Antimicrobial and antioxidative effects of Ugandan medicinal barks

Despite a rich tradition of medicinal plants use by local communities in Uganda their direct antimicrobial effectives together with potential to protect human health against diseases induced by oxidative stress are still poorly documented. The aim of this study is to investigate the in vitro antimicrobial and total antioxidative activities of barks from five tree species selected using information on their traditional use by Karamojong healers in Uganda. The antimicrobial activity of crude ethanol extracts of Fagaropsis angolensis (Engl.) H. M. Gardener (Rutaceae), Trichilia prieuriana A. Juss. (Meliaceae), Turraea floribunda Hochst. (Meliaceae), Warburgia salutaris Sprague (Canellaeceae) and Zanthoxylum chalybeum Engl. (Rutaceae) were tested against four bacteria and one yeast species using the broth microdilution method. The total antioxidative activity was determined by 2,2-diphenyl-1- picrylhydrazil free radical scavenging assay. It was found that the extract of F. angolensis possess the strongest antimicrobial activity inhibiting growth of Staphylococcus aureus and Candida albicans with minimum inhibitory concentrations of 64 and 32 μg/ml, respectively. Among all plants tested, W. salutaris showed the most promising antioxidative properties (IC50 = 6.59 μg/ml). As a result of this study, F. angolensis and W. salutaris possessed significant antimicrobial and antioxidative effects which indicates prospective pharmacological properties of both species.Key words: Antimicrobial activity, total antioxidative activity, crude extracts, medicinal plants, Uganda

ANTIOXIDATIVE ACTIVITY OF UGANDAN MEDICINAL PLANTS

Plant drugs used in African traditional medicine are important source of compounds with various biological activities [1]. For the specific situation of Uganda, there is little information on medicinal plant use by traditional healers in Karamoja region (north-east Uganda). Moreover, even though there are some reports on pharmacology of Ugandan medicinal plants [2], their antioxidative activities are still poorly documented. Thus we decided to investigate antioxidative activity of seven Ugandan tree species selected according to their use in traditional medicine as evidenced by ethnobotanical research. The crude ethanolic extracts of seven barks traditionally used by Karamojong healers, namely Capparis tomentosa (Capparaceae), Dregea rubicunda (Asclepiadaceae), Fagaropsis angolensis (Rutaceae), Trichilia prieuriana (Meliaceae), Turraea floribunda (Meliaceae), Warburgia ugandensis (Canellaeceae), and Zanthoxylum chalybeum (Rutaceae) was tested for antioxidative activity using 2,2-diphenyl-1-picrylhydrazil (DPPH) free radical scavenging assay. The most promising results showed extract of W. ugandensis, which exhibited DPPH scavenging activity with IC50 value (7 µg/ml) very closed to the effect achieved by reference compounds Trolox (IC50= 4 µg/ml) and ascorbate (IC50= 2 µg/ml). Among the other plants tested, Z. chalybeum, F. angolensis and T. prieuriana exhibited certain antioxidative potential with IC50 values of 23 µg/ml, 175 µg/ml and 377 µg/ml, respectively. C. tomentosa, D. rubicunda and T. floribunda showed no free radical scavenging activity in the assay. Acknowledgements: Czech Ministry of Education, Youth and Sports (Project No. 6046070901 and ME08070). References: 1.Katerere, D.R. et al. (2003) Phytochemistry 63:81-88. 2. Katuura, E. et al. (2007) Afr J Ecol 45:48-51

The role of biogeochemical hotspots, landscape heterogeneity, and hydrological connectivity for minimizing forestry effects on water quality

Protecting water quality in forested regions is increasingly important as pressures from land-use, long-range transport of air pollutants, and climate change intensify. Maintaining forest industry without jeopardizing sustainability of surface water quality therefore requires new tools and approaches. Here, we show how forest management can be optimized by incorporating landscape sensitivity and hydrological connectivity into a framework that promotes the protection of water quality. We discuss how this approach can be operationalized into a hydromapping tool to support forestry operations that minimize water quality impacts. We specifically focus on how hydromapping can be used to support three fundamental aspects of land management planning including how to (i) locate areas where different forestry practices can be conducted with minimal water quality impact; (ii) guide the off-road driving of forestry machines to minimize soil damage; and (iii) optimize the design of riparian buffer zones. While this work has a boreal perspective, these concepts and approaches have broad-scale applicability

The recovery of European freshwater biodiversity has come to a halt

Owing to a long history of anthropogenic pressures, freshwater ecosystems are among the most vulnerable to biodiversity loss(1). Mitigation measures, including wastewater treatment and hydromorphological restoration, have aimed to improve environmental quality and foster the recovery of freshwater biodiversity(2). Here, using 1,816 time series of freshwater invertebrate communities collected across 22 European countries between 1968 and 2020, we quantified temporal trends in taxonomic and functional diversity and their responses to environmental pressures and gradients. We observed overall increases in taxon richness (0.73% per year), functional richness (2.4% per year) and abundance (1.17% per year). However, these increases primarily occurred before the 2010s, and have since plateaued. Freshwater communities downstream of dams, urban areas and cropland were less likely to experience recovery. Communities at sites with faster rates of warming had fewer gains in taxon richness, functional richness and abundance. Although biodiversity gains in the 1990s and 2000s probably reflect the effectiveness of water-quality improvements and restoration projects, the decelerating trajectory in the 2010s suggests that the current measures offer diminishing returns. Given new and persistent pressures on freshwater ecosystems, including emerging pollutants, climate change and the spread of invasive species, we call for additional mitigation to revive the recovery of freshwater biodiversity