SummaryThe digestive vacuole of the malaria parasite Plasmodium falciparum is the site of haemoglobin digestion and haem detoxification, and is the target of chloroquine and other antimalarials. The mechanisms for genesis of the digestive vacuole and transfer of haemoglobin from the host cytoplasm are still debated. Here, we use live-cell imaging and photobleaching to monitor the uptake of the pH-sensitive fluorescent tracer SNARF-1-dextran from the erythrocyte cytoplasm in ring-stage and trophozoite-stage parasites. We compare these results with electron tomography of serial sections of parasites at different stages of growth. We show that uptake of erythrocyte cytoplasm is initiated in mid-ring-stage parasites. The host cytoplasm is internalised via cytostome-derived invaginations and concentrated into several acidified peripheral structures. Haemoglobin digestion and haemozoin formation take place in these vesicles. The ringstage parasites can adopt a deeply invaginated cup shape but do not take up haemoglobin via macropinocytosis. As the parasite matures, the haemozoin-containing compartments coalesce to form a single acidic digestive vacuole that is fed by haemoglobin-containing vesicles. There is also evidence for haemoglobin degradation in compartments outside the digestive vacuole. The work has implications for the stage specificity of quinoline and endoperoxide antimalarials.

Parasitic diseases represent one of the causes for significant global economic, environmental and public health impacts. The efficacy of currently available anti-parasitic drugs has been threatened by the emergence of single drug- or multidrug-resistant parasite populations, vector threats and high cost of drug development. Therefore, the discovery of more potent anti-parasitic drugs coming from medicinal plants such as Quercus infectoria is seen as a major approach to tackle the problem. A systematic review was conducted to assess the efficacy of Q. infectoria in treating parasitic diseases both in vitro and in vivo due to the lack of such reviews on the anti-parasitic activities of this plant. This review consisted of intensive searches from three databases including PubMed, Science Direct and Scopus. Articles were selected throughout the years, limited to English language and fully documented. A total of 454 potential articles were identified, but only four articles were accepted to be evaluated based on inclusion and exclusion criteria. Although there were insufficient pieces of evidence to account for the efficacy of Q. infectoria against the parasites, this plant appears to have anti-leishmanial, anti-blastocystis and anti-amoebic activities. More studies in vitro and in vivo are warranted to further validate the anti-parasitic efficacy of Q. infectoria.

Christia vespertilionis (L.F) Bakh. F. (red butterfly wing) is commonly used as a herbal medicine to treat symptoms of many diseases. The present study aimed to determine the in vitro antimalarial and cytotoxic activities as well as investigate the chemical compositions of the methanolic extract of C. vespertilionis leaves (CVME). The antimalarial activity of CVME against a chloroquine-sensitive (3D7) strain of Plasmodium falciparum was assessed by using a malarial SYBR Green I fluorescence-based (MSF) assay. The cytotoxic effect of CVME on cancerous (MDA-MB-231 and MCF-7) and noncancerous (NIH/3T3) cell lines were evaluated by using methyl tetrazolium (MTT) assay. Chemical constituents of CVME were analysed by using a gas chromatography/mass spectrometry (GCMS). CVME exhibited a moderate antimalarial activity with an IC50 value of 43.87 ± 2.04 µg/mL. CVME is considered as weak cytotoxic and significantly inhibited proliferation of MDA-MB-231 cells with an IC50 value of 37.45 ± 1.05 µg/mL (p<0.05) as compared to standard MCF-7 (IC50>100 μg/mL) and NIH/3T3 cells (IC50>100 μg/mL). This effect is selectively cytotoxic towards certain cancerous cells only. GCMS analysis suggests that CVME potentially contains several pharmacologically bioactive compounds such as tetrahydro-2-methyl- thiophene (61.77%), phytol (8.59%), 10-undecenoic acid (5.00%), 6-methyl heptyl-2-propanoate  (4.96%) and 2-(2-benzothiazolylthio)-1-(3,5-dimethylpyrazolyl)-ethanone  (2.70%) that might possess antimalarial and cytotoxic activities. It implies that CVME has selective cytotoxic activity against the breast cancer cell line (MDA-MB-231) and possesses an antimalarial activity against the 3D7 malaria parasite, suggesting the presence of bioactive compounds in C. vespertilionis leaves that could be a potential source of phytochemicals with high medicinal value to be used in cancer and malaria treatment.     Keywords: Christia vespertilionis, antimalarial activity, anticancer activity, cytotoxic activity, bioactive compounds.

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Malaria remains one of the most common human infections worldwide. in endemic areas, malaria is a leading cause of morbidity and mortality and it imposes significant socioeconomic burdens on the people affected. Monocytes are part of the immune system controlling parasite burden and protecting the host against malaria infection. Monocytes play their protective roles against malaria via phagocytosis, cytokine production and antigen presentation. though monocytes are crucial for clearance of malaria infection, they have also been shown to cause adverse clinical outcomes. in this review, we discuss recent findings regarding the role of monocytes in malaria via mechanisms such as parasite detection and clearance, pro-inflammatory activities, and activation of other immune components. We also highlight the role of different monocyte subsets, and other myeloid cells that are involved in malaria infection. however, more investigations are required in order to explore the exact roles of these monocytes in malaria infection.