Synthesis and antimycobacterial activities of ring-substituted quinolinecarboxylic acid/ester analogues. Part 1

Structural optimization of recently discovered new chemical entity, 2,8-dicyclopentyl-4-methylquinoline (DCMQ; MIC= 6.25 microg/mL, M. tuberculosis H37Rv) resulted in the synthesis of four new series of ring-substituted quinolinecarboxylic acids/esters constituting 45 analogues. All new derivatives were evaluated for in vitro antimycobacterial activities against M. tuberculosis H37Rv. Certain ring-substituted-2-quinolinecarboxylic acid ester and ring-substituted-2-quinoline acetic acid ester analogues described herein showed moderate to good inhibitory activity. In particular, three analogues methyl 4,5-dicyclopentyl-2-quinolinecarboxylate (3b), methyl 4,8-dicyclopentyl-2-quinolinecarboxylate (3c) and ethyl 2-(2,8-dicyclopentyl-4-quinolyl)acetate (14g) exhibited excellent MIC values of 1.00, 2.00 and 4.00microg/mL, respectively. Results obtained indicate that substitution of the quinoline ring with dicyclopentyl substituent presumably enhances the antimycobacterial activities in the quinoline analogues described herein.     

Role of alpha-helical conformation of histatin-5 in candidacidal activity examined by proline variants

Human salivary histatin-5 (Hsn-5) is a potent in vitro anticandidal agent. The aim of this study was to investigate the importance of alpha-helical structure of Hsn-5 for its candidacidal activity. The following three Hsn-5 variants, where one or more functionally nonessential residues were replaced with proline (potent alpha-helix breaker), were produced by Escherichia coli expression system: H21P (1P), H19P/H21P (2P), and E16P/H19P/H21P (3P). The activities of purified proteins were determined by candidacidal assays, and the secondary structures by circular dichroism (CD) spectroscopy in trifluoroethanol (TFE) that is considered the helix-promoting solvent, and lysophosphatidyl-glycerol (LPG) micelles, the environment that more closely resembles the biological membranes. Our results indicated that 3P variant displayed a candidacidal activity which was similar to that of unaltered Hsn-5 (0P), while 1P and 2P variants showed lower cidal activity. The CD spectra in TFE indicated that 3P variant has less helical characteristics than the 0P, 1P and 2P. These results suggested that the alpha-helical content of Hsn-5 proline variants does not correlate with the candidacidal activity. Further, the CD spectral analysis of peptides in LPG micelles indicated the formation of beta-turn structures in 0P and 3P variants. In conclusion, 3P variant which exhibited comparable candidacidal activity to 0P contains lower percentage of alpha-helical structure than 1P and 2P variants, which exhibited lower candidacidal activity. This suggests alpha-helix may not be important for anticandidal activity of Hsn-5.     

Association of urinary levels of 6-sulfatoxymelatonin (aMT6s) with prevalent and incident hypertension

Laboratory studies indicate that melatonin has beneficial vascular effects. However, epidemiologic studies on the relationship between endogenous levels of melatonin and hypertension in humans are limited. We examined the association of quartile levels of 6-sulfatoxymelatonin (aMT6s) in first morning urines with prevalent and incident hypertension in 777 postmenopausal women who were originally part of a case–control study of breast cancer nested in the Women’s Health Initiative Observational Study. A total of 321 prevalent and 172 incident cases of hypertension were studied. In cross-sectional analyses, higher quartile level of aMT6s was associated with lower odds of hypertension (Q4 versus Q1; odds ratio = 0.57; 95% confidence interval [CI]: 0.3–0.9), after adjustment for age, body mass index and other risk factors. We also examined the association between baseline aMT6s levels and risk of incident hypertension. Compared to women in the lowest quartile of urinary aMT6s, the multivariable-adjusted hazard ratios and 95% CIs of incident hypertension for women in the second, third and highest quartile were 1.16 (0.8–1.8), 0.96 (0.6–1.5) and 1.02 (0.6–1.6), respectively. The mean change in systolic and diastolic blood pressure over 3 years also did not vary by baseline quartile levels of aMT6s. Although we found no evidence of a prospective association between urinary levels of aMT6s and risk of incident hypertension in postmenopausal women, our cross-sectional results provide some possible evidence of a role for physiologic levels of melatonin in hypertension. Additional larger studies are warranted, preferably with a wider range of ages, both genders and multiple melatonin measurements.     

Biochemistry of epidermal stem cells

Background

The epidermis is an important protective barrier that is essential for maintenance of life. Maintaining this barrier requires continuous cell proliferation and differentiation. Moreover, these processes must be balanced to produce a normal epidermis. The stem cells of the epidermis reside in specific locations in the basal epidermis, hair follicle and sebaceous glands and these cells are responsible for replenishment of this tissue.

Scope of review

A great deal of effort has gone into identifying protein epitopes that mark stem cells, in identifying stem cell niche locations, and in understanding how stem cell populations are related. We discuss these studies as they apply to understanding normal epidermal homeostasis and skin cancer.

Major conclusions

An assortment of stem cell markers have been identified that permit assignment of stem cells to specific regions of the epidermis, and progress has been made in understanding the role of these cells in normal epidermal homeostasis and in conditions of tissue stress. A key finding is the multiple stem cell populations exist in epidermis that give rise to different structures, and that multiple stem cell types may contribute to repair in damaged epidermis.

General significance

Understanding epidermal stem cell biology is likely to lead to important therapies for treating skin diseases and cancer, and will also contribute to our understanding of stem cells in other systems. This article is part of a Special Issue entitled Biochemistry of Stem Cells.     

Development and evaluation of an enzyme-linked immunosorbent assay (ELISA) and dot immunobinding assay (DIBA) for the detection of Ganoderma infecting palms

The genus Ganoderma has a worldwide distribution causing root and stem rot of many plantation crops. A limiting factor in controlling the BSR disease is the lack of reliable diagnostic method(s) for early diagnosis. In this study, we developed polyclonal antiserum for Ganoderma mycelial and extracellular protein, and evaluated its efficacy with different plant samples collected from artificially inoculated coconut seedlings and Ganoderma infected field palms. We also tested the cross-reactivity with the soil-borne and saprophytic fungus collected from different parts of coconut palm. The antisera developed against the crude mycelial protein (CMP) and extracellular protein (ECP) showed a 1:1000 titre value for the detection of Ganoderma. The CMP antisera developed showed more cross-reaction when compared to ECP antisera of Ganoderma. In the DIBA test, at a 1:10 dilution of antigen, 1:1000 dilution of CMP and ECP antisera, 1:5000 dilution of secondary antibody gave clear distinctions in colour development between healthy and diseased samples. In the DIBA test, ECP antisera detected positive control (ECP of Ganoderma MTP and CRS-1 isolate), artificially inoculated roots, infected field roots, infected basal trunk and additionally lesions gave positive reactions which were not found in the CMP antisera tested. Therefore, both ELISA and DIBA tests may be useful for screening a large number of samples and help in the detection of infection at the earliest stage of disease development and this will certainly help to adopt suitable management strategies against Ganoderma disease in palm crops in advance.     

Early immunodiagnosis of Ganoderma infecting coconut seedlings and palms by using monospecific polyclonal antibodies

Among the various fungal diseases affecting plantation crops viz., coconut, aracanut, oil palm, etc. in India, basal stem rot (BSR) caused by species of Ganoderma is the most destructive. A limiting factor in controlling the BSR disease is the lack of reliable diagnostic method(s) for early diagnosis. In this study we generated two different types of antiserum for diagnosis of Ganoderma using the purified monospecific protein (62 kDa) (MS) and crude sporophore extract (SE). We also tested the cross-reactivity with the soil-borne and saprophytic fungus collected from different parts of coconut palm. The antiserum developed against the MS and SE showed 1:700 and 1:3000 titre values for the detection of Ganoderma. The MS antisera developed showed very low or almost no cross-reaction when compared to SE antisera of Ganoderma. In the DIBA test, at a 1:10 dilution of antigen, 1:1000 dilution of CMP and ECP antisera, 1:5000 dilution of secondary antibody gave clear distinctions in colour development between healthy and diseased samples. In DIBA test, both types of antisera were used separately for pathogenicity tests. MS antisera showed a positive reaction for purified protein, artificially infected roots and infected field palm. A mild reaction was observed against infected field trunk but a negative reaction was observed for lesions and leaf samples. In the case of SE antisera, a negative reaction was observed for all leaf samples, healthy roots and healthy trunk samples but positive reactions were observed for positive control, artificially inoculated roots, infected field roots, infected trunk and lesions samples. Therefore, both ELISA and DIBA tests may be useful in the detection of infection at the earliest stage of disease development and this will certainly help in the development of management strategies against Ganoderma disease in palm crops in advance.     

Docking analysis insights quercetin can be a non-antibiotic adjuvant by inhibiting Mmr drug efflux pump in Mycobacterium sp. and its homologue EmrE in Escherichia coli

Drug efflux pumps (EP) like Mmr in Mycobacterium transported drugs out of cell, a main reason for drug resistance developing in Mycobacterium tuberculosis. In this in silico study, mainly analysed EP inhibitory potential of a plant-derived flavonoid, quercetin, through docking analysis. Mmr present in Mycobacterium smegmatis and M. tuberculosis, and its homologue EmrE of Escherichia coli was used. Initially, homology modelling of EP monomers and dimers constructed from M. smegmatis, M. tuberculosis and E. coli; the stabilities of models were analysed from Ramachandran plots prepared in PROCHECK. Docking analysis of quercetin with EP protein showed that in all three organisms, the residues for function and stability are important and quercetin had best interactions comparing to compounds such as, verapamil, reserpine, chlorpromazine, Carbonyl Cyanide m- Chloro Phenylhydrazone. Molecular dynamics and simulation studies showed that during the entire course of simulation quercetin-Mmr complex were stable. It insights quercetin can act as a non-antibiotic adjuvant for treatment of tuberculosis by bring down the efflux of drug from bacteria.