The study of three beaches of South-West Cameroon polluted by polycyclic aromatic hydrocarbons.

The US Environmental Protection Agency (US-EPA) published a priority list of 16 polycyclic aromatic hydrocarbons (PAHs), which are compounds that are studied in a variety of matrices due to their wide range of risks. Environmental compartments can be contaminated with PAHs from different sources, such as wastewater from industries and petroleum spills. For the case of Cameroon, there are no recorded data concerning the sources, distributions, and toxicity levels of PAHs in water and sediment from Cameroon beaches which are found in South-West, Littoral, and South Regions. In this work, only three beaches from South-West Region were studied regarding the sources, distributions, and toxicity levels of PAHs in water and sediment. The analyzed samples came from Bobende coastal beach, Down-beach, and Cape-Limboh beach. To achieve the analyses, liquid-liquid extraction and gas chromatography enabled the identification and quantification of PAH compounds from sediments and marine water. Out of the 16 PAHs listed by US-EPA, twelve were identified and quantified among which four of them were light molecular weight PAHs (acenaphthylene, fluorene, phenanthrene, and anthracene). Anthracene in the Cape-Limboh sample presented the highest concentration (477.57 ng/kg weight of dry sediment) of LMW-PAHs. Eight identified and quantified PAHs of high molecular weight as a whole, three absent PAHs (benzo[a]anthracene, dibenzo[a,h]anthracene, and benzo[g,h,i]perylene) in the Cape-Limboh sample, while only one is absent in the Bobende samples (dibenzo[a,h]anthracene) and Down Beach (benzo[g,h,i]perylene). According to the ratios used for the determination of the sources of PAHs, it came out that the source of PAHs from all beaches is pyrolytic. In all samples, BaA is the only high molecular weight PAH presenting serious toxicity and ecological risk.

Is drinking water from 'improved sources' really safe? A case study in the Logone valley (Chad-Cameroon).

Within a cooperation project coordinated by the Association for Rural Cooperation in Africa and Latin America (ACRA) Foundation, water supplies were sampled across the villages of the Logone valley (Chad-Cameroon) mostly from boreholes, open wells, rivers and lakes as well as from some piped water. Microbiological analyses and sanitary inspections were carried out at each source. The microbiological quality was determined by analysis of indicators of faecal contamination, Escherichia coli, Enterococci and Salmonellae, using the membrane filtration method. Sanitary inspections were done using WHO query forms. The assessment confirmed that there are several parameters of health concern in the studied area; bacteria of faecal origins are the most significant. Furthermore, this study demonstrated that Joint Monitoring Programme (JMP) classification and E. coli measurement are not sufficient to state water safety. In fact, in the studied area, JMP defined 'improved sources' may provide unsafe water depending on their structure and sources without E. coli may have Enterococci and Salmonellae. Sanitary inspections also revealed high health risks for some boreholes. In other cases, sources with low sanitary risk and no E. coli were contaminated by Enterococci and Salmonellae. Better management and protection of the sources, hygiene improvement and domestic water treatment before consumption are possible solutions to reduce health risks in the Logone valley.

Potential use of essential oils from Cameroon applied as fumigant or contact insecticides against Sitophilus zeamais Motsch. (Coleoptera: Curculionidae).

Essential oils from seven plants species currently found in Cameroon were extracted by steam distillation and tested for their insecticidal activities against Sitophilus zeamats Motsch. Responses varied with the test applied and the plant species. For the contact toxicity, the acetone was used in order to dilute the pure essential oil. Formulations of 1% of essential oils of Xylopia aethiopica and Ocimum gratissimum were the most toxic and led to 96 and 98% of mortality respectively after 24 h. There was no death in control (0% of mortality). Fumigation test were done by applying 300 microl of pure essential oils in the bottom of closed 800 ml glass containers. In that case, the essential oil of Hyptis spicigera was the most toxic (fumigant) after 48 hours of fumigation followed by Annona seregalensis and Xylopia aethiopica 96 and 95% of mortality respectively. Some of the essential oils of plant species tested are promising for pest control in farmer granaries. However, further investigations are to be done on formulation and side effects.

Antibacterial and antifungal activity of Xylopia aethiopica, Monodora myristica, Zanthoxylum xanthoxyloi;des and Zanthoxylum leprieurii from Cameroon.

The essential oils of Xylopia aethiopica, Monodora myristica, Zanthoxylum xanthoxyloïdes and Z. leprieurii, four Cameroonian plants used as spices in local food, showed antibacterial and antifungal activity.

Antimicrobial study of essential oils of Ocimum gratissimum leaves and Zanthoxylum xanthoxyloides fruits from Cameroon.

An investigation of antimicrobial activities of essential oils of fresh leaves of Ocimum gratissimum and the essential oil of the dried fruits of Zanthoxylum xanthoxyloides was carried out. The essential oils showed extensive inhibition zones and are, therefore, effective antimicrobial systems.

Persistance of the insecticidal activity of five essential oils on the maize weevil Sitophilus zeamais (Motsch.) (Coleoptera: Curculionidae).

Essential oils of aromatic plants are popularise as protectant with low persistance. The evaluation of this duration of activity was carried out for five aromatic plants: Annona senegalensis (Annonaceae), Eucalyptus citriodora et Ecalyptus saligna (Myrtaceae), Lippia rugosa (Verbenaceae) and Ocimum gratissimum (Lamiaceae). They have significant insecticidal activity on S. Zeamais, on the first day of application, this activity decreases after 2 or 4 days. After 8 more than 50% of the efficacy is lossed for all the plants excepted A. senegalensis.

Antioxidant activities of some cameroonian plants extracts used in the treatment of intestinal and infectious diseases.

Antioxidant activity test using two different methods namely 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azinobis(3-ethylbenzothialozinesulfonate) diammonium salt free radical scavenging test has been carried out on three Cameroonian plant extracts used in the treatment of intestinal and infectious diseases: Pittosporum mannii Hook f. (Pittosporaceae), Vepris heterophylla R. Letouzey (Rutaceae) and Ricinodendron heudelotii (Baill) Pierre ex Pax (Euphorbiaceae). Results of this study in the 2,2-diphenyl-1-picrylhydrazyl scavenging test show that the ethyl acetate extract of P. mannii and the methanol extract of V. heterophylla exhibit high free radical scavenging activities with IC(50) values of 177.74 and 204.69 mug/ml, respectively while the methanol/dichloromethane (1+1) extract of R. heudelotii showed weak free radical scavenging activities as compared to Trolox (939.19 mug/ml) used as standard. In the same manner, 2,2'-azinobis(3-ethylbenzothialozinesulfonate) diammonium salt radical scavenging test of these extracts was in accordance of the result of 2,2-diphenyl-1-picrylhydrazyl test. The antioxidant properties of these extracts probably explain partly, the use of these plants in traditional medicine for the treatment of infectious diseases and inflammations.

Analysis of leaf volatiles of Zanthoxylum gillettii used in folk medicine of Cameroon.

The essential oil and the corresponding headspace sample of the leaves of ZONTHIOXYLUM GILLETTII (Rutaceae) were analyzed by gas chromatographic-spectroscopic and olfactoric methods. Mainly monoterpenes such as myrcene, TRANS-beta-ocimene, limonene, camphene, alpha- and beta-pinene which are impact compounds were found in the essential oil and headspace sample. Sesquiterpenes such as beta-caryophyllene, alpha- and beta-farnesene, beta-bisabolol, gamma-cadinene and nerolidol and alphatic components such as 2-undecanone and dodecanal were also identified and contribute to the typical odor impression as well as to the reported therapeutic properties of this ZONTHOXYLUM species.

Protection of stored maize against Sitophilus zeamais (Motsch.) by use of essential oils of spices from Cameroon.

In storage, maize as other cereals is currently attacked by insects. The main specie present in Cameroon is Sitophilus zeamais (Coleop. Curculionidae). The popular way to prevent its damages is the use of synthetic insecticides. These chemicals extend their activities to non target animals. They are potentially dangerous for consumers and are implicated in the pollution of the environment. The development of products killing pests which are consumer-friendly is to be improved. In this respect, the use of essential oils from spices and aromatic plants could help. Six essential oils were tested, 3 are causes of high insect mortality. Xylopia aethiopica Dunal (Anonaceae) killed 97% of adults weevils and Ocimum gratissimum, (L.) (Lamiaceae) 74% after 4 days after ingestion. Piper nigrum (L.) (Piperaceae) killing more than 96% of weevil 48 hours after the contact. The potential of these non toxic products to protect stored maize against attacks of S. zeamais is hereby appraised.