From Bush Medicine to Modern Phytopharmaceutical: A Bibliographic Review of Devil’s Claw (Harpagophytum spp.)

Abstract

Devil’s claw (Harpagophytum spp., Pedaliaceae) is one of the best-documented phytomedicines. Its mode of action is largely elucidated, and its efficacy and excellent safety profile have been demonstrated in a long list of clinical investigations. The author conducted a bibliographic review which not only included peer-reviewed papers published in scientific journals but also a vast amount of grey literature, such as theses and reports initiated by governmental as well as non-governmental organizations, thus allowing for a more holistic presentation of the available evidence. Close to 700 sources published over the course of two centuries were identified, confirmed, and cataloged. The purpose of the review is three-fold: to trace the historical milestones in devil’s claw becoming a modern herbal medicine, to point out gaps in the seemingly all-encompassing body of research, and to provide the reader with a reliable and comprehensive bibliography. The review covers aspects of ethnobotany, taxonomy, history of product development and commercialization, chemistry, pharmacology, toxicology, as well as clinical efficacy and safety. It is concluded that three areas stand out in need of further investigation. The taxonomical assessment of the genus is outdated and lacking. A revision is needed to account for intra- and inter-specific, geographical, and chemo-taxonomical variation, including variation in composition. Further research is needed to conclusively elucidate the active compound(s). Confounded by early substitution, intermixture, and blending, it has yet to be demonstrated beyond a reasonable doubt that both (or all) Harpagophytum spp. are equally (and interchangeably) safe and efficacious in clinical practice.

The Fight against Infection and Pain: Devil’s Claw (Harpagophytum procumbens) a Rich Source of Anti-Inflammatory Activity: 2011–2022

“…They open during the day to allow pollination by bees [ 41 ]. The genus Harpagophytum consists of two related species procumbens and zeyheri [ 28 , 29 ]. Of the two species, H. procumbens is considered to be more medicinally efficient than H. zeyheri .…”

“…The superiority of H. procumbens over H. zeyheri was attributed to the presence of higher chemical constituents in H. procumbens [ 30 ]. This has led to medicinal product(s) derived from it being sold as one or the other or mixed [ 28 ].…”

“…The Harpagophytum genus is widely identified as Devil’s claw belonging to the sesame seed family, Pedaliaceae which is a family of 22 genera with 90 species [ 28 ]. It is further characterized as a perennial tuberous plant with visually appealing fruits [ 29 ].…”

Buchu (Agathosma betulina and A. crenulata): Rightfully Forgotten or Underutilized?

“…Initially noted by the early settlers, knowledge and use of buchu spread to Europe and later to the United States (US). Buchu belongs to a handful of Southern African medicinal plants which reached international markets through colonial interests and entrepreneurship, more or less unaffected by barriers of entry which were more recently introduced by health product regulations in the target markets as well as bioprospecting legislation in the countries of origin (Brendler et al, 2008;Brendler, 2009;Stander et al, 2019;Brendler, 2020;Brendler, 2021;Brendler and Cock, 2021;. It has been compendial since 1826 for its diuretic effects and use in the treatment of genito-urinary tract infections, however, became obsolete in the 20th century due to the sparsity of scientific evidence for its efficacy and the advent of antibiotics.…”

In vitro antioxidant activity of crude extracts of Harpagophytum zeyheri and their anti-inflammatory and cytotoxicity activity compared with diclofenac

“…Other indirect side effects of diclofenac include serious ecological impacts such as the catastrophic decline in vulture populations in the Indian subcontinent which has negative consequences on the environment [30,40]. Thus, studies on medicinal plants with similar properties as synthetic drugs, are becoming increasingly important as they are deemed safer alternatives, and research is focused on this topic worldwide (reviewed in [7]).…”