Showing items 1 - 14 of 14

Your selections:

Flavonoids from the Genus Euphorbia

  • Authors: Magozwi, Douglas K , Dinala, Mmabatho , Mokwana, Nthabiseng , Siwe-Noundou, Xavier , Krause, Rui W M , Sonopo, Molahleli , McGaw, Lyndy J , Augustyn, Wilma A , Tembu, Vuyelwa J
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/191736 , vital:45159 , xlink:href="https://doi.org/10.3390/ph14050428"
  • Description: Plants of the genus Euphorbia are widely distributed across temperate, tropical and subtropical regions of South America, Asia and Africa with established Ayurvedic, Chinese and Malay ethnomedical records. The present review reports the isolation, occurrence, phytochemistry, biological properties, therapeutic potential and structure–activity relationship of Euphorbia flavonoids for the period covering 2000–2020, while identifying potential areas for future studies aimed at development of new therapeutic agents from these plants. The findings suggest that the extracts and isolated flavonoids possess anticancer, antiproliferative, antimalarial, antibacterial, anti-venom, anti-inflammatory, anti-hepatitis and antioxidant properties and have different mechanisms of action against cancer cells. Of the investigated species, over 80 different types of flavonoids have been isolated to date. Most of the isolated flavonoids were flavonols and comprised simple O-substitution patterns, C-methylation and prenylation. Others had a glycoside, glycosidic linkages and a carbohydrate attached at either C-3 or C-7, and were designated as d-glucose, l-rhamnose or glucorhamnose. The structure–activity relationship studies showed that methylation of the hydroxyl groups on C-3 or C-7 reduces the activities while glycosylation loses the activity and that the parent skeletal structure is essential in retaining the activity. These constituents can therefore offer potential alternative scaffolds towards development of new Euphorbia-based therapeutic agents.
  • Full Text:
  • Date Issued: 2021

In vitro cytotoxic effects of chemical constituents of Euphorbia grandicornis Blanc against breast cancer cells

  • Authors: Kemboi, Douglas , Peter, Xolani , Langat, Moses K , Mhlanga, Richwell , Vukea, Nyeleti , de la Mare, Jo-Anne , Siwe-Noundou, Xavier , Krause, Rui W M , Tembu, Vuyelwa J
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/191747 , vital:45160 , xlink:href="https://doi.org/10.1016/j.sciaf.2021.e01002"
  • Description: Euphorbia grandicornis Blanc is widely utilized in traditional medicine for a variety of ailments including body pains associated with skin irritations, inflammation, and snake or scorpion bites. Compounds from E. grandicornis were characterized using spectroscopic techniques, NMR, IR, MS, and melting points and alongside the extracts were evaluated for in vitro anticancer activity against several cancer cell lines. The root extract afforded known, β-glutinol (1), β-amyrin (2), 24-methylenetirucalla-8-en-3β-ol (3), tirucalla-8,25-diene-3β,24R-diol (4), stigmasterol (5), sitosterol (6), and hexyl (E)-3-(4-hydroxy-3-methoxyphenyl)-2-propenoate (7) based on their NMR spectroscopic data for the first report in E. grandicornis. The extracts and isolated compounds were evaluated for anticancer activities against hormone receptor-positive breast cancer (MCF-7), triple-negative breast cancer (HCC70), and non-tumorigenic mammary epithelial (MCF-12A) cell lines. The CH2Cl2 extract exhibited potent, cytotoxicity against MCF-7, HCC70, and MCF-12A cells. The aerial extract exhibited IC50 values of 1.03, 0.301, and 1.68 µg/mL, and root extract displayed IC50 values of 0.83, 0.83 and 3.98 µg/mL against MCF-7, HCC70, and MCF-12A cells respectively. The root extract thus showed selectivity for the cancer cell lines over the non-cancerous control cell line (SI = 4.80). Hexyl (E)-3-(4-hydroxy-3-methoxyphenyl)-2-propenoate (7) showed significant activity with IC50 values of 23.41, 29.45 and 27.01 µM against MCF-7, HCC70 and MCF-12A cells respectively, suggesting non-specific cytotoxicity.
  • Full Text:
  • Date Issued: 2021

Rapid Synthesis of Thiol-Co-Capped-CdTe/CdSe/ZnSe Core Shell-Shell Nanoparticles

  • Authors: Daramola, Olamide , Siwe-Noundou, Xavier , Tseki, Potlaki , Krause, Rui W M
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/191758 , vital:45161 , xlink:href="https://doi.org/10.3390/nano11051193"
  • Description: CdTe QDs has been demonstrated in many studies to possess good outstanding optical and photo-physical properties. However, it has been established from literature that the toxic Cd2+ that tends to leak out into nearby solutions can be protected by less toxic ZnS or ZnSe shells leading to the synthesis of core-shells and multi-core-shells. Hence, this has allowed the synthesis of CdTe multi-core-shells to have gained much interest. The preparation of most CdTe multi-core-shells reported from various studies usually has a longer reaction time (6–24 h) in reaching their highest emission maxima. The synthesis of CdTe multi-core-shells in this study only took 35 min to obtain a highest emission maximum compared to what has been reported from the literature. CdTe multi-core-shells were synthesized by injecting 7, 14, and 21 mL each of Zn complex solution and Se ions into the reacting mixture containing CdTe core-shells (3 h) at 5 min intervals over a 35 min reaction time. The emission maxima of the MPA-TGA-CdTe multi-core-shells at 21 mL injection was recorded around 625 nm. Therefore, we are reporting the rapid synthesis of five different thiol co-capped CdTe/CdSe/ZnSe multi-core-shell QDs with the highest emission maxima obtained at 35 min reaction time.
  • Full Text:
  • Date Issued: 2021

Review of the Traditional Uses, Phytochemistry, and Pharmacological Activities of Rhoicissus Species (Vitaceae)

  • Authors: Dube, Nondumiso , Siwe-Noundou, Xavier , Krause, Rui W M , Kemboi, Douglas , Tembu, Vuyelwa J , Manicum, Amanda-Lee
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/191769 , vital:45162 , xlink:href="https://doi.org/10.3390/molecules26082306"
  • Description: Species within the genus Rhoicissus (Vitaceae) are commonly used in South African traditional medicine. The current review discusses the occurrence, distribution, traditional uses, phytochemistry, and pharmacological properties of Rhoicissus species covering the period 1981–2020. The data reported were systematically collected, read, and analysed from scientific electronic databases including Scopus, Scifinder, Pubmed, and Google Scholar. Reported evidence indicates that species in this genus are used for the treatment of gastrointestinal complaints, sexually transmitted infections (STIs), and infertility, as well as to tone the uterus during pregnancy and to facilitate delivery. Pharmacological studies have further shown that members of the Rhoicissus genus display antidiabetic, uterotonic, ascaricidal, hepatoprotective, antioxidant, antimicrobial, anticancer, and anti-inflammatory properties. They are linked to the presence of bioactive compounds isolated from the genus. Hence, Rhoicissus species can potentially be an alternative therapeutic strategy to treat diseases and develop safer and more potent drugs to combat diseases. Plant species of this genus have valuable medicinal benefits due to their significant pharmacological potential. However, scientific investigation and information of the therapeutic potential of Rhoicissus remain limited as most of the species in the genus have not been fully exploited. Therefore, there is a need for further investigations to exploit the therapeutic potential of the genus Rhoicissus. Future studies should evaluate the phytochemical, pharmacological, and toxicological activities, as well as the mode of action, of Rhoicissus crude extracts and secondary compounds isolated from the species.
  • Full Text:
  • Date Issued: 2021

Terminaliamide, a new ceramide and other phytoconstituents from the roots of Terminalia mantaly H. Perrier and their biological activities

  • Authors: Mbosso, Emmanuel , Siwe-Noundou, Xavier , Fannang, Simone V , Song, Achille M , Assob, Jules C N , Hoppe, Heinrich C , Krause, Rui W M
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/191779 , vital:45163 , xlink:href="https://doi.org/10.1080/14786419.2019.1647425"
  • Description: Terminaliamide (1), a new ceramide was isolated from the roots of Terminalia mantaly H. Perrier (Combretaceae) along with 4 known compounds (2–5). The structures of the compounds were elucidated using 1D and 2D NMR spectroscopy analysis and mass spectrometry. Compound 1 exhibited moderated antibacterial activity towards Staphylococcus aureus with MIC value of 62.5 μg/mL. The crude MeOH extract (TMr) highly reduced Plasmodium falciparum growth with an IC50 value of 10.11 μg/mL, while hexane fraction (F1) highly reduced Trypanosoma brucei brucei growth with an IC50 value of 5.60 µg/mL. All tested samples presented little or no in vitro cytotoxicity on HeLa cell line. The present work confirms that T. mantaly is medicinally important and may be used effectively as an antimicrobial, an antiplasmodial and an antitrypanosomial with promising therapeutic index.
  • Full Text:
  • Date Issued: 2021

Anti-cancer and anti-trypanosomal properties of alkaloids from the root bark of Zanthoxylum leprieurii Guill and Perr

  • Authors: Eze, Fabian I , Siwe-Noundou, Xavier , Isaacs, Michelle , Patala, Srivinas , Osadebe, Patience O , Krause, Rui W M
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/193352 , vital:45324 , xlink:href="http://dx.doi.org/10.4314/tjpr.v19i11.19"
  • Description: Purpose: To isolate the anti-cancer and anti-trypanosomal principles of Zanthoxylum leprieurii, a medicinally versatile wild tropical plant used for managing tumours, African trypanosomiasis, and inflammation in southeastern Nigeria. Methods: The pure compounds were isolated using chromatographic methods. The structural elucidation of the pure compounds was based on their NMR (1D and 2D) and mass spectral data as well as chemical test results. Structure-activity relationships were based on the structural differences among the compounds. The cytotoxicity of the extracts and compounds (1, 2, 3, and 4) was evaluated in HeLa (human cervix adenocarcinoma) cell line while the trypanocidal activities were evaluated on Trypanosoma brucei brucei. Results: Two acridone alkaloids, 1-hydroxy-3-methoxy-10-methylacridin-9 (10H)-one, named fabiocinine (1), and 1-hydroxy-2,3-dimethoxy-10-methylacridin-9 (10H)-one (arborinine, 2), together with a furoquinoline alkaloid, skimmianine (3), and a chelerythrine derivative, 6-acetonyl-5,6-dihydrochelerythrine (4) were isolated from the root bark of Zanthoxylum leprieurii. Skimmianine (3) exhibited cytotoxicity and anti-trypanosomal IC50 of 12.8 and 13.2 µg/mL respectively (p less than 0.05). Compound (1) and arborinine (2) were selectively cytotoxic to HeLa cells with cytotoxicity IC50 of 28.49 and 62.71 µg/mL, respectively, while (4) did not show significant activity (p less than 0.05). Conclusion: Zanthoxylum leprieurii root bark contains cytotoxic and trypanocidal compounds, and is thus a potential source of anti-cancer and anti-trypanosomal leads.
  • Full Text:
  • Date Issued: 2020

Antiplasmodial Activity of the n-Hexane Extract from Pleurotus ostreatus (Jacq. ex. Fr) P. Kumm

  • Authors: Afieroho, Ozadheoghene E , Siwe-Noundou, Xavier , Onyia, Chiazor P , Festus, Osamuyi H , Chukwu, Elizabeth C , Adedokun, Olutayo M , Isaacs, Michelle , Hoppe, Heinrich C , Krause, Rui W M , Abo, Kio A
  • Date: 2019
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/194981 , vital:45516 , xlink:href="https://doi.org/10.4274/tjps.18894"
  • Description: Objectives: Several mushrooms species have been reported to be nematophagous and antiprotozoan. This study reported the antiplasmodial and cytotoxic properties of the n-hexane extract from the edible mushroom Pleurotus ostreatus and the isolation of a sterol from the extract. Materials and Methods: Antiplasmodial and cytotoxicity assays were done in vitro using the plasmodium lactate dehydrogenase assay and human HeLa cervical cell lines, respectively. The structure of the isolated compound from the n-hexane extract was elucidated using spectroscopic techniques. Results: The n-hexane extract (yield: 0.93% w/w) showed dose dependent antiplasmodial activity with the trend in parasite inhibition of: chloroquine (IC50=0.016 μg/mL) > n-hexane extract (IC50=25.18 μg/mL). It also showed mild cytotoxicity (IC50>100 μg/mL; selectivity index >4) compared to the reference drug emetine (IC50=0.013 μg/mL). The known sterol, ergostan-5,7,22-trien-3-ol, was isolated and characterized from the extract. Conclusion: This study reporting for the first time the antiplasmodial activity of P. ostreatus revealed its nutraceutical potential in the management of malaria.
  • Full Text:
  • Date Issued: 2019

Cordidepsine is A Potential New Anti-HIV Depsidone from Cordia millenii

  • Authors: Zeukang, Rostanie D , Siwe-Noundou, Xavier , Fotsing, Maurice T , Mbafor, Joseph T , Krause, Rui W M , Choudhary, Muhammad I , Atchade, Alex de Theodore
  • Date: 2019
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/193988 , vital:45413 , xlink:href="https://doi.org/10.3390/molecules24173202"
  • Description: Chemical investigation of Cordia millenii, Baker resulted in the isolation of a new depsidone, cordidepsine (1), along with twelve known compounds including cyclooctasulfur (2), lup-20(29)-en-3-triacontanoate (3), 1-(26-hydroxyhexacosanoyl)glycerol (4), glyceryl-1-hexacosanoate (5) betulinic acid (6), lupenone (7), β-amyrone (8), lupeol (9), β-amyrin (10), allantoin (11), 2′-(4-hydroxyphenyl)ethylpropanoate (12) and stigmasterol glycoside (13). Hemi-synthetic reactions were carried out on two isolated compounds (5 and 6) to afford two new derivatives, that is, cordicerol A (14) and cordicerol B (15), respectively. The chemical structures of all the compounds were established based on analysis and interpretation of spectroscopic data such as electron ionization mass spectrometry (EI–MS), high resolution electrospray ionization mass spectrometry (HR-ESI–MS), fast atom bombardment mass spectrometry (FAB–MS), one dimension and two dimension nuclear magnetic resonance (1D and 2D-NMR) spectral data as well as X-ray crystallography (XRC). Lupeol ester derivatives [Lup-20(29)-en-3-triacontanoate (3)], monoglycerol derivatives [1-(26-hydroxyhexacosanoyl)glycerol (4) and glyceryl-1 hexacosanoate (5)] were isolated for the first time from Cordia genus while sulfur allotrope [cyclooctasulfur (2)] was isolated for the first time from plant origin. Biological assays cordidepsine (1) exhibited significant anti-HIV integrase activity with IC50 = 4.65 μM; EtOAc extract of stem barks, EtOAc fraction of roots and leaves were not toxic against 3T3 cells.
  • Full Text:
  • Date Issued: 2019

Green synthesis of zinc oxide nanoparticles using Solanum torvum (L) leaf extract and evaluation of the toxicological profile of the ZnO nanoparticles–hydrogel composite in Wistar albino rats

  • Authors: Ezealisiji, Kenneth E , Siwe-Noundou, Xavier , Maduelosi, Blessing , Nwachukwu, Nkemakolam , Krause, Rui W M
  • Date: 2019
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/194015 , vital:45416 , xlink:href="https://doi.org/10.1007/s40089-018-0263-1"
  • Description: Current study reports a simple and one-pot synthesis of zinc oxide nanoparticles (ZnONPs) using an aqueous extract of Solanum torvum and evaluation of its toxicological profile (0.5% w/w and 1.0% w/w) in Wistar albino rats with respect to the biochemical index. The nanoparticles were characterized using ultraviolet–visible spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction technique. Dynamic light scattering (DLS) and zeta potential of synthesized nanoparticles were analyzed to know the average size and stability of particles. Synthesized nanoparticles were stable, discreet, and mostly spherical, and size of particles was within the nanometre range. Biochemical markers of hepatic and renal functions were measured. Zinc oxide nanoparticles significantly decreased serum uric acid level (p  less than  0.001) in a dose-dependent manner, while the serum alkaline phosphatase level was increased at the two test doses. The level of alanine transaminase was increased after exposure for 28 days (p  less than  0.05). This study concludes that biogenic zinc oxide nanoparticles-infused hydrogel applied dermatologically could affect hepatic and renal performance in rats, and there was an observed cumulative toxicological effect with time of exposure.
  • Full Text:
  • Date Issued: 2019

In vitro antimalarial, antitrypanosomal and HIV-1 integrase inhibitory activities of two Cameroonian medicinal plants

  • Authors: Fouokeng, Yannick , Feumo Feusso, H M , Mbosso Teinkela, Jean E , Siwe-Noundou, Xavier , Wintjens, René T , Isaacs, Michelle , Hoppe, Heinrich C , Krause, Rui W M , Azébazé, Anatole G B , Vardamides, Juliette C
  • Date: 2019
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/195014 , vital:45519 , xlink:href="https://doi.org/10.1016/j.sajb.2018.10.008"
  • Description: Antiplasmodial, antitrypanosomal and anti-HIV-1 activities of crude extracts, fractions and some isolated compounds from two Cameroonian medicinal plants: Antrocaryon klaineanum Pierre (Anacardiaceae) and Diospyros conocarpa Gürke ex K. Schum. (Ebenaceae) were assessed. The phytochemical studies led to the isolation of eight compounds (1–8) from Diospyros conocarpa and six compounds (6, 9–13) from Antrocaryon klaineanum. These compounds were identified as mangiferolic acid (1), 3β, 22(S)-dihydroxycycloart-24E-en-26-oic acid (2), lupeol (3), aridanin (4), betulin (5), betulinic acid (6), bergenin (7), D-quercitol(8), entilin C(9), entilin A(10), antrocarine A(11), 7R,20(S)-dihydroxy-4,24(28)-ergostadien-3-one(12) and stigmasterol glucoside (13). The criteria for activity were set as follows: an IC50 value more than 10 μg/mL for crude extracts and more than 1 μg/mL for pure compounds. The hexane/ethyl acetate (1:1) fraction of A.klaineanum root bark (AKERF1) and the hexane/ethyl acetate (1:1) fraction of A.klaineanum trunk bark (AKETF1) presented the strongest antiplasmodial activities with IC50 values of 0.4 and 4.4 μg/mL, respectively. Aridanin (4) and antrocarine A(11), as well as the crude extract of D.conocarpa roots (EDCR), AKERF1 and AKETF1 showed moderate trypanocidal effects. The crude extract of A.klaineanum root bark (AKER) and AKETF1 exhibited attractive activities on HIV-1 integrase with IC50 values of 1.96 and 24.04 μg/mL, respectively. The results provide baseline information on the use of A.klaineanum and D.conocarpa extracts, as well as certain components, as sources of new antiplasmodial, antitrypanosomal and anti-HIV drugs.
  • Full Text:
  • Date Issued: 2019

Nano-enabled liposomal mucoadhesive films for enhanced efavirenz buccal drug delivery

  • Authors: Okafor, Nnamadi I , Ngoepe, Mpho , Siwe-Noundou, Xavier , Krause, Rui W M
  • Date: 2019
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/194032 , vital:45417 , xlink:href="https://doi.org/10.1016/j.jddst.2019.101312"
  • Description: Buccal films (BFs) were prepared using a solvent casting method using the liposomal suspension as the dispersing medium. Optimization of some physical properties of the films containing different amounts of polymers was done using digital Vernier calliper and digital weighing balance. The physiochemical properties of the best optimized properties were characterized using Differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transfer infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM), Energy dispersive X-ray spectroscopy (EDS), and Scanning Electron Microscopy (SEM). Permeation study of the BFs composed of Carbopol (CP) alone and CP to Pluronic 127 (PF127) demonstrated better bio-adhesive properties than the films made of other polymers such as HPMC (hydroxyl propyl methyl cellulose) and HPMC-PF127. These CP based BFs (without and with PF127) exhibited good film thickness 0.88 ± 0.10 and 0.76 ± 0.14 mm, with weight uniformity 68.22 ± 1.04 and 86.28 ± 2.16 mg, satisfactory flexibility values 258 and 321, and slightly acidic pH 6.43 ± 0.76 and 6.32 ± 0.01. The swelling percentage was found to be 50% for CP and 78% for CP-PF127. The cumulative amount of drug that permeated through the buccal epithelium after 24 h was about 66% from CP and 75% from CP-PF127.
  • Full Text:
  • Date Issued: 2019

Phytochemical, anti-inflammatory and anti-trypanosomal properties of Anthocleista vogelii Planch (Loganiaceae) stem bark

  • Authors: Eze, Fabian I , Siwe-Noundou, Xavier , Osadebe, Patience , Krause, Rui W M
  • Date: 2019
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/194059 , vital:45419 , xlink:href="https://doi.org/10.1016/j.jep.2019.111851"
  • Description: Ethnopharmacological relevance: Anthocleista vogelii Planch (Loganiaceae) is used in African Traditional Medicine for the treatment of pain and inflammatory disorders as well as sleeping sickness. Aim of the study: To determine the in vivo anti-inflammatory and in vitro anti-trypanosomal activities of the extracts of A. vogelii stem bark and identify the phytochemical classes of the fractions responsible for the activities. Materials and methods: The in vivo anti-inflammatory activity of the extracts was evaluated using the egg albumin-induced rat paw oedema model while the in vitro anti-trypanosomal activity was assessed on Trypanosoma brucei brucei. The in vitro cytotoxicity was assessed on HeLa (human cervix adenocarcinoma) cell line. Results: The methanolic extract of A. vogelii stem bark, with 11.2% yield, gave LD50 > 5000 mg/kg. The n-hexane fraction of the extract contains steroids, terpenes and fatty acids and yielded non-cytotoxic terpenoidal column fraction with anti-trypanosomal IC50 of 3.0 μg/mL. The ethylacetate fraction at 100 mg/kg dose significantly (p less than 0.05) provoked 37.8, 62.5 and 69.7% inhibition of oedema induced by egg-albumin at the second, fourth and sixth hours respectively. Conclusion: The study demonstrated that the anti-inflammatory and anti-trypanosomal activities of A. vogelii are probably due to non-cytotoxic terpenoids and validated the traditional use of A. vogelii in the treatment of inflammation and sleeping sickness.
  • Full Text:
  • Date Issued: 2019

Facile synthesis of glutathione-l-Cysteine co-capped CdTe core shell system

  • Authors: Daramola, Olamide A , Siwe-Noundou, Xavier , Krause, Rui W M , Marks, John A
  • Date: 2017
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/195003 , vital:45518 , xlink:href="https://doi.org/10.1166/jnn.2017.13823"
  • Description: Semiconductor nanoparticles also known as quantum dots (QDs) have been used in diverse areas of application due to their good optical and photo-physical properties. The synthesis of core–shell QDs have assisted to improve the stability of most nano-particles but the size and long term stability of such materials have been problematic. However, thiol-capped CdTe QDs have been regarded as some of the most widely synthesized nanoparticles due to their unique optical properties. The use of un-stable tellurium source such as NaHTe or highly toxic H2Te gas makes the reaction condition cumbersome. In this study, we prepared some CdTe QDs and core–shell QDs using K2TeO3 as a stable source of tellurium without inert gas protection. This was done using a co-capped bio-compatible coating such as cysteine and glutathione following a modified standard method to produce QDs in the yields of about 60 to 80%. All the synthesized materials were subsequently characterized using various characterization techniques. The systematic optimization of the reaction parameters such as reaction time, pH and mole ratio results with a drastic red shift in wavelength (546–600 nm) by the CdTe core proved that an extra material has been deposited unto the surface of the CdTe core. The 60 days stability test conducted demonstrated that the core–shell nanoparticles were quite stable. Since this reaction was performed under open air conditions and no special ligand or buffer solution was used, it may suitably be applied on an industrial scale.
  • Full Text:
  • Date Issued: 2017

Antibacterial effects of Alchornea cordifolia (Schumach. and Thonn.) Müll. Arg extracts and compounds on gastrointestinal, skin, respiratory and urinary tract pathogens

  • Authors: Siwe-Noundou, Xavier , Krause, Rui W M , van Vuuren, Sandy , Tantoh Ndinteh, Derek , Olivier, Denise K
  • Date: 2016
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/195418 , vital:45563 , xlink:href="https://doi.org/10.1016/j.jep.2015.12.043"
  • Description: Ethnopharmacological relevance:The leaves, stems and roots ofAlchornea cordifolia(Schumach. andThonn.) Müll. Arg. are used as traditional medicine in many African countries for the management ofgastrointestinal, respiratory and urinary tract infections as well as for the treatment of wounds.Aim of the study:To determine the in vitro antibacterial activity of the crude extracts of leaves and stemsofA. cordifoliaon gastrointestinal, skin, respiratory and urinary tract pathogens and to identify thecompounds in the extracts that may be responsible for this activity.Materials and methods:The antibacterial activities of crude extracts [hexane, chloroform (CHCl3), ethylacetate (EtOAc), ethanol (EtOH), methanol (MeOH) and water (H2O)] as well as pure compounds isolatedfrom these extracts were evaluated by means of the micro-dilution assay against four Gram-positivebacteria, i.e.Bacillus cereusATCC 11778,Enterococcus faecalisATCC 29212, Staphylococcus aureusATCC25923 andS. saprophyticusATCC 15305,as well as four Gram-negative bacterial strains, i.e.EscherichiacoliATCC 25922, Klebsiella pneumoniaeATCC 13883, Moraxella catarrhalisATCC 23246 andProteus mir-abilisATCC 43071. The isolation of the active constituents was undertaken by bio-autographic assays inconjunction with chromatographic techniques. The identification and characterisation of the isolatedcompounds were done using mass spectrometry (MS) and Fourier transformed infrared spectrometry(FTIR) as well as 1D- and 2D- nuclear magnetic resonance (NMR) analyses.Results:The leaves and stems ofA. cordifoliaexhibited varied antibacterial activity against all eight pa-thogens. Most of the MIC values ranged between 63 and 2000mg/ml. The highest activities for the crudeextracts (63mg/ml) were observed againstS. saprophyticus[stem (EtOAc, CHCl3and hexane), leaves(MeOH, EtOH, EtOAc and CHCl3)],E. coli[stem (MeOH and EtOH), leaves (MeOH, EtOH, EtOAc andCHCl3)],M. catarrhalis[leaves (EtOAc and CHCl3)],K. pneumoniae[stem (CHCl3), leaves (CHCl3)] andS.aureus[leaves (CHCl3)]. Seven constituents [stigmasterol (1), stigmasta-4,22-dien-3-one (2), friedelin (3),friedelane-3-one-28-al (4), 3-O-acetyl-aleuritolic acid (5), 3-O-acetyl-erythrodiol (6) and methyl-3,4,5-trihydroxybenzoate (methyl gallate) (7)] were isolated from the stem MeOH extract. All these com-pounds displayed some antibacterial activity against the eight pathogens with highest activity againstS.saprophyticus(2mg/ml). Furthermore, this is thefirst report of compounds1,2,3,4,6and7isolated fromA. cordifoliaand where a complete set of 2D-NMR data for fridelane-3-one-28-al (4) is presented.Conclusion:The study demonstrated that the antibacterial activities ofA. cordifoliaextracts may be dueto the presence of the seven isolated compounds, where compounds3–6showed the best activity. Theobserved activity against gastrointestinal, skin, respiratory and urinary tract pathogens supports thetraditional use for the treatment of such ailments.
  • Full Text:
  • Date Issued: 2016
  • 1
  • Disclaimer
  • Privacy
  • Copyright
  • Contact