Tannins, flavonoids and stilbenes in extracts of African savanna woodland trees Terminalia brownii, Terminalia laxiflora and Anogeissus leiocarpus showing promising antibacterial potential

Terminalia laxiflora, Terminalia brownii and Anogeissus leiocarpus are used as decoctions, macerations, infusions and fumigations in East and West African traditional medicine for treatment of infectious diseases and their symptoms. Using this ethnopharmacological information as a guideline for our research and owing to the fact that these species have not been subjected to in depth antibacterial and phytochemical studies, thirty-nine extracts of various polarities of the stem bark, stem wood and roots were studied for growth inhibitory effects against the human pathogenic bacteria Staphylococcus epidermidis, Staphylococcus aureus, Micrococcus luteus and Pseudomonas aeruginosa. Our results indicate that the studied species contain antibacterial compounds of a wide range of polarities. All polar root extracts of T. laxiflora and various polar extracts of T. brownii roots, including hot water decoctions, gave broad-spectrum antibacterial effects and low MIC values of 39 mu g/ml. The main ellagitannins in an ethyl acetate extract of the root of T. laxiflora were found to be corilagin and its derivative and punicalagin. A methanol extract of the roots of T. brownii contained methyl-(S)-flavogallonate and its derivative as the main identified ellagitannins. Moreover, both Terminalia species were found to contain ellagic acid xylopyranoside and methyl ellagic acid xyloside and pure ellagic acid was present in T. brownii. Pure punicalagin did not give as low MIC as an ethyl acetate extract of the roots of T. laxiflora, containing punicalagin as one of its main compounds, although this ellagitannin totally inhibited the growth of S. aureus at 125 mu g/ml and P. aeruginosa at 500 mu g/ml. Similarly, pure ellagic and gallic acid gave higher MIC values than the methanolic root extract of T. brownii against S. aureus and P. aeruginosa. Moreover, a Sephadex LH-20 fraction of the methanolic extract of the roots of T. brownii, enrichedwithmethyl-(S)-flavogallonate and its isomer, gave higher MIC values than the crude methanolic extract. These results suggest that the polyphenols in the extracts might act synergistically with each other. A methanolic soxhlet extract of the roots of A. leiocarpus, containing ampelopsin, aromadendrin, taxifolin, pinosylvin and 4'-methylpinosylvin gave a low MIC value of 39 mu g/ml against all bacterial strains used in this investigation. Our results demonstrate that the roots, stem bark and stem wood of T. brownii, T. laxiflora and A. leiocarpus are rich sources of (new) antimicrobial compounds and justify the uses of these plants for treatment of infections in African traditional medicine.Peer reviewe

Energy System Planning towards Renewable Power System: Energy Matrix Change in Cuba by 2030

Since 2013, the biggest Caribbean island, Cuba, has been undertaking an energy matrix change. There is a strong political intention to replace fossil fuels by renewable energy and improve efficiency and security of the national energy system. By 2030, 24% of electric power shall be produced from renewable sources. Transition from centralized fossil fuel fired power system towards distributed renewable generation based system requires changes to conventional energy planning and system design procedures as well as physical structures of the national energy system. This paper introduces three analysis axis: Scenario building for future supply-demand balance, scenario for a 100% renewable energy system for Cuba, and a roadmap from existing power system to the system with high share of distributed renewable generation. This work is a part of European Union funded Erasmus+ project "Capacity Building for Renewable Energy Planning in Cuban Higher Education Institutions", CRECE.<br /

Tree knowledge and livelihood activities in a changing environment: views from smallholder farmers in Kosti, Sudan

Integrated agriculture and forestry land-use practices are critical in countries like Sudan, which faces accelerated deforestation, as they can make land-use and agricultural production systems more sustainable. The accelerated loss of forest vegetation is often perceived to result from increased unsustainable exploitation by poor rural populations for their livelihood needs. To explore this critique, we examined smallholder farmers' (SHFs) views on the management and utilization of trees for livelihood improvement and environmental protection. The study involved a cross-sectional survey conducted with SHFs from two villages in Kosti province through questionnaire-based interviews, focus group discussions, and Participatory Learning and Action methodology. Descriptive statistics suggest that forest product exploitation by SHFs has the potential to be sustainable, and is important for both subsistence and income generation. Management strategies adopted by the SHFs to ensure improved yields include (a) the use of drought-tolerant crop varieties; and (b) tree management practices such as assisted natural regeneration, pollarding, and selective harvesting. Such practices are viewed as valuable land-use technologies by SHFs in Sudan to reduce the loss of forest and woodlands that is speeding up environmental degradation. This study concludes that SHFs have a wide range of experience and practical knowledge relevant to ensure and achieve a sustainable management of natural resources and environmental protection alongside livelihood improvement

The modified taungya system in Ghana’s transitional zone: a win–win practice for forestry and adaptation to climate change?

The formulation and implementation of an adaptation strategy is of growing concern to governments. The adaptation policy framework (APF) sets out indicative activities and features of an adaptation strategy. Understanding the extent to which existing practices can support adaptation in societies and ecosystems is an important step towards the solution. This study uses vulnerability, policy and financial analyses to investigate the compatibility of the modified taungya system (MTS) (a reforestation programme) in Ghana with the indicative activities of the APF. The findings indicate that MTS takes into consideration most of the activities of an adaptation strategy, is a profitable venture (BCR > 1) and has a high potential to reduce vulnerability due to short-term food production and long-term plantation establishment. Resource management in MTS is promising in the short term, but challenges remain to meet livelihood and adaptation needs in the medium and long term. Policy instruments related to MTS align with the forestry, climate change and the development goals of Ghana. We conclude that MTS is a potential win–win practice for forestry and adaptation. The legalization of all contractual arrangements coupled with continuous monitoring, evaluation and improvement may drive MTS to become a lasting activity that will support the long-term horizon of an adaptation strategy

Population genetic survey of Populus cathayana originating from Southeastern Qinghai-Tibetan plateau of China based on SSR markers

In this study, the genetic diversity of Populus cathayana Rehd was investigated using microsatellite markers. In a total of 150 individuals collected from six natural populations in the southeastern part of the Qinghai-Tibetan Plateau in China, a high level of microsatellite polymorphism was detected. At the seven investigated microsatellite loci, the number of alleles per locus ranged from 5 to 16, with a mean of 11.3, the observed heterozygosities across populations ranged from 0.408 to 0.986, with a mean of 0.792, and the expected heterozygosities across populations ranged from 0.511 to 0.891, with a mean of 0.802. The proportion of genetic differentiation among populations accounted for 37.3% of the whole genetic diversity. The presence of such a high level of genetic diversity could be attributed to the features of the species and the habitats where the sampled populations occur: The southeastern part of the Qinghai-Tibetan Plateau is regarded as the natural distribution and variation center of the genus Populus in China. Variation in environmental conditions and selection pressures in different populations, and topographic dispersal barriers could be factors associated with the high level of genetic differentiation found among populations. The populations possessed significant heterozygosity excesses, which may be due to extensive population mixing at the local scale. The cluster analysis showed that the populations are not strictly grouped according to their geographic distances but the habitat characteristics also influence the divergence pattern. In addition, we suggest that population SHY should be regarded as an ecologically divergent species of P. cathayana