SOMATIC EMBRYOGENESIS AND BIOASSAY STUDIES OF SCHIZOZYGIA COFFAEOIDES BAIL (MPELEPELE) FOR POTENTIAL EXPLOITATION OF SECONDARY METABOLITES.

Abstract

Schizozygia coffeoides (Mpelepele) is an endangered medicinal shrub geographically distributed in Kenya, with substantial antifungal and antibacterial properties. The sustainable utilization of this shrub is hindered by its limited propagation potential through seeds and cuttings. The aim of this study was to develop an appropriate regeneration protocol for in vitro regeneration via somatic embryogenesis. Sterilization was optimized using NaOCl at concentrations of 5.2mM, 7.8mM, 10.4mM and 13mM at exposure times of 10, 15, 20 and 25 minutes. The different concentrations of NaOCl were observed to have a significant effect on the survival of explants to sterilization (P<0.0001). Similarly, the time explants were subjected to the sterilization substances was also found to significantly affect their ability to survive the sterilization process . The best callus formation frequency of 73% was observed in MS Media supplemented with 2.0mg/l BAP+0.8mg/l KIN+0.4mg/l NAA+0.5mg/l TDZ, compared to 39% callus in media supplemented with 1.5mg/l BAP+0.6mg/l Kin+0.3mg/l NAA+0.1mg/l TDZ and at 13% observed in media supplemented with 1.0mg/l BAP+0.4mg/l Kin+0.2mg/l NAA+0.05mg/l TDZ. The Callus were maintained on MS media supplemented with 2.0mg/l BAP+0.8mg/l KIN+0.4mg/l NAA+0.5mg/l TDZ for 28 days which led to rapid somatic embryo at all the stages of somatic embryogenesis observed. Roots primordia only formed in shoots cultured in media supplemented with 1.0mg/l BAP+0.5mg/l IBA. Leaf, root, stem and calli were subjected to phytochemicals screening and extracts obtained using ethanol, methanol, acetone, chloroform, hexane di-ethyl and water were subjected to microorganism and observed for their antimicrobial assay by disc diffusion assay method. The zone of inhibition results were compared to Ampicillin, chloramphenicol and Nystatin standard antibiotics at (p<0.05). Leave and root extracts showed a relatively better antimicrobial activity than stem extracts, with callus extracts showing no antimicrobial activity at all. There was a significant difference in antimicrobial activity based on the solvent used for extraction, with methanol, ethanol and water being the best solvents (P<0.001). Followed by diethyl and hexane roots extract. All the antibiotics had significant inhibition against all microorganism. Lower concentrations of Mpelepele leaf, stem and root extracts were all found to be toxic to xiv brime shrimps compared to higher concentrations (P<0.001). Significant differences were also observed in toxicity based on the solvents used for extraction (P<0.005). The successful development of sterilization protocol and regeneration via somatic embryogenesis will greatly contribute to mass production and conservation of the plant, furthermore through antimicrobial activity and toxicity screening there will be great knowledge available towards the use of mpelepele for pharmaceutical purposes. This research findings will adequately explored areas for maximizing somatic embryogenesis plantlet in mpelepele that will be fully exploited.