Comparative efficacy of tocotrienol and tocopherol (vitamin E) on atherosclerotic cardiovascular diseases in humans.

Objective: To compare the efficacy of tocotrienol and tocopherol in the management of patients with atherosclerotic cardiovascular diseases. METHODS: The systematic review was conducted in line with Preferred Reporting Items for Systematic Reviews and Meta- Analyses guidelines 2020, and comprised literature search from 2002 till January 5, 2023, on PubMed, Google Scholar, Cochrane Library, Google, Wiley-Inter Science Library, Medline, SpringerLink, Taylor and Francis databases. The search was conducted using key words, such as: "tocopherol", "tocotrienol", "vitamin E", "dyslipidaemia", "cardiovascular diseases" "cardioprotective", "hypercholesterolemia" and "atherosclerosis" along with Boolean operators. Human clinical studies regarding the use of tocotrienol or tocopherol or comparison of its efficacy in patients having atherosclerosis, dyslipidaemia leading to cardiovascular diseases, and studies including details of efficacy of any of the four alpha, beta, gamma, delta isomers of tocopherol or tocotrienol were included. Pertinent data from the eligible studies was retrieved and reviewed. RESULTS: Of the 516 articles identified, 26 (5%) articles met eligibility criteria. Of them 5(19%) were subjected to detailed analysis. Tocotrienol showed significant anti-oxidant efficacy at (250 mg/d) by decreasing cholesterol and serum inflammatory biomarkers i.e C-reactive protein (40%), malondialdehyde (34%), gamma-glutamyl transferase (22%) (p<0.001). Total anti-oxidant status (TAS) levels raised 22% (p<0.001) and Inflammatory cytokines i.e resistin, interleukin (IL)-1, IL-12, Interferon-gamma were decreased 15-17% (p<0.05-0.01) respectively by tocotrienol. Several microRNA (miRNA-133a, miRNA-223, miRNA-214, miRNA-155) were modulated by δ-tocotrienol. Whereas, tocopherol showed heterogeneity of results by either decreasing or increasing the risk of mortality in atherosclerotic cardiovascular diseases. Conclusion: Compared to tocopherol, tocotrienol was found to be safe and potential candidate for improving cardiovascular health in the management of atherosclerotic cardiovascular diseases.

Pharmacokinetics and bioavailability of tocotrienols in healthy human volunteers: a systematic review.

OBJECTIVE: To evaluate and compare the pharmacokinetic parameters, especially bioavailability, of annatto-based tocotrienol with palm tocotrienol-rich fraction in healthy human volunteers for better therapeutic outcome. METHODS: The systematic review was conducted between April and August 2021 in accordance with the Preferred Reporting Items for Systematic Review and Meta Analysis guidelines, and comprised search on PubMed, Google Scholar, Pakmedinet and Google search engines for open-label or double-blind randomised controlled trials involving healthy human volunteers published till January 2021. Key words used included annatto-based tocotrienol, palm tocotrienol-rich fraction, absorption and bioavailability. Boolean operators were also used, like tocotrienol AND bioavailability, annatto tocotrienol AND pharmacokinetics. RESULTS: Of the 230 articles identified, 50(21.7%) articles met the eligibility criteria. Of them, 7(14%) were selected for data extraction and detailed analysis. Pharmacokinetic parameters of annatto-based tocotrienol were better than palm-derived tocotrienol. Oral administration of all the isomers of annatto-based tocotrienols resulted in dose-dependent increase in area under curve and plasma levels. Amongst all the isomers of annatto-based and palm-derived tocotrienol, delta isomer of annatto-based tocotrienol had the highest bioavailability with area under curve 7450±89 ng/ml, time to reach peak plasma levels 4 hours, maximum plasma concentration 1591±43 ng/nl and elimination half-life 2. 68 ±0.29 hrs. Pharmacokinetic parameters of delta isomer of annatto-based tocotrienol was greater than palm tocotrienol-rich fraction. CONCLUSIONS: Bioavailability of annatto-based tocotrienol was better than that of palm-derived tocotrienol-rich fraction. Delta isomer of annatto-based tocotrienol had the highest bioavailability amongst all isomers of tocotrienol.

Comparative Study of Protective Effects of Salbutamol and Beclomethasone against Insulin Induced Airway Hyper-reactivity on Isolated Tracheal Smooth Muscle of Guinea Pig.

Inhalational insulin was withdrawn from the market due to its potential to produce airway hyper-reactivity and bronchoconstriction. So the present study was designed to explore the acute effects of insulin on airway reactivity of guinea pigs and protective effects of salbutamol and beclomethasone against insulin induced airway hyper-responsiveness on isolated tracheal smooth muscle of guinea pig. Effects of varying concentrations of insulin (10(-7) to 10(-3) M), insulin pretreated with fixed concentration of salbutamol (10(-7) M) and beclomethasone (10(-6) M) were studied on isolated tracheal tissue of guinea pig by constructing cumulative concentration response curves. Changes in tracheal smooth muscle contractions were recorded on four channel oscillograph. The mean ± SEM of maximum amplitudes of contraction with increasing concentrations of insulin, insulin pretreated with fixed concentration of salbutamol and beclomethasone were 35 ± 1.13 mm, 14.55 ± 0.62 mm and 22 ± 1.154 mm respectively. Although salbutamol and beclomethasone both had a profound inhibitory effect on insulin induced airway hyper-reactivity, yet salbutamol is more efficacious than beclomethasone. So we suggest that pretreatment of inhaled insulin with salbutamol may be preferred over beclomethasone in amelioration of its potential respiratory adverse effects such as bronchoconstriction.

EFFECT OF NEBIVOLOL ON TONE OF TRACHEAL MUSCLE OF GUINEA PIG.

BACKGROUND: The use of ß-blockers is limited by adverse effects such as bronchospasm in asthmatics. Third generation ß-blockers such as nebivolol may show better tolerability in asthmatic subjects because they lack ß-blocker induced bronchoconstriction. Methods: Effects of nebivolol on the tracheal muscle strips prepared from ovalbumin-sensitised guinea pigs of both sexes were studied. Two sets of experiments were designed after dividing the animals randomly into two groups. Using oxygenated Krebs-Henseleit solution as the nutrient medium, the trachealis muscle activity was measured with isometric force displacement transducer and recorded on 4-channel Oscillograph. RESULT: Nebivolol 10(-6) M did not produce significant effect on contractions evoked by histamine in concentrations ranging from 10(-7) M to 10(-3) M. The mean of amplitude of contraction for different concentrations of histamine were calculated and compared with the group treated with histamine only. Mean of amplitude of contraction, percent responses and percent deviations when compared with the control group were insignificant (p>0.05). CONCLUSION: Nebivolol did not affect the tone of airway smooth muscle in ovalbumin-sensitised guinea pigs. Nebivolol may be considered safe in patients with airway disease however, further clinical evaluation and exploratory work is required.

A comparative study of the beneficial effects of ipratropium and beclomethasone against insulin-induced tracheal tissue contraction in a guinea pig model.

OBJECTIVE: To evaluate the acute effects of insulin on airway reactivity and the protective effects of beclomethasone and ipratropium against insulin-induced airway hyperresponsiveness on isolated tracheal smooth muscle in a guinea pig model. MATERIALS AND METHODS: The trachea of each guinea pig was excised; one end of the tracheal strip was attached to the hook of the oxygen tube of a tissue bath and the other end was connected to a research-grade isometric force displacement transducer. The effects of varying concentrations of insulin (10(-7) to 10(-3)M) and insulin pretreated with a fixed concentration of beclomethasone (10(-6)M) and ipratropium (10(-6)M) on the isolated tracheal tissue were studied by constructing cumulative concentration-response curves. Changes in tracheal smooth muscle contractions were recorded on a 4-channel oscillograph. RESULTS: The means ± standard error of the mean of the maximum amplitude of contraction with increasing concentrations of insulin and of insulin pretreated with fixed concentrations of beclomethasone and ipratropium were 35 ± 1.13, 22 ± 1.15 and 27.8 ± 1.27 mm, respectively. CONCLUSION: The data showed that beclomethasone inhibited the contractile response of insulin to a greater extent than ipratropium. Thus we suggest that inhalational insulin pretreated with beclomethasone may be more efficacious than with ipratropium for the amelioration of potential respiratory adverse effects such as bronchoconstriction.

Protective effects of beclomethasone against insulin induced airway hyper-reactivity in guinea pig and exploration of its mechanism of action.

BACKGROUND: Inhalational insulin was withdrawn from market in 2007 due to its potential to produce airway hyper-reactivity and bronchoconstriction. So we explored the possible mechanism underlying the acute contractile effects of insulin and protective effects of beclomethasone against insulin induced airway hyper-responsiveness on isolated tracheal smooth muscle of guinea pig in vitro. METHODS: This was a laboratory based experimental study. Effects of increasing concentrations of histamine (10(-8)-10(-3) M), insulin (10(-8)-10(-3) M), insulin pretreated with fixed concentration of indomethacin (10(-6) M), and beclomethasone (10(-6) M), were studied on isolated tracheal tissue of guinea pig in vitro by constructing cumulative concentration response curves. The tracheal smooth muscle contractions were recorded with Transducer on Four Channel Oscillograph. RESULTS: Histamine and insulin produced a concentration dependent reversible contraction of isolated tracheal muscle of guinea pig. The mean ± SEM of maximum amplitudes of contraction with histamine, insulin and insulin pretreated with indomethacin and beclomethasone were 92.5 ± 1.20 mm, 35 ± 1.13 mm, 14.55 ± 0.62 mm and 22 ± 1.154 mm respectively. Beclomethasone shifted the concentration response curve of insulin to the right and downwards. CONCLUSION: Beclomethasone significantly inhibited the contractile response of insulin which was presumably prostaglandin mediated. So pretreatment of inhaled insulin with beclomethasone may have clinical implication in amelioration of its notential resniratorv adverse effects such as bronchoconstriction.

Acute effect of insulin on guinea pig airways and its amelioration by pre-treatment with salbutamol.

OBJECTIVE: To study the magnitude of insulin-mediated airway hyper-reactivity and to explore the protective effects of salbutamol in inhibiting the insulin-induced airway hyper-responsiveness on tracheal smooth muscle of guinea pigs in vitro. METHODS: The quasi-experimental study was conducted at the Pharmacology Department of Army Medical College, Rawalpindi, in collaboration with the Centre for Research in Experimental and Applied Medicine from December 2011 to July 2012. It used 18 healthy Dunkin Hartely guinea pigs of either gender. Effects of increasing concentrations of histamine (10-8-10-3M), insulin (10-8-10-3 M) and insulin pre-treated with salbutamol (10-6 M) were observed on isolated tracheal strip of guinea pig in vitro by constructing cumulative concentration response curves. The tracheal smooth muscle contractions were recorded with Transducer on Four Channel Oscillograph. Mean and standard error of mean were calculated. SPSS 16 was used for statistical analysis. RESULTS: Histamine and insulin produced a concentration-dependent reversible contraction of isolated tracheal muscle of guinea pig. The mean of maximum amplitudes of contraction with histamine, insulin and insulin pretreated with salbutamol were 92.5 +/- 1.20 mm, 35 +/- 1.13 mm and 14.55 +/- 0.62 mm respectively. Salbutamol shifted the concentration response curve of insulin to the right and downwards. CONCLUSIONS: Salbutamol significantly reduced the insulin mediated airway hyper-reactivity in guinea pigs, suggesting that pre-treatment of inhaled insulin with salbutamol may have clinical implication in the amelioration of its potential respiratory adverse effects such as bronchoconstriction.