Search

Rural communities in Kenya largely depend on plant resources for their livelihood. The utilization of these resources depends on the availability of plant resources and the level of knowledge of the residents. We conducted an ethnobotanical study in Tharaka-Nithi County in Kenya to determine the knowledge and utilization of various plant species by the local communities. The study was conducted in four major administrative regions from June 2018 to February 2019, involving interview schedules using semi-structured open-ended questionnaires and guided field collections with 48 informants. A total of 214 plant species distributed in 73 families and 169 genera with 616 Use Reports (URs) were documented. Fabaceae was the highest family cited by the informants (31 species) followed by Lamiaceae and Euphorbiaceae (each with 11 species). Trees (49%) and shrubs (32%) were the top life forms of the plants frequently utilized by the local residents. The general plant uses reported were medicinal, food, fodder, construction, fuel, pesticidal, religious, live fencing, and making crafts. Zanthoxylum gilletii, Prunus africana, and Solanum incanum were found to be highly valued by the local communities. Plant utilization as food and medicinal uses against snake-bite related problems had the highest Informant Consensus Factor (ICF). Only 29 (13.6%) of the species reported had their status assessed by the International Union for Conservation of Nature (IUCN). Conservation measures, alongside awareness creation in this region, are highly recommended for the species endemic to the region, highly depended on by the community, and those threatened according to IUCN standards.

Sterculia tragacantha Lindl., Zanthoxylum gilletii (De Wild.) P. G. Waterman and Annickia polycarpa (DC.) Setten & Maas ex I.M.Turner are commonly used folk medicinal plants, particularly against malaria, in tropical and warm African areas. Besides, S. tragacantha and Z. gilletii are used traditionally to manage rheumatism, boils, ulcer, gonorrhea, and snake bite. On the other hand, A. polycarpa is used for the treatment of Trypanosoma, and stomach ulcer. Some pharmacological studies have been undertaken and the phytochemical profile established. Nonetheless, there is still a shortage of studies that have attempted to compile such data in a single review. Given the medicinal values that these plants possess and potential relevance towards bioproducts development and future bioprospecting studies, an endeavor has been made herein to provide an updated report on the therapeutic potential of S. tragacantha, Z. gilletii, and A. polycarpa. A comprehensive literature search via key databases (Google scholar, Pubmed, Scopus, Science Direct and Web of Science) was conducted to probe and compile relevant published information (1959–2018) such as ethnobotanical uses, phytochemistry and in vitro and in vivo studies of these three plants. This study also highlights important research gaps that need to be addressed in future studies. Despite the panoply of biological and pharmacological research already carried out and showing numerous biological activities of the studied species, an extensive investigation is needed to exploit other therapeutic utilities and validate other ethnobotanical uses of these species. It is anticipated that such compilation will also stimulate ongoing scientific documentation of African medicinal plants for future generations and possible application of this knowledge as instruments for sustainable therapeutic bioproducts development. However, further research needs to be designed to evaluate other potential activities of the crude extracts as well as the compounds already characterized.

The charcoal sector constitutes an important source of employment and revenue for many tropical agroecosystems. Better understanding of the effects of charcoal-making is thus warranted to guide actions aimed at minimising environmental externalities. Conversion of trees to charcoal eliminates canopy effects associated with the living trees while at the same time creates new conditions in and around spots where the charcoal is produced due to increased concentration of pyrogenic organic matter (PyOM). It is unclear, whether such unintentional PyOM additions play a role in the abundance and distribution patterns of soil macrofauna. A study was conducted in South Nandi (Kenya) to assess effects of PyOM on soil macrofauna, taking advantage of abandoned traditional earth-mound charcoal kilns, where Croton megalocarpus Hutch. and Zanthoxylum gilletii (De Wild.) P.G.Waterman trees were used in charcoal making. Soil and soil macrofauna samples were collected at increasing distances from the centre of the spots. Total C, non-pyrogenic C (non-PyC) and total N progressively increased with increasing distance from the centre of the spots, whereas soil pH, pyrogenic C (PyC), available P and exchangeable K decreased. The number of earthworms and centipedes in Z. gilletii spots (119 and 14 individuals m−2, respectively) was twice as high as in kilns where C. megalocarpus was used. Notably, while the number of earthworms in spots rich in Z. gilletii PyOM significantly increased with increasing distance from the centre of the spots, the opposite trend was observed for centipedes. In contrast, no significant differences in the spatial distribution of earthworms or centipedes were found in spots rich in C. megalocarpus PyOM. Furthermore, beetles, termites and crickets were significantly higher in C. megalocarpus than Z. gilletii spots, but sampling distance also had no significant influence. As hypothesised, source of PyOM played a major role in determining soil properties and macrofauna distribution patterns thus showing the value of abandoned charcoal-making spots in contributing to a mosaic of soil conditions that could ultimately affect soil productivity in tropical agricultural systems.

Introduction: Multidrug resistance remains a major obstacle hindering successful antimalarial chemotherapy. In the current study, 50% methanol in dichloromethane extract and six compounds from the stem bark of Zanthoxylum gilletii were explored for their antiplasmodial potential against three strains of Plasmodium falciparum. Materials and Methods: The extract was obtained by cold percolation using 50 % MeOH in CH2Cl2 and the antiplasmodial activities were assayed using a non–radioactive Malaria SYBR Green I assay to determine a concentration that inhibits growth of 50% of parasites in culture (IC 50 ). Results and Discussion: Chromatographic separation of the crude extract yielded six known compounds including: one lignan, sesamin (1), an alkamide, fagaramide (2), three benzo [c] phenanthridine alkaloids, 8–acetonyldihydrochelerythrine (3), dihydrochelerythine (4), norchelerythrine (5) and one pentacyclic triterpenoid, lupeol (6). The extract and sesamin (1) showed promising antiplasmodial activities against the chloroquine resistant (W2), chloroquine sensitive (D6) and 3D7 strains of P. falciparum, with IC50 values of 2.52, 1.48 and 1.43 µg/mL and 5.4, 9.1 and 8.3 µM, respectively. To the best of our knowledge, this is the first report on antiplasmodial activities of the stem bark extract (50% MeOH in CH2Cl2) and compound 1–3 and 6. Furthermore, three of the isolated compounds; 1, 3, 6 are reported from this species for the first time. Conclusion: The good antiplasmodial activities exhibited by the stem bark of Z. gilletii against three different strains of P. falciparum may be attributed to the presence of 1-3 exhibiting good activities against all strains of P. falciparum.

Africa is famous for its floral biodiversity, exploited by local people for therapeutic purposes. However, such plants need to be scrutinised scientifically for the presence of bioactive compounds and possible biological properties. This study attempts for the first time to highlight the pharmacological and phytochemical profile of extracts prepared from leaves and stem barks of three African plants (Macaranga hurifolia Beille, Sterculia tragacantha Lindl. and Zanthoxylum gilletii (De Wild.) P. G. Waterman. The extracts were tested for antioxidant and enzyme inhibitory effects. Free radical scavenging, metal chelator, reducing power and phosphomolybdenum assays were performed to evaluate antioxidant effects. To identify enzyme inhibitory effects, cholinesterases (acetylcholinesterase (AChE) and butrylcholinesterase (BChE)), tyrosinase, α-amylase and α-glucosidase were selected as target enzymes. High performance liquid chromatography-Electrospray tandem mass spectrometry (HPLC-ESI-MS) technique was also used for chemical profiling. ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging assays showed that the stem barks of all three African plants were better scavenger than leaf extracts. Sterculia tragacantha was found to be a better metal chelator (64.10 ± 4.66 mg EDTAE/g) among the studied plants. All extracts exhibited good clinical enzyme inhibitory activities. The stem bark of S. tragacantha exhibited the best acetylcholinesterase activity compared to the other plants. HPLC-ESI-MS characterization showed that the most abundant compounds in stem bark were flavonoids in M. hurifolia (4.2 ± 0.2 mg/g DE), proanthocyanidins in S. tragacantha (42 ± 1 mg/g DE) and similar concentrations of phenolic acids and flavonoids in Z. gilletii (2.8–3.1 mg/g DE). Based on the biological activity, the most abundant and relevant bioactive compounds in the extracts were studied using molecular modelling approach against tyrosinase. The studied African plants showed good antioxidant and enzymatic propensities and thus can be considered as potential bioresources for future development of nutraceuticals and/or for pharmaceutical applications.

Soil organic matter (SOM) is considered an important determinant of soil fertility in tropical agroecosystems. While numerous studies have shown the value of agroforestry in increasing soil nutrients and improving crop yield, few have addressed the systematic impacts of duration of cultivation on soil aggregation and C storage in such systems. A study was conducted in South Nandi (Kenya) to assess spatial influence of three dominant trees (Croton megalocarpus, Eucalyptus grandis and Zanthoxylum gilletii) on soil aggregation and C content in agroforestry systems. The study was conducted in a chronosequence experimental set-up where farms were continuously cultivated for 10, 16 and 62 years since conversion from primary forest. It was hypothesized that soil aggregates and whole soil and aggregate-associated C would decrease with duration of cultivation, with the magnitude of influence being reduced by the presence of trees and abundance of earthworms and termites. Greater abundance of small macroaggregates and microaggregates were recorded in soils under the canopy of Z. gilletii with an average weight of 62.8 g and 9.4 g 100 g−1 of soil compared to 53.9 g and 3.1 g 100 g−1 in soils under C. megalocarpus and 48.7 g and 3.9 g 100 g−1 in soils under E. grandis, respectively. These differences could be attributed to the high number of endogeic earthworm species, Nematogenia lacuum (Ocnerodrilidae) in soils under the canopy of Z. gilletii trees. Since N. lacuum is a small-sized species (40–55 mm long), it produces small faecal pellets and thus, we could infer that this species may have contributed to the fragmentation of large macroaggregates into small macroaggregates and microaggregates. The C content decreased by almost 40% in soils under longer duration of cultivation, with higher magnitude of differences associated with Z. gilletii trees. Increased microbial population in earthworms’ casts can increase mineralization rates, which may explain the low aggregate-associated C content under Z. gilletii trees where high number of N. lacuum were recorded. This study shows the significance of specific trees in shaping soil aggregation process and soil C content which could have far-reaching implications for the long-term C storage in the soil and hence net contributions to climate change mitigation.

Ethnopharmacological relevance Plants from Kenyan flora are traditionally used against many ailments, including cancer and related diseases. Cancer is characterized as a condition with complex signs and symptoms. Recently there are recommendations that ethnopharmacological usages such as immune and skin disorders, inflammatory, infectious, parasitic and viral diseases should be taken into account when selecting plants that treat cancer. Aim The present study was aimed at investigating the cytotoxicity of a plethora of 145 plant parts from 91 medicinal plants, most of which are used in the management of cancer and related diseases by different communities in Kenya, against CCRF-CEM leukemia cell line. Materials and methods Extracts from different plant parts (leaves, stems, stem bark, roots, root barks, aerial parts and whole herb) were obtained by cold percolation using different solvent systems, such as (1:1 v/v) dichloromethane (CH2Cl2) and n-hexane (1), methanol (MeOH) and CH2Cl2 (2); neat MeOH (3), 5% H2O in MeOH (4) and with ethanol (EtOH, 5); their cytotoxicities were determined using the resazurin reduction assay against CCRF-CEM cells. Results At a single concentration of 10 μg/mL, 12 out of 145 extracts exhibited more than 50% cell inhibition. These include samples from the root bark of Erythrina sacleuxii (extracted with 50% n-hexane-CH2Cl2), the leaves of Albizia gummifera, and Strychnos usambarensis, the stem bark of Zanthoxylum gilletii, Bridelia micrantha, Croton sylvaticus, and Albizia schimperiana; the root bark of Erythrina burttii and E. sacleuxii (extracted with 50% CH2Cl2–MeOH), the stem bark of B. micrantha and Z. gilletii (extracted using 5% MeOH–H2O) and from the berries of Solanum aculeastrum (extracted with neat EtOH). The EtOH extract of the berries of S. aculeastrum and A. schimperiana stem bark extract displayed the highest cytotoxicity towards leukemia CCRF-CEM cells, with IC50 values of 1.36 and 2.97 µg/mL, respectively. Other extracts having good activities included the extracts of the stem barks of Z. gilletii and B. micrantha and leaves of S. usambarensis with IC50 values of 9.04, 9.43 and 11.09 µg/mL, respectively. Conclusions The results of this study provided information related to the possible use of some Kenyam medicinal plants, and mostly S. aculeastrum, A. schimperiana, C. sylvaticus, Z. gilletii, B. micrantha and S. usambarensis in the treatment of leukemia. The reported data helped to authenticate the claimed traditional use of these plants. However, most plants are used in combination as traditional herbal concoctions. Hence, the cytotoxicity of corresponding plant combinations should be tested in vitro to authenticate the traditional medical practitioners actual practices.

International audience; L’analyse UPLC-MS/MS de l’extrait brut hydroacétonique des feuilles de Zanthoxylum gilletii a permis l’identification de composés phénoliques tels l’acide gallique et dérivés (9,40 mg EAG/g ms), l’acide protocatéchique (0,22 mg EAP/g ms), des flavonoïdes (6,34 mg EQ/g ms) et des acides hydroxycinnamiques (4,24 mg EAC/g ms). L’étude de la cytotoxicité a montré que cet extrait possède une activité antiproliférative sur les cellules cancéreuses C6, SNB 75, GLI7 et GLI4F11 (CI50 < 0,01 mg/ml).

Objectif: Connaitre les plantes medicinales utilisees comme remede dans le traitement des maladies de la peau dans le departement d’Agboville, en Cote d’Ivoire. Methode et resultats: Une etude ethnobotanique realisee dans le departement d’Agboville a permis de recenser 32 especes utilisees dans le traitement des infections cutanees. La methode de la double dilution sur milieu PDA a ete utilisee pour tester in vitro la sensibilite de deux souches fongiques de Sclerotium rolfsii aux extraits de Zanthoxylum gilletii (olon). L’extrait ethanolique a ameliore 8 fois l’activite inhibitrice de l’extrait aqueux. Les CMI et CMF de Sv et St sont de 100 mg/ml et 200 mg/ml pour l’Eaq et 12,5 mg/ml et 25 mg/ml pour l’Eeth, Au niveau des sclerotes La CMI a ete de 6,25 mg/ml pour les deux souches et la CMF, de 12,5 mg/ml et 25 mg/ml pour les souches Sv et St respectivement. Conclusion et application: Les populations rurales du departement d’Agboville detiennent une bonne connaissance des plantes utilisees dans la lutte contre les dermatoses. Zanthoxylum gilletii ., l’une des plantes les plus citees, possede une activite antifongique contre Sclerotium rolfsii , Elle constitue un fongicides pouvant etre utilise dans la lutte biologique contre les champignons telluriques. Mots cles: Zanthoxylum gilletii , extrait aqueux, extrait ethanolique, antifongique, Sclerotium rolfsii English Title: Ethnobotany study and in vitro evaluation of antifungal activity of bark extracts of Zanthoxylum gilletii (De Wild Waterman) on two phytopathogenic strain of Sclerotium rolfsii English Abstract Objective: Learn about medicinal plants used as medicine in the treatment of skin diseases in the department of Agboville, in Cote d’Ivoire. Methods and Results: An ethnobotanical study carried out in the department of Agboville allowed to identified 32 species used in the treatment of skin infections. The method of double dilution on PDA medium was used to test the in vitro sensitivity of two fungal strains of Sclerotium rolfsii to extracts of Zanthoxylum gilletii . Ethanolic extract improved 8 times the inhibitory activity of the aqueous extract. The MIC and MFC of St and Sv were 100 mg / ml and 200 mg / ml for the QAR and 12.5 mg / ml and 25 mg / ml for EETH. Concerning sclerotia, the MIC was 6,25 mg / ml for both strains. The MFC was 12.5 mg / ml and 25 mg / ml for St and Sv strains respectively Conclusion and Application: Rural people of Agboville department hold a good knowledge of plants used in the fight against skin diseases. Zanthoxylum gilletii , one of the most cited plant has antifungal activity against Sclerotium rolfsii . It is a fungicide which can be used in biological control against soil fungi. Keywords: Zanthoxylum gilletii , water extract, ethanol extract, antifungal, Sclerotium rolfsii