METHODS: Three different varieties of CoNPs were synthesized by utilizing hydrothermal and ultrasonication methods and were thoroughly characterized by X-ray diffraction and field emission scanning electron microscopy. Amoebicidal, encystation, excystation, and host cell cytopathogenicity assays were conducted to study the antiacanthamoebic effects of CoNPs.
RESULTS: The results of the antimicrobial evaluation revealed that cobalt phosphate Co3(PO4)2 hexagonal microflakes, and 100 nm large cobalt hydroxide (Co(OH)2) nanoflakes showed potent amoebicidal activity at 100 and 10 µg/ml against Acanthamoeba castellanii as compared to granular cobalt oxide (Co3O4) of size 35-40 nm. Furthermore, encystation and excystation assays also showed consistent inhibition at 100 µg/ml. CoNPs also inhibited amoebae-mediated host cell cytotoxicity as determined by lactate dehydrogenase release without causing significant damage to human cells when treated alone.
CONCLUSIONS: To our knowledge, these findings determined, for the first time, the effects of composition, size and morphology of CoNPs against A. castellanii. Co3(PO4)2 hexagonal microflakes showed the most promising antiamoebic effects as compared to Co(OH)2 nanoflakes and granular Co3O4. The results reported in the present study hold potential for the development of antiamoebic nanomedicine.
METHODS: In this study, various species of vertebrates and invertebrates were procured including Columba livia, Gallus gallus domesticus, Varanus salvator, Cuora kamamora amboinensis, Reticulatus malayanus, Oreochromis mossambicus, Rattus rattus, American bullfrog, Donax sp., Polymesoda coaxans, Tenebrio molitor, Lumbricus terrestris, Blatta lateralis, Grammostola rosea, and Penaeus monodon. Species were dissected and their organ lysates/sera/haemolymph were prepared. Cytotoxicity assays were performed using Prostate Cancer cells (PC3), Henrietta Lacks cervical adenocarcinoma cells (HeLa) and human breast adenocarcinoma cells (MCF7) as well as human keratinized skin cells (Hacat), by measuring lactate dehydrogenase release as an indicator for cell death. Growth inhibition assays were performed to determine the effects on cancer cell proliferation. Liquid Chromatography-Mass Spectrometry (LC-MS/MS) was performed for molecular identification.
RESULTS: The results revealed that body lysates of Polymesoda coaxans demonstrated more than 99% growth inhibition of all cancer cell lines tested but not on normal Hacat cells. More importantly, the serum of M. reticulatus abolished growth and produced cytotoxicity. Hence these samples were subjected to Liquid Chromatography- Mass Spectrometry (LC-MS/MS), which detected 81 small molecules and putatively identified 20 molecules when matched against the METLIN database. Out of 1094 peptides, 21 peptides were identified, while 1074 peptides were categorized as novel peptides. Based on properties such as peptide amino acid composition, binary profile, dipeptide composition and pseudo-amino acid composition, 306 potential peptides were identified.
CONCLUSION: To our knowledge, here for the first time, we report a comprehensive analysis of sera exhibiting cytotoxicity against cancer cell lines tested and identified several molecules using LC-MS/MS.
KEY FINDINGS: Majority of antimicrobials have been discovered from prokaryotes and those which are of eukaryotic origin are derived mainly from fungal and plant sources. With this in mind, it is important to note that pests, such as cockroaches come across pathogenic bacteria routinely, yet thrive in polluted environments. Other animals, such as snakes thrive from feeding on germ-infested rodents. Logically, such species must have developed an approach to protect themselves from these pathogens, yet they have largely been ignored as a potential source of antimicrobials despite their remarkable capability to fight disease-causing organisms.
SUMMARY: Animals living in polluted environments are an underutilized source for potential antimicrobials, hence it is believed that several novel bioactive molecule(s) will be identified from these sources to counter increasingly resistant bacterial infections. Further research will be necessary in the development of novel antimicrobial(s) from these unusual sources which will have huge clinical impact worldwide.
MATERIALS AND METHODS: A PubMed search using antibacterials, antimicrobials, invertebrates, and natural products as keywords was carried out. In addition, we consulted conference proceedings, original unpublished research undertaken in our laboratories, and discussions in specific forums.
RESULTS: Representative of a stupefying 95% of the fauna, invertebrates are fascinating organisms which have evolved strategies to survive germ-infested environments, yet they have largely been ignored. Since invertebrates such as cockroaches inhabit hazardous environments which are rampant with pathogens, they must have developed defense mechanisms to circumvent infections. This is corroborated by the presence of antimicrobial molecules in the nervous systems and hemolymph of cockroaches. Antimicrobial compounds have also been unraveled from the nervous, adipose, and salivary glandular tissues of locusts. Interestingly, the venoms of arthropods including ants, scorpions, and spiders harbor toxins, but also possess multiple antimicrobials.
CONCLUSION: These findings have rekindled the hopes for newer and enhanced therapeutic agents derived from a plentiful and diverse resource to combat fatal infectious diseases. Such antimicrobials from unusual sources can potentially be translated into clinical practice, however intensive research is needed over the next several years to realize these expectations.
METHOD: We undertook a search of bibliographic databases for peer-reviewed research literature and also summarized our published results in this field.
RESULTS: The present review focuses on novel diagnostic and therapeutic strategies in details which can provide access to management and treatment of Acanthamoeba keratitis. This coupled with the recently available genome sequence information together with high throughput genomics technology and innovative approaches should stimulate interest in the rational design of preventative and therapeutic measures. Current treatment of Acanthamoeba keratitis is problematic and often leads to infection recurrence. Better understanding of diagnosis, pathogenesis, pathophysiology and therapeutic regimens, would lead to novel strategies in treatment and prophylaxis.
SIGNIFICANCE AND IMPACT OF THE STUDY: The bacteria isolated from unusual dwellings such as the cockroaches' gut are a useful source of antibacterial and antiamoebal molecules. These are remarkable findings that will open several avenues in our search for novel antimicrobials from unique sources. Furthermore studies will lead to the identification of molecules to develop future antibacterials from insects.
RESULTS: A new dimethyl aminopyridine based stabilizing agent named as DMAP-PTA was synthesized and used for stabilization of gold nanoparticles. Gold nanoparticles coated with DMAP-PTA abbreviated as DMAP-PTA-AuNPs were thoroughly characterized by UV-visible, FT-IR spectroscopic methods and transmission electron microscope before biological assay. DMAP-PTA, DMAP-PTA-AuNPs and Pefloxacin were examined for their antibacterial potential against E. coli, and the minimum inhibitory concentration (MIC) was determined to be 300, 200 and 50 µg/mL respectively. Gold nanoparticles conjugation was found to significantly enhance the antibacterial activity of DMAP-PTA as compared to pure compound. Moreover, effects of DMAP-PTA-AuNPs on the antibacterial potential of Pefloxacin was also evaluated by combination therapy of 1:1 mixture of DMAP-PTA-AuNPs and Pefloxacin against E. coli in a wide range of concentrations from 5 to 300 µg/mL. The MIC of Pefloxacin + DMAP-PTA-AuNPs mixture was found to be 25 µg/mL as compared to Pefloxacin alone (50 µg/mL), which clearly indicates that DMAP-PTA-AuNPs increased the potency of Pefloxacin. AFM analysis was also carried out to show morphological changes occur in bacteria before and after treatment of test samples. Furthermore, DMAP-PTA-AuNPs showed high selectivity towards Pefloxacin in spectrophotometric drug recognition studies which offers tremendous potential for analytical applications.
CONCLUSIONS: Gold nanoparticles conjugation was shown to enhance the antibacterial efficacy of DMAP-PTA ligand, while DMAP-PTA-AuNPs also induced synergistic effects on the potency of Pefloxacin against E. coli. DMAP-PTA-AuNPs were also developed as Pefloxacin probes in recognizing the drug in blood and water samples in the presence of other drugs.