Comparing Medicinal Uses of Cochlospermaceae Throughout Its Geographic Range with Insights from Molecular Phylogenetics
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diversity Article Comparing Medicinal Uses of Cochlospermaceae throughout Its Geographic Range with Insights from Molecular Phylogenetics Susannah B. Johnson-Fulton 1,* and Linda E. Watson 2 1 Department of Biology, Shasta College, Redding, CA 96003, USA 2 Department of Plant Biology, Ecology, and Evolution, Oklahoma State University, Stillwater, OK 74078, USA; [email protected] * Correspondence: [email protected] Received: 13 September 2018; Accepted: 8 November 2018; Published: 15 November 2018 Abstract: Species of the Cochlospermaceae, a small mostly pantropical plant family, were evaluated at a continental scale for medicinal uses in traditional medicine. This ethnobotanical information was placed in a phylogenetic framework to make informed predictions in the search for new medicines and bioactive compounds. Medicinal plant-use data were mapped onto a molecular phylogeny based on DNA sequences of nuclear and chloroplast markers. Associations of medicinal uses among closely related species occurring in different geographic regions and among diverse cultures were evaluated. The most common medicinal uses for these species are those used to treat skin ailments, gastro-intestinal problems, malaria, and liver issues. The plant species with the most numerous uses is Cochlospermum tinctorium, which occurs primarily in West Africa. Closely related species being used by cultural groups in different geographic regions to treat the same illnesses suggests the presence of bioactive compounds with potential biomedical value, since they may represent independent discoveries of similar medicinally-active compounds. This leads to the speculation that those closely related species not currently being used to treat these ailments may also contain identical or similar medicinally-active compounds and are worthy of laboratory investigations. Keywords: Cochlospermaceae; Cochlospermum; Amoreuxia; medicinal plants; comparative ethnobotany; phylogenetics; molecular systematics; biogeography; culture; pharmacology 1. Introduction Humans, like much of life on Earth, depend almost entirely on plants for survival [1–3]. Most of our food comes from plants both directly and indirectly. Much of our clothing and building materials consist of plant material. And although most drugs in western medicine are produced in the laboratory, these synthesized compounds usually mimic bioactive compounds first discovered in the plants in which they naturally occur [2,4,5]. According to the World Health Organization (WHO), approximately 80% of developing countries still depend on traditional folk medicines, 85% of which are plant extracts with the other 15% being mineral, fungal, and animal based. Thus, with over 250,000 species of angiosperms alone, and a plethora of plant use knowledge available, the potential for making many new discoveries, making new connections, and finding new medicinal plants and medicinally-active compounds for drug development is enormous. With the effects of global warming, the increased loss of the world’s biodiversity, and the disappearance of unique human cultures, it has become even more important to discover and conserve Earth’s species, to document and conserve cultural histories, traditions, and languages, and to search for new medicines and new drought tolerant foods [6–9]. Comparing the medicinal uses of closely related plant species throughout their geographic ranges among different cultural groups can offer a new perspective into the search for effective Diversity 2018, 10, 123; doi:10.3390/d10040123 www.mdpi.com/journal/diversity Diversity 2018, 10, x FOR PEER REVIEW 2 of 20 Diversity 2018, 10, 123 2 of 19 Comparing the medicinal uses of closely related plant species throughout their geographic ranges among different cultural groups can offer a new perspective into the search for effective botanical medicines and and other other plant plant species species with with economic economic value value [10]. [10 ].Cochlospermaceae Cochlospermaceae Planch. Planch. is isa small, a small, ethnobotanically ethnobotanically important important pantropical pantropical plant plant family family with with species species distributed distributed in in west and central Africa,Africa, India,India, Southeast Southeast Asia, Asia, Northern Northern Australia, Australia, Central Central and Southand South America, America, the West the Indies, West Mexico,Indies, Mexico, and Southwestern and Southwestern United United States States (Figure (Figure1). It is 1). composed It is composed of two of genera, two genera,Amoreuxia AmoreuxiaDC., fourDC., herbaceousfour herbaceous species, species, and Cochlospermum and CochlospermumKunth, Kunth, 12 woody 12 woody species species (Figure 2(Figure). Of its 2). 16 Of species, its 16 12species, are known 12 are to known be used to by be many used culturesby many on cultures different on continents different [continents11–19]. The [11–19]. widespread The widespread distribution ofdistribution its species of combined its species with combined its rich ethnobotanical with its rich ethnobotanical use makes Cochlospermaceae use makes Cochlospermaceae an ideal family an to exploreideal family any to tendencies explore any for tendencies closely related for closely species rela toted be species used in to similar be used ways in similar by people ways ofby diverse people culturalof diverse groups. cultural If, groups. for example, If, for example, closely related closely species related are species used are insimilar used in ways similar by ways distantly by distantly related cultures,related cultures, then those then species those may,species in fact,may, provide in fact, moreprovide effective more medicineseffective medicines because they because represent they independentrepresent independent discoveries discoveries of similar medicinally-activeof similar medicinally-ac compounds.tive compounds. Figure 1.1. Distribution of the twotwo generagenera ofof Cochlospermaceae.Cochlospermaceae. Blue == CochlospermumCochlospermum; OrangeOrange == Amoreuxia;; YellowYellow == overlappingoverlapping rangesranges ofof thethe twotwo genera.genera. Numbers indicate the numbers of species in different geographicgeographic regions.regions. 8—the8—the Americas; 5—Africa; 1—Asia; 2—Australia.2—Australia. Four major strategies are generally used in thethe searchsearch forfor medicinally-activemedicinally-active plants:plants: (1) random approach—randomly selecting selecting plants plants to sampleto sample in a particularin a particular area; (2) area; phylogenetic (2) phylogenetic approach— approach— choosing specieschoosing that species are closely that are related closely to other related species to other with species known with medicinally-active known medicinally-active compounds; (3)compounds; ecological approach—selecting(3) ecological approach—selecting plants that live inplants certain that habitats live orin thatcertain exhibit habitats specific or characteristics that exhibit, suchspecific as anti-herbivorycharacteristics, compounds;such as anti-herbivory and (4) ethnobotanical compounds; and approach—choosing (4) ethnobotanical plants approach—choosing that are used by plants local peoplethat areto used treat by illness local people [2]. The to ethnobotanical treat illness [2]. approach The ethnobotanical is currently approach known to is becurrently the most known successful to be ofthe the most major successful strategies of the [10 major,20]. Herestrategies we have [10,20]. combined Here we both have the combined phylogenetic both the and phylogenetic ethnobotanical and approachesethnobotanical by approaches choosing aby geographically-widespread choosing a geographically-widespread plant family, plant reconstructing family, reconstructing a molecular a phylogenymolecular phylogeny for the family, for the mapping family, ethnobotanical mapping ethnobot dataanical onto thedata resulting onto the phylogeny, resulting phylogeny, and evaluating and correlationsevaluating correlations between thebetween evolutionary the evolutionary relatedness relatedness of the speciesof the species and their and ethnobotanicaltheir ethnobotanical uses byuses different by different cultural cultural groups groups who who live live in differentin different geographic geographic regions. regions. Studies Studies such such asas thisthis that utilize phylogenetic phylogenetic patterns patterns of ofme medicinaldicinal properties properties within within plant plant lineages lineages are few are [10,21–29]. few [10, 21Saslis-–29]. Saslis-LagoudakisLagoudakis et al. [10] et al.concluded [10] concluded that phylogenet that phylogeneticic cross-cultural cross-cultural comparisons comparisons can focus canscreening focus screeningefforts on the efforts closest on therelatives closest of relatives medicinal of pl medicinalants already plants in use already as traditional in use as medicines. traditional medicines. Few comparative ethnobotanical studies, in general, have been conducted, and those that have been conducted usually compare the total use of plantsplants among different culturalcultural groups rather than examining the uses of a singlesingle plantplant lineagelineage acrossacross itsits geographicgeographic rangerange [[10,30–32].10,30–32]. This research focuses on a single plantplant familyfamily withwith aa widespreadwidespread distributiondistribution and compares how diversediverse ethnic groups from different geographicgeographic regionsregions useuse thethe closelyclosely relatedrelated speciesspecies medicinally.medicinally.