https://ir.cut.ac.zw:8080/xmlui/handle/123456789/305 Research publications 2026-06-06T04:29:44Z https://ir.cut.ac.zw:8080/xmlui/handle/123456789/746 Chemical composition by PTP 1B inhibitory activity guided analysis of a plantbased antidiabetic polyherbal drug used in ethnomedical systems Mugari, Pardon; Dzomba, Pamhidzai; Nyoni, Stephen Background Due to growing resistance and continued depletion of drugs that can be used as replacements, people turn to herbal antidiabetic medicines. A polyherbal drug consisting of a mixture of two herbal plants, Zanthoxylum chalybeum and Xeroderris stuhlmannii root powder mixed in equal amounts using a tea cup, was studied to investigate its chemical composition and possible mode of action. Methods Phytochemicals were isolated using Column and Thin Layer Chromatography, and antidiabetic activity was ascertained using an enzyme inhibition model. Active compounds identity was established using 1HNMR, 13CNMR, HSQC-NMR, UV, FT-IR and MS spectroscopy. Results Results showed that the polyherbal drug consisted of two alkaloids and three anthocyanins as the major active components. PTP 1B inhibition of alkaloids was not significantly different from that of metformin with percentage inhibition of 78.6 ± 3.2 and 79.6 ± 2.3%. The anthocyanins inhibited PTP 1B enzyme significantly better than metformin with percentage inhibition of 88.2 ± 3.2, 90.3 ± 2.3 and 93.6 ± 2.9%. One new compound, an alkaloid, 1, 2-dimethoxy-12-methyl-7-(3-methylbut-2-en-1-yl)-12, 13-dihydro [1,3] benzodioxolo [5,6-c] phenanthridin-13-ol, one previously reported alkaloid berberine, IUPAC name, 9,10-dimethoxy-5,6-dihydro[1,3] dioxolo [4’,5’:6,7] isoquinolino [2,1-b][2] benzazin-7-ium and three anthocyanins,, malvidin 3-o-glucoside, pelargonidin-3-O-gucoside and malvidin 3, 5-O-diglucoside were identified as the active compounds in the polyherbal drug extract. Conclusion Presence of alkaloids and anthocyanins that have PTP 1B inhibitory activity showed that the polyherbal drug is a potential medicine for managing diabetes. 2025-01-01T00:00:00Z https://ir.cut.ac.zw:8080/xmlui/handle/123456789/713 In Silico, In Vitro, and In Vivo Antidiabetic Activity of an Alkaloid, 1, 2-Dimethoxy-12-Methyl-7-(3-Methylbut-2-en-1- yl)-12, 13-Dihydro [1,3] Benzodioxolo [5,6-c] Phenanthridin- 13-ol, Isolated From a Zimbabwean Herbal Antidiabetic Medicine Dzomba, Pamhidzai; Mugari, Pardon; Nyoni, Stephen; Mudewairi, Elias Protein tyrosine phosphatase 1B (PTP1B) is a crucial drug target for treating diabetes mellitus Type 2 (DMT2) because of its link to insulin resistance. Currently there are no approved clinical drugs targeting PTP1B. Therefore, the present study was aimed at investigating the mode of action of an alkaloid, 1, 2-dimethoxy-12-methyl-7-(3-methylbut-2-en-1-yl)-12, 13-dihydro [1,3] benzodioxolo [5,6-c] phenanthridin-13-ol (1, 2 DMMDBP), previously isolated from a popular Zimbabwean antidiabetic herbal medicine. Molecular docking studies using PDB, 2QBP (catalytic site) and IT48 (allosteric site), in vitro PTP1B enzyme inhibition, and in vivo assays using streptozotocin induced diabetic rats were applied to investigate antidiabetic effect. Drug-like and toxicity properties were evaluated using SwissADME and Protox 3.0 webservers, respectively. Molecular docking results showed that the test compound (1, 2 DMMDBP) has a greater binding affinity (11.1 kcal/mol, rmsd, 0.000 Å) for the allosteric site than the catalytic site (9.6 kcal/mol, rmsd, 0.000 Å). In vitro inhibition assay showed that 1, 2 DMMDBP was more potent (IC50 = 1.10 M ) than that of ursolic acid (IC50 = 7.13 M). Additionally, in in vivo studies, 1, 2 DMMDBP maintained normal hypoglycemia and mass better than the reference drug metformin. In absorption, distribution, metabolism, and excretion predictive studies, 1, 2 DMMDBP showed good drug-like properties. It did not violate any of Lipinski's classic rules. It showed good physicochemical properties such as absorption, (log of skin permeability (log Kp) value was −4.95), bioavailability with a score of 0.55 and biotransformation by cytochrome-P enzymes CYP1A2 and CYP3A4. Protox 3.0 webserver predicted LD50 value of 1000 mg/kg, showing that it may be toxic if swallowed. Based on the evidence presented, 1, 2 DMMDBP is a highly promising compound in the development of potent and selective allosteric modulator drugs of PTP1B for the treatment of DMT2 upon further studies. 2026-02-14T00:00:00Z https://ir.cut.ac.zw:8080/xmlui/handle/123456789/686 Comparative electrocatalytic studies of nanocomposites of mixed and covalently linked multiwalled carbon nanotubes and 4-(4,6- diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) Nyoni, Stephen; Nyokong, Tebello Electrocatalytic behavior of 4-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninato cobalt(II) (CoPyPc) when mixed or covalently mixed to multiwalled carbon nanotubes (MWCNTs) is reported. Infra-red spectroscopy was used to confirm amide linkage of the covalently linked nanocomposite. Rotating disk electrode (RDE) and cyclic (CV) voltammetry studies were used for the electrochemical characterization of the prepared phthalocyanine and MWCNT nanocomposite. The electrocatalytic effects of the nanocomposites of the cobalt phthalocyanine derivative were then investigated towards L-cysteine oxidation using both RDE and CV experiments, and the electrocatalytic performance of the covalently linked cobalt phthalocyanine-MWCNT was found to be superior over the mixed nanocomposite. 2015-05-28T00:00:00Z https://ir.cut.ac.zw:8080/xmlui/handle/123456789/685 Electrocatalytic behahiour of cobalt tetraamino-phthalocyanine in thepresence of a composite of reduced graphene nanosheets and ofmulti-walled carbon nanotubes Nyoni, Stephen; Nyokong, Tebello A composite of multi-walled carbon nanotubes (MWCNT) with reduced graphene nanosheets (rGNS-2)was developed in order to minimize the restacking of the latter. The composite was used to modify a glassycarbon electrode (GCE). GCE was further modified with cobalt tetraamino phthalocyanine (CoTAPc). Themodified electrode is represented as rGNS-2-MWCNT-CoTAPc-GCE. X-ray photoelectron spectroscopy,transmission electron microscopy, scanning electrochemical microscopy and Raman spectroscopy wereused to explore into surface functionalities, morphology and topography of the nanocomposite. The rGNS-2-MWCNT-CoTAPc-GCE had a low limit of detection of 3.32 × 10−8M towards the detection of paraguatas a test analyte. A mechanism for paraquat detection using an rGNS-2-MWCNT-CoTAPc-GCE is alsoproposed in this work 2014-05-18T00:00:00Z