An overview of anti-diabetic plants used in Gabon: Pharmacology and Toxicology

© 2017 Elsevier B.V. All rights reserved.Ethnopharmacological relevance: The management of diabetes mellitus management in African communities, especially in Gabon, is not well established as more than 60% of population rely on traditional treatments as primary healthcare. The aim of this review was to collect and present the scientific evidence for the use of medicinal plants that are in currect by Gabonese traditional healers to manage diabetes or hyperglycaemia based here on the pharmacological and toxicological profiles of plants with anti-diabetic activity. There are presented in order to promote their therapeutic value, ensure a safer use by population and provide some bases for further study on high potential plants reviewed. Materials and methods: Ethnobotanical studies were sourced using databases such as Online Wiley library, Pubmed, Google Scholar, PROTA, books and unpublished data including Ph.D. and Master thesis, African and Asian journals. Keywords including ‘Diabetes’ ‘Gabon’ ‘Toxicity’ ‘Constituents’ ‘hyperglycaemia’ were used. Results: A total of 69 plants currently used in Gabon with potential anti-diabetic activity have been identified in the literature, all of which have been used in in vivo or in vitro studies. Most of the plants have been studied in human or animal models for their ability to reduce blood glucose, stimulate insulin secretion or inhibit carbohydrates enzymes. Active substances have been identified in 12 out of 69 plants outlined in this review, these include Allium cepa and Tabernanthe iboga. Only eight plants have their active substances tested for anti-diabetic activity and are suitables for further investigation. Toxicological data is scarce and is dose-related to the functional parameters of major organs such as kidney and liver. Conclusion: An in-depth understanding on the pharmacology and toxicology of Gabonese anti-diabetic plants is lacking yet there is a great scope for new treatments. With further research, the use of Gabonese anti-diabetic plants is important to ensure the safety of the diabetic patients in Gabon.Peer reviewedFinal Accepted Versio

Studies of the switchable photovoltaic effect in co-substituted BiFeO3 thin films

We report the photovoltaic properties of doped ferroelectric [Bi0.9La0.1][Fe0.97Ti0.02Zr0.01]O-3 (BLFTZO) thin films. Polycrystalline BLFTZO films were fabricated on Pt/TiO2/SiO2/Si substrates by pulsed laser deposition technique. Al-doped ZnO transparent top electrodes complete the ZnO:Al/BLFTZO/Pt metal-ferroelectric-metal capacitor structures. BLFTZO showed switchable photoresponse in both polarities. The open circuit voltage (V-OC) and short circuit current (J(SC)) were found to be similar to 0.022V and similar to 650 mu A/cm(2), respectively after positive poling, whereas significant difference in V-OC similar to 0.018V and J(SC) similar to 700 mu A/cm(2) was observed after negative poling. The observed switchable photocurrent and photovoltage responses are explained on the basis of polarization flipping in BLFTZO due to the applied poling field

Strain-mediated ferromagnetism and low-field magnetic reversal in Co doped monolayer WS2

Strain-mediated magnetism in 2D materials and dilute magnetic semiconductors hold multifunctional applications for future nano-electronics. Herein, First principles calculations are employed to study the influence of biaxial strain on the magnetic properties of Co-doped monolayer WS2. The non-magnetic WS2 shows ferromagnetic signature upon Co doping due to spin polarization, which is further improved at low compressive (-2 %) and tensile (+2 %) strains. From the PDOS and spin density analysis, the opposite magnetic ordering is found to be favourable under the application of compressive and tensile strains. The double exchange interaction and p-d hybridization mechanisms make Co-doped WS2 a potential host for magnetism. More importantly, the competition between exchange and crystal field splittings, i.e. (Delta(ex) > Delta(cfs)), of the Co-atom play pivotal roles in deciding the values of the magnetic moments under applied strain. Micromagnetic simulation reveals, the ferromagnetic behavior calculated from DFT exhibits low-field magnetic reversal (190 Oe). Moreover, the spins of Co-doped WS2 are slightly tilted from the easy axis orientations showing slanted ferromagnetic hysteresis loop. The ferromagnetic nature of Co-doped WS2 suppresses beyond +/- 2 strain, which is reflected in terms of decrease in the coercivity in the micromagnetic simulation. The understanding of low-field magnetic reversal and spin orientations in Co-doped WS2 may pave the way for next-generation spintronics and straintronics applications