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Bioactive Compounds from Kefir and Their Potential Benefits on Health: A Systematic Review and Meta-Analysis.
Vieira, CP, Rosario, AILS, Lelis, CA, Rekowsky, BSS, Carvalho, APA, Rosário, DKA, Elias, TA, Costa, MP, Foguel, D, Conte-Junior, CA
Oxidative medicine and cellular longevity. 2021;2021:9081738
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Plain language summary
Kefir – such as milk kefir, is the result of fermentation by a symbiotic complex of microorganisms that make up kefir grains. Lactic bacteria and acetic acid bacteria are the predominant species of this complex. An abundance of evidence speaks about the health benefits of kefir consumption. However, the identification of the bioactive compounds and controlled experiments are limited. This systematic review and meta-analysis sought to gather the current evidence on the health-promoting qualities and bioactive compounds from kefir consumption. Included were in-vitro and in-vivo studies encompassing 88 papers for the review and 45 papers for the meta-analysis. The authors looked at bioactive compounds in kefir and their antimicrobial and antioxidant activity. Before examining the impact of kefir on gut microbiome composition, the immune system, its anticancer properties, kefir's effects on fat metabolism, blood pressure, neurodegenerative diseases and osteoporosis. It also considered whether kefir from industrial production with a previously selected starter culture and artisanal kefir, using grains, exhibit different functional benefits. In conclusion, kefir has various bioactive compounds and this meta- analysis affirms it's health promoting benefits. Kefir and its compounds demonstrate antimicrobial, anticancer, and immune modulating properties. And artisanal kefir is associated with a more diverse microbial profile resulting in a wider array of bioactive compounds and antioxidant potential. How these bioactive compounds from kefir exert their effects is complex and hence the authors advocate for more standardised methodologies in future studies to strengthen existing findings.
Abstract
Despite evidence of health benefits from kefir administration, a systematic review with meta-analysis on bioactive compounds associated with these benefits is still absent in the literature. Kefir is fermented milk resulting from the metabolism of a complex microbiota in symbiosis. Recent researches have investigated the bioactive compounds responsible for the preventive and therapeutic effects attributed to kefir. However, differences in functional potential between industrial and artisanal kefir are still controversial. Firstly, we identified differences in the microbial composition among both types of kefir. Available evidence concerning the action of different bioactive compounds from kefir on health, both from in vitro and in vivo studies, was subsequently summarized to draw a primary conclusion of the dose and the intervention time for effect, the producer microorganisms, the precursor in the milk, and the action mechanism. Meta-analysis was performed to investigate the statistically significant differences (P < 0.05) between intervention and control and between both types of kefir for each health effect studied. In summary, the bioactive compounds more commonly reported were exopolysaccharides, including kefiran, bioactive peptides, and organic acids, especially lactic acid. Kefir bioactive compounds presented antimicrobial, anticancer, and immune-modulatory activities corroborated by the meta-analysis. However, clinical evidence is urgently needed to strengthen the practical applicability of these bioactive compounds. The mechanisms of their action were diverse, indicating that they can act by different signaling pathways. Still, industrial and artisanal kefir may differ regarding functional potential-OR of 8.56 (95% CI: 2.27-32.21, P ≤ .001)-according to the observed health effect, which can be associated with differences in the microbial composition between both types of kefir.
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Partial purification and characterization of extrinsic pathway inhibitor (the factor Xa-dependent plasma inhibitor of factor VIIa/tissue factor).
Warn-Cramer, BJ, Maki, SL, Zivelin, A, Rapaport, SI
Thrombosis research. 1987;48(1):11-22
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Plain language summary
Green tea (GT) consumption has been associated with the prevention and control of type 2 diabetes, cardiovascular and metabolic disease as well as having a positive effect on body weight and composition. However, the polyphenols in GT have been shown to interact with mineral distribution within the body and those minerals have been shown to be deficient in obesity. Studies to measure mineral status in obese subjects supplementing with GT have been inconclusive and this study aimed to measure the serum concentrations of minerals (calcium, copper, iron, zinc, magnesium), body mass index, total antioxidant status (TAS), lipid profile and glucose concentration. 46 obese patients were randomised into 2 groups, one group were supplemented with 279mg of green tea extract (GTE) and 208mg of the polyphenol epigallocatechin-3-gallate (EGCG) and the other group were issued with a placebo for 3 months. The study concluded that GTE improved Zn and Mg, however decreased levels of FE. The results confirmed a positive effect on body mass, lipid profile, glucose and TAS. It was concluded that more studies are required on a larger population over a longer period of time.
Abstract
We report a procedure to purify partially from plasma (approximately 1200 fold) the factor Xa-dependent inhibitor of factor VIIa/tissue factor (i.e., the extrinsic pathway inhibitor or EPI) and describe some of its properties. An assay for EPI was developed based upon inhibition of factor VIIa/tissue factor induced release of activation peptide from tritiated factor IX by a test sample in the presence but not in the absence of factor Xa. Approximately 50% of the total EPI activity in plasma was found in the lipoprotein fraction, which was used as the starting material for purification. Total lipoproteins (isolated by density ultracentrifugation) were delipidated and the urea soluble apoproteins gel filtered on Sephacryl S-200. The inhibitory activity co-eluted with the major protein peak, which primarily contained apoprotein A-I. Inhibitory activity was separated from apoprotein A-I by anion-exchange chromatography on Q-Sepharose and was further resolved from higher and lower molecular weight contaminating proteins by polypreparative disc gel electrophoresis in the presence of 0.1% SDS. Functional inhibitory activity eluted from the polypreparative disc gel in two discrete pools of different molecular weights (approximately 34,000 and approximately 43,000 D). Apoprotein E was identified by immunological techniques as the major protein present in both of these pools. However, incubation with a monospecific polyclonal antibody to human apoprotein E did not decrease EPI activity either in plasma or in the partially purified polypreparative disc gel fractions. A rabbit antiserum was prepared against material from the polypreparative disc gel. The IgG fraction neutralized approximately 95% of the total inhibitory activity present in plasma. Therefore, EPI in the lipoprotein fraction and in the non-lipoprotein fraction of plasma appears to be antigenically similar.