Bio-products from algae-based biorefinery on wastewater: A review.

Increasing resource demand, predicted fossil resources shortage in the near future, and environmental concerns due to the production of greenhouse gas carbon dioxide have motivated the search for alternative 'circular' pathways. Among many options, microalgae have been recently 'revised' as one of the most promising due to their high growth rate (with low land use and without competing with food crops), high tolerance to nutrients and salts stresses and their variability in biochemical composition, in so allowing the supply of a plethora of possible bio-based products such as animal feeds, chemicals and biofuels. The recent raising popularity of Circular Bio-Economy (CBE) further prompted investment in microalgae, especially in combination with wastewater treatment, under the twofold aim of allowing the production of a wide range of bio-based products while bioremediating wastewater. With the aim of discussing the potential bio-products that may be gained from microalgae grown on urban wastewater, this paper presents an overview on microalgae production with particular emphasis on the main microalgae species suitable for growth on wastewater and the obtainable bio-based products from them. By selecting and reviewing 76 articles published in Scopus between 1992 and 2020, a number of interesting aspects, including the selection of algal species suitable for growing on urban wastewater, wastewater pretreatment and algal-bacterial cooperation, were carefully reviewed and discussed in this work. In this review, particular emphasis is placed on understanding of the main mechanisms driving formation of microalgal products (such as biofuels, biogas, etc.) and how they are affected by different environmental factors in selected species. Lastly, the quantitative information gathered from the articles were used to estimate the potential benefits gained from microalgae grown on urban wastewater in Campania Region, a region sometimes criticized for poor wastewater management.

Anti-rhinovirus activity of 3-methylthio-5-aryl-4-isothiazolecarbonitrile derivatives.

A series of 3-methylthio-5-aryl-4-isothiazolecarbonitriles has been evaluated as anti rhinovirus agents against a panel of 17 representative human rhinovirus (HRV) serotypes, belonging to both A and B groups. No anti rhinovirus activity was detected for 3-methylthio-5-phenyl-4-isothiazolecarbonitrile (IS-2). Isothiazole derivatives with bulky substituents (O-Bn or O-But groups) on the para position of the phenyl ring were the most effective compounds of this series. In fact, a reduction in virus-induced cytopathogenicity was demonstrated for the O-Bn substituted IS-50 compound against the majority (88%) of the rhinoviruses tested, whereas the compound with an O-Ts group (IS-44) was found to be a specific inhibitor of group B serotypes, exhibiting the lowest IC(50) against HRVs type 2, 85 and 89. Our studies on the mechanism of action of IS-44 demonstrated that it prevents the thermal inactivation of HRV 2 infectivity, probably due to a conformational shift in the viral capsid and a decrease in affinity for the cellular receptor, resulting in an inhibition of attachment of the virions.

Synthesis of new 3,4,5-trisubstituted isothiazoles as effective inhibitory agents of enteroviruses.

The synthesis and evaluation of 3,4,5-trisubstituted isothiazoles as antiviral agents led to the discovery of several compounds effective in vitro against enteroviruses polio 1 and ECHO 9. Structure-activity relationship studies revealed that a short thioalkyl chain in the 3-position and a methyl ester group in the 4-position are the structural components that, to a large extent, contribute to the positive biological profile in terms of both selectivity and low cytotoxicity. Under one-step growth conditions, methyl 3-methylthio-5-phenyl-4-isothiazolecarboxilate caused the greatest activity if added within 1 h after poliovirus adsorption. These data suggest interference with early events of viral replication.

Sub-MIC ciprofloxacin effect on fimbrial production by uropathogenic Escherichia coli strains.

The urine from 210 patients with acute urinary tract infection (UTI) was examined to study the in vitro effect of ciprofloxacin on fimbriae production by uropathogenic Escherichia coli isolates. Forty-nine bacterial samples of density 10(5) CFU/ml were not considered. From the resulting 161 samples, E. coli was the major strain found, present in 54 samples. Other microoganisms found were: Enterococcus sp. (34 samples), Staphylococcus epidermis (22), yeasts (11), Proteus sp. (11), Pseudomonas sp. (11), Klebsiella sp. (8), Enterobacter sp. (6), Citrobacter sp. (3), and Acinetobacter sp. (1). The uropathogenic E. coli strains found were P-fimbriated, as demonstrated by hemoagglutination activity against human erythrocytes with and without mannose, SDS-PAGE of fimbrial proteins and transmission electron microscopy (TEM). All E. coli strains found were exposed in vitro to sub-inhibitory concentrations of ciprofloxacin (1/8 MIC). Our results showed that: 1) P-fimbriated E. coli is the most prevalent microorganism in acute UTI (34%); 2) exposure to sub-MICs of ciprofloxacin inhibits fimbrial production in 79% of E. coli strains; 3) the pattern of SDS-PAGE fimbrial proteins is modified after exposure; in particular, the most affected synthesis involves the protein at 18 kD known as P-fimbriae.

Synthesis and antiviral activity of a new series of 4-isothiazolecarbonitriles.

A series of 4-isothiazolecarbonitriles was synthesized and screened for in vitro antiviral activity. The effect of various substituents on the phenyl ring, as well as the substitution of the phenyl for other aromatic and heteroaromatic rings, was examined to establish the requirements for optimum activity. The most active member of the series, 3methylthio-5-phenyl-4-isothiazolecarbonitrile, exhibited a high level of activity against enteroviruses polio 1 and ECHO 9. Preliminary studies on its mechanism of action indicated that this compound had an effect on an early event in the replication of poliovirus type 1.

Antipoliovirus activity of isothiazole derivatives: mode of action of 5,5'-diphenyl-3,3'-diisothiazole disulfide (DID).

In this report we describe the antiviral activity of 5,5'-diphenyl-3,3'-diisothiazole disulfide (DID) and discuss its mode of action. DID selectively inhibits the replication of poliovirus type 1 (therapeutic index = 255) by affecting some early process of the virus growth cycle. The compound does not interfere with adsorption and internalization of virus to HEp-2 cells, nor with uncoating of the viral RNA. However, no viral RNA synthesis occurs after 2 h post-infection in the presence of 50 microM DID. Thus, we investigated some molecular events in poliovirus replication occurring between uncoating and viral RNA synthesis. In our experimental design, we studied the activity of RNA polymerase complex isolated from HEp-2 infected cells in the presence or absence of DID. Our results showed that the RNA polymerase complex was formed in the presence of DID. On the contrary, DID markedly inhibited poliovirus RNA synthesis in a cell-free system using RNA polymerase complex isolated from infected cells. These findings indicate that DID may exert its antiviral activity by preventing viral RNA chain elongation via the inhibition of replicase activity and/or interfering with viral RNA polymerase complex.

In vitro antiviral activity of four isothiazole derivatives against poliovirus type 1.

The in vitro effects of four isothiazoles [5,5'-diphenyl-3,3'-diisothiazole disulfide, 5-phenyl-3-mercapto-isothiazole, 5,5'-(4-chlorophenyl)-3,3'- diisothiazole disulfide, and 5-(4-chlorophenyl)-3-mercapto-isothiazole] on poliovirus type 1 were studied. The derivatives tested demonstrated remarkable viral inhibition, with a higher selectivity index than the previously studied iminodithiole precursors. Under one-step growth conditions, all the isothiazole derivatives caused the greatest activity if added during or after (within 1 h) poliovirus adsorption. These data suggest interference with early events of viral replication. [5-3H]Uridine incorporation into RNA showed that the compounds tested reduced poliovirus RNA synthesis, which was completely shut off after 2 h of incubation and reduced by 50-60% after 4 h. Also, pretreatment of the cell cultures with the compounds for 24 h caused a substantial inhibition of viral replication. The data suggest that the four isothiazole derivatives may have a multi-step antiviral mode of action different from their iminodithiole precursors.

AO 1535 inhibits O2- production by human macrophages.

AO 1535 is a semisynthetic monoglycosylceramide derived from O-glycosilated sphingosine, with a chemical structure similar to the glycolipids present in many mammalian tissues. In the epidermis monoglycosylceramides contribute to consolidate the structure of cutaneous layers. It has been recently shown that sphingosine and its derivatives are potent inhibitors of Protein kinase C, and block the 'respiratory burst' of phagocitic cells. In macrophages, like in neutrophils, the reactive oxygen intermediates are produced by a membrane associated enzymatic complex, NADPH-oxidase, which is activated by Protein kinase C. This study demonstrates that AO 1535 is able to inhibit the production of reactive oxygen intermediates in human monocytes and macrophages stimulated by phorbol ester and chemotactic tetrapeptide, suggesting a potential clinical application of AO 1535 in the treatment of inflammatory dermatoses.

Inhibitory effects of 3-imino-5-phenyl-3H-1,2-dithiole on poliovirus type 1 replication in vitro.

The effect of 3-imino-5-phenyl-3H-1,2-dithiole (PDTI) on different steps of the replicative cycle of poliovirus type 1 in HEp-2 cells was studied. This compound inhibited the replication of poliovirus type 1 as shown by cytopathic effect and virus yield reduction. This inhibitory action was not due to a virucidal effect, nor did the cells to have been pretreated. Under one-step growth conditions 3-imino-5-phenyl-3H-1,2-dithiole caused the greatest inhibition if added within 1 h after poliovirus adsorption. [5-3H]uridine incorporation into RNA showed that PDTI reduced poliovirus RNA synthesis. In fact, in the presence of PDTI viral RNA synthesis was shut off completely at 2 h post infection, and at 4 h post infection viral RNA synthesis was reduced by 50%. The compound may have an inhibitory effect on the early transcriptional and/or replicative functions of the poliovirus genome.

Antioxidant enzymatic systems in neuronal and glial cell-enriched fractions of rat brain during aging.

The activities of Cu,Zn superoxide dismutase, glutathione peroxidase, catalase and glutathione reductase in neuronal and glial cell-enriched fractions obtained from the cerebral cortex of rat brain during aging (15, 30, 90, 350, 750 days of age) were assayed. Our results showed that glutathione peroxidase, catalase and glutathione reductase activities varied little during the examined periods. Only the Cu,Zn superoxide dismutase activity decreased notably from 15th to 750th day of age in both neuronal and glial cells, moreover the activities of all enzymes studied were always detected at lower levels in neuronal cells with respect to glial cells. In agreement with diminished SOD activity, the lipid peroxidation showed an elevated increase with aging; this fact is more evident in neuronal than in glial cells. In conclusion our data show that Cu,Zn superoxide dismutase is the most affected antioxidant enzymatic system of brain aging and it could be responsible for the increased lipid peroxidation in both cell types examined.

Lipid peroxidation in pigmented and unpigmented liver tissues: protective role of melanin.

The protective role of melanin as an antioxidant biopolymer against lipid peroxidation was investigated. In pigmented frog liver and in albino rat liver the following were tested: thiobarbituric acid (TBA) reactive material (to show the induced lipoperoxidation in vitro), fatty acids, and reduced glutathione content. Our results show that susceptibility to the in vitro lipoperoxidation induced by ferrous ions is lower in the tissue containing melanin, though the content of the polyunsaturated fatty acids is higher in pigmented than in unpigmented tissues and reduced glutathione levels are lower in pigmented tissue. Our data support the hypothesis that melanin could reduce lipoperoxidation in pigmented tissue.

Antioxidant enzymatic systems in pigment tissue of amphibia.

Superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase activities in pigmented and unpigmented liver tissues of frog and albino rat, respectively, were studied. Our results show that pigmented tissue is lacking in manganese superoxide dismutase activity and that the main enzymatic activity utilized in the cytosol by pigmented cells to reduce the hydrogen peroxide to water is represented by catalase; on the contrary, for the same reaction, the cells of albino rat liver primarily utilize the glutathione peroxidase activity. Both a low glutathione peroxidase activity and a low glutathione reductase activity were found in pigmented tissue of frog liver when compared with unpigmented tissue of rat liver. In light of our results, we also report a hypothetical interrelationship between melanin and reduced glutathione: We believe that in pigmented cells the melanin could act as a reducing physiological agent replacing the glutathione in the reduction of hydrogen peroxide. This reducing action of melanin could cause a diminished need for GSH and therefore could provoke the low glutathione peroxidase and reductase activities in pigmented tissue.

Relationship between melanin content and superoxide dismutase (SOD) activity in the liver of various species of animals.

The scavenger effect of melanin and of superoxide dismutase (SOD) activity on superoxide anion has been shown. In this work we show the relationship between melanin content and SOD activity in livers containing different quantities of melanin which were taken from various species of animals. The mitochondrial SOD activity disappears when the melanin content in the liver is very high; moreover it increases, in the liver of various species of animals examined, proportionally to the decrease of melanin content. No significant variation of the SOD activity localized in the soluble fraction has been detected when related to the melanin content. We think that in the pigmented liver the antioxidant activity of the melanin could mimic part of the function of SOD. The loss of Mn SOD activity could be mediated by a low intracellular level of superoxide anion due to the scavenger effect of melanin on superoxide anion; in fact, it is well known that the biosynthesis of Mn SOD is induced by intracellular levels of superoxide anion.

Alterations in ornithine decarboxylase and transglutaminase activities in lymphocytes from untreated patients with chronic lymphocytic leukemia.

Ornithine decarboxylase (L-ornithine carboxylase, EC 4.1.1.17) and transglutaminase (R-glutaminylpeptide: amine gamma-glutamyltransferase, EC 2.3.2.13), enzymes implicated in the regulation of growth processes, were studied in lymphocytes from untreated patients with chronic lymphocytic leukemia. A marked increase of ornithine decarboxylase activity was found in lymphocytes from chronic lymphocytic leukemia patients when compared to normal human lymphocytes; in contrast, no transglutaminase activity was found in lymphocytes from untreated patients with chronic lymphocytic leukemia.

Transglutaminase activity in Yoshida ascites tumor cells.

Transglutaminase may be an important intracellular regulator of protein function through its ability to catalyze the calcium-dependent covalent linkage of primary amines to glutamine residues in peptide linkage with the generation of ammonia. This study provides further evidence that a major alteration in tumor cells is the marked decline in the expression of transglutaminase activity. This may alter its known protein cross-linking activity and favor lack of differentiation and proliferation.

Superoxide dismutase activities in Yoshida ascites tumor cells.

Cu-Zn and Mn superoxide dismutase (SOD) activities in Yoshida ascites tumor cells and in the liver of ascitic rats were assayed. The cytosolic and soluble mitochondrial fractions were used for assay of Cu-Zn SOD and Mn SOD respectively. The specific activities of Cu-Zn SOD as well as Mn SOD were found diminished in Yoshida ascites tumor cells and in the liver of ascitic rats when compared to normal rat liver.

Superoxide dismutase activity and reduced glutathione content in erythrocytes of uremic patients on chronic dialysis.

Superoxide dismutase (SOD) activity and reduced glutathione (GSH) content in erythrocytes (RBC) of uremic patients on chronic dialysis were determined. Specific SOD activity and GSH content were found lower in RBC from uremic patients before hemodialysis compared to normal RBC; after hemodialysis, the specific activity of SOD and GSH content were significantly increased.

RNA synthesis in different regions of rat brain at various time intervals after cerebellectomy.

RNA synthesis was studied in cerebral cortex, thalamus and brain stem of rat, on the 3rd, 8th, 30th and 75th day after cerebellectomy. An increased RNA synthesis was detected in thalamus at the 30th day and in cerebral cortex and brain stem at the 75th day after cerebellectomy. Our findings suggest that motor compensation following the cerebellectomy could be supported by a spatio-temporal organization of macromolecular synthesis in different brain regions.

Effects of undernutrition on nucleic acid synthesis in neuronal and glial cells from different regions of developing rat brain.

Rats were undernourished by being given half their normal diet from the 10th day of pregnancy, 10-, 15- and 30-day-old rats were studied. Incorporation of labelled precursors into brain DNA and RNA was carried out in vitro with slices from cerebral cortex, brain stem and cerebellum. Neuronal and glial cells were subsequently isolated and analyzed for specific radioactivity. The proliferation and differentiation of all brain cells were affected by undernutrition. Glial cells in particular and the small neuronal cells appeared most vulnerable probably because of their intense postnatal development.