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Introduction: A reverse-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for the simultaneous analysis of two drugs, levamisole hydrochloride (LH) and oxyclozanide (OX), in co-formulation for veterinary use. Materials and Methods: The new HPLC method was validated as per the ICH and other guidelines. A C18 column was used with a gradient program; eluent A was an equal mixture of methanol and acetonitrile, and eluent B included a 25 mM phosphate buffer at pH 7.0 containing 30 mM sodium decanesulfonate and triethylamine (50:50:1 v/v) with pH adjusted to 7.0 using H3PO4 [51:49 v/v] .The detection wavelength was set at 220 nm. For the final gradient program, the retention times were 8.2(for LH) and 13.6(for OX) minutes, respectively, at a flow rate of 1 ml/min over 20 minutes run time. Results: The method was precise, specific and robust. The correlation coefficient, R2 was 0.9998 and 0.9999 for LH and OX, respectively in the range of 5 – 280 μg / mL. The percent y-intercepts and percent residual standard deviations were 1.6%/0.4% and 1.4%/1.0% for LH and OX, respectively. The LOD and LOQ of the method were 0.21 μg / mL and 0.62 μg / mL for LH and 0.06 μg / mL and 0.18 μg / mL for OX. The method has an average accuracy of 100.5% for LH and 101.1% for OX when tested on veterinary bolus formulations, and the samples could be stored under typical lab conditions for about 7 days without significant degradation. Conclusion: This HPLC method is suitable for assaying levamisole hydrochloride and oxyclozanide simultaneously from veterinary formulations.

Medicinal plants have been traditionally used to treat cancer in Ethiopia. However, very few studies have reported the in vitro anticancer activities of medicinal plants that are collected from different agro-ecological zones of Ethiopia. Hence, the main aim of this study was to screen the cytotoxic activities of 80% methanol extracts of 22 plants against human peripheral blood mononuclear cells (PBMCs), as well as human breast (MCF-7), lung (A427), bladder (RT-4), and cervical (SiSo) cancer cell lines. Active extracts were further screened against human large cell lung carcinoma (LCLC-103H), pancreatic cancer (DAN-G), ovarian cancer (A2780), and squamous cell carcinoma of the esophagus (KYSE-70) by using the crystal violet cell proliferation assay, while the vitality of the acute myeloid leukemia (HL-60) and histiocytic lymphoma (U-937) cell lines was monitored in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) microtiter assay. Euphorbia schimperiana, Acokanthera schimperi, Kniphofia foliosa, and Kalanchoe petitiana exhibited potent antiproliferative activity against A427, RT-4, MCF-7, and SiSo cell lines, with IC50 values ranging from 1.85 ± 0.44 to 17.8 ± 2.31 µg/mL. Furthermore, these four extracts also showed potent antiproliferative activities against LCLC-103H, DAN-G, A2780, KYSE-70, HL-60, and U-937 cell lines, with IC50 values ranging from 0.086 to 27.06 ± 10.8 µg/mL. Hence, further studies focusing on bio-assay-guided isolation and structural elucidation of active cytotoxic compounds from these plants are warranted.

Additional file 1: Fig. S1. Isolation protocol of knipholone (2). Fig. S2. Isolation protocol of dianellin (1). Fig. S3. I: 1H, 13C, DEPT and HRMS of YKFM-2 (Dianellin). Fig. S4. II: 1H, 13C, DEPT and HRMS of KFP-1 (Knipholone). Table S1. Antimalarial activity of the phenolic fractions of Kniphofia folosia in mice infected with Plasmodium berghei. Table S2. Prediction of partition coefficient Log P, aqueous solubility Log S and partition coefficient for partially dissociated compounds Log D of the compounds. Table S3. Docking result of compounds on the crystal structure of plasmepsin II (4cku) and plasmodium falciparum l-lactate dehydrogenase (pfLDH) (PDB 1ldg). Table S4. Acute oral toxicity results of dianellin. Fig. S4. Microscope slide photos of the negative control groups (A and B), dianellin and knipholone treated groups (C-E) and positive control group (F).

Abdrrahman Shemsu Surur,1 Solomon Assefa Huluka,2 Melese Legesse Mitku,3 Kaleab Asres4 1CDT-Africa, Addis Ababa University, Addis Ababa, Ethiopia; 2Department of Pharmacology and Clinical Pharmacy, Addis Ababa University, Addis Ababa, Ethiopia; 3Department of Pharmaceutical Chemistry, University of Gondar, Gondar, Ethiopia; 4Department of Pharmaceutical Chemistry and Pharmacognosy, Addis Ababa University, Addis Ababa, EthiopiaCorrespondence: Abdrrahman Shemsu SururCDT-Africa, Addis Ababa University, P. O Box 182932, Addis Ababa, EthiopiaTel +251-911171194Email Abdrrahman.Surur@hotmail.comAbstract: Malaria remains a global public health problem due to the uphill fight against the causative Plasmodium parasites that are relentless in developing resistance. Indole-based antiplasmodial compounds are endowed with multiple modes of action, of which inhibition of hemozoin formation is the major mechanism of action reported for compounds such as cryptolepine, flinderoles, and isosungucine. Indole-based compounds exert their potent activity against chloroquine-resistant Plasmodium strains by inhibiting hemozoin formation in a mode of action different from that of chloroquine or through a novel mechanism of action. For example, dysregulating the sodium and osmotic homeostasis of Plasmodium through inhibition of PfATP4 is the novel mechanism of cipargamin. The potential of developing multi-targeted compounds through molecular hybridization ensures the existence of indole-based compounds in the antimalarial pipeline.Keywords: indole, antimalarial agents, hemozoin inhibition, PfATP4, multi-target approach