Xysmalobium undulatum (Uzara) research- how everything began

Uzara (Xysmalobium undulatum) - An underutilized anti-diarrhoeic and spasmolytic herbal remedy

ETHNOPHARMACOLOGICAL RELEVANCE

Uzara, Xysmalobium undulatum (L.) W.T.Aiton, a herbal medicine for diarrhoea and smooth-muscle cramps is little-known outside Germany, where it has had a market presence for ∼110 years. The early introduction of this Southern African medicinal plant into Europe and the US was entrepreneurially driven, similar to buchu (Agathosma spp.) and Umckaloabo (Pelargonium sidoides DC.). Much of its history of commercialization, from its origin, identity and supply chain to its composition and clinical evidence of efficacy and safety, has been poorly studied and/or scantly published.

AIM OF THE STUDY

The aim of this review is to uncover enough data to create a coherent timeline, many of which are published here for the first time, and to evaluate all published data, mostly historical and/or elusive, to corroborate Uzara's status as a safe and efficacious botanical medicine.

MATERIALS AND METHODS

Multiple searches were conducted in the PubMed, Scopus, Web of Science, Science Direct, and Google Scholar databases with the following keywords: all scientific and common plant names combined with taxonomy, nomenclature, ethnobotany, traditional use, ecology, cultivation, sustainability, economy, trade, CITES, chemistry, biochemistry, compounds, pre-clinical, pharmacology, clinical, RCT, safety, toxicology, veterinary, review for the period of 1600-2022. Reference sections of selected publications were searched manually. Additionally, product registration databases of national competent health authorities in Europe were consulted for products, license holders and formulations.

RESULTS

The authors find an underutilized potential of uzara as anti-diarrhoeic (with or without underlying infection) and spasmolytic remedy. A by-product of this review is a largely inclusive bibliography of publications on uzara.

CONCLUSIONS

Further clinical research supporting antidiarrhoeal and spasmolytic efficacy would be desirable.

Antidepressant Effects of South African Plants: An Appraisal of Ethnobotanical Surveys, Ethnopharmacological and Phytochemical Studies

Globally, the search for safe and potent natural-based treatment for depression is receiving renewed interest given the numerous side-effects associated with many existing drugs. In South Africa, the use of plants to manage depression and related symptoms is fairly documented among different ethnic groups. In the current study, we reviewed existing ethnobotanical, ethnopharmacological and phytochemical studies on South African medicinal plants used to manage depression. Electronic databases were accessed for scientific literature that meets the inclusion criteria. Plants with ethnobotanical evidence were subjected to a further pharmacological review to establish the extent (if any) of their effectiveness as antidepressants. Critical assessment resulted in 20 eligible ethnobotanical records, which generated an inventory of 186 plants from 63 plant families. Due to the cultural differences observed in the definition of depression, or lack of definition in some cultures, most plants are reported to treat a wide range of atypical symptoms related to depression. Boophone disticha, Leonotis leonurus and Mentha longifolia were identified as the three most popular plants, with over eight mentions each from the ethnobotanical records. The dominant families were Asteraceae (24), Fabaceae (16), Amaryllidaceae (10), and Apocynaceae (10) which accounted for about 32% of the 186 plants. Only 27 (≈14.5%) of the plants have been screened for antidepressant activity using in vitro and in vivo models. Agapanthus campanulatus, Boophone disticha, Hypericum perforatum, Mondia whitei and Xysmalobium undulatum, represent the most studied plants. Phytochemical investigation on nine out of the 27 plants revealed 24 compounds with antidepressant-like effects. Some of these included buphanidrine and buphanamine which were isolated from the leaves of Boophone disticha, Δ⁹-tetrahydrocannabinol, cannabidiol and cannabichromene obtained from the buds of Cannabis sativa and carnosic acid, rosmarinic acid and salvigenin from Rosmarinus officinalis, A significant portion (≈85%) of 186 plants with ethnobotanical records still require pharmacological studies to assess their potential antidepressant-like effects. This review remains a valuable reference material that may guide future ethnobotanical surveys to ensure their robustness and validity as well as database to identify promising plants to screen for pharmacology efficacy.

A Novel Cardenolide Glycoside Isolated from Xysmalobium undulatum Reduces Levels of the Alzheimer's Disease-Associated β-Amyloid Peptides Aβ42 In Vitro

Elevated levels of the amylo β-proteins (Aβ), particularly Aβ42, are associated with a high risk of Alzheimer’s disease (AD). The Aβ proteins are produced from cellular processing of the amyloid precursor proteins (APPs). To identify natural products that block the formation of Aβ-proteins from APPs, we previously screened a library of plant extracts and identified Xysmalobium undulaum (Apocynaceae) as a potential plant for further research. Here, we provide a report on the isolation and identification of the active principles from the plant species using a bioassay-guided fractionation. Fractions and resulting pure compounds from the purification process of the extract of X. undulatum were screened in vitro against APPs transfected HeLa cell lines. Three compounds, acetylated glycosydated crotoxogenin (1), xysmalogenin-3, β-d-glucopyranoside (2), and crotoxigenin 3-O-glucopyranoside (3), were subsequently isolated and their structures elucidated using NMR and mass spectrometry. Compound 1, a novel cardenolide, and 2 significantly decreased the Aβ42 levels in a dose-dependent manner while compound 3 was inactive. In silico investigations identified the AD’s β-secretase enzyme, BACE1, as a potential target for these compounds with the glycoside moiety being of significance in binding to the enzyme active site. Our study provides the first report of a novel cardenolide and the potential of cardenolides as chemical scaffolds for developing AD treatment drugs.

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

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.

Potential of South African medicinal plants targeting the reduction of Aβ42 protein as a treatment of Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Twenty South African medicinal plant species were selected by conducting a literature review based on the relevant information of their reported traditional medicinal uses and scientific reports against Alzheimer's disease, dementia, anxiety, mental illness, depression, acetylcholinesterase inhibition, headache, epilepsy, convulsion, hysteria, and sedative effects.

AIM OF STUDY

The goal of this study was to investigate the biological activity of the traditionally used medicinal plant extracts against Alzheimer's disease by in vitro screening of the extracts to determine their potential to decrease levels of Aβ42 protein.

MATERIAL AND METHODS

Different plant parts (leaves, stem, bark, and stalks) of twenty selected plants were collected from the Manie van der Schijff Botanical Garden, University of Pretoria. Plant parts were dried, ground and then extracted using DCM:MeOH (1:1). We measured the levels of β-amyloid precursor protein proteolytic products in HeLa cells stably transfected with APP carrying the Swedish mutation using ELISA.

RESULTS

Of 33 plant extract 10 (30.3%) were found active based on the potential to significantly reduce the production of Aβ42. Amongst them extracts of leaves of Xysmalobium undulatum (Apocynaceae), leaves of Cussonia paniculata (Araliaceae) and leaves of Schotia brachypetala (Fabaceae) potently decreased the production of Aβ42 by 77.3 ± 0.5%, 57.5 ± 1.3%, and 44.8 ± 0.1%, respectively. X. undulatum and S. brachypetala enhanced non-amyloidogenic processing of β-amyloid precursor protein, thereby decreasing Aβ42 level. We also showed that C. paniculata induced the decrease of Aβ42 level through inhibiting APP processing. In addition, we isolated two cardenolides, compound [A] and [B], from X. undulatum and found that they potently decreased the Aβ42 production.

CONCLUSION

These data suggest that the extract of X. undulatum, C. paniculata, and S. brachypetala have potential to be developed for Alzheimer's disease treatment. These active extracts and compounds are considered for further studies which examine their efficacy towards the reduction of Aβ42 through inhibiting APP process.