Cognitive enhancing effects and anticholinesterase activity of stem bark and leaf extracts of Prunus africana

Alzheimer's disease is ranked among the top five causes of death for old people. Globally, it is approximated that there are 7.7 million new cases of Alzheimer's disease per annum and it is expected that by the year 2050, as many as 1.5% of people will be victims of Alzheimers or other types of dementia. Currently there is no cure for Alzheimer's disease and the conventional therapeutics agents available either have low efficacy or are associated with serious side effects. In the current study, in vivo cognitive advancing and anticholinesterase effects of crude methanol extracts of stem bark and leaf of Prunus africana were investigated in scopolamine treated mice. Passive avoidance task was used to evaluate cognitive enhancing effects of the two plant extracts. Donepezil was used as the standard drug. Scopolamine butylbromide (5 mg/kg bw) was administered intraperitoneally to induce Alzheimer's disease in mice during the study. A completely controlled randomised experimental design was employed in the current study. The two extracts displayed significant anticholinesterase activities and improved cognition in a dose dependent fashion as indicated by escape latency trends. From the current study, it is concluded that methanol extracts of stem bark and leaf of P. africana contain phytochemicals with anticholinesterase activity and cognitive enhancing effects in scopolamine treated mice. The study therefore supports use of leaf and stem bark extracts of P. africana for management of dementia by traditional herbal practitioners

Diversity of mangrove fungal endophytes from selected mangrove species of coastal Kenya

Endophytes are bacteria or fungi living asymptomatically in the internal tissues of plants. They are symbiotic in nature and can be exploited for novel bioactive metabolites with applications in agriculture, medicine and industry. Mangrove fungal endophytes from the marine environment are abundant and have been recognized as sources of bioactive natural products. The study was designed to isolate, purify and identify mangrove fungal endophytes from selected common mangrove species of Gazi Bay, Tudor and Mida creek on the Kenya coast. The colonization rate and isolation rate of the mangrove fungal endophytes were determined. The studied mangrove species were Rhizophora mucronata (red mangrove), Sonneratia alba (mangrove apple), Avicennia marina (grey or white mangrove), and Ceriops tagal (spurred mangrove). Samples from twigs of these mangrove species were collected and analyzed using standard methods. Isolation of pure cultures of the endophytes was performed using Potato Dextrose Agar (PDA) incubated at 28 ± 1ºC for 5 days. The fungal isolates were identified under a light microscope based on colony morphology characteristics, type and presentation of conidiophores and conidia. A total of 18 different mangrove fungal endophytes were identified and these belonged to 5 genera. These were Aspergillus, Penicillium, Fusarium, Cephalosporium and Blastomyces, with Aspergillus being the most dominant genus. Tudor Creek recorded the highest fungal community diversity (H’ = 1.35) and Gazi Bay had the lowest diversity (H’ = 0.45). Fungal community similarity based on the identified genera was highest between Gazi Bay and Mida Creek (0.80) and lowest between Tudor Creek and Mida Creek (0.57). The selected mangrove species recorded a colonization rate of endophytic fungi of between 38.9 – 94.4 % with the highest habitation being associated with S. alba and C. tagal. There were differences and similarities in the colonization rate within mangrove species across study sites. Findings of this study have confirmed that the selected mangrove species exhibit high diversity of fungal endophytes with host recurrence and spatial heterogeneity