Isolation,characterisation and complement fixation activity of acidic polysaccharides from Argemone mexicana used as antimalarials in Mali

ContextGlobal studies on Argemone mexicana L. (Papaveraceae) traditionally used against malaria in Mali are limited to its low-mass compounds activities, and little information on its bioactive polysaccharides is available.ObjectiveThis study determines the structure and the immunomodulatory activity of polysaccharides from aerial parts of A. mexicana.Materials and methodsAcidic polysaccharides from this plant material named HMAmA1 and HMAmA2 were isolated from water extracts. Their monosaccharide composition was determined by gas chromatography. Glycosidic linkages were determined using GC-MS. NMR was also applied. The polymers were tested for effects on the human complement system in vitro at different doses.ResultsThe monosaccharide composition showed that the two polysaccharides contained in different amounts the following monomers: arabinose, rhamnose, galactose, and galacturonic acid. Overall structural analysis showed the presence of a low ratio of 1,2-linked rhamnose compared to 1,4-linked galacturonic acid with arabinogalactans substituted on position 4 of rhamnose. NMR data showed the presence of galacturonans alternated by rhamnogalacturonans bearing arabinose and galactose units. α-Linkages were found for l-arabinose, l-rhamnose and d-galacturonic acid, while β-linkages were found for d-galactose. The two polysaccharides exhibited strong complement fixation activities, with HMAmA1 being the highest potent fraction. ICH₅₀ value of HMAmA1 was 5 µg/mL, compared to the control BPII being 15.9 µg/mL.Discussion and conclusionsPolysaccharides form A. mexicana presented a complement fixation effect. The complement system is an important part of the immune defense, and compounds acting on the cascade are of interest. Therefore, these polymers may be useful as immunodulatory agents.     

Anti-ulcer polysaccharides from Cola cordifolia bark and leaves

Ethnopharmacological relevance

Aqueous extracts of bark and leaves of C. cordifolia are traditionally used in Mali (West Africa) in the treatment of wounds and gastric ailments like abdominal pain, gastritis and gastric ulcers.

Aim of the study

To evaluate and compare the anti-ulcer and immunological activities, as well as the toxicity of polysaccharide rich water extracts from the bark and leaves of C. cordifolia.

Materials and methods

Gastric ulcers were induced in rats and the inhibition of ulcer formation was calculated based on lesion index. Immunological activities were measured by complement fixation and macrophage activation. Toxicity was tested on brine shrimps. The two extracts were characterised by GC, Yariv-precipitation and quantification of phenolic compounds. An ethnomedical survey on C. cordifolia was carried out in Siby (Mali, West-Africa) to generate more knowledge about the traditional use.

Results

Bark and leaf extracts from C. cordifolia significantly inhibited the formation of gastric lesions in rodents in a dose depending manner. CCbark50 showed a high complement fixation activity in vitro. No toxicity was found. The ethnomedical survey showed that C. cordifolia was mainly used for treating pain and wounds.

Conclusions

Our results shows that the bark and the leaves comprise a dose dependant anti-ulcer activity in an experimental rat model (no statistical difference between the plant parts). Clinical studies should be performed to evaluate the effect of both bark and leaves of C. cordifolia as a remedy against gastric ulcer in human.     

Terminalia macroptera, its current medicinal use and future perspectives

The tree Terminalia macroptera (Combretaceae) is widespread in Western Africa, and in this area, different parts have been utilized in the treatment of various diseases. In this article, we report on the medicinal use of T. macroptera in three different districts in Mali (Siby, Dioïla and Dogonland), based on interviews with 78 healers in these districts. Roots, root bark, stem bark, leaves and fruits have all been employed by healers, as has parasitic Loranthus species growing on the tree. Major areas of use comprise treatment of wounds and sores, infections, pain, cough, tuberculosis and hepatitis. Some of the medicinal uses of T. macroptera appear to be rationally explained by its chemical constituents.     

Structural and functional effects of conventional and low pesticide input crop-protection programs on benthic macroinvertebrate communities in outdoor pond mesocosms

The impacts of current and alternative wheat crop protection programs were compared in outdoor pond mesocosms in a 10-month long study. Realistic exposure scenarios were built based upon the results of modelling of drift, drainage and runoff of pesticides successively applied under two environmental situations characteristics of drained soils of northern France. Each situation was associated to two crop protection programs (“Conventional” and “Low-input”) differing in the nature of pesticides used, number of treatments and application rate. Both programs induced significant direct negative effects on various invertebrate groups. Bifenthrin and cyprodynil were identified as the main responsible for these effects in conventional and low-input program, respectively. Indirect effects were also demonstrated especially following treatments with cyprodynil. Litter breakdown was significantly reduced in all treated mesocosms as the functional consequence of the decrease in the abundance of shredders (asellids, Gammarus pulex) illustrating the link between structural and functional effects of pesticides on macroinvertebrate communities. Recovery was observed for many taxa before the end of the study but not for the most sensitive non mobile taxa such as G. pulex. No influence of the agropedoclimatic situation on the effects was shown, suggesting than the main impacts were associated to inputs from drift. The results confirm that the proposed low-input program was less hazardous than the conventional program but the observed structural and functional impact of the low-input program suggest that further improvement of alternative crop protection programs is still needed.     

Evaluation of immunization coverage within the Expanded Program on Immunization in Kita Circle,Mali: a cross-sectional survey

Background

In 1986, the Government of Mali launched its Expanded Program on Immunization (EPI) with the goal of vaccinating, within five years, 80% of all children under the age of five against six target diseases: diphtheria, tetanus, pertussis, poliomyelitis, tuberculosis, and measles. The Demographic and Health Survey carried out in 2001 revealed that, in Kita Circle, in the Kayes region, only 13% of children aged 12 to 23 months had received all the EPI vaccinations. A priority program was implemented in 2003 by the Regional Health Department in Kayes to improve EPI immunization coverage in this area.

Methods

A cross-sectional survey using Henderson's method (following the method used by the Demographic and Health Surveys) was carried out in July 2006 to determine the level of vaccination coverage among children aged 12 to 23 months in Kita Circle, after implementation of the priority program. Both vaccination cards and mothers' declarations (in cases where the mother cannot make the declaration, it is made by the person responsible for the child) were used to determine coverage.

Results

According to the vaccination cards, 59.9% [CI 95% (54.7-64.8)] of the children were fully vaccinated, while according to the mothers' declarations the rate was 74.1% [CI 95% (69.3-78.4)]. The drop-out rate between DTCP1 and DTCP3 was 5.5%, according to the vaccination cards. The rate of immunization coverage was higher among children whose mothers had received the anti-tetanus vaccine [OR = 2.1, CI 95% (1.44-3.28)]. However, our study found no difference associated with parents' knowledge about EPI diseases, distance from the health centre, or socio-economic status. Lack of information was one reason given for children not being vaccinated against the six EPI diseases.

Conclusion

Three years after the implementation of the priority program (which included decentralization, the active search for missing children, and deployment of health personnel, material and financial resources), our evaluation of the vaccination coverage rates shows that there is improvement in the EPI immunization coverage rate in Kita Circle. The design of our study did not, however, enable us to determine the extent to which different aspects of the program contributed to this increase in coverage. Efforts should nevertheless be continued, in order to reach the goal of 80% immunization coverage.

Abstract in French

See the full article online for a translation of this abstract in French.

     

Polysaccharides with complement fixing and macrophage stimulation activity from Opilia celtidifolia, isolation and partial characterisation

Aim of the study

The present study is aimed to determine the bioactivity and structure of polysaccharides present in the leaves from the Malian medicinal plant Opilia celtidifolia [Guill. &; Perr. Endl. ex Walp (Opiliaceae)].

Materials and methods

The polysaccharides from the leaves of Opilia celtidifolia were isolated from water extracts of the leaves using gelfiltration and anion exchange chromatography giving the fractions Oc50A₁ and Oc50A₂. Monosaccharide composition was determined by gas chromatography of the derived TMS-derivatives of the methyl-glycosides. Linkages were determined of the partly methylated, partly acetylated alditol acetates obtained after a process including reduction, methylation, hydrolysis, reduction and acetylation followed by GC-MS. Effects on the complement system and the macrophages were determined using specific methods aimed for studying those activities.

Results

The polysaccharide fractions isolated from the leaves of Opilia celtidifolia has high complement fixing activity and induce nitrite oxide release from macrophages in a dose dependent manner. The fractions had an ICH₅₀ of 0.5 and 0.9 μg/ml respectively in the complement fixing assay. They induced the release of 7.2 and 7.3 μM of nitrite oxide from macrophages respectively at a dose of 100 μg/ml. The monosaccharide composition in Oc50A₁ and Oc50A₂, analysed, showed the presence of arabinose (26.7 and 13.2%), galactose (31.5 and 28%) and galacturonic acid (5.3 and 7.8%) respectively. The Yariv test confirmed the presence of arabinogalactan type II in both fractions. Structural analyses did also show the presence of terminal and 1-4 linked galacturonic acid and terminal and 1-2 linked rhamnose. Endo-polygalacturonanase treatment was performed to isolate the heavily substituted parts of the polysaccharides. These parts contained the same monosaccharides in similar proportion, and showed stronger dose dependent complement fixing activity and also stimulated macrophages to release nitrite oxide.

Conclusions

The leaves of Opilia celtidifola contains polysaccharides of pectic type that have both complement fixing and macrophage stimulating activity.     

Anti-ulcer polysaccharides from Cola cordifolia bark and leaves

Ethnopharmacological relevance

The study documented medicinal plants that are traditionally used for treatment of malaria in Shinile District, eastern Ethiopia, and evaluated selected medicinal plants for their antiplasmodial activities against Plasmodium berghei.

Materials and methods

The study was conducted in four kebeles of Shinile District, Somali Region, Ethiopia. A total of 15 traditional healers were sampled based on recommendations of local elders and administrators. Specimens of the reported antimalarial plants were collected and stored at the Mini Herbarium of the Aklilu Lemma Institute of Pathobiology, Addis Ababa University, following identification. Crude aqueous and ethanol extracts of Aloe sp., Azadirachta indica and Tamarindus indica were tested in vivo against Plasmodium berghei. The three plants were selected based on the frequency antimalarial use report by healers.

Results

The study revealed 27 antimalarial plants, the majority of which were harvested from the wild. Root was the most frequently sought plant part. Most of the remedies were used in decoction form. Aloe sp., Azadirachta indica and Tamarindus indica were the most commonly reported plants for their antimalarial use. For the in vivo test, all the plant extracts were given to mice orally. Ethanol and aqueous leaf extracts of Aloe sp. caused 73.94% and 58.10% parasitaemia suppression, respectively at dose of 650 mg/kg. Ethanol extract of Azadirachta indica leaves induced 54.79% parasitaemia suppression at the dose of 650 mg/kg and its water extract induced 21.47% parasite suppression at a similar dose. Water extract of the fruits of Tamarindus indica showed the highest parasitaemia suppression (81.09%) at the dose of 650 mg/kg. Most Plasmodium berghei infected mice treated with high dose of plant extracts survived relatively longer compared to their respective controls although the difference was not significant.

Conclusions

The result of this study may support the traditional use of Aloe sp., Azadirachta indica and Tamarindus indica in the study area against malaria. Results of this study can be used as a basis for further phytochemical and pharmacological investigations in the effort for search of new and locally affordable antimalarial agents.