Natural furin inhibitor(s) as potent therapeutic molecule to mitigate SARS-CoV-2 infection

The COVID 2019 has had been going pandemic as per WHO situation reports. The major differentiating point in this virus is the presence of a unique furin cleavage site. Our insilico study points out to the effectiveness of a potent plant origin furin inhibitor. We exploited the aspect of the cleavage machinery of furin subunits which is critical and indispensible to the entry of SARS-CoV-2 in human cells and subsequent massive contagion. In-silico analysis was done to observe the interactions of proposed analogs of protease inhibitor of plant origin against furin protein as well as the furin spike glycoprotein (SGP) binding machinery. This was done by docking protocols using Hex 6.0 software followed by molecular Dynamic simulation (MDS) analysis in 100 ns scale using Amber94. Further, the images were analysed with PyMol software. The analogs I, II and III included in our study showed strong interactivity against furin individually, as well as the furin-Spike Glycoprotein 1 binding machinery. The findings were confirmed using molecular dynamic simulation analysis which indicated good structural stability and ability to neutralise furin and furin-spike glycoprotein 1. Analog II was found to be the best interactive molecule against furin, showing the least deviation (1.484 ± 0.0064). Also, it was the most effective against furin + Spike glycoprotein I machinery [1.575 ± 0.01]. We report the first of its kind of natural furin inhibitor(s) which would disrupt the furin machinery of SARS-CoV-2 and help in controlling the COVID-19 contagion.Communicated by Ramaswamy H. Sarma.

A randomized controlled trial on the efficacy of alternative treatment regimens for uncomplicated falciparum malaria in a multidrug-resistant falciparum area of Bangladesh--narrowing the options for the National Malaria Control Programme?

We performed an open, randomized chemotherapy trial comparing the recommended first-, second- and third-line drug regimens, as well as mefloquine, for uncomplicated falciparum malaria in Bangladesh in 1996-97. The regimens were chloroquine for 3 days (CQ, Group I), quinine sulphate for 3 days followed by single-dose sulfadoxine-pyrimethamine (Q3 + SP, Group II), quinine for 7 days (Q7, Group III), and mefloquine 20 mg/kg single dose (MEF, Group IV). Subjects were symptomatic patients, aged > or = 12 years, with parasite density 500-250,000/mm3 and no history of taking antimalarials during the previous week. Drug administration was supervised and subjects were followed clinically and with blood slides in the hospital for 8 days, then as outpatients on days 14, 21 and 28. A total of 413 subjects (149, 145, 49 and 70 in Groups I-IV, respectively) completed the study. Early treatment failures (persistent or worsening clinical manifestations by day 3 confirmed with parasitological examinations) occurred only in the chloroquine group. RII and RIII parasitological failures occurred in 56%, 12%, 8% and 14% in Group I-IV, respectively. There were significantly more clinical and parasitological failures with chloroquine than with Q3 + SP, which we now recommend as a better (but far from ideal) choice for first-line therapy. The alternative compounds show parasitogical evidence of Plasmodium falciparum resistance. Further studies are needed to determine the optimum treatment for malaria in Bangladesh.

Novel naphthoquinones from a Streptomyces sp

Cdc25A assay-guided fractionation of a fermentation broth derived from a Streptomyces sp. resulted in the isolation of four novel naphthoquinones 1-4. Structures of these compounds were deduced by NMR and mass spectrometry. Two of them, 3 and 4, incorporate a modified cysteine residue which is observed for the first time in this class of natural products. Naphthoquinones 1-4 showed weak activity against cdc25A phosphatase.

In vitro pharmacology of cryptophycin 52 (LY355703) in human tumor cell lines

PURPOSE

Cryptophycin 52 (LY355703) is a new member of the cryptophycin family of antitumor agents that is currently undergoing clinical evaluation for cancer chemotherapy. The mechanism of action of the cryptophycin class of compounds is associated with an action on microtubules. This report details the pharmacological profile of this new clinical compound in a panel of human tumor cell lines.

METHODS

Antiproliferative effects of cryptophycin 52 were measured indirectly by detection of the metabolic reduction of alamarBlue. Cytoxicity was assessed by enzymatic dye activation (calcein AM) combined with dye exclusion (ethidium homodimer) and by clonogenicity assay. Cell cycle effects were evaluated using flow cytometry and fluorescence microscopy.

RESULTS

Both antiproliferative and cytotoxic effects of cryptophycin 52 were concentration- and time-dependent. IC50 values for antiproliferative activity in both solid and hematologic tumor cell lines were in the low picomolar range, and without exception, were significantly below values for the antimitotic agents paclitaxel and vinblastine. Flow cytometry and microscopic examination of tumor cells treated with cryptophycin 52 indicated that they accumulated in the mitotic phase of the cell cycle. Cryptophycin 52 was tested for its sensitivity to multidrug-resistance in several paired cell lines in which a sensitive parental line was matched with a multidrug-resistant derivative line. The resistant lines have been shown to over express Pgp and/or MRP multidrug-resistance transport factors. Compared to other antimitotic agents (paclitaxel, vinblastine, vincristine), the potency of cryptophycin 52 was shown to be minimally affected in multidrug-resistant cells compared to their sensitive parental lines.

CONCLUSION

Cryptophycin 52 has potent antimitotic, antiproliferative and cytotoxic activity in in vitro human tumor cell models. It is significantly more potent and less sensitive to multidrug resistance mechanisms than other antimitotic antitumor agents currently used in cancer therapy. These characteristics may translate into therapeutic advantages for the clinical use of cryptophycin 52 in cancer chemotherapy.

Nuclear and cytoplasmic localization of the beta-amyloid peptide (1-43) in transfected 293 cells

Cultures of transformed human embryonic kidney 293 cells were transiently transfected with minigene constructs coding for the Abeta peptide (1-43). The Abeta minigene used in this study consisted of exons 16 and 17 of the amyloid precursor protein gene, including the 6000+ bp intronic region. Two of the constructs used in this study, human amyloid precursor protein (APP) promoter-driven Abeta minigene and BK virus enhancer/adenovirus major late promoter-driven Abeta minigene, did not contain a signal peptide sequence, whereas the third, human APP promoter-signal peptide Abeta minigene did not contain the human APP signal sequence. The resulting Abeta products were detected by immune precipitation, using 10D5 antibody and Western blot analysis, using R1280 antisera, as SDS stable oligomers in cell lysates of cells containing all three constructs or in culture media when produced by the signal peptide construct. Evaluation of the cells by immunocytochemistry using conventional and transmission electron microscopy indicated that the cells transfected with constructs without the signal peptide accumulated immunoreactive Abeta primarily in the nucleus.

Intermittent administration of bovine PTH-(1-34) increases serum 1,25-dihydroxyvitamin D concentrations and spinal bone density in senile (23 month) rats

We examined the effect of intermittent administration of bovine parathyroid hormone (1-34) (bPTH) on spinal bone mineral content (BMC) and bone mineral density (BMD), serum 1,25-dihydroxyvitamin D concentrations, and serum markers of osteoblast function in senile male and female rats (23 and 24 months of age, respectively). Sexually mature young (3 month) male rats were similarly treated for comparison. bPTH administration increased serum osteocalcin concentrations without changing serum inorganic phosphate or calcium concentrations in either group of old animals. In young animals, PTH administration increased the serum calcium and inorganic phosphate concentrations significantly (p less than 0.05), although values remained within the normal range. In the vehicle-treated male rats, serum 1,25-dihydroxyvitamin D concentrations were lower in the senile than in the young animals (18 +/- 5 versus 47 +/- 6 pg/ml, p less than 0.05). PTH administration resulted in significantly increased serum 1,25-dihydroxyvitamin D concentrations in the senile and young male animals (both, p less than 0.05) and the final mean serum 1,25-dihydroxyvitamin D concentrations were not statistically different (68 +/- 9 versus 85 +/- 6 pg/ml respectively; p = NS). Serum 1,25-dihydroxyvitamin D concentrations were significantly (p less than 0.05) higher in the PTH-treated senile female rats than the sex-matched, vehicle-treated controls. The pretreatment spinal BMC and BMD as assessed by dual-energy x-ray absorptiometry (DEXA) were significantly higher in the senile male animals than in the young animals. Spinal BMC and BMD decreased in the vehicle-treated senile male rats (p less than 0.05) over the 3 weeks of the study despite a gain in weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of antiestrogenic compounds on avian medullary bone formation

Administration of estradiol to male Japanese quail induced the formation of medullary bone in the marrow cavities of the bird's femora and tibiae. This was accompanied by increased serum levels of calcium, phosphorus, and alkaline phosphatase activity. We examined the effects of two structurally distinct "antiestrogens" on the estrogen-induced formation of medullary bone in this quail model. Trioxifene (LY133314) and tamoxifen are members of a group of compounds commonly referred to as antiestrogens that elicit mixed agonist-antagonist actions on estrogen target tissues. In our experiments, these compounds did not display estrogen agonist properties with respect to medullary bone formation. They also did not elicit changes in serum calcium, phosphorus, or alkaline phosphatase activity. When given concurrently with estradiol, the compounds inhibited both the estrogen-induced formation of medullary bone and the associated changes in serum parameters. Trioxifene appears to be somewhat more potent than tamoxifen in antagonizing estrogen effects in this model.

Effects of estrogen and tamoxifen on serum osteocalcin levels in ovariectomized rats

Serum osteocalcin levels were measured in ovariectomized rats treated for 35 days with either estrogens (ethynylestradiol administered orally or 17 beta-estradiol administered by subcutaneous injection) or the antiestrogenic compound tamoxifen (administered both orally and subcutaneously). Tamoxifen is a non-steroidal compound that has mixed agonist/antagonist actions in several biological models, but is commonly referred to as an 'antiestrogen'. Administration of tamoxifen, like estrogen, caused a reduction in the increases in animal body weight and femur length during the test period, and greater bone density in the distal femur metaphysis compared to ovariectomized control animals. Both the estrogens and tamoxifen caused a dose-dependent decrease in serum osteocalcin as compared to the levels in the serum of ovariectomized control rats; however, tamoxifen displayed both reduced potency and efficacy compared to estrogens. Serum osteocalcin levels declined in a linear fashion throughout the estrogen dose range, and at the highest doses tested (400 micrograms/kg/d ethynylestradiol; 100 micrograms/kg/d 17 beta-estradiol), osteocalcin levels were reduced by 45-50% compared to those found in ovariectomized control animals. The reduction in serum osteocalcin concentrations in tamoxifen-treated animals, on the other hand, was reduced maximally by about 30% compared to those found in the ovariectomized controls at a dose of 100 micrograms/kg/d. Further reduction in serum osteocalcin beyond this level was not observed with increasing doses of tamoxifen. We conclude that tamoxifen acts as an estrogen agonist with respect to effects on serum osteocalcin levels, but fails to reduce serum levels of osteocalcin to the extent observed with steroidal estrogens.

Chlorpromazine inhibits mitosis of mammalian cells

Chlorpromazine (CPZ) at minimally effective concentrations accumulates mammalian cells in mitosis without lethal effects on the cells. Star-metaphase morphology similar to effects seen with classical antimitotic compounds probably results from the preferential action of CPZ on a specific class of microtubules--the pole-to-pole microtubules of the mitotic spindle. At CPZ concentrations of 8 X 10(-6) M, flow cytometry indicates no effect of CPZ on the progress of cells through phases of the cell cycle other than mitosis (M). These results suggest a possible mechanism for toxic side effects of CPZ in man such as granulocytopenia and light sensitization.

Immunocytochemical demonstration of human proinsulin chimeric polypeptide within cytoplasmic inclusion bodies of Escherichia coli

Immunocytochemical techniques were used to identify human proinsulin chimeric protein in cytoplasmic inclusion bodies of genetically modified Escherichia coli. Antibodies to proinsulin chimeric protein (human proinsulin coupled at its amino-terminus to a portion of the E. coli tryptophan E gene product) were localized in E. coli using post-embedding staining with protein A-peroxidase labelling for transmission electron microscopy. The observable distribution of the labelled antibody was limited to that portion of the E. coli cytoplasm occupied by inclusion bodies. The localization of human peptides as insoluble masses within the bacterial cytoplasm has important implications in relation to the synthesis, recovery and purification of pharmacologically useful substances produced through the application of recombinant DNA technology.

Immunocytochemical localization of plasminogen activator on porcine kidney cell strain: LLC-PK1 (LP100)

An antibody to plasminogen activator (PA) produced by the cultured cells of the pig kidney cell strain LLC-PK1 (LP100) was used to localize PA on the cell's free (unattached) surface. Localization was accomplished by the unlabeled antibody enzyme method (PAP) at the light microscopic level and at the electron microsopic level. Localization was commonly more intense at cell to cell junctions and was associated with blebs and vesiculation in this area. We are proposing that membrane shedding by blebs and vesiculation may be the mechanism of PA release in the LLC-PK1 (LP100) cell strain.