Tea (Camellia sinensis) cultivated in three agro-ecological regions of Bangladesh: Unveiling the variability of methylxanthine, bioactive phenolic compound, and antioxidant activity

Tea (Camellia sinensis) is a widely consumed beverage known for its numerous health benefits, largely attributed to its rich content of quality determining secondary metabolites such as methylxanthine compounds and bioactive phenolic compounds. The goal of this study was to find out variations of the levels of methylxanthines, bioactive phenolic compounds, and antioxidant activity in methanolic and hot water extracts of 129 tea samples grown in three different ecological regions of Bangladesh named Panchagar, Sylhet, and Chattogram. Methylxanthine and bioactive phenolic compounds were determined by using HPLC-DAD, and the antioxidant profile was analysed by UV-vis spectrophotometric methods for methanol and hot water extracts of tea leaves. The IC50 values showed the trend as Panchagar > Sylhet > Chattogram and Sylhet > Chattogram > Panchagar for water and methanol extract, respectively. The results revealed significant (p < 0.05) variations in the levels of methylxanthines content: Panchagar > Chattogram > Sylhet. Caffeine was significantly higher (103.02 ± 5.55 mg/g of dry extract) in the methanolic extract of tea leaves of Panchagar district and lower (53.33 ± 4.30 mg/g of dry extract) in the hot water extract of Sylhet district. Panchagar and Chattogram possessed significantly (p < 0.05) higher catechin content for methanol (57.01 ± 5.50 mg/g dry extract) and hot water (55.23 ± 4.11 mg/g dry extract) extracts, respectively. The utilization of canonical discriminant functions yielded highly favorable outcomes in the classification of tea from three distinct cultivation origins in Bangladesh, relying on their inherent features. This study demonstrated the potential effects of geographical variations on the bioactive compounds and antioxidant properties of tea, emphasizing the importance of regional differences in tea cultivation for optimizing its health benefits as well as dispersing tea cultivation across the country.

Anti-inflammatory activity of caffeine (1,3,7-trimethylxanthine) after experimental challenge with virulent Listeria monocytogenes in Swiss mice

BACKGROUND

Immunomodulatory therapies are claimed to enhance antimicrobial immunity and counterbalance antimicrobial resistance mechanisms of pathogenic bacteria.

PURPOSE

To investigate whether caffeine can be useful for control of inflammation derived from experimental systemic infection with Listeria monocytogenes.

METHODS

Peritoneal macrophages (pMØ) from Swiss mice were cultured with caffeine in 96-well plates, and then infected with virulent L. monocytogenes 619. In another experiment, the pMØ were first infected with the bacterium and then treated with caffeine. Swiss mice were inoculated intraperitoneally with L. monocytogenes and then treated intravenously with caffeine (0.05; 0.5 or 5 mg/Kg).

RESULTS

Caffeine did not exert direct antibacterial activity in vitro against L. monocytogenes. Macrophages exposed to caffeine before or after infection with L. monocytogenes had increased cell viability, although the intracellular bacterial loads were similar to the control groups. Caffeine treatments of Swiss mice reduced leukocyte infiltration into the peritoneal cavity after L. monocytogenes infection. However, the bacterial burden was reduced in the spleen and liver. The mRNA expressions of IL-1β, IL-6 and the enzyme inducible nitric oxide synthase (iNOS) were reduced whereas IL-10 was increased.

CONCLUSION

Caffeine has an anti-infectious potential and ameliorated infection-derived inflammation following experimental infection with L. monocytogenes.

Neuroprotective effects of theobromine in transient global cerebral ischemia-reperfusion rat model

Transient global cerebral ischemia (tGCI) is a cerebrovascular disorder characterized by a brief decline in blood flow, neurological deficits, and is often predictive of stroke. Theobromine (TBR) is consumed worldwide in chocolates, tea, and cocoa products. TBR is a natural stimulant and vasoactive alkaloid that may protect against ischemic injury. In this study, neuroprotective potential of theobromine (TBR) was evaluated in 2-vessel occlusion transient global cerebral ischemia-reperfusion (tGCI/R) rat model. Rats were treated with TBR (50, 100 mg/kg, p.o.) for 7 successive days, and subjected to bilateral common carotid artery occlusion (20 min) or sham surgery after last dose of TBR. Severe neurological deficits accompanied by brain infarction, blood-brain barrier abnormalities, and oedema were noted in rats subjected to tGCI/R, and these effects were prevented by TBR. TBR protected against lipid peroxidation and enhanced glutathione level in brain against tGCI/R. TBR pre-treatment for 7 days prevented tGCI/R induced cell death (lactate dehydrogenase, caspase-3), vascular injury (MMP-9), and inflammation (TNF-α, NFκB) in rat whole brain. TBR protected against glutamate excitotoxicity and GABAergic decline in the brain of rats against tGCI/R injury. Findings of this study showed that TBR can alleviate chances of stroke by preventing acute episodes of cerebral ischemia.

Pharmacokinetics, pharmacodynamics and metabolism of caffeine in newborns

The plasma elimination half-life of caffeine in the newborn is approximately 100 h. Caffeine is rapidly absorbed with complete bioavailability following oral dosing. Switching between parenteral and oral administration requires no dose adjustments. Caffeine has wide interindividual pharmacodynamic variability and a wide therapeutic index in preterm newborns. Thresholds of measurable efficacy on respiratory drive have been documented at plasma levels around 2 mg/L. At these low levels, caffeine competitively inhibits adenosine receptors (A1 and A2A). The toxicity threshold is ill-defined and possibly as high as 60 mg/L which can be lethal in adults. High doses of caffeine may produce better control of apnea. However, at high systemic drug concentrations, the pharmacodynamic actions of caffeine become more complex and worrisome. They include inhibition of GABA receptors and cholinergic receptors in addition to adenosine receptor inhibition, intracellular calcium mobilization and actions on adrenergic, dopaminergic and phosphodiesterase systems. The role of pharmacogenomic factors as determinants of neonatal pharmacologic response and clinical effects remains to be explored.

Tea and coffee consumption and pathophysiology related to kidney stone formation: a systematic review

OBJECTIVE

To explore the mechanisms behind the potential protective effect of coffee and tea consumption, regarding urinary stone formation, previously demonstrated in large epidemiological studies.

METHODS

A systematic review was performed using the Medline, Cochrane library (CENTRAL) and Scopus databases, in concordance with the PRISMA statement. English, French and Spanish language studies, regarding the consumption of caffeinated and decaffeinated coffee and tea, and the relationship to urinary stone formation were reviewed. Meta-analyses, systematic reviews, case reports and letters, unpublished studies, posters and comments abstracts were excluded.

RESULTS

As per the inclusion criteria, 13 studies were included in the final review. The major findings show that caffeine increases urinary excretion of calcium, sodium and magnesium, in addition to a diuretic action with consumption > 300-360 mg (approximately four cups of coffee). Together with other components of coffee, this beverage might have potential protective effects against the formation of urinary stones. Tea exerts many protective effects against stone formation, through the accompanying water intake, the action of caffeine and the effects of components with antioxidant properties.

CONCLUSION

Caffeine has a hypercalciuric effect, balanced partially by a diuretic effect which appears after consumption of large quantities of caffeine. The current available literature supports in general, a potentially protective role for tea against stone formation, mainly for green tea. Additional standardization in this field of research, through specification of tea and coffee types studied, and their respective compositions, is needed for further clarification of the relation between coffee, tea and urinary stones.

Caffeine not associated with irritable behaviour in very low-birth-weight infants

This paper is an examination of irritable behaviour in very low-birth-weight infants in relation to caffeine or aminophylline. We assessed tremulous movement (a sub-score of General Movements Optimality Score) in 18 caffeine-treated subjects and 18 aminophylline-treated subjects. Caffeine, unlike aminophylline, was not associated with irritable behaviour at standard dose.

Caffeine supplementation in diet mitigates Aeromonas hydrophila-induced impairment of the gill phosphotransfer network in grass carp Ctenopharyngodon idella

Some evidence suggests the involvement of phosphotransfer network in the pathogenesis of fish bacterial diseases, catalyzed by creatine kinase (CK), pyruvate kinase (PK) and adenylate kinase (AK); nevertheless, the effects on fish affected by Aeromonas hydrophila remain unknown. Recent evidence suggested a potent protective effect of caffeine on the branchial phosphotransfer network of fish subjected to challenge conditions. Therefore, the aim of this study was to evaluate whether A. hydrophila infection impaired branchial bioenergetics. We also determined whether dietary supplementation with caffeine protected against A. hydrophila-induced gill bioenergetic imbalance. We found that branchial cytosolic CK and AK activities were significant lower in fish experimentally infected with A. hydrophila than in uninfected fish, while mitochondrial CK activity was significant higher. Branchial lactate dehydrogenase (LDH) activity and lactate levels were significant higher in fish experimentally infected by A. hydrophila than in uninfected fish, while sodium-potassium ion pump (Na⁺, K⁺-ATPase) activity and adenosine triphosphate (ATP) levels were significant lower. No significant difference was observed between groups with respect to branchial PK activity. The dietary supplementation with 8% caffeine improved the branchial CK (cytosolic and mitochondrial), AK, and LDH activities, as well as ATP levels, but did not prevent increases in branchial lactate levels or the inhibition of Na⁺, K⁺-ATPase activity elicited by aeromonosis. Based on this evidence, we believe that reduction of CK (cytosolic) and AK activities contributes to impairment of bioenergetic homeostasis, while augmentation of mitochondrial CK activity can be considered an attempt to prevent or reduce the energetic imbalance during aeromonosis caused by A. hydrophila. The use of 8% caffeine dietary supplementation improved the energetic metabolism via protective effects on CK and AK activities, avoiding the necessity of using anaerobic metabolism. In summary, 8% dietary caffeine can be used to improve branchial energetic homeostasis during aeromonosis caused by A. hydrophila.

High-versus low-dose caffeine in preterm infants: a systematic review and meta-analysis

AIM

Though caffeine is a consolidated treatment in preterm infants, the efficacy and safety of a higher dose have not been systematically appraised.

METHODS

A systematic review was conducted to compare high (loading dose >20 mg/kg and maintenance >10 mg/kg/day) versus low dose of caffeine. MEDLINE, EMBASE, Central and conference proceedings for randomised controlled trials (RCTs) and quasi-RCTs were searched. Two authors independently screened the records, extracted the data and assessed the risk of bias.

RESULTS

As only six RCTs enrolling a total of 816 preterm infants were included, the required information size was not reached. The loading and maintenance doses varied between 20 and 80 mg/kg/day and 3 and 20 mg/kg/day, respectively. The use of high dose had no impact on mortality (RR: 0.85; 95% CI: 0.53-1.38; RCTs = 4). However, it resulted in fewer cases of extubation failure, apnoeas and bronchopulmonary dysplasia (RR: 0.76; 95% CI: 0.60-0.96; studies = 4) and shorter duration of mechanical ventilation. The quality of the evidence was low due to imprecision of the estimates.

CONCLUSION

Due to imprecision, it is not possible to determine whether high-dose caffeine is more effective and safe than a low dose. High dose might improve short-term respiratory function and reduce bronchopulmonary dysplasia.

Chocolate and chocolate constituents influence bone health and osteoporosis risk

Bone loss resulting in increased risk for osteoporosis is a major health issue worldwide. Chocolate is a rich source of antioxidant and antiinflammatory flavonoids and dietary minerals with the potential to benefit bone health. However, other chocolate constituents such as cocoa butter, sugar, and methylxanthines may be detrimental to bone. Human studies investigating the role of chocolate consumption on serum bone markers and bone mineral density (BMD) have been inconsistent. A contributing factor is likely the different composition and thereby the nutrient and bioactive content among chocolate types. White and milk chocolate are high in sugar and low in flavonoids and most minerals. Dark chocolate (45-85% cocoa solids) is high in flavonoids, most minerals, and low in sugar with ≥70% cocoa solids resulting in higher fat and methylxanthine content. The aim of this review was to examine the relationship between chocolate consumption and its constiuents, including flavonoid content, on bone health and osteoporosis risk. Studies showed postmenopausal women had no bone effects at moderate chocolate intakes, whereas adolescents consuming chocolate had greater longitudinal bone growth. Based on flavonoid and mineral content, unsweetened cocoa powder appeared to be the best option followed by dark chocolate with higher cocoa content in terms of supporting and preserving bone health. Determining dietary recommendations for chocolate consumption relative to bone health is important because of the growing popularity of chocolate, particularly dark chocolate, and an expected increase in consumption owing to suggestions of health benefits against various degenerative diseases.

Aminophylline increases parasternal muscle action in awake canines

The traditional theophylline bronchodilator, aminophylline, is still widely used, especially in the treatment of COPD. The effects of aminophylline on ventilation and action of the costal diaphragm have been previously defined, but other respiratory muscles - notably the chest wall, are not well determined. Therefore, we investigated the effects of aminophylline on the Parasternal intercostal, a key obligatory inspiratory muscle, examining muscle length, shortening and EMG. We studied 11 awake canines, chronically implanted with sonomicrometer crystals and fine-wire EMG electrodes in the parasternal muscle. Ventilatory parameters, muscle length (shortening), and moving average muscle EMG activity, were measured at baseline and with aminophylline, during resting and hypercapnic stimulated breathing. Experiments were carried out prior to administration of aminophylline (baseline), and 1.5 h after loading and ongoing infusion. Minute ventilation, tidal volume and respiratory frequency all increased significantly with aminophylline, both during resting breathing and at equivalent levels of hypercapnic stimulated breathing. Parasternal baseline muscle length was entirely unchanged with aminophylline. Parasternal shortening increased significantly with aminophylline while corresponding parasternal EMG activity remained constant, consistent with increased contractility. Thus, in awake, intact mammals, aminophylline, in the usual therapeutic range, elicits increased ventilation and increased contractility of all primary inspiratory respiratory muscles, including both chest wall and diaphragm.

Optimizing Caffeine Use and Risk of Bronchopulmonary Dysplasia in Preterm Infants: A Systematic Review, Meta-analysis, and Application of Grading of Recommendations Assessment, Development, and Evaluation Methodology

Caffeine reduces the risk of bronchopulmonary dysplasia (BPD). Optimizing caffeine use could increase therapeutic benefit. We performed a systematic-review and random-effects meta-analysis of studies comparing different timing of initiation and dose of caffeine on the risk of BPD. Earlier initiation, compared to later, was associated with a decreased risk of BPD (5 observational studies; n = 63,049, adjusted OR 0.69; 95% CI 0.64-0.75, GRADE: low quality). High-dose caffeine, compared to standard-dose, was associated with a decreased risk of BPD (3 randomized trials, n = 432, OR 0.65; 95% CI 0.43-0.97; GRADE: low quality). Higher quality evidence is needed to guide optimal caffeine use.

Theophylline toxicity: An old poisoning for a new generation of physicians

A healthy 4-year-old female presented to the emergency department for vomiting and diarrhea. She was diagnosed with a urinary tract infection, treated with antibiotics and anti-emetics and discharged. Within four hours, her symptoms recurred, followed by decreasing responsiveness and seizures. She had significant hypokalemia, hyperglycemia, and a combined respiratory and metabolic acidosis. A sibling then mentioned that the patient ingested their father's 200 mg sustained-release theophylline tablets the previous morning. A serum theophylline level was immediately ordered and returned >444 μmol/L. The patient was intubated and treated with activated charcoal, antiemetics, potassium and intravenous fluids. She underwent continuous renal replacement therapy and her levels declined over the next 24 hours. She was extubated on hospital day 2 and discharged without sequelae. Theophylline ingestions are rare but potentially very serious. Physicians need to know how to diagnose and treat these ingestions.

Colorimetric theophylline aggregation assay using an RNA aptamer and non-crosslinking gold nanoparticles

The authors are presenting a rapid method for the determination of theophylline using unique non-crosslinking gold nanoparticle (AuNP) aggregation. An RNA aptamer against theophylline is firstly split into two RNA fragments which then interact with bare AuNPs. The two RNA probes cause an enhancement of the salt tolerance of AuNPs. However, in the presence of theophylline, the RNA probes form a complex with theophylline so that less RNA probes are available to protect the AuNPs from salt-induced aggregation. Theophylline induced aggregation of AuNPs is accompanied by a color change from red to blue. The color change can be detected visually and via UV-vis absorptiometry by ratioing the absorbances at 650 and 520 nm. The ratio increases linearly in the 0.1 to 20 μM theophylline concentration range, with a 67 nM limit of detection. The method is highly sensitive and selective. Graphical abstract Single-stranded split RNA aptamers (R1 and R2) protect gold nanoparticles (AuNPs) from salt-induced non-crosslinking aggregation. After recognition of theophylline by the RNA probe, the unprotected AuNPs aggregate and undergo a color change from red to blue, and this is used to quantify the theophylline concentration.

Aminophylline-associated irritable behaviour in preterm neonates

AIM

This study investigated the effect of aminophylline on behaviour and autonomic function in the preterm period.

METHOD

Subjects were preterm infants cared for in the Oita University hospital from August 2012 to October 2014. The group that was administered aminophylline (Am+) and the group that received no aminophylline (Am-) included 11 cases that exhibited a mean gestational age of 28weeks 5days and a mean birth weight of 1109g and 8 cases that exhibited a mean gestational age of 30weeks 5days and a mean birth weight of 1223g, respectively. Intravenous aminophylline was administered continuously at a dose of 4-6mg/kg/day followed by oral therapy when the infant suffered repetitive apnoea. Two-hour video recordings were obtained every 2weeks, and electrocardiograms were performed simultaneously. Onset-offset and tremulous movements in general movement (GM) optimality list were used as indices of behaviour. Autonomic functions were investigated via heart-rate and heart-rate variability measurements using frequency domain spectral analysis and the MemCalc method. We compared indices in 4 periods: 30-31, 32-33, 34-35 and 36-37weeks gestation.

RESULTS

The Am+ group exhibited significantly low optimality of tremulous movements at 32-33weeks gestation. The autonomic parameters did not differ significantly between the Am+ and Am- groups. There was no significant correlation between GMs optimality score and serum theophylline concentration.

CONCLUSION

Aminophylline administration was associated with transient irritable behaviour without autonomic changes in the preterm period.

Caffeine/sleep-deprivation interaction in mice produces complex memory effects

BACKGROUND

Sleep deprivation negatively impacts memory, causing deficits in memory processes. Of interest is any agent that can offset such deficits. Mice were given varying doses of caffeine for 14 days and then deprived of sleep for 6 hours by the 'gentle handling' method. Memory was assessed using the Novel Object Recognition Test and Y maze alternation.

PURPOSE

The study was designed to ascertain the impact of varying doses of caffeine combined with total sleep-deprivation on spatial and non spatial memory in mice.

METHODS

Adult Swiss Webster mice of both sexes were assigned to six groups viz., vehicle (distilled water), or one of five selected doses of caffeine (10, 20, 40, 80 and 120 mg/kg) for 14 days via the oral route. Open field novel object recognition test and Y maze spatial working memory tests were carried out on day 14. Results were analysed using multi-factorial ANOVA followed by Tukey HSD test and expressed as mean ± S.E.M, with p values less than 0.05 were considered statistically significant.

RESULTS

Novel object recognition tests (NOR) revealed that pre-training and pre-test sleep deprivation and caffeine combination impaired non spatial and spatial memory in male and female mice.

CONCLUSION

The study shows the complex interactions with memory that may arise when total sleep deprivation is superimposed on caffeine administration.

Caffeine and diuresis during rest and exercise: A meta-analysis

OBJECTIVES

Although ergogenic, acute caffeine ingestion may increase urine volume, prompting concerns about fluid balance during exercise and sport events. This meta-analysis evaluated caffeine induced diuresis in adults during rest and exercise.

DESIGN

Meta-analysis.

METHODS

A search of three databases was completed on November 1, 2013. Only studies that involved healthy adults and provided sufficient information concerning the effect size (ES) of caffeine ingestion on urine volume were included. Sixteen studies met the inclusion criteria, providing a total of 28 ESs for the meta-analysis. Heterogeneity was assessed using a random-effects model.

RESULTS

The median caffeine dosage was 300 mg. The overall ES of 0.29 (95% confidence interval (CI) = 0.11-0.48, p = 0.001) corresponds to an increase in urine volume of 109 ± 195 mL or 16.0 ± 19.2% for caffeine ingestion vs. non-caffeine conditions. Subgroup meta-analysis confirmed exercise as a strong moderator: active ES = 0.10, 95% CI = -0.07 to 0.27, p = 0.248 vs. resting ES = 0.54, 95% CI = 0.22-0.85, p = 0.001 (Cochran's Q, p = 0.019). Females (ES = 0.75, 95% CI = 0.38-1.13, p < 0.001) were more susceptible to diuretic effects than males (ES = 0.13, 95% CI = -0.05 to 0.31, p = 0.158) (Cochran's Q, p = 0.003).

CONCLUSIONS

Caffeine exerted a minor diuretic effect which was negated by exercise. Concerns regarding unwanted fluid loss associated with caffeine consumption are unwarranted particularly when ingestion precedes exercise.

Differences between the nonselective adenosine receptor antagonists caffeine and theophylline in motor and mood effects: studies using medium to high doses in animal models

RATIONALE

Caffeine and theophylline are methylxanthines that are broadly consumed, sometimes at high doses, and act as minor psychostimulants. Both are nonselective adenosine antagonists for A1 and A2A receptors, which are colocalized with dopamine D1 and D2 receptors in striatal areas. Adenosine antagonists generally have opposite actions to those of dopamine antagonists. Although the effects of caffeine are widely known, theophylline has been much less well characterized, especially at high doses.

METHODS

Adult male CD1 mice were used to study the effect of a broad range of doses (25.0, 50.0 or 100.0mg/kg) of caffeine and theophylline on measures of spontaneous locomotion and coordination, as well as the pattern of c-Fos immunoreactivity in brain areas rich in adenosine and dopamine receptors. In addition, we evaluated possible anxiety and stress effects of these doses.

RESULTS

Caffeine, at these doses, impaired or suppressed locomotion in several paradigms. However, theophylline was less potent than caffeine at suppressing motor parameters, and even stimulated locomotion. Both drugs induced corticosterone release, however caffeine was more efficacious at intermediate doses. While caffeine showed an anxiogenic profile at all doses, theophylline only did so at the highest dose used (50mg/kg). Only theophylline increased c-Fos immunoreactivity in cortical areas.

CONCLUSION

Theophylline has fewer disruptive effects than caffeine on motor parameters and produces less stress and anxiety effects. These results are relevant for understanding the potential side effects of methylxanthines when consumed at high doses.

Caffeine protects neuronal cells against injury caused by hyperoxia in the immature brain

Caffeine administered to preterm infants has been shown to reduce rates of cerebral palsy and cognitive delay, compared to placebo. We investigated the neuroprotective potential of caffeine for the developing brain in a neonatal rat model featuring transient systemic hyperoxia. Using 6-day-old rat pups, we found that after 24 and 48h of 80% oxygen exposure, apoptotic (TUNEL(+)) cell numbers increased in the cortex, hippocampus, and central gray matter, but not in the hippocampus or dentate gyrus. In the dentate gyrus, high oxygen exposure led to a decrease in the number of proliferating (Ki67(+)) cells and the number of Ki67(+) cells double staining for nestin (immature neurons), doublecortin (progenitors), and NeuN (mature neurons). Absolute numbers of nestin(+), doublecortin(+), and NeuN(+) cells also decreased after hyperoxia. This was mirrored in a decline of transcription factors expressed in immature neurons (Pax6, Sox2), progenitors (Tbr2), and mature neurons (Prox1, Tbr1). Administration of a single dose of caffeine (10mg/kg) before high oxygen exposure almost completely prevented these effects. Our findings suggest that caffeine exerts protection for neonatal neurons exposed to high oxygen, possibly via its antioxidant capacity.