Harriet Okatch

Determination of potentially toxic heavy metals in traditionally used medicinal plants for HIV/AIDS opportunistic infections in Ngamiland District in Northern Botswana.

The determination of four potentially toxic heavy metals, arsenic, chromium, lead and nickel in twelve plant species used for the treatment of perceived HIV and AIDS-associated opportunistic infections by traditional healers in Ngamiland District in Northern Botswana, a metal mining area, was carried out using atomic absorption spectrometry. The medicinal plants; Dichrostachys cinerea, Maerua angolensis, Mimusops zeyheri, Albizia anthelmintica, Plumbago zeylanica, Combretum imberbe, Indigofera flavicans, Clerodendrum ternatum, Solanum panduriforme, Capparis tomentosa, Terminalia sericea and Maytenus senegalensis contained heavy metals in varying quantities: arsenic 0.19-0.54 μg g(-1), chromium 0.15-1.27 μg g(-1), lead 0.12-0.23 μg g(-1) and nickel 0.09-0.21 μg g(-1) of dry weight. Chromium was found to be the most abundant followed by arsenic and lead. Nickel was undetectable in nine plant species. M. senegalensis contained the largest amounts of arsenic, chromium and lead. All metals determined were below the WHO permissive maximum levels. The possible maximum weekly intakes of the heavy metals following treatment regimes were insignificant compared to the provisional tolerable weekly intake levels recommended by WHO and the Joint FAO/WHO Expert Committee on Food Additives. This suggests that heavy metal exposure to patients originating from consumption of traditional medicinal plant preparations is within non health-compromising limits.

Characterisation of legumes by enzymatic hydrolysis, microdialysis sampling, and micro-high-performance anion-exchange chromatography with electrospray ionisation mass spectrometry.

An assay based on enzymatic hydrolysisand microdialysis sampling, micro-high-performance anion-exchange chromatography (micro-HPAEC) with electrospray ionisation mass spectrometry (ESI-MS) for the characterisation of legumes is presented. Characterisation of two bean varieties; Phaseolus mungo and P. acutifilous was based upon enzymatic hydrolysis using an endo-beta-mannanase from Aspergillus niger with subsequent analysis of the hydrolysates with HPAEC-MS. The hydrolysates were detected in the positive ionisation mode after desalting the chromatographic effluent, employing a cation-exchange membrane desalting device with water as the regenerating liquid. Mass chromatograms, acquiredafter hydrolysis of both bean samples for 12 h, showed two different profiles of hydrolysates. The P. mungo bean hydrolysate showed the presence of saccharides with a degree of polymerisation (DP) in the range of 2-6, whereas that of P. acutifilous showed only DPs of 2-5. Both bean samples had one type of DP 2, but showed different types of DPs 3, 4 and 5. Only the P. mungo sample showed the presence of DP 6. The most abundant fraction for P. mungo was DP 4, whereas that for P. acutifilous was DP 5. Tandem MS of the hydrolysates showed that the DP 2 hydrolysates observed for the samples were of the same type, having a 1,6 linkage. Also tandem MS data for DPs 3, 4, and 5 showed that similar hydrolysates were present within the same sample as well as among the two samples. The data also showed the existence of 1,6 linkages for DP 3, 4, and 5 hydrolysates. The single enzymatic hydrolysis in combination with microdialysis and HPAEC with ESI-MS proved to be sufficient and reproducible for profiling and showing the difference between the two bean samples.

Profiling of carbohydrate polymers in biotechnology using microdialysis sampling, high performance anion exchange chromatography with integrated pulsed electrochemical detection/mass spectrometry

The analysis of carbohydrate polymers is very demanding and challenging because of the similar physical and chemical properties they possess. Enzymatic hydrolysis is employed to cleave the polymers. The use of enzymes in analytical chemistry requires an analytical system that has on-line capability, is fast, reproducible, robust, and offers sensitive detection. More importantly the system employed should offer in-situ sampling and sample clean-up so as to reduce the sample handling steps and the analysis time. One such system consists of microdialysis sampling, high performance anion exchange chromatography with integrated pulsed electrochemical detection/mass spectrometry. The on-line system offers sampling, sample clean-up, separation and detection of saccharides as a way of profiling carbohydrate polymers. The wealth of information attained include carbohydrate polymer sequencing, glycosidic linkages, anomericity and result in the unequivocal characterisation of the polymers. This review focuses on the applications of a total on-line system for the profiling of carbohydrate hydrolysates. The above-mentioned analytical system has been employed to carbohydrate polymers and hydrolysates from starch, lignocellulosic material and legumes.

Employing Solid Phase Microextraction as Extraction Tool for Pesticide Residues in Traditional Medicinal Plants.

HS-SPME was optimised using blank plant sample for analysis of organochlorine pesticides (OCPs) of varying polarities in selected medicinal plants obtained from northern part of Botswana, where OCPs such as DDT and endosulfan have been historically applied to control disease carrying vectors (mosquitos and tsetse fly). The optimised SPME parameters were used to isolate analytes from root samples of five medicinal plants obtained from Maun and Kasane, Botswana. The final analytes determination was done with a gas chromatograph equipped with GC-ECD and analyte was confirmed using electron ionisation mass spectrometer (GC-MS). Dieldrin was the only pesticide detected and confirmed with MS in the Terminalia sericea sample obtained from Kasane. The method was validated and the analyte recoveries ranged from 69.58 ± 7.20 to 113 ± 15.44%, with RSDs ranging from 1.19 to 17.97%. The method indicated good linearity (R 2 > 0.9900) in the range of 2 to 100 ng g−1. The method also proved to be sensitive with low limits of detection (LODs) ranging from 0.48 ± 0.16 to 1.50 ± 0.50 ng g−1. It can be concluded that SPME was successfully utilized as a sampling and extraction tool for pesticides of diverse polarities in root samples of medicinal plants.

The dialectics of indigenous knowledge: Community views from Botswana

Indigenous knowledge (IK) has become a popular subject in the last decade. IK has been recognized by global institutions as a valuable source for scientific innovation and significant in promoting development for poorer communities. However, little attention has been paid to how communities themselves particularly conceptualize IK and how they situate this knowledge in everyday life context. This paper summarizes perceptions of IK from 20 rural communities in the Ghanzi (4) and North-East (16) districts in Botswana. Our findings indicate that IK cannot be defined by contrasting it to other knowledge systems. Rather, IK is abstract and concrete, individual and collective, specific and holistic in a dialectical manner. This inherent “unity of opposites” promotes constant change of IK. Applied to the challenge of linking IK to development, community perceptions inform us that a dialectical process-oriented approach to IK is necessary to harness it for a sustainable development and meaningful education of indigenous people in Botswana.