Ehrlichia risticii is the causative agent of Potomac horse fever (PHF), which continues to be an important disease of horses. Commercial inactivated whole-cell vaccines are regularly used for immunization of horses against the disease. However, PHF is occurring in large numbers of horses in spite of vaccination. In a limited study, 43 confirmed cases of PHF occurred between the 1994 and 1996 seasons; of these, 38 (89%) were in horses that had been vaccinated for the respective season, thereby clearly indicating vaccine failure. A field study of horses vaccinated with two PHF vaccines indicated a poor antibody response, as determined by immunofluorescence assay (IFA) titers. In a majority of horses, the final antibody titer ranged between 40 and 1,280, in spite of repeated vaccinations. None of the vaccinated horses developed in vitro neutralizing antibody in their sera. Similarly, one horse experimentally vaccinated three times with one of the vaccines showed a poor antibody response, with final IFA titers between 80 and 160. The horse did not develop in vitro neutralizing antibody or antibody against the 50/85-kDa strain-specific antigen (SSA), which is the protective antigen of the original strain, 25-D, and the variant strain of our laboratory, strain 90-12. Upon challenge infection with the 90-12 strain, the horse showed clinical signs of the disease. The horse developed neutralizing antibody and antibody to the 50/85-kDa SSA following the infection. Studies of the new E. risticiiisolates from the field cases indicated that they were heterogeneous among themselves and showed differences from the 25-D and 90-12 strains as determined by IFA reactivity pattern, DNA amplification finger printing profile, and in vitro neutralization activity. Most importantly, the molecular sizes of the SSA of these isolates varied, ranging from 48 to 85 kDa. These studies suggest that the deficiency in the antibody response to the PHF vaccines and the heterogeneity ofE. risticii isolates may be associated with the vaccine failure.

Ehrlichia risticii is the causative agent of Potomac horse fever (PHF), an acute infectious disease of horses. In the last few years, there have been several reports of PHF cases occurring even in vaccinated horses. We isolated a new strain of E. risticii (90-12 strain) from a vaccinated horse suffering from clinical PHF. The major pathogenic, immunologic, and molecular differences between the 90-12 strain and the 25-D strain, which was originally isolated during the outbreaks in 1984, were studied. The 90-12 strain was more pathogenic for mice and horses compared with the 25-D strain. In enzyme-linked immunosorbent assay and immunofluorescence assay with mouse and horse antisera of both the strains, two-to fourfold differences were observed between homologous and heterologous antigens. The differences in antigen profiles were demonstrated by Western blot (immunoblot) with mouse and horse antisera and also with the recombinant clone-specific antibodies. Though several antigens were similar in both the strains, there were significant differences between them in the 110-, 85-, 70-, 51-, and 33-kDa antigens. The 85-kDa antigen was present only in the 90-12 strain but cross-reacted with a 50-kDa antigen of the 25-D strain. The 51-kDa antigens of both strains had different migration patterns. Southern blot hybridization of the genome from both the strains with DNA probes made from the 51-, 55-, and 85-kDa recombinant clones of the 90-12 strain showed a similar pattern with probes of the 51-and 55-kDa clones for both the strains, whereas the probe of the 85-kDa clone showed a completely different pattern. The 16S rRNA gene sequences from the two strains were identical. Neither strain replicated in gamma interferontreated mouse peritoneal macrophages. In in vitro neutralization assay, sera from the 25-D strain-infected horse neutralized the homologous strain but did not neutralize the 90-12 strain, whereas sera from the 90-12 strain-infected horse neutralized both the strains. In mouse protection experiments, there was complete homologous protection. But in cross-protection, mice immunized with the 25-D strain were only partially protected against challenge with the 90-12 strain, whereas mice immunized with the 90-12 strain were completely protected against the 25-D strain challenge. These results clearly indicate that there are major differences between the 90-12 and 25-D strains which may have implications regarding the vaccine failure for PHF and the development of an efficient vaccine.

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Ethanolic extracts of pneumatophores of two mangrove species- Avicennia alba and Sonneratia apetala were studied in vitro for antioxidant capacity by measuring their ability to scavenge free radicals and determining total phenolic, flavonoid and tannin contents. In vivo measurement of antihyperglycemic activity of extracts was done by oral glucose tolerance test. In considering the antioxidant activity, S. apetala extract showed superior IC50 (concentration of sample required to inhibit 50% of free radicals) value for scavenging DPPH radical (71.77 μg/ml), hydrogen peroxide radical (97.27 mg/l), hydroxyl radical (79.62 mg/l) and superoxide anion (108.89 mg/l). For A. alba, the values for the radical scavenging assays were much higher. In addition, total phenol, flavonoid and tannin content demonstrated by S. apetala were 204.03 mgGAE/g, 228.68 mgQE/g and 235.89 mgGAE/g whereas for A. alba, they were 65.52 mgGAE/g, 44 mgQE/g and 37.71 mgGAE/g, respectively. In oral glucose tolerance test, S. apetala reduced the blood glucose level to a higher extent than A. alba. So, S. apetala with higher amount of secondary metabolites (phenol, flavonoid, tannin) is a superior source of natural antioxidants and antihyperglycemics. Dhaka Univ. J. Pharm. Sci. 17(2): 205-211, 2018 (December)

Lupin holds an important place among the legumes and the utilization of lupin as a dietary protein source is an excellent environmentally friendly alternative to animal-based products for human nutrition. In the present study, nutritional, thermal, rheological and functional properties of nine Australian lupin cultivars have been assayed in order to find the most valuable one, both nutritiously and industrially. The set comprised six Lupinus angustifolius L. viz., Barlock, Gunyadi, Jenabillup, Jindalee, Jurien, Mandelup and three Lupinus albus L. viz., Luxor, Rosetta, WK388 cultivars. The tests included analysis of color, macronutrient and micronutrient composition, pasting, textural and thermal properties, electrophoretic profile of protein isolates, swelling power, water and oil absorption capacity, emulsifying capacity, emulsion stability, creaming stability, foaming capacity and stability of the cultivars’ dehulled seed flours. The results indicated substantial variation in macro and micro-nutritional value as well as satisfactory swelling ability, solubility, surface hydrophobicity, foaming ability, emulsifying capacity and gelation property of lupin flours. Superior nutritional, thermal, rheological and functional potential was demonstrated by the L. albus cultivars compared to the L. angustifolius cultivars with the exception of Mandelup.

Cancer or uncontrolled cell proliferation is a major health issue worldwide and is the second leading cause of deaths globally. The high mortality rate and toxicity associated with cancer chemotherapy or radiation therapy have encouraged the investigation of complementary and alternative treatment methods, such as plant-based drugs. Moreover, over 60% of the anti-cancer drugs are molecules derived from plants or their synthetic derivatives. Therefore, in the present review, an attempt has been made to summarize the cytotoxic plants available in the Indian subcontinent along with a description of their bio-active components. The review covers 99 plants of 57 families as well as over 110 isolated bioactive cytotoxic compounds, amongst which at least 20 are new compounds. Among the reported phytoconstituents, artemisinin, lupeol, curcumin, and quercetin are under clinical trials, while brazilin, catechin, ursolic acid, β-sitosterol, and myricetin are under pharmacokinetic development. However, for the remaining compounds, there is little or no information available. Therefore, further investigations are warranted on these subcontinent medicinal plants as an important source of novel cytotoxic agents.

Cancer is a disorder that rigorously affects the human population worldwide. There is a steady demand for new remedies to both treat and prevent this life-threatening sickness due to toxicities, drug resistance and therapeutic failures in current conventional therapies. Researchers around the world are drawing their attention towards compounds of natural origin. For decades, human beings have been using the flora of the world as a source of cancer chemotherapeutic agents. Currently, clinically approved anticancer compounds are vincristine, vinblastine, taxanes, and podophyllotoxin, all of which come from natural sources. With the triumph of these compounds that have been developed into staple drug products for most cancer therapies, new technologies are now appearing to search for novel biomolecules with anticancer activities. Ellipticine, camptothecin, combretastatin, curcumin, homoharringtonine and others are plant derived bioactive phytocompounds with potential anticancer properties. Researchers have improved the field further through the use of advanced analytical chemistry and computational tools of analysis. The investigation of new strategies for administration such as nanotechnology may enable the development of the phytocompounds as drug products. These technologies have enhanced the anticancer potential of plant-derived drugs with the aim of site-directed drug delivery, enhanced bioavailability, and reduced toxicity. This review discusses mechanistic insights into anticancer compounds of natural origins and their structural activity relationships that make them targets for anticancer treatments.

Potomac horse fever, caused by Ehrlichia risticii, is an important disease of equines. The major features of the disease are fever, leukopenia, and diarrhea. The organism has been detected from the blood mononuclear cells of infected horses, but its presence in the feces has not been known. A method for immunomagnetic separation of E. risticii from the feces of infected horses was developed, and the separated organisms were detected by PCR. Coating immunomagnetic beads (Dynabeads) with a 1:5 dilution of rabbit anti-E. risticii serum and incubating the Dynabeads with fecal samples for 25 min at room temperature gave optimum results. E. risticii was detected from the feces during the course of diarrhea from two experimentally infected horses. In horse 1, watery diarrhea occurred from days 11 to 16 postinfection (p.i.), after which the feces became soft on day 17 p.i. and then returned to normal. The organisms were first detected from the feces on day 11 p.i., peaked on day 13 p.i., and then gradually decreased until day 16 p.i., after which they became undetectable. In horse 2, first, on day 12 p.i., there was soft feces which continued and progressed to diarrhea on day 17 p.i. The feces became normal after day 18 p.i. The organisms in the feces of this horse were first detected on day 12 p.i. and peaked on day 14 p.i., after which they declined until day 16 p.i. and then became undetectable. In both horses, the number of organisms in the mononuclear cells peaked on days 10 and 11 p.i., respectively, 3 days prior to the respective peaks in the feces. E. risticii was not detected from the plasma samples obtained from these horses. There was a drastic reduction in PCR amplification of E. risticii DNA for fecal samples stored frozen at-20°C in comparison with those stored at 4°C. The presence of the organism in the feces only during the softor diarrheal-feces phase supports the previous hypothesis that the diarrhea is caused by the organisms replicating in cells lining the intestines. This rapid and simple method of detection of the organisms from the feces will be helpful in diagnostic and epidemiologic studies of Potomac horse fever.