A Bibliographic Assessment Using the Degrees of Publication Method: Medicinal Plants from the Rural Greater Mpigi Region (Uganda)

Abstract

In ethnopharmacological research, many field assessment tools exist. Yet, these miss that critical point of how to really determine which species merit the costly lab studies, e.g., evaluation of traditional use via pharmacological assays and isolation of bioactive secondary metabolites. This gap can be filled with the introduction of a new tool for literature assessment: the Degrees of Publication (DoPs). In this study, its application is illustrated through an extensive bibliographic assessment of 16 medicinal plant species that were recently identified in the Greater Mpigi region of Uganda as being frequently used by local traditional healers in the treatment of medical disorders (namely, Albizia coriaria, Cassine buchananii, Combretum molle, Erythrina abyssinica, Ficus saussureana, Harungana madagascariensis, Leucas calostachys, Microgramma lycopodioides, Morella kandtiana, Plectranthus hadiensis, Securidaca longipedunculata, Sesamum calycinum subsp. angustifolium, Solanum aculeastrum, Toddalia asiatica, Warburgia ugandensis, and Zanthoxylum chalybeum). These species are suspected to be understudied, and a thorough bibliographic assessment has not been previously performed. Thus, the objectives of our study were to undertake a comparative assessment of the degree to which each of these plant species has been studied in the past, including evaluation of the quality of the journals where results were published in. The determination of the DoPs enabled successful assessment of the degrees to which each individual plant species has been studied so far, while also taking into account the methodological “research chain of ethnopharmacology” from ethnobotanical studies (“traditional use”) to pharmacological assays (“bioactivity”) and finally to pharmacognostic research (“structure elucidation”). The significance of a research paper was assessed by determining whether its journal and publishing house were members of the Committee on Publication Ethics (COPE). In total, 634 peer-reviewed publications were reviewed covering the period of 1960–2019, 53.3% of which were published in journals and by publishing houses affiliated with COPE (338 publications). The literature assessment resulted in the identification of understudied plants among the selected species. The majority of plants reviewed have not been sufficiently studied; six species were classified as being highly understudied and three more as being understudied: C. buchananii, F. saussureana, L. calostachys, M. lycopodioides, M. kandtiana, and S. calycinum subsp. angustifolium and A. coriaria, P. hadiensis, and S. aculeastrum, respectively. The newly introduced DoPs are a useful tool for the selection of traditionally used species for future laboratory studies, especially for pharmacological bioassays, isolation procedures, and drug discovery strategies.

1. Introduction

Throughout human history and across the globe, plants were regarded as the major source of medicine and natural remedies. Traditional medicine is defined by the World Health Organization (WHO) as “the knowledge, skills, and practices based on the theories, beliefs, and experiences indigenous to different cultures, used in the maintenance of health and in the prevention, diagnosis, and improvement or treatment of physical and mental illness”. In the developing world, over 80% of the population still rely on traditional herbal medicines for their day-to-day healthcare needs. This is largely attributed to their ease of access, affordability, perceived fewer side effects, and cultural appropriateness, among other reasons. Despite the general loss of cultural practices worldwide, traditional medicine practices and medicinal plant use are still the predominant form of healthcare services in East and Central Africa today. The global importance of plants as a source of medicine is also often emphasized by scientists worldwide. Around 25% of the Western drugs prescribed contain active ingredients that were initially isolated as natural products from plants. Still, the majority of Earth’s plant species has never been screened for pharmacological effects in a research facility.

In consideration of this global importance, there are many assessment tools applied when reporting field studies in the science of ethnopharmacology. These include field assessment indices for medicinally used species, such as the frequency of citation, use value, informant consensus factor, and fidelity level, among others. However, none of these take into account how to really determine which species merit the costly lab studies. This is why we introduce the Degrees of Publication (DoPs), providing a standardized way to examine how well studied individual species are (or are not) in an ethnopharmacological context. In this study, 16 medicinal plant species from the Greater Mpigi region were selected to illustrate how the new tool works.

Situated in West-Central Uganda, the tropical Greater Mpigi region displays a high abundance of traditional medicine practitioners and diverse use of a vast amount of medicinal plant species. Consequently, local people are still highly dependent on these traditional healers and their medicinal plants in order to secure their primary health care.

A recently published ethnobotanical survey from the Greater Mpigi region and an ethnopharmacological study identified 16 medicinal plant species that are often used in the treatment of medical disorders in the local traditional medicine system while displaying high pharmacological activity in our ongoing in vitro evaluation in a lab setting. A preliminary literature review resulted in a few results. Therefore, these 16 plants are suspected to be understudied species, and a thorough literature review using the new DoP method for bibliographic assessment enables the selection of traditionally used species for pharmacological bioassays and drug discovery strategies. Our study, therefore, aims to undertake a comparative literature assessment, applying the DoP method, regarding (a) other reports of these species, (b) the quality of the journals where results were published in (assessment of international standards and best practice in scholarly publication ethics), and (c) the degree to which each plant species has been studied thus far.