the quintessence, ω q, and the normalization constant related to the density of quintessence c. We show that when varying the entropy of the black hole a phase transition is observed in the black hole. Moreover, when increasing the density of quintessence, the transition point is shifted to lower entropy and the temperature of the black hole decreases. © 2012 Springer Science+Business Media, LLC.
Mune Mune M.A.,University of Maroua
Journal of Food Processing and Preservation | Year: 2015
Enzymatic hydrolysis of Bambara bean protein concentrate was investigated with the view to produce hydrolysates with desirable functional properties. A Box-Behnken design was used for experiments and models capable of predicting functional properties depending on hydrolysis conditions were developed. These models were then used to determine optimum hydrolysis conditions. It was found that hydrolysis parameters had significant influence on the functional properties. Nitrogen solubility and oil-holding capacity of Bambara bean protein hydrolysates were improved, while a slight increase in foaming capacity and decrease in emulsifying activity were observed. The optimum hydrolysis conditions were: time 97.5min, solid-to-liquid ratio 6/75 (w/v) and enzyme substrate ratio 1.90% (w/w). The properties obtained were: nitrogen solubility at pH 7 of ≥75%, nitrogen solubility at pH 4.5 of ≥33% and oil-absorption capacity of ≥4.1g/g. Finally, it was shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis that protein breakdown was selective. © 2015 Wiley Periodicals, Inc.
Mune Mune M.A.,University of Maroua
Journal of Food Processing and Preservation | Year: 2015
The effects of limited enzymatic hydrolysis with pepsin on the functional properties and molecular characteristics of cowpea protein concentrate (CPC) were investigated. Hydrolysates were prepared at degrees of hydrolysis (DH) 5-30%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis demonstrated that globulin was the major protein component of CPC, and enzymatic breakdown of polypeptides was selective. As a result, significant changes in the functional properties of hydrolysates were noticed as compared to the protein concentrate. Then, cowpea protein hydrolysates (CPHs) showed good water solubility index at pH7 (>95%) and pH4.5 (>55%), at DH 20 and 30%, respectively. Oil-holding capacity, emulsifying activity and foaming capacity were also improved by the enzymatic hydrolysis, while proteolysis was detrimental to foam stability and did not improve emulsion stability at DH 10-30%. Therefore, CPHs showed good potential for utilization in food formulations. © 2015 Wiley Periodicals, Inc.
Nsangou M.,University of Maroua
Computational and Theoretical Chemistry | Year: 2011
Geometry optimization at the B3LYP/6-31++G* level of calculation have been undertaken on clusters containing L-Threonine (L-Thr) or L-serine (L-Ser) surrounded by seven water molecules. This first step has been followed by the calculation of the harmonic vibrational modes. The comparison of the structural parameters of L-Thr and L-Ser with X-ray experimental values shows that the explicit model of solvation is more convenient. The discrepancies between the calculated values of bond lengths and bond angles with the experimental ones are less than 3%, excepted for O-H, N t-H, C β-O-H and C β-C α-H. The frequencies of the assigned modes are in good agreement with available IR and Raman values within 5%. © 2011 Elsevier B.V.
Tsamo C.,University of Maroua
International Journal of ChemTech Research | Year: 2014
In Cameroon like many African countries, awareness on e-waste is very low despite increasing dependence on modern technologies that generate e-waste. This paper presents a case study of Maroua town Cameroon. A survey of 33 EEE repair workshops was conducted, the regional government service in charge of environment, local councils and HYSACAM, a private company, responsible for handling waste in Maroua were visited where through questionnaires a number of findings were undertaken. A total of 1628 different e-waste items were found with an average flux rate of 1-4 items per week. Only 6% of items brought to the workshops could be repaired as over 90% enters the e-waste stream. The majority of the waste is stored in the workshops, and parts recycled when necessary. 87.9% of those manipulating these e-waste items do so without any protection, as 12% of them are aware of the toxicity of these wastes. The local councils have no e-waste management plan as no legislation exists to that effect. There is complete lack of awareness on this type of waste to the public as well as the main actors that should be responsible for their management stemming from poor policy and regulatory systems.
Nkwetisama C.M.,University of Maroua
International Journal of Applied Linguistics and English Literature | Year: 2013
Literature was once regarded as being inappropriate for the teaching of the English language. Nowadays, the importance of applying literature in the development of learners’ language skills is receiving a lot of attention by EFL/ESL practitioners worldwide (Lee 2009). In spite of such “remarkable revival of interest in literature" in the English language classroom (Duff & Maley 1990: 3), literature as a component of the English language teaching programme in secondary schools in Cameroon "remains the exception rather than the rule" (Macalister 2008: 248). This paper seeks to examine the impact of the withdrawal of English Literature from the English as a foreign language curriculum of French-speaking Cameroonians. In the article, we statistically compare the performances of Frenchspeaking and English-speaking Cameroonian teacher trainees of the department of Bilingual Studies of the Higher Teachers’ Training College of the University of Maroua in English Literature and in French Literature. We also discuss the importance and effectiveness of the different models and approaches in the development of the cultural competence and communicative skills of learners. The results obtained reveal that the studying of literatures in French by Anglophones at the Advanced Level positively influences their performances in French in Higher Education. The poor performances of Francophone Student-teachers in courses like LBL 11 (Introduction to English Literature) are attributable to the fact that they do not study literatures in English at the secondary school level. © Australian International Academic Centre, Australia.
Nourou M.,University of Maroua
International Food and Agribusiness Management Review | Year: 2015
This paper analyzes the volatility transmission between poultry and other commodity prices. The main question it addresses is as follows: Is there any commonality in the volatility processes of poultry and other agricultural food commodities' prices? Using standard dispersion indicators to measure the degree of poultry prices volatility and the GARCH-type models to specify poultry international price volatility at time 't' as a function of lagged shocks, we obtain the following results: poultry prices experienced less volatility in recent years relatively to other commodity prices; and the transmission of price volatility from other commodities to poultry prices is rather weak. These results could help to design better risk management tools in agribusiness. © 2015 International Food and Agribusiness Management Association (IFAMA).