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Since the outbreak in December 2019, in Wuhan (China) of COVID-19, approved drugs are still lacking and the world is seeking effective treatment. The purpose of this article is to review the medicinal plants with potential to be used as complementary therapies against COVID-19. Bibliographic information was searched in several databases (Google Scholar, PubMed, Scopus, ScienceDirect, PROTA, ResearchGate and GLOBEinMED), to retrieve relevant papers on (1) plants used to manage common symptoms of COVID-19, (2) plant secondary metabolites with confirmed inhibitory effects on COVID-19 and (3) plants exhibiting pharmacological activities of relevance for COVID-19 management. A total of 230 species was recorded as potential source of ingredients for the fight against the 2019 novel corona virus. Of these species, 30 contain confirmed antiCOVID-19 secondary metabolites, 90 are used traditionally to manage at least 3 common symptoms of COVID-19, 10 have immunostimulant activity, 52 have anti-inflamatory activity, 14 have antiviral properties and 78 species are documented as used to treat malaria. A PCA analysis showing cluster formatting among the recorded species indicates 4 groups of species and an array of possibility of using individual species or a combination of species for their complementary effects. The authors argue that Cameroonian medicinal plants can be of potential contribution to the fight against COVID-19. Further applied research is needed to provide more scientific evidence for their efficacy, to establish standard formulations and clinical studies as part of efforts to develop therapies for COVID-19.

Powder X-ray diffraction and dynamic light scattering (DLS) sizing of silver (Ag) and palladium (Pd) nanoparticles produced within aqueous plant extract and the effect of introducing of an ionic liquid are reported in this paper. The simple and novel synthesis of silver and palladium nanoparticles using the reducing power of Persea americana(Pa) bark extract is reported and the effect of adding 1-ethyl-3-methylimidazolium tosylate [EMIm][Tos] is described. Detailed powder X-ray interpretation allowed determination of the crystalline grain sizes of 16±4nm for Ag–Pa, 13±2nm for Ag–Pa[EMIm][Tos], 16±3nm for Pd–Pa and 9±1nm for Pd–Pa[EMIm][Tos] according to the Scherrer peak analysis. A size contraction occurs when moving from plant extract alone to plant extract/ionic liquid. These grain sizes are 9nm for Ag–Pa and for 9nm Ag–Pa[EMIm][Tos], 15nm for Pd–Pa and 7nm for Pd–Pa[EMIm][Tos] when the Williamson–Hall plot intercept is used. Modal hydrodynamic sizes were determined by DLS as 57nm for Ag–Pa, 72nm for Ag–Pa[EMIm][Tos], 390nm for Pd–Pa and 98nm for Pd–Pa[EMIm][Tos] providing indications on how the particles behave in solution. Intrinsic stresses of 0.177GPa for Ag–Pa, 0.219GPa for Ag–Pa[EMIm][Tos], 0.382GPa for Pd–Pa and 0.190GPa for Pd–Pa[EMIm][Tos] and dislocation densities of (6±3)×10−3nm−2for Ag–Pa, (9±3)×10−3nm−2for Ag–Pa[EMIm][Tos], (5±2)×10−3nm−2for Pd–Pa and (16±4)×10−3nm−2for Pd–Pa[EMIm][Tos] have been obtained.

The determination of CD4 cells is of crucial clinical importance for patients with AIDS. However, the high costs involved represent limitations for CD4 cell counting in developing countries. In order to provide an affordable technique, we introduced a simplified volumetric counting (SVC) technique without sample manipulations and investigated it in a multicentre study. Blood samples from 434 healthy donors and immunodeficient patients were tested in eight hospital laboratories in Europe, Africa and Asia. CD4 cell counts were compared using inhouse flow cytometric methods and the SVC technique. The SVC method was performed on a low-cost flow cytometer (CyFlow SL, Partec, Münster, Germany) after 15 min antibody incubation without pre-analytic manipulations, such as washing or erythrocyte lysing procedures. Linear regression analysis demonstrated a correlation of r=0.942 (Europe), r=0.952 (Africa) and r=0.989 (Asia) between the SVC technique and the in-house methods. Bland Altman plot analysis of all patient data showed a mean bias between the two methods of +26 CD4 cells in favour of the SVC technique (measured range: 6–1905 cells/µl; median CD4 cell count: 388/µl). Three centres used the FACS-count technique (Becton-Dickinson, San José, Calif., USA) as an in-house method dispensing with pre-analytic manipulations. The comparison of SVC and FACS-count method revealed a mean bias of +32 CD4 cells/µl (median CD4 cell count: 349/µl). The accuracy of the SVC was tested on standards with known CD4 cell counts (n=6) and was shown to be 95.2%. The low-cost device and the simplified no-lyse, no-wash test procedure reduces the costs per determination and facilitates the use of flow cytometry in developing countries.