Catherine W. Lukhoba

An ethnobotanical study of medicinal plants used by the Nandi people in Kenya.

ETHNOPHARMACOLOGICAL RELEVANCE The study of local knowledge about natural resources is becoming increasingly important in defining strategies and actions for conservation or recuperation of residual forests. AIMS OF THE STUDY This study therefore sought to collect information from local populations concerning the use of Nandi Forest medicinal plants; verify the sources of medicinal plants used and determine the relative importance of the species surveyed. MATERIALS AND METHODS Data was obtained using semi-structured forms to record the interviewees personal information and topics related to the medicinal use of specific plants. A total of 40 medicinal plants used locally for the treatment and/or control of human ailments were collected through interviews conducted with selected traditional doctors and professional healers. RESULTS This study demonstrated that local people tend to agree with each other in terms of the plants use and that leaf material form the major component of plant parts exploited. The other harvested materials consist of stem bark, the roots and the whole plant, though at a lower intensity for making liquid concoctions from different plants. Majority of the remedies were prepared from a single species. In most cases, the mode of administration was oral. In the forest, some of the plants collected were scarce. This scarcity was attributed to indiscriminate logging, overexploitation, poor harvesting methods and current agricultural trends. CONCLUSION Conservation procedures and creation of awareness were identified as the main remedies to the current situation.

In vivo antimalarial activity, toxicity and phytochemical screening of selected antimalarial plants

ETHNOPHARMACOLOGICAL RELEVANCE Malaria continues to kill over a million people each year and in many populations affected by malaria, conventional drugs are often unaffordable or inaccessible. Historically, plants have been a prominent source of antimalarial drugs. Those plants currently used by indigenous people to treat malaria should be documented and investigated as potential sources of new antimalarial drugs. AIM OF THE STUDY To investigate in vivo antimalarial activity, toxicity and carry out phytochemical screening of selected plants which have been used in traditional medicine for the treatment of malaria. MATERIALS AND METHODS Organic and water extracts of four medicinal plants used for the treatment of malaria in traditional health systems of Msambweni people in Kenya were tested for antimalarial activity against Plasmodium berghei and brine shrimp lethality. They were also screened for their major phytochemical constituents. RESULTS Aqueous extract of the stem bark of Adansonia digitata exhibited highest chemosuppression of parasitaemia, >60% in a murine model of Plasmodium berghei infected mice. Aqueous and organic extracts of Launaea cornuta and Zanthoxylum chalybeum were toxic to the brine shrimp (LD50<1000μg/ml) while aqueous and organic extracts of Adansonia digitata and aqueous extracts of Canthium glaucum were not toxic to brine shrimp (LD50>1000μg/ml). Phytochemical screening revealed the presence of alkaloids and flavonoids in all the crude extracts of the selected plant species studied. Sesquiterpene lactones and saponis were present in organic extracts but absent in the aqueous extracts of Adansonia digitata, Canthium glaucum, Launaea cornuta and Zanthoxylum chalybeum. CONCLUSION The results showed that the crude extracts of Adansonia digitata and Canthium glaucum demonstrated promising antimalarial activity and there is potential for isolation of lead compounds from their extracts.

ANTIFUNGAL ACTIVITY OF CRUDE EXTRACTS OF GLADIOLUS DALENII VAN GEEL (IRIDACEAE)

Bulb extracts of Gladiolus dalenii reportedly used in the treatment of fungal infections in HIV/AIDS patients in the Lake Victoria region were tested for antifungal activity using the disc diffusion assay technique. Commercially used antifungal drugs, Ketaconazole and Griseofulvin (Cosmos Pharmaceuticals) were used as standards. Dichloromethane (CH₂CL₂)/Methanol (MeOH) in the ratio 1:1. Soluble extracts showed antifungal activity against Aspergillus niger. Direct bioautography on silica gel Thin Layer Chromatography (TLC) and appropriate spraying agents were used to identify the active component in the extract. The activities of both the extracts were higher than that of Griseofulvin. CH₂CL₂ soluble extract in addition showed ability to delay sporulation in A.niger. The active group of compounds in the extracts was identified as alkaloids, which offer immense potential for development of new and valuable pharmaceutical products.

Evaluation of Herbs as Potential Drugs/Medicines

Herbal drugs have been used since ancient times as medicines for the treatment of a wide range of diseases, for both human and livestock. A study conducted in the Lake Victoria Basin Kenya revealed vast knowledge and reliance on traditional medicine as a source of healthcare. The study documented 34 medicinal plant species distributed among 21 botanical families and 34 genera, used in the management of human ailments. The highest numbers of species were from the families Asteraceae and Leguminosae. The most commonly harvested plant parts were leaves (46.51%) and roots (34.88%). The most common growth forms utilised were herbs (40.54%) followed by shrubs (27.03%). The major methods of herbal drug preparation were concoction (31.03%) and decoction (24.14%) administered mainly through oral and dermal routes, (64.29%) and (32.14%) respectively. The use of herbal drugs as mixtures was reported to be a common practice by the herbal practitioners; 57.14% of the preparations were dispensed as mixtures while 42.86% of the preparations composed of single plants. A rich knowledge of medicinal plants was recognized and phytochemical and bioactivity analyses of these herbal plants are recommended to determine their safety and efficacy.

A New Species and New Variety in Plectranthus L'Hér. (Labiatae) from Eastern Africa

A new species, P caespitosus Lukhoba & A. J. Paton, similar to P. pubescens Baker, is described. Two varieties within P barbatus Andrews, namely P barbatus var. barbatus and P barbatus var. grandis (L. H. Gramer) Lukhoba & A. J. Paton are delimited. P barbatus var. grandis is widely cultivated and its treatment here reflects the ease of its distinction from other forms in Africa south of Ethiopia, while recognizing the morphological continuity within the P barbatus complex.