Antifungal Activity of Euclea divinorum Root and Study of its Ethnobotany and Phytopharmacology

Ethnobotanical uses, phytochemistry and biological activity of the genus Euclea: A review

Euclea (Ebenaceae) is a genus of flowering shrubs and trees widely distributed in Africa, the Comoro Islands, and Arabia. This review aimed to evaluate the ethnobotanical uses, phytochemistry, and biological activities of the genus Euclea on available research reports. This was achieved through PubMed, Medline, Google Scholar, Science Direct, Taylor and Francis Online, Wiley Online Library which provides access to scientific and medical research. The extensive literature survey revealed that plants that belong to this genus are used as folkloric medicine for the treatment of diabetes mellitus, toothache, diarrhea, cancer, malaria, leprosy, and genital and oral diseases in the case of HIV/AIDS-related diseases. To date, more than 40 secondary metabolites have been isolated and identified from these plants, especially from E natalensis and E. divinorum. Among these, naphthoquinones, terpenes, and flavonoids are potential secondary metabolites with profound biological activities. Euclea plant extracts and their bioactive compounds possess outstanding pharmacological properties, especially antimalarial, antidiabetic, anticancer, antimicrobial, and antioxidant properties.

Euclea divinorum Hiern: Chemical Profiling of the Leaf Extract and Its Antioxidant Activity In Silico, In Vitro and in Caenorhabditis elegans Model

Euclea divinorum Hiern is a medicinal plant widely distributed in the northeast parts of South Africa. This plant has been used to treat miscarriage and to alleviate gastrointestinal problems. It can also be used externally for the treatment of ulcers and gonorrhea. In this study, we investigated the phytochemical composition of E. divinorum leaf extract using LC-MS and explored its antioxidant properties in vitro and in vivo. The total polyphenolic content of the extract was determined by the Folin–Ciocalteu method. DPPH and FRAP assays were employed to confirm the plant’s antioxidant potential in vitro. A survival assay in the Caenorhabditis elegans model was used to evaluate the extract’s ability to counteract juglone-induced oxidative stress. Moreover, a docking study was performed for the extract’s metabolites, in order to predict possible molecular targets that could explain the antioxidant effect of the plant on a molecular level. This in silico approach was accomplished on three different proteins; xanthine oxidase enzyme, heat shock protein 90 (Hsp90), and induced nitric oxide synthase (iNOS). Docking scores of the resulting poses and their interactions with binding sites’ residues were explored for each protein and were compared to those of simultaneously docked respective co-crystallized and reference substrates. The extract furnished promising antioxidant activities in vitro and in vivo in the C. elegans model that might be attributed to the presence of 46 compounds, which showed several interactions and low binding scores with the tested enzymes. In conclusion, E. divinorum is a promising, safe, and effective antioxidant candidate that could be used to ameliorate oxidative stress-related disorders.

Synthesis and comparison of in vitro dual anti-infective activities of novel naphthoquinone hybrids and atovaquone

A principal factor that contributes towards the failure to eradicate leishmaniasis and tuberculosis infections is the reduced efficacy of existing chemotherapies, owing to a continuous increase in multidrug-resistant strains of the causative pathogens. This accentuates the dire need to develop new and effective drugs against both plights. A series of naphthoquinone-triazole hybrids was synthesized and evaluated in vitro against Leishmania (L.) and Mycobacterium tuberculosis (Mtb) strains. Their cytotoxicities were also evaluated, using the human embryonic kidney cell line (HEK-293). The hybrids were found to be non-toxic towards human cells and had demonstrated micromolar cellular antileishmanial and antimycobacterial potencies. Hybrid 13, i.e. 2-{[1-(4-methylbenzyl)-1H-1,2,3-triazol-4-yl]methoxy}naphthalene-1,4-dione was the most active of all. It was found with MIC₉₀ 0.5 µM potency against Mtb in a protein free medium, and with half-maxima inhibitory concentrations (IC₅₀) of 0.81 µM and 1.48 µM against the infective promastigote parasites of L. donavani and L. major, respectively, with good selectivity towards these pathogens (SI 22 - 65). Comparatively, the clinical naphthoquinone, atovaquone, although less cytotoxic, was found to be two-fold less antimycobacterial potent, and six- to twelve-fold less active against leishmania. Hybrid 13 may therefore stand as a potential anti-infective hit for further development in the search for new antitubercular and antileishmanial drugs. Elucidation of its exact mechanism of action and molecular targets will constitute future endeavour.

Green Separation and Extraction Processes: Part I

Supercritical fluid extraction comprises a known technology applied to obtain volatile compounds from flowers, i [...]

Tree Bark Phenols Regulate the Physiological and Biochemical Performance of Gladiolus Flowers

The postharvest physiology of cut flowers is largely dependent on vase life, which is the maximum number of days before flower senescence. The use of tree bark extracts (major forest plant residues), as an eco-friendly and natural antioxidant preservative in holding solutions, is a novel tool for extending flower longevity. The morphological, physiological, biochemical, and genetic responses of Gladiolus grandiflorus cut spikes to Magnolia acuminata and Taxus cuspidata bark extracts as additives in holding solutions were investigated. G. grandiflorus subjected to bark extracts as well as catechin and protocatechuic acid (main phenols) displayed significant increased longevity (up to 18 days), an increased number of open florets, and increased floret fresh weight. Increases in the relative water content, leaf chlorophyll, carotenoids, soluble sugars, and protein content were observed in addition to a reduction in microbial growth in the cut spikes. Gas exchange parameters were higher in the bark extract treatments than in the controls. Higher antioxidant activities were detected and associated with increased superoxide dismutase and catalase enzyme activities and reduced H2O2 accumulation. The bark extract treatments associated with reduced expression of GgCyP1 (produces cysteine protease) and increased expression of both GgDAD1 (defends against apoptotic activity) and GgEXPA1 (regulates petal expansion). Several mechanisms were implicated in these effects, including maintenance of water content, enhanced management of reactive oxygen species (ROS), increased sugar and protein composition, and control of microbial growth. Thus, bark extracts and isolated phenols could be developed as an eco-friendly, non-toxic, and cost-effective natural preservative for cut gladiolus flowers.