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Terrestrial plants have contributed massively to the development of modern oncologic drugs. Despite the wide acceptance of Mauritian endemic flowering plants in traditional medicine, scientific evidence of their chemotherapeutic potential is lacking. This study aimed to evaluate the in vitro tumor cytotoxicity of leaf extracts from five Mauritian endemic medicinal plants, namely Acalypha integrifolia Willd (Euphorbiaceae), Labourdonnaisia glauca Bojer (Sapotaceae), Dombeya acutangula Cav. subsp. rosea Friedmann (Malvaceae), Gaertnera psychotrioides (DC.) Baker (Rubiaceae), and Eugenia tinifolia Lam (Myrtaceae). The cytotoxicities of the extracts were determined against six human cancer cell lines, including cervical adenocarcinoma, colorectal carcinoma, oesophageal adenocarcinoma, and oesophageal squamous cell carcinoma. The potent extracts were further investigated using cell cycle analysis and reverse phase protein array (RPPA) analysis. The antioxidant properties and polyphenolic profile of the potent extracts were also evaluated. Gas chromatography mass spectrometry (GC-MS) analyses revealed the presence of (+)-catechin and gallocatechin in E. tinifolia and L. glauca, while gallic acid was detected in A. integrifolia. L. glauca, A. integrifolia, and E. tinifolia were highly selective towards human oesophageal squamous cell carcinoma (KYSE-30) cells. L. glauca and E. tinifolia arrested KYSE-30 cells in the G2/M phase, in a concentration-dependent manner. RPPA analysis indicated that the extracts may partly exert their tumor growth-inhibitory activity by upregulating the ntracellular level of 5′AMP-activated kinase (AMPK). The findings highlight the potent antiproliferative activity of three Mauritian endemic leaf extracts against oesophageal squamous cell carcinoma and calls for further investigation into their chemotherapeutic application

Tropical forests constitute a prolific sanctuary of unique floral diversity and potential medicinal sources, however, many of them remain unexplored. The scarcity of rigorous scientific data on the surviving Mascarene endemic taxa renders bioprospecting of this untapped resource of utmost importance. Thus, in view of valorizing the native resource, this study has as its objective to investigate the bioactivities of endemic leaf extracts. Herein, seven Mascarene endemic plants leaves were extracted and evaluated for their in vitro antioxidant properties and antiproliferative effects on a panel of cancer cell lines, using methyl thiazolyl diphenyl-tetrazolium bromide (MTT) and clonogenic cell survival assays. Flow cytometry and comet assay were used to investigate the cell cycle and DNA damaging effects, respectively. Bioassay guided-fractionation coupled with liquid chromatography mass spectrometry (MS), gas chromatography-MS, and nuclear magnetic resonance spectroscopic analysis were used to identify the bioactive compounds. Among the seven plants tested, Terminaliabentzo&euml, was comparatively the most potent antioxidant extract, with significantly (p &lt, 0.05) higher cytotoxic activities. T. bentzo&euml, extract further selectively suppressed the growth of human hepatocellular carcinoma cells and significantly halted the cell cycle progression in the G0/G1 phase, decreased the cells&rsquo, replicative potential and induced significant DNA damage. In total, 10 phenolic compounds, including punicalagin and ellagic acid, were identified and likely contributed to the extract&rsquo, s potent antioxidant and cytotoxic activities. These results established a promising basis for further in-depth investigations into the potential use of T. bentzo&euml, as a supportive therapy in cancer management.

Tropical forests constitute prolific sanctuary of unique floral diversity and potential medicinal sources, however, many of them remains unexplored. Herein, seven Mascarene endemic plants leaves were extracted and evaluated for their in vitro antioxidant properties and antiproliferative effects on a panel of cancer cell lines using MTT and clonogenic cell survival assay. Flow cytometry and comet assay were used to investigate the cell cycle and DNA damaging effects, respectively. Bioassay guided-fractionation coupled with LC-Mass spectrometry (MS), gas chromatography-MS, and nuclear magnetic resonance spectroscopy analysis were used to identify the bioactive compounds. Among the seven plants tested, Terminalia bentzoë was comparatively the most potent antioxidant extract with significantly (p < 0.05) higher cytotoxic activities. T. bentzoë extract further selectively suppressed the growth of human hepatocellular carcinoma cells and significantly halted the cell cycle progression in G0/G1 phase, decreased the cells replicative potential and induced significant DNA damage. Ten phenolic compounds including punicalagin and ellagic acid were identified and likely contributed to the extract potent antioxidant and cytotoxic activities. These results established a promising basis for further in-depth investigations on the potential use of T. bentzoë as supportive therapy in cancer management.

Stillingia lineata (Lam.) Mull. Arg. subsp. lineata (Euphorbiaceae) is a heterophyllous shrub to tree. The species is widespread in the Pacific and the Indian Ocean. This subspecies is endemic to Mauritius and Reunion islands. Plant parts are recommended for the treatment of dermatological conditions and viral infections. Despite the plant's widespread ethnomedicinal application, there is limited evidence of its therapeutic efficacy in animal or human subjects. Reported bioactivities of the S. lineata subsp. lineata mainly emphasize the in vitro activity of the leaf and bark extracts against the chikungunya virus. The antiviral activity of the subspecies has been primarily ascribed to its terpenoid content including tonantzitlolone derivatives. This chapter includes a brief botanical description and distribution of S. lineata subsp. lineata, its ethnobotanical uses, and the reported in vitro antimicrobial and antidiabetic effect of the plant extracts.

Acalypha integrifolia Willd (Euphorbiaceae) is a monoecious shrub. The species is endemic to the Mascarenes, and this subspecies is endemic to the Mascarenes islands of Reunion and Mauritius. The leaves are used as part of alternative medicine on both islands. Herbalists recommend a decoction of the leaf for their anthelmintic and depurative properties but also for various dermatological pathologies. However, although the leaf is commonly administered orally, scientific evaluation of its efficacy, phytochemical, and safety profile for human consumption is scarce. The reported biological activity has focused on the in vitro antibacterial and antifungal properties. This chapter presents a general view of the botanical description, ethnomedicinal uses, and antimicrobial properties of the Indian Ocean A. integrifolia subspecies.

The evaluation of herbal extracts’ toxicity profiles are crucial when validating their therapeutic potential. Hence, an in vitro model using embryonic dorsal aorta region from day 11 mice embryo and cKit+ cells from B6 mice bone marrow was used to evaluate the hematotoxicity of three Mauritian endemic medicinal plants. At high concentration, all three extracts exhibited a significant (P=.001) drop in the adult’s hematopoietic stem cell number. At the highest dose tested both Acalypha integrifolia (P=.001) and Labourdonaisia glauca Bojer (P=.002) decreased the total cell number of adult progenitors, while no significant change was observed following treatment with Eugenia tinifolia. Only A. integrifolia caused a significant (P=.001) decline in embryonic total cell number. Moreover, A. integrifolia reduced the progenitor/stem cell number in both models. At a low dose, A. integrifolia induced development of lymphoid cell lineages while E. tinifolia upregulated the production of both erythroid and myeloid cells.

With about 25% of life-saving pharmaceutical drugs derived from plants, unexplored flora offer much promise as a source of new pharmacologically active molecules. Despite the number of challenges associated with plants as a drug discovery source, the thousands to millions of different molecules that plants produce cannot be disregarded in the wake of drug resistance and emerging diseases. This book chapter thus provides an insight of the historical evidence of plants as a source of drugs, with a view to discussing the barriers that limit further research and development in this area, and provides an overview of how these challenges could be overcome. The importance of partnerships among scientists, pharmaceutical industries, and indigenous communities to identify species and isolate compounds, social scientists to assess community needs and ensure community empowerment, and policy makers to produce legislation to guide protection and to develop models for sustainable agriculture and research involving modern biotechnology and chemistry are proposed.

Terminalia bentzoe (L.) L.f. subsp. bentzoe (Combretaceae) is a threatened canopy tree of the drier forest of the Mascarenes. The species is endemic to the Mascarene archipelago, with this subspecies found in both Reunion and Mauritius and a different subspecies being endemic to the island of Rodrigues. The species is highly used locally for several ailments. The documented ethnomedicinal usage of this subspecies varies on both islands. Herbalists prescribed different plant parts as single herb decoction or as part of polyherbal formulations against communicable and infectious diseases. However, scientific literature reporting the phytochemical constituents—biological efficacy and toxicity profile in human subjects—is scarce. Majority of the reported bioactivities are limited to in vitro assays, and only a few activities have been validated in in vivo rodent models. This chapter summarizes the botanical description, distribution, ethnopharmacological usage, and reported phytoconstituents and bioactivities of T. bentzoe.

Flowering plants from the Syzygium genus have long been used in different ethnomedicinal systems worldwide and have been under scrutiny for their biological activities. Syzygium coriaceum, an endemic plant of Mauritius has been poorly studied for its potential application against cancer. Herein, Syzygium coriaceum leaf extract has been investigated for its anticancer effect against hepatocellular carcinoma (HepG2) cells. The anticancer activity was assessed using cell proliferation assays, flow cytometry, JC-1 mitochondrial membrane potential assay, and the COMET assay. Un-targeted metabolite profiling via ultra-performance liquid chromatography coupled to high-resolution qTOF-MS (UPLC-MS) and aided by molecular networking was employed to identify the crude extract metabolites. S. coriaceum treatment induced a dose-dependent increase in lactate dehydrogenase leakage into the culture media, peaking up to 47% (p ≤ 0.0001), compared to untreated control. Moreover, at 40 μg/mL, S. coriaceum led to 88.1% (p ≤ 0.0001) drop in mitochondrial membrane potential and 5.7% (p ≤ 0.001) increased in the number of the cell population in G0/G1 phase as well as increased (p < 0.05) the proportion of cells undergoing apoptotic/necrotic cell death. More so, at 10 μg/mL, S. coriaceum induced DNA damage which was 19 folds (p < 0.001) higher than that of untreated control cells. Metabolite profiling indicated the presence of 65 metabolites, out of which 59 were identified. Tannins, flavonoids, nitrogenous compounds, and organic acids were the most predominant classes of compounds detected. Our findings showed that the presence of tannins and flavonoids in S. coriaceum leaf extract could account for the multiple mechanisms of actions underlying the antiproliferative effect against HepG2 cells.

Multiple myeloma is of great concern since existing therapies are unable to cure this clinical condition. Alternative therapeutic approaches are mandatory, and the use of plant extracts is considered interesting. Punica granatum and its derived products were suggested as potential anticancer agents due to the presence of bioactive compounds. Thus, polypenolic-rich extracts of the non-edible parts of P. granatum were investigated for their antiproliferative and apoptotic effects on U266 multiple myeloma cells. We demonstrated that there were dose-dependent decreases in the proliferation of U266 cells in response to P. granatum extracts. Also, exposure to the extracts triggered apoptosis with significant increases in loss of mitochondrial membrane potential in U266 cells exposed to the leaves and stem extracts, while the flower extract resulted in slight increases in loss of MMP. These results were confirmed by Annexin-V analysis. These results documented the cytotoxic and apoptotic effects of P. granatum extracts on human U266 multiple myeloma cells via disruption of mitochondrial membrane potential and increasing cell cycle arrest. The data suggest that the extracts can be envisaged in cancer chemoprevention and call for further exploration into the potential application of these plant parts.

Ethnopharmacological relevance The Mauritian endemic flora has been recorded to be used as medicines for nearly 300 years. Despite acceptance of these endemic plants among the local population, proper documentation of their therapeutic uses is scarce. This review aims at summarising documented traditional uses of Mauritian endemic species with existing scientific data of their alleged bioactivities, in a view to appeal for more stringent validations for their ethnomedicinal uses. Material and methods A comprehensive bibliographic investigation was carried out by analysing published books on ethnopharmacology and international peer-reviewed papers via scientific databases namely ScienceDirect and PubMed. The keywords “Mauritius endemic plants” and “Mauritius endemic medicinal plants” were used and articles published from 1980 to 2016 were considered. 675 works of which 12 articles were filtered which documented the ethnomedicinal uses and 22 articles reported the biological activities of Mauritian endemic plants. Only materials published in English or French language were included in the review. Available data on the usage of Mauritian endemic plants in traditional medicine and scientific investigation were related. Results and discussion We documented 87 taxa of Mauritian endemic plants for their medicinal value. Endemic plants are either used as part of complex herbal formulations or singly, and are prescribed by herbalists to mitigate a myriad of diseases from metabolic disorders, dermatological pathologies, arthritis to sexually transmissible diseases. However, these species have undergone a limited consistent evaluation to validate their purported ethnomedicinal claims. As the World Health Organization Traditional Medicine Strategy 2014–2023 emphasises on moving traditional medicine into mainstream medicine on an equally trusted footage, the re-evaluation and modernization of Mauritius cultural heritage become necessary. Conclusions With a consumer-driven ‘return to nature’, scientific validation and valorization of the herbal remedies, including efficacy and safety are, therefore, important. This review reports the scarcity of research on validating the efficacy and safety of medicinal endemic plants. This calls for the use of optimised methodologies to investigate the claims of therapeutic effects resulting from the use of these traditional medicines.