Unravelling the Anticancer Mechanisms of Traditional Herbal Medicines with Metabolomics

Metabolite profiling of cancer cells presents many opportunities for anticancer drug discovery. The Chinese, Indian, and African flora, in particular, offers a diverse source of anticancer therapeutics as documented in traditional folklores. In-depth scientific information relating to mechanisms of action, quality control, and safety profile will promote their extensive usage in cancer therapy. Metabolomics may be a more holistic strategy to gain valuable insights into the anticancer mechanisms of action of plants but this has remained largely unexplored. This review, therefore, presents the available metabolomics studies on the anticancer effects of herbal medicines commonly used in Africa and Asia. In addition, we present some scientifically understudied ‘candidate plants’ for cancer metabolomics studies and highlight the relevance of metabolomics in addressing other challenges facing the drug development of anticancer herbs. Finally, we discussed the challenges of using metabolomics to uncover the underlying mechanisms of potential anticancer herbs and the progress made in this regard.

A Molecular Modeling Approach to Identify Potential Antileishmanial Compounds Against the Cell Division Cycle (cdc)-2-Related Kinase 12 (CRK12) Receptor of Leishmania donovani

The huge burden of leishmaniasis caused by the trypanosomatid protozoan parasite Leishmania is well known. This illness was included in the list of neglected tropical diseases targeted for elimination by the World Health Organization. However, the increasing evidence of resistance to existing antimonial drugs has made the eradication of the disease difficult to achieve, thus warranting the search for new drug targets. We report here studies that used computational methods to identify inhibitors of receptors from natural products. The cell division cycle-2-related kinase 12 (CRK12) receptor is a plausible drug target against Leishmania donovani. This study modelled the 3D molecular structure of the L. donovani CRK12 (LdCRK12) and screened for small molecules with potential inhibitory activity from African flora. An integrated library of 7722 African natural product-derived compounds and known inhibitors were screened against the LdCRK12 using AutoDock Vina after performing energy minimization with GROMACS 2018. Four natural products, namely sesamin (NANPDB1649), methyl ellagic acid (NANPDB1406), stylopine (NANPDB2581), and sennecicannabine (NANPDB6446) were found to be potential LdCRK12 inhibitory molecules. The molecular docking studies revealed two compounds NANPDB1406 and NANPDB2581 with binding affinities of −9.5 and −9.2 kcal/mol, respectively, against LdCRK12 which were higher than those of the known inhibitors and drugs, including GSK3186899, amphotericin B, miltefosine, and paromomycin. All the four compounds were predicted to have inhibitory constant (Ki) values ranging from 0.108 to 0.587 μM. NANPDB2581, NANPDB1649 and NANPDB1406 were also predicted as antileishmanial with Pa and Pi values of 0.415 and 0.043, 0.391 and 0.052, and 0.351 and 0.071, respectively. Molecular dynamics simulations coupled with molecular mechanics Poisson–Boltzmann surface area (MM/PBSA) computations reinforced their good binding mechanisms. Most compounds were observed to bind in the ATP binding pocket of the kinase domain. Lys488 was predicted as a key residue critical for ligand binding in the ATP binding pocket of the LdCRK12. The molecules were pharmacologically profiled as druglike with inconsequential toxicity. The identified molecules have scaffolds that could form the backbone for fragment-based drug design of novel leishmanicides but warrant further studies to evaluate their therapeutic potential.

Amaryllis belladonna L. (Amaryllidaceae, Amaryllidoideae), first record as naturalized geophyte in Tunisia and continental North Africa

Amaryllis belladonna L. is recorded for the first time as a naturalized non-native geophyte new to Tunisian and continental North African flora. Additional information on its current distribution and habitat, a brief morphological description, as well as some taxonomic notes, are provided.

Senecio cymbalarifolius (L.) Less. is the correct name for S. sonchifolius (L.) J.C.Manning & Magoswana, nom. illeg. and clarification of the name S. sonchifolius (L.) Moench (Asteraceae: Senecioneae)

Background: Ongoing systematic studies in the African flora necessitate periodic nomenclatural adjustments and corrections. Objectives: To effect requisite nomenclatural changes. Method: Relevant literature was surveyed and type material located and examined. Results: The combination Senecio sonchifolius (L.) J.C.Manning & Magoswana (2017), based on Othonna sonchifolia L., is an illegitimate later homonym for S. sonchifolius (L.) Moench (1802). Conclusions: The name Senecio cymbalarifolius (L.) Less. is the earliest legitimate name in Senecio for the taxon previously known as S. sonchifolius (L.) J.C.Manning & Magoswana, nom. illeg. On internal evidence, we conclude that S. sonchifolius (L.) Moench was intended as a combination based on Cacalia sonchifolia L. and that the citation of the basionym as Cineraria sonchifolia L. was an error.

A third of the tropical African flora is potentially threatened with extinction

Preserving tropical biodiversity is an urgent challenge when faced with the growing needs of countries. Despite their crucial importance for terrestrial ecosystems, most tropical plant species lack extinction risk assessments, limiting our ability to identify conservation priorities. Using a novel approach aligned with IUCN Red List criteria, we conducted a continental-scale preliminary conservation assessment of 22,036 vascular plant species in tropical Africa. Our results underline the high level of extinction risk of the tropical African flora. Thirty-three percent of the species are potentially threatened with extinction, and another third of species are likely rare, potentially becoming threatened in the near future. Four regions are highlighted with a high proportion (>40%) of potentially threatened species: Ethiopia, West Africa, central Tanzania, and southern Democratic Republic of the Congo. Our approach represents a first step toward data-driven conservation assessments applicable at continental scales providing crucial information for sustainable economic development prioritization.

Allium roseum L. extract inhibits amyloid beta aggregation and toxicity involved in Alzheimer’s disease

ABSTRACTAllium roseum is an important medicinal and aromatic plant, specific to the North African flora and a rich source of important nutrients and bioactive molecules including flavonoids and organosulfur compounds whose biological activities and pharmacological properties are well known. In the present study, the inhibition of amyloid beta protein toxicity by the ethanolic extract of this plant is investigated for the first time. Preliminary biochemical analyses identified kæmpferol and Luteolin-7-o-glucoside as the more abundant phenolic compounds. The effects of A. roseum extract (ARE) on amyloid beta-42 (Aβ42) aggregation and aggregate cytotoxicity, were investigated by biophysical (ThT assay, Dynamic light scattering and transmission electron microscopy) and cellular assays (cytotoxicity, aggregate immunolocalization, ROS measurement and intracellular Ca2+ imaging). The biophysical data suggest that ARE affects the structure of Aβ42 peptide, inhibits its polymerization, and interferes with the path of fibrillogenesis. The data with cultured cells shows that ARE reduces Aß42 aggregate toxicity by inhibiting aggregate binding to the cell membrane and by decreasing both oxidative stress and intracellular Ca2+. Accordingly, ARE could act as a neuroprotective factor against Aβ aggregate toxicity in Alzheimer’s disease.

Massonia villosa (Hyacinthaceae), a new species from the Roggeveld, Northern Cape, South Africa

Background: Ongoing systematic studies in the African flora periodically reveal the existence of undescribed species.Objectives: To describe the new species.Method: Relevant literature was surveyed, and herbarium and fresh material were examined.Results: Collections of a Massonia (Hyacinthaceae) from the escarpment near Sutherland in Northern Cape with unique, softly hairy foliage represent an undescribed species.Conclusions: Massonia villosa J.C.Manning is a new species distinguished by the small, markedly convex leaves with recurved apex and pilose adaxial surface covered with soft, shaggy hairs up to 7 mm long and slender flowers without marked sigmoid coiling of the tepals.

New synonyms and combinations in Drimia Jacq. (Hyacinthaceae) in southern Africa

Background: Ongoing systematic studies in the African flora necessitate periodic nomenclatural adjustments and corrections.Objectives: To effect requisite nomenclatural changes.Method: Relevant literature was surveyed and relevant material was examined.Results: Nomenclatural adjustments are provided for recently described taxa of Hyacinthaceae subfamily Urgineoideae in order to accommodate them in the alternative classification system in use in South African herbaria.Conclusion: A broadly circumscribed Drimia Jacq. has the advantages of nomenclatural stability and utility. The newly described segregate genera Austronea Mart.-Azorín et al. and Zingela N.R.Crouch et al. are formally included in Drimia, and A. densiflora Mart.-Azorín et al., A. hispidoplicata Mart.-Azorín et al. and A. pinguis Mart.-Azorín et al. are transferred to that genus as D. densiflora (Mart.-Azorín et al.) J.C.Manning Goldblatt, D. hispidoplicata(Mart.-Azorín et al.) J.C.Manning Goldblatt and D. pinguis (Mart.-Azorín et al.) J.C.Manning Goldblatt, respectively, whereas A. grandiflora Mart.-Azorín et al. and A. linearis Mart.-Azorín et al. are treated as synonyms of D. vermiformis J.C.Manning Goldblatt; A. olifanta Mart.-Azorín et al. is treated as a synonym of D. barkerae Oberm. ex J.C.Manning Goldblatt; and A. papillosa Mart.-Azorín et al. and A. pygmaea (A.V. Duthie) Mart.-Azorín et al. are treated a synonyms of D. virens (Schltr.) J.C.Manning Goldblatt. Zingela pooleyorum N.R.Crouch is considered to be conspecific with Urginea zambesiacaBaker, for which the new combination D. zambesiaca (Baker) J.C.Manning Goldblatt is provided. The combination D. zebrina (Mart.-Azorín et al.) J.C.Manning Goldblatt is provided for an allied species. Examination of recent collections of Ornithogalum toxicarium C.Archer R.H.Archer confirms that it is actually a species of Drimia and it is accordingly transferred to that genus as D. toxicaria (C.Archer R.H.Archer) J.C.Manning Goldblatt.

Electrochemical Screening and Evaluation of Lamiaceae Plant Species from South Africa with Potential Tyrosinase Activity

South Africa is a country with a wide variety of plants that may contain excellent anti-tyrosinase inhibitors. With wide applications in cosmetics, pharmaceuticals and food products, tyrosinase inhibitors have received very special attention in the recent past as a way of preventing the overproduction of melanin in epidermal layers which often over time brings detrimental effects on human skin. In this present study, a fast screening method using a cyclic voltammetry technique was applied in the evaluation of methanolic extracts of twenty-five species of plants from the Lamiaceae family for anti-tyrosinase activity. Among these plants, those that showed a fast current inhibition rate at a minimum concentration when compared to a kojic acid standard were classified as having the greatest anti-tyrosinase activity. These include Salvia chamelaeagnea, S. dolomitica, Plectranthus ecklonii, P. namaensis, and P. zuluensis. The results presented herein focused in particular on providng firsthand information for further extensive research and exploration of natural product materials with anti-tyrosinase activity from South African flora for use in cosmetics, skin care and medicinal treatments.