Olwen M. Grace

Antidiabetic screening and scoring of 11 plants traditionally used in South Africa

AIMnTo investigate the traditional antidiabetic uses of indigenous or naturalised South African plants using an optimised screening and scoring method.nnnMATERIALS AND METHODSnEleven plant species were screened against Chang liver, 3T3-L1 adipose and C2C12 muscle cells measuring glucose utilisation in all three cell lines and toxicity in the hepatocytes and adipocytes only. A scoring system was devised to aid interpretation of results.nnnRESULTSnCatharanthus roseus results correlated with previously reported in vivo results, with best stimulation of glucose utilisation in hepatocytes. Momordica foetida and Momordica balsamina extracts were active in myocytes but only the latter stimulated glucose utilisation in hepatocytes. Brachylaena discolor gave the best overall results, with all plant parts giving high activity scores and negligible toxicity. In vitro toxicity results for Catharanthus roseus, Vinca major, Momordica balsamina and some Sclerocarya birrea extracts raise concern for chronic use.nnnCONCLUSIONnThis screening system increases the likelihood of identifying drug candidates using in vitro antidiabetic screening of crude plant extracts, whilst the scoring system aids data interpretation.nnnETHNOPHARMACOLOGICAL RELEVANCEnThe multitude of metabolic steps affected by Type II diabetes offer many drug targets but they complicate in vitro screening to validate traditional uses or find new drug leads from plants.

Evolutionary history and leaf succulence as explanations for medicinal use in aloes and the global popularity of Aloe vera

BackgroundAloe vera supports a substantial global trade yet its wild origins, and explanations for its popularity over 500 related Aloe species in one of the world’s largest succulent groups, have remained uncertain. We developed an explicit phylogenetic framework to explore links between the rich traditions of medicinal use and leaf succulence in aloes.ResultsThe phylogenetic hypothesis clarifies the origins of Aloe vera to the Arabian Peninsula at the northernmost limits of the range for aloes. The genus Aloe originated in southern Africa ~16 million years ago and underwent two major radiations driven by different speciation processes, giving rise to the extraordinary diversity known today. Large, succulent leaves typical of medicinal aloes arose during the most recent diversification ~10 million years ago and are strongly correlated to the phylogeny and to the likelihood of a species being used for medicine. A significant, albeit weak, phylogenetic signal is evident in the medicinal uses of aloes, suggesting that the properties for which they are valued do not occur randomly across the branches of the phylogenetic tree.ConclusionsPhylogenetic investigation of plant use and leaf succulence among aloes has yielded new explanations for the extraordinary market dominance of Aloe vera. The industry preference for Aloe vera appears to be due to its proximity to important historic trade routes, and early introduction to trade and cultivation. Well-developed succulent leaf mesophyll tissue, an adaptive feature that likely contributed to the ecological success of the genus Aloe, is the main predictor for medicinal use among Aloe species, whereas evolutionary loss of succulence tends to be associated with losses of medicinal use. Phylogenetic analyses of plant use offer potential to understand patterns in the value of global plant diversity.

Global medicinal uses of Euphorbia L. (Euphorbiaceae)

ETHNOPHARMACOLOGICAL RELEVANCEnThe genus Euphorbia (spurges, Euphorbiaceae) is the third largest genus of flowering plants, with almost 2000 species. Its exceptional diversity of growth forms and near-cosmopolitan distribution have attracted human interest since ancient times. For instance in Australia, topical application of latex of Euphorbia peplus L. is used as a home treatment for skin cancer and actinic keratosis. Its use in Australian folk medicine has inspired the release of the drug Picato® (ingenol mebutate), and further fostered interest in natural products and medicinal uses of Euphorbia in recent years.nnnAIM OF THE STUDYnTo provide an indicative overview of medicinal uses of the genus Euphorbia driven by the recent interest in biologically active natural products from Euphorbia in drug discovery. We assess documented medicinal knowledge and value of the genus Euphorbia and the taxonomic distribution of this value.nnnMATERIALS AND METHODSnWe undertook an extensive survey of over 260 multidisciplinary publications on the online repository JSTOR using the search term Euphorbia medicinal.nnnRESULTSnMedicinal uses were identified for >5% of the species in the genus, including descriptions of treatments for a variety of diseases. The most-cited medicinal uses around the world were treatments for digestive system disorders, skin ailments and, especially in the Southern hemisphere, infections. Consensus ratios indicated that the most-valued medicinal uses of Euphorbia species are in the treatment of digestive and respiratory complaints, inflammation and injuries, especially by members of Euphorbia subg. Chamaesyce.nnnCONCLUSIONSnThe present study gives a first indicative overview of Euphorbia species used for health and wellbeing around the world. The exceptional diversity of the genus Euphorbia is not only represented by its growth forms but also by its diverse medicinal uses. Our results highlight the importance of research into medicinal uses of Euphorbia species and their importance as a source of natural products. Furthermore the medicinally highly valuable subgenus Chamaesyce was identified as chemically under-investigated, emphasizing the need for further studies investigating the chemical diversity to which the high medicinal value of Euphorbia subg. Chamaesyce can be attributed.

Monosaccharide analysis of succulent leaf tissue in Aloe.

INTRODUCTIONnThe succulent leaf mesophyll in Aloe species supports a burgeoning natural products industry, particularly in Africa. Comparative data necessary to prioritise species with economic potential have been lacking.nnnOBJECTIVEnTo survey leaf mesophyll monosaccharide composition in the genus Aloe using a predictive phylogenetic approach.nnnMETHODOLOGYnMonosaccharide composition was assessed in 31 species, representing the morphological and taxonomic diversity of Aloe sensu stricto. Leaf mesophyll polysaccharides were partially hydrolysed in a trifluoroacetic acid (TFA)-SilA assay. Oximes and trimethylsilyl ether products were detected by GC-MS. Constituent monosaccharides accounting for the greatest variation among species were identified by principal component analysis. Two plant DNA barcoding regions were sequenced in 28 of the sampled species and the resulting maximum likelihood tree was used to evaluate phylogenetic signal in monosaccharide composition throughout the genus.nnnRESULTSnNineteen peaks (Rt=16.76-23.67 min) were identified in the GC-MS spectra. All samples were dominated by one constituent; glucose was the major monosaccharide in 19 species, mannose in eight species, and xylose in one species (Aloidendron pillansii). Three monosaccharides therefore account for 90% of the variation in leaf mesophyll in Aloe. Species which do not share this typical monosaccharide profile appear to group outside the core Aloe clade in the phylogeny.nnnCONCLUSIONnPreliminary findings suggest that leaf mesophyll monosaccharide composition is conservative in Aloe. Characterisation of within-species variation and quantitative differences between species will be necessary to authenticate leaf mesophyll products, whereas unusual monosaccharide profiles could be diagnostic in some species. The common glucose-mannose-xylose profile identified in commercially important species is shared by many other Aloe species.

Evolutionary prediction of medicinal properties in the genus Euphorbia L.

The current decrease of new drugs brought to the market has fostered renewed interest in plant-based drug discovery. Given the alarming rate of biodiversity loss, systematic methodologies in finding new plant-derived drugs are urgently needed. Medicinal uses of plants were proposed as proxy for bioactivity, and phylogenetic patterns in medicinal plant uses have suggested that phylogeny can be used as predictive tool. However, the common practice of grouping medicinal plant uses into standardised categories may restrict the relevance of phylogenetic predictions. Standardised categories are mostly associated to systems of the human body and only poorly reflect biological responses to the treatment. Here we show that medicinal plant uses interpreted from a perspective of a biological response can reveal different phylogenetic patterns of presumed underlying bioactivity compared to standardised methods of medicinal plant use classification. In the cosmopolitan and pharmaceutically highly relevant genus Euphorbia L., identifying plant uses modulating the inflammatory response highlighted a greater phylogenetic diversity and number of potentially promising species than standardised categories. Our interpretation of medicinal plant uses may therefore allow for a more targeted approach for future phylogeny-guided drug discovery at an early screening stage, which will likely result in higher discovery rates of novel chemistry with functional biological activity.

Knowledge-Sharing Networks in Hunter-Gatherers and the Evolution of Cumulative Culture

Humans possess the unique ability for cumulative culture [1, 2]. It has been argued that hunter-gatherers complex social structure [3-9] has facilitated the evolution of cumulative culture by allowing information exchange among large pools of individuals [10-13]. However, empirical evidence for the interaction between social structure and cultural transmission is scant [14]. Here we examine the reported co-occurrence of plant uses between individuals in dyads (which we define as their shared knowledge of plant uses) in BaYaka Pygmies from Congo. We studied reported uses of 33 plants of 219 individuals from four camps. We show that (1) plant uses by BaYaka fall into three main domains: medicinal, foraging, and social norms/beliefs; (2) most medicinal plants have known bioactive properties, and some are positively associated with childrens BMI, suggesting that their use is adaptive; (3) knowledgexa0ofxa0medicinal plants is mainly shared between spouses and biological and affinal kin; and (4) knowledge of plant uses associated with foraging and social norms is shared more widely among campmates, regardless of relatedness, and is important for camp-wide activities that require cooperation. Our results show the interdependence between social structure and knowledge sharing. We propose that long-term pair bonds, affinal kin recognition, exogamy, and multi-locality create ties between unrelated families, facilitating the transmission of medicinal knowledge and its fitness implications. Additionally, multi-family camps with low inter-relatedness between camp members provide a framework for the exchange of functional information related to cooperative activities beyond the family unit, such as foraging and regulation of social life.

The uses of Kenyan aloes: an analysis of implications for names, distribution and conservation

BackgroundThe genus Aloe is renowned for its medicinal and cosmetic properties and long history of use. Sixty-three Aloe species occur in Kenya, of which around 50xa0% are endemic. Several species of aloes are threatened with extinction and knowledge about their use is of major importance for sound conservation strategies. The main aims of this study were to assess the biocultural value of Aloe in Kenya by documenting local uses of aloes and evaluating how the vernacular names reflect the relative importance in different ethnic groups.MethodsEthnobotanical and ethnotaxonomical data were collected using field observations and semi-structured interviews. Information was collected by interviewing 63 respondents from nine different ethnic groups, representing different ages, gender and occupations. Statistical analyses were performed using R version 3.1.2.ResultsA total of 19 species of Aloe were found in the study area, of which 16 were used. On the generic level Aloe was easily distinguished. At species level, the local and scientific delimitation were almost identical for frequently used taxa. Aloe secundiflora, with 57 unique use records was the most important species. The two most frequently mentioned Aloe treatments, were malaria and poultry diseases. In our study area neither age nor gender had a significant influence on the level of knowledge of Aloe use. Finally, no correlation was found between extent of use and people’s perception of decrease in local aloe populations. The aloes are highly appreciated and are therefore propagated and transported over large areas when people relocate.ConclusionBiocultural value is reflected in the ethnotaxonomy of Aloe in Kenya. Different ethnic groups recognise their most-valued Aloe at the genus level as “the aloe” and add explanatory names for the other species, such as the “spotted aloe” and the “one-legged aloe”. Widespread species of Aloe have the highest number of uses. There is no obvious correlation with high use and decrease in abundance of aloes locally, and we found no compelling evidence for local uses causing devastating damage to populations of the 19 species in use, whereas habitat loss and commercial harvesting appear to be of urgent concern for these important plants.

Karyotypes in Ethiopian Aloe species (Xanthorrhoeaceae: Asphodeloideae)

SummaryA cytogenetic survey of 17 species in the succulent-leaved genus Aloe L. (Xanthorrhoeaceae subfamily Asphodeloideae) in Ethiopia was undertaken towards a more complete genetic characterisation of the genus throughout its distribution in Africa, Arabia and Madagascar. Somatic metaphase chromosomes of all species studied showed the same diploid chromosome number of 2n = 14, consisting of four pairs of long and three pairs of short chromosomes. Symmetry was characterised as Stebbins type 2B and the asymmetry indices AsK%, TF%, A1 and A2 revealed minor karyotypic variation common in closely related species. The metrics showed that A. benishangulana has a marginally higher degree of asymmetry than is typical, and the pubescent-flowered A. trichosantha has a more symmetrical karyotype than most other species. We suggest that the stable karyotype morphology in Aloe indicates that structural genome changes and ecological factors play a more prominent role in speciation in Aloe.

Did a plant-herbivore arms race drive chemical diversity in Euphorbia?

The genus Euphorbia is among the most diverse and species-rich plant genera on Earth, exhibiting a near-cosmopolitan distribution and extraordinary chemical diversity, especially across highly toxic macro-and polycyclic diterpenoids. However, very little is known about drivers and evolutionary origins of chemical diversity within Euphorbia. Here, we investigate 43 Euphorbia species to understand how geographic separation over evolutionary time has impacted chemical differentiation. We show that the structurally highly diverse Euphorbia diterpenoids are significantly reduced in species native to the Americas, compared to the Eurasian and African continents, where the genus originated. The localization of these compounds to young stems and roots suggest ecological relevance in herbivory defense and immunomodulatory defense mechanisms match diterpenoid levels, indicating chemoevolutionary adaptation to reduced herbivory pressure. One Sentence Summary Global chemo-evolutionary adaptation of Euphorbia affected immunomodulatory defense mechanisms.

A phylogenetic road map to antimalarial Artemisia species

ETHNOPHARMACOLOGICAL RELEVANCEnThe discovery of the antimalarial agent artemisinin is considered one of the most significant success stories of ethnopharmacological research in recent times. The isolation of artemisinin was inspired by the use of Artemisia annua in traditional Chinese medicine (TCM) and was awarded a Nobel Prize in 2015. Antimalarial activity has since been demonstrated for a range of other Artemisia species, suggesting that the genus could provide alternative sources of antimalarial treatments. Given the stunning diversity of the genus (c. 500 species), a prioritisation of taxa to be investigated for their likely antimalarial properties is required.nnnMATERIALS AND METHODSnHere we use a phylogenetic approach to explore the potential for identifying species more likely to possess antimalarial properties. Ethnobotanical data from literature reports is recorded for 117 species. Subsequent phylogenetically informed analysis was used to identify lineages in which there is an overrepresentation of species used to treat malarial symptoms, and which could therefore be high priority for further investigation of antimalarial activity.nnnRESULTSnWe show that these lineages indeed include several species with documented antimalarial activity. To further inform our approach, we use LC-MS/MS analysis to explore artemisinin content in fifteen species from both highlighted and not highlighted lineages. We detected artemisinin in nine species, in eight of them for the first time, doubling the number of Artemisia taxa known to content this molecule.nnnCONCLUSIONSnOur findings indicate that artemisinin may be widespread across the genus, providing an accessible local resource outside the distribution area of Artemisia annua.