Leonidah K. Omosa

Cytotoxicity of 91 Kenyan indigenous medicinal plants towards human CCRF-CEM leukemia cells.

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 (1:1v/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 10μg/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 2.97µg/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 11.09µg/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.

Selected ethno-medicinal plants from Kenya with in vitro activity against major African livestock pathogens belonging to the "Mycoplasma mycoides cluster".

Ethnopharmocological relevance Members of ‘Mycoplasma mycoides cluster’ are important ruminant pathogens in Africa. Diseases caused by these Mycoplasma negatively affect the agricultural sector especially in developing countries through losses in livestock productivity, mortality and international trade restrictions. There is therefore urgent need to develop antimicrobials from alternative sources such as medicinal plants to curb these diseases. In Kenya, smallholder farmers belonging to the Maasai, Kuria and Luo rely on traditional Kenyan herbals to treat respiratory symptoms in ruminants. In the current study extracts from some of these plants were tested against the growth of members of Mycoplasma mycoides cluster. Aim This study aimed at identifying plants that exhibit antimycoplasmal activities using an ethnobotanical approach. Materials and methods Kenyan farmers of Maasai, Luo and Kuria ethnic groups were interviewed for plant remedies given to livestock with respiratory syndromes. The plant materials were thereafter collected and crude extracts prepared using a mixture of 50% of methanol (MeOH) in dichloromethane (CH2Cl2), neat methanol (MeOH), ethanol (EtOH) and water to yield four crude extracts per plant part. The extracts were tested in vitro against five strains of Mycoplasma mycoides subsp. capri, five strains of Mycoplasma mycoides subsp. mycoides and one strain of Mycoplasma capricolum subsp capricolum using broth micro-dilution assays with an initial concentration of 1 mg/ml. Minimum inhibitory concentration (MIC) of the most active extracts were determined by serial dilution. Results Extracts from five plants namely: Solanum aculeastrum, Albizia coriaria, Ekebergia capensis, Piliostigma thonningii and Euclea divinorum exhibited the highest activities against the Mycoplasma strains tested. Mycoplasma mycoides subsp. mycoides were more susceptible to these extracts than Mycoplasma mycoides subsp. capri and Mycoplasma capricolum susp. capricolum. The activities of the crude extracts varied with the solvent used for extraction. The MICs mean values of the active extracts varied from 0.02 to 0.6 mg/ml. Conclusions The results suggested that these plants could potentially contain antimicrobial compounds that might be useful for the treatment of respiratory diseases in ruminants. Future work should focus on the isolation and identification of the active compounds from the plant extracts that showed interesting activities and evaluation of their antimicrobial and cytotoxic potential.

Semi-Synthetic Pyrazoline Derivatives from Polygonum senegalense Chalcones and their Anti-Microbial Activities

This paper describes the semi-synthesis and anti-microbial activity of novel pyrazoline derivatives of Polygonum senegalense chalcones. The study was carried out on the understanding that heterocycles with pyrazoline ring systems are known to possess a broad spectrum of biological activities. The derivatives were afforded by refluxing mixtures of chalcones and phenylhydrazine, hydrazine hydrate, and / or acetic acid in DMSO or ethanol at low temperatures between 40-60°C in an oil-bath. The products were characterized in by 1H-NMR (200 or 400 MHz), 13C-NMR spectroscopy and ESI-HRMS. NMR data was described in detail for each derivative. The compounds 6-15 have been screened for their in vitro anti-bacterial activity against one gram positive bacteria (S. aureus) and anti-fungal activity against five strains C. krusei, C. neoformans, and C. glabrata. They all showed insignificant antimicrobial activities with lower IC50 as compared to positive control, except compound 7 that demonstrated moderate antifungal activity with IC50 values ranging between 8.01 13.74 μg/mL against C. krusei, C. neoformans and C. glabrata. The compound also showed antibacterial activity of IC50 value 7.56μg/mL against S. aureus. Based on these findings, we recommend that compound 7 should undergo further structural modification in order to optimize its anti-microbial activity.

Antimycoplasmal Activities of Compounds from Solanum aculeastrum and Piliostigma thonningii against Strains from the Mycoplasma mycoides Cluster

Infections caused by Mycoplasma species belonging to the ‘mycoides cluster’ negatively affect the agricultural sector through losses in livestock productivity. These Mycoplasma strains are resistant to many conventional antibiotics due to the total lack of cell wall. Therefore, there is an urgent need to develop new antimicrobial agents from alternative sources such as medicinal plants to curb the resistance threat. Recent studies on extracts from Solanum aculeastrum and Piliostigma thonningii revealed interesting antimycoplasmal activities hence the motivation to investigate the antimycoplasmal activities of constituent compounds. The CH2Cl2/MeOH extracts from the berries of S. aculeastrum yielded a new β-sitosterol derivative (1) along with six known ones including; lupeol (2), two long-chain fatty alcohols namely undecyl alcohol (3) and lauryl alcohol (4); two long-chain fatty acids namely; myristic acid (5) and nervonic acid (6) as well as a glycosidic steroidal alkaloid; (25R)-3β-O-α-L-rhamnopyranosyl-(1→2)-O-[α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranosyloxy-22α-N-spirosol-5-ene (7) from the MeOH extracts. A new furan diglycoside, (2,5-D-diglucopyranosyloxy-furan) (8) was also characterized from the CH2Cl2/MeOH extract of stem bark of P. thonningii. The structures of the compounds were determined on the basis of spectroscopic evidence and comparison with literature data. Compounds 1, 3, 4, 7, and 8 isolated in sufficient yields were tested against the growth of two Mycoplasma mycoides subsp. mycoides (Mmm), two M. mycoides. capri (Mmc), and one M. capricolum capricolum (Mcc) using broth dilution methods, while the minimum inhibitory concentration (MIC) was determined by serial dilution. The inhibition of Mycoplasma in vitro growth was determined by the use of both flow cytometry (FCM) and color change units (CCU) methods. Compounds 4 and 7 showed moderate activity against the growth of Mmm and Mmc but were inactive against the growth of Mcc. The lowest MIC value was 50 μg/ml for compound 7 against Mmm. The rest of the compounds showed minimal or no activity against the strains of Mycoplasma mycoides tested. This is the first report on the use of combined FCM and CCU to determine inhibition of in vitro growth of Mycoplasma mycoides. The activity of these compounds against other bacterial strains should be tested and their safety profiles determined.

Standardization of commiphora abyssinica engl. Gum resin from kajiado, Kenya

Information on the physical and chemical characteristics of Commiphora abyssinica gum resin is scanty. The aim of this work was to establish the composition and physicochemical properties of above mentioned gum resin and on that basis propose its standard specifications for commercial use. Samples from three sites in Kajiado in Kenya were characterized in terms of parameters commonly used in the evaluation of the quality of crude oleogumresins and their products. There was no substantial variability with collection location observed on most physical properties including pH, density, refractive index, viscosity and optical rotation. Composition parameters such as moisture, ash, nitrogen, metals, extraneous impurities, essential oils, ethanol and water soluble matter varied from location to location. The ethanol-soluble matter which is crucial in the formulation of traditional gum resin products varied significantly and ranged between 26.37 and 47.79%. The gum-resin was found to have 1.31 to 1.87% essential oils and the yield of water soluble matter was high at 82.25-84.50%. In general, the gum resin had relatively low content of extraneous impurities (2.27-3.17%) and ash (2.24-3.04%) in comparison with gum resins from related Commiphora species. Saponification value, acid value as well as free fatty acids also varied with location. Values of parameters obtained in this study were found suitable for proposing standard specifications of local Commiphora abyssinica gum resin from the location. From the results, standard specifications that can be used in commerce for identification and quality specification of Commiphora abyssinica gum resin sourced in Kenya were suggested. Magnesium could be used to identify the gum resin from the area due to its very low variability. It was also recommended that freshly harvested material be stored for a few months before processing.