Soft corals of the genus Lobophytum (Alcyoniidae) have been well recognized as a rich source of various secondary metabolites that have attracted much interest for the natural products chemists due to their structural complexity and remarkable pharmacological activities such as cytotoxicity, antibacterial activities, anti-inflammatory properties, and antiviral activity. Twelve cembrane diterpenes including six new secondary metabolites 1−6 were isolated organic extracts of soft coral Lobophytum durum collected at Dongsha Atolls. The structures of these six new cembranolides were determined by 1H, 13C, DEPT, COSY, HMBC, HSQC, NOESY, IR and Mass spectra. Furthermore, these six new secondary metabolites 1−6 were evaluated in vitro for the cytotoxicity against A-459 (human lung carcinoma), HT-29 (human colon adenocarcinoma), and P-388 (mouse lymphocytic leukemia) cancer cell lines, and antiviral activity against HCMV (human cytomegalovirus) cells.

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La tendance au retour vers le naturel encourage les scientifiques à rechercher de nouvelles sources d'actifs biologiques, notamment de nouveaux conservateurs et antimicrobiens biodégradables, pour les substituer aux additifs synthétiques. Ce travail est le résultat de la combinaison de l'étude chimique et biologique des huiles essentielles issues de 15 espèces aromatiques camerounaises du genre Aframomum (Zingiberaceae), utilisées couramment comme épices mais également en médecine traditionnelle.Les extraits volatils obtenus par hydrodistillation des feuilles, graines, péricarpes et racines d'échantillons représentatifs de ces 15 espèces d'Aframomum récoltés au Cameroun dans diverses zones géographiques et à différentes périodes de récolte ont été analysés par chromatographie en phase gazeuse (GC/FID), chromatographie couplée à la spectrométrie de masse (GC/MS) ou chromatographie chirale pour préciser la distribution énantiomérique de certains composés caractéristiques (113 échantillons d'huiles essentielles analysés au total).Le potentiel antibactérien de 41 extraits volatils et de leurs composés majeurs, isolés à partir de ces huiles essentielles et caractérisés, a été testé sur deux bactéries : Escherichia coli (Gram-) et Micrococcus luteus (Gram +) par une technique de dilution en milieu liquide; les résultats montrent une plus grande efficacité des dérivés oxygénés tels que le linalol, le géraniol, le myrténol ou le (E)-nérolidol avec l'observation, dans certains cas, d'une potentialisation de ces effets, dans les huiles essentielles, probablement par effet de synergie avec d'autres composés présents dans le mélange.Globalement, les essences des graines sont les plus efficaces, notamment celles de: A. citratum, A. dalzielii, A. pruinosum, A. letestuianum et A. polyanthum, ce qui justifie l'intérêt de leur utilisation traditionnelle dans l'alimentation ou dans la confection des préparations médicinales et ouvre des perspectives d'applications comme conservateurs naturels en agroalimentaire et dans les industries cosmétiques ou pharmaceutiques. / The antimicrobial properties of plant volatile oils have been assessed and there appears to be a revival in the use of traditional approaches to protecting livestock and food in industrial countries. This work is the result of combined chemical and biological studies of essential oils obtained from 15 Cameroonian aromatic species of the genus Aframomum (Zingiberaceae), commonly used as spices or as ingredients in traditional medicine.The volatile extracts were obtained by hydrodistillation of leaves, seeds, pericarps and rhizomes of representative samples of these 15 Aframomum species collected in different geographical zones of Cameroon; their chemical analysis was performed by gas chromatography (GC/FID), by gas chromatography coupled with mass spectrometry (GC/MS) and chiral chromatography to assess the enantiomeric distribution of some characteristic components (113 samples of essential oils were analyzed in the total).The antimicrobial activities of 41 volatile extracts and of their main components, after isolation and characterization, were tested against two bacteria: Escherichia coli (Gram-) and Micrococcus luteus (Gram +) by a broth dilution technique; the results show a higher efficiency of oxygenated compounds such as linalol, geraniol, myrtenol or (E)-nerolidol, with possible synergistic interactions between components in essential oils.Globally, the seed essential oils are the most efficient, in particular those extracted from: A. citratum, A. dalzielii, A. letestuianum, A. pruinosum and A. polyanthum, justifying their traditional use in food as well as in medicinal preparations or their potential application as natural preservatives in the cosmetic, food or pharmaceutical industries.

<p>Over three million infections were reported in the United States of America in 2019. These infections were caused by either antibiotic-resistant pathogens or <i>Clostridioides difficile</i> and resulted in more than 50,000 deaths. Unfortunately, antibacterial agents are rapidly losing their ability to treat infections and the process of discovering new antibiotics is too slow to cope up with bacterial evolution. Repurposing FDA-approved drugs of well-studied safety, pharmacology and pharmacokinetics represents a faster alternative method of antibacterial drug discovery. Repurposing is more successful and less depleting method of drug discovery than classical de novo method in regard to both cost and time. In the following studies, two major pathogens are targeted, vancomycin-resistant <i>Enterococcus</i> (VRE) and <i>C. difficile</i>. Both bacteria are more prevalent in healthcare settings were more vulnerable population of elderly and immunocompromised individuals reside. In addition, healthcare settings are usually associated with higher frequency of receiving antibiotics which in turn, compromises the integrity of normal microbiota responsible for protection against invading pathogens. Furthermore, hospital stays are associated with exposure to bacterial shedding from other patients. Our aim was to identify FDA-approved drugs with novel ability to eradicate these two bacterial pathogens in the gastrointestinal tract (GIT). Notably, the GIT is considered the actual site of infection in case of <i>C. difficile while it is only a transition site for VRE where the bacteria colonize before causing true infections in other tissues. Studies against both bacteria started with an <i>in vitro</i> screening of FDA-approved drugs and clinical molecules to identify potential candidates for further investigation.</i></p><p><i>For VRE, two drugs where identified with potent inhibitory activity and favorable pharmacokinetic profiles, auranofin and ebselen. Auranofin was approved in the 1960s for the treatment of rheumatoid arthritis due to its anti-inflammatory activity. Auranofin was found to exert potent bacteriostatic activity against both vancomycin-sensitive and vancomycin-resistant <i>Enterococcus</i> strains (minimum inhibitory concentration against 90% of the strains, MIC90 = 1 µg/mL). In addition, bacteria could not develop resistant mutants against auranofin upon prolonged exposure. On the other hand, ebselen is an organoselenium compounds currently in clinical trials for several indications. Similarly, ebselen was found to be a potent inhibitor of VRE growth (MIC90 = 2 µg/mL). In addition, ebselen successfully inhibited bacterial biofilm formation and eradicated mature biofilms. In a mouse model of VRE colonization, both drugs inhibited bacterial shedding and reduced bacterial counts in the GIT of the colonized animals.</i></p><p><i>For <i>C. difficile</i>, auranofin was also found to exert potent inhibitory activity against bacterial growth (MIC90 = 2 µg/mL), toxin production and spore formation. Additionally, it was beneficial in protecting colon cells against <i>C. difficile</i> toxin-induced inflammation. Further, auranofin was found to not promote growth of VRE as seen with the current anticlostridial agents. In addition to auranofin, two more antiprotozoal drugs were found to potently inhibit <i>C. difficile</i> growth, ronidazole and secnidazole. Both drugs are 5-nitroimidazoles approved for human (secnidazole) or veterinary (ronidazole) applications. Secnidazole and ronidazole halted <i>C. difficile</i> growth at very low concentrations (MIC90 = 0.5 and 0.125 µg/mL, respectively). Furthermore, both drugs were superior to metronidazole in bacterial killing and had favorable activities against protective gut microbiota. In addition, they demonstrated efficient protection to mice in a <i>C. difficile</i> infection model. </i></p><p><i>Overall, several drugs were presented to possess favorable activities against <i>C. difficile</i> or VRE. These drugs merit more evaluation as potential candidates for the treatment of infection caused by either bacteria. </i></p><div><i><br></i></div>

M. Tech. (Department of Chemistry and Biotechnology, Faculty of Applied and Computer Sciences), Vaal University of Technology. / Context: Pelargonium alchemilliodes L L' Her is an evergreen shrub, cultivated principally for the medicinal essence and decoction in Southern Africa for the treatment of skin problems, and wounds. Objective: the aim of the study was to optimize the extraction of phenolics and flavonoids from P. graveolens by response surface methodology with particular attention on the proliferative and cytotoxic effects on human keratinocytes, as well as the antioxidant and antibacterial activities and also to isolate active compounds. Materials and Methods: The optimization was achieved by Box-Behnken design. Extract, metabolite yields, and minimal inhibitory concentrations (MIC) were determined by gravimetric, spectrophotometric, and microdilution methods, respectively. The antiradical potentials were evaluated using the phosphomolybdate. 2,2-diphenyl-1-picrylhydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), and lipid peroxidation assays, the diterpenoids were isolated and purified using open column chromatography, PTLC, and characterized with FTIR, NMR. The kinetics of the lipid protective activity was studied and fitted into models. The proliferative and cytotoxic effects were evaluated using the CellTiter® Blue cell viability and lactate dehydrogenase assay. Results: The regression coefficient r2 ≥ 0.9775 indicated a close correlation between actual and predicted values of the responses. The ideal parameter for the extraction of phenolics and flavonoids by macerations was determined as an extraction time: 9.63-12.01 h, material mass: 2.62-3.00 g, agitation speed: 143.11-197.11 rpm, and solvent volume: 68.06-69.87 mL. The optimal extractable acetone and methanol crude, flavonoids, and phenolic are (28.87±2.15%, 24.11±1.15%), (7.11±1.03 mg QE/g, 5.98±0.87 mg QE/g) and (58.08±0.88 mg GAE/g, 55.91±1.15 mg GAE/g), respectively. The detected different chemical groups of polyphenolic compounds such as alkaloids, saponins , sterols, terpenoids, flavonoids, tannins, phenols and cardiac glycosides from methanol and acetone extracts were in correlation with optimized yields. Two triterpenoids compounds 1-hydroxy-30-norlanosta-6, 8-diene and 1 2,3,4a,8,9,10,10a-octahydro-2-(2-hydroxypent-4-enyl)-4a-vinyl-1H-benzo[c]chromen-6(10bH)-one were isolated form methanol extracts. The main components of essential oils were citronellal (5.99%), citranellol (26.2%), geraniol (8.56%), citronellyl butyrate (20.3%), trans-farnesol (9.53%) and they were characterized by high amounts of oxygenated hydrocarbons (67.6%), followed by sesquterpene hydrocarbons and oxygenated sesquiterpene (9.32%) and the least being mornoterpene hydrocarbons (5.20%). Total antioxidant capacity and reducing power were comparable to standard gallic acid, while the antiradical activity has IC50 value of 0.18±0.03-8.98±0.15 mg/mL. Further, the lipid protective revealed a dose-dependent activity fitting into a pseudo-second-order kinetic model. MIC value of 1.56 mg/mL for extracts was registered against Staphylococcus aureus and salmonella typhi comparable to chloramphenicol. There was a significant (P < 0.05) increase in cell proliferation and viability when the extract was administered at concentrations of ≤50 μg/mL. However, at ≥100 μg/mL concentrations at ≤ 1000 μg/mL for essential oil exhibited a significnt cytotoxicity in comparison to the untreated cell. Conclusion: These biological activities are confirmation of the phytomedicinal application and possible source of pharmaceutical compounds. However, administration of the decoction should take into cognizance the antiproliferative effect at doses ≥100 μg/mL as well as the potential to induce and maintain keratinocyte proliferation at low concentration with an eye on the antiproliferative effect at concentrations ≥100 μg/mL, except the P. Alchemilliodes essential oils at ≤ 1000 μg/mL.

D. Tech. (Department of Biotechnology and Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology. / The synthesis of Ag and Cu nanoparticles was carried out using the thermal decomposition method in the presence of oleylamine as a capping agent. This method was used because it can produce uniform and monodisperse nanoparticles with controlled size distribution. The nanoparticles synthesized under various conditions were characterized by transmission electron microscopy (TEM), UV/Vis spectroscopy, photoluminescence spectroscopy (PL), and X-ray diffraction (XRD). The effect of precursor concentration on the morphology and size of the nanoparticles was investigated. It was observed that an increase in the precursor concentration resulted in an increase in particle sizes with different morphologies for both Ag and Cu nanoparticles. The increase in particle sizes for Ag nanoparticles was due to Ostwald ripening, while for Cu nanoparticles it was due to agglomeration, as Cu tends to oxidize in the atmosphere, leading to a change in particle size and shape. However, the ability to control and manipulate their physical and chemical properties depends on tuning their size and shape. Therefore, varying the precursor concentration helped in selecting the optimal concentration for this study. The nanoparticles produced were used in another study as fillers or additives for the production of nanofiber composites. The development of nanofibers by electrospinning process has led to potential applications in filtration, tissue engineering scaffolds, drug delivery, wound dressing and etc. The current study is an attempt to fabricate composite nanofibers that can be used as wound dressing material for effective wound healing. The approach involves the blending of two different polymers both being biocompatible and biodegradable were one is a natural polymer and the other is a synthetic polymer. In this study, different weight ratios of CS/PVA blends, Ag/Cu/CS/PVA, Ag/CS/PVA and Cu/CS/PVA composite fibers have been successfully prepared by the electrospinning process. The tip-to-collector distance was kept at 15 cm and the applied voltage was varied from 15 to 25 kV. The effects of the weight ratios applied voltage and the nanoparticles loading on the morphology and diameter of the fibers were investigated. The resultant fibers were characterized using scanning electron microscopy (SEM), XRD, Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric analysis (TGA) and UV-Vis spectroscopy. The SEM results showed that an increase the amount of chitosan in the CS/PVA blend resulted in a decrease in the fiber diameters while an increase in the voltage from 15 to 25 kV led to a decrease in the fiber diameters. Furthermore, an increase in fiber diameters was observed with irregular morphologies upon addition of Ag/Cu nanoparticles into the blend. The latter changes are perceived to be as a result of an increased conductivity and a higher charge density. The XRD results showed peaks which correspond to Ag in the face centred cubic. Ag peaks are more dominant than Cu peaks in the XRD of the mixed nanoparticles. The FTIR spectra of the Ag/Cu/CS/PVA composite fibers gave almost identical features as the blend. This proves that there was an interaction between CS and PVA polymer due to intermolecular hydrogen bonding. The TGA curves showed no significant effect on the thermal stability of the composite fibers upon addition of different nanoparticles loadings. The absorption spectra of the composite fibers showed an improved optical properties compared to the blend. For Ag and Cu nanoparticles composite fibers it was observed that addition of Ag nanoparticles in the blend resulted in an increase in fiber diameters with uniform morphology whereas for Cu resulted in a decrease in fiber diameters. Both Ag and Cu composite fibers showed an improved optical properties. The effect of CS/PVA, Ag/Cu, Ag, and Cu nanofibers on the selected microorganism (K.pneumoniae, S. aureus, P. aeruginosa, and E.coli) was evaluated using the disk diffusion method. It was observed that Ag/Cu/CS/PVA composite fibers showed greater activity against all microorganisms compared to Ag and Cu composite fibers. The alamar blue and Pierce Lactase dehydrogenase (LDH) assay were used to assess the effect of the blend and the composite fibers on cell viability and cytotoxicity, respectively. The results show that the prepared blend and the composite fibers did not have any toxic effect on human adipose derived stem cells (hADSC). The results also showed that as the concentration of Ag/Cu nanoparticles was increased the viability of the cells also increased after 24 hour incubation. More proliferation was observed in day 1 compared to day 3. The 30/70 blend showed more viable cell compared to the negative control. For Ag and Cu composite fibers the 30/70 CS/PVA blend increased cell proliferation after 3 days with 17% more viable cells compared to the negative control. These results show that the prepared blend with its composite fibers are biocompatible with human (ADSC) and may be suitable for use in biomedical application such as wound dressing.