Department of Biochemistry

Therapeutic Potential of Cinnamomum Zeylanicum Blum Aqueous Bark Extract on Doxorubicin Induced Cardiotoxicity in Wistar rats

2025-01-23T04:02:44Z

Therapeutic Potential of Cinnamomum Zeylanicum Blum Aqueous Bark Extract on Doxorubicin Induced Cardiotoxicity in Wistar rats Sandamali, J.A.N.; Hewawasam, R.P.; Jayatilaka, K.A.P.W.; Mudduwa, L.K.B. The effectiveness of doxorubicin as an anti-cancer agent is hampered by its’ life-threatening cardiotoxicity induced by oxidative-stress. As Cinnamomum zeylanicum Blum has proven antioxidant activity, the objective of this study was to find out the therapeutic potential of aqueous Cinnamomum bark extract against cardiotoxicity induced by doxorubicin in Wistar rats. Sample size of the study group was determined and an equal number of male and female Wistar rats were randomly selected into five groups. Group 1: normal-control (distilled water for 14 days, normal saline (10 mL/kg) on 11th day); group 2: plant control (2.0 g/kg of freeze dried plant extract for 14 days, normal saline (10 mL/kg); group 3: doxorubicin control (distilled water for 14 days, doxorubicin (18 mg/kg) on 11th day); group 4: freeze dried plant extract (2.0 g/kg) for 14 days, doxorubicin (18 mg/kg) on 11th day; group 5: distilled water for 14 days, dexrazoxane (180 mg/kg) 0.5 h before doxorubicin (18 mg/kg). Animals were sacrificed on the 15th day, blood was drawn for biochemical analysis and heart tissues were collected for estimation of antioxidant parameters and histological assessment of tissue damage. A significant (p ˂ 0.05) elevation in cardiac biomarkers including cardiac troponin I, AST, LDH and NT-proBNP activity were observed in doxorubicin-control group compared to the normal-control. Pretreatment with Cinnamomum bark extract in the doxorubicin treated rats showed a significant reduction (p ˂ 0.05) in above cardiac biomarkers compared to the doxorubicin-control. A significant reduction (p ˂ 0.05) in reduced glutathione, glutathione peroxidase and glutathione reductase was observed in the doxorubicin control group (Group 3) compared to the normal-control. Total antioxidant capacity as well as superoxide dismutase and catalase activity were markedly reduced (p < 0.05) in the doxorubicin control group. However, pretreatment with Cinnamomum extract was capable of significantly increasing (p ˂ 0.05) all of the above antioxidant parameters compared to the rat group which was treated with doxorubicin alone. A significant increase (p ˂ 0.05) in malondialdehyde concentration, which measures the lipid peroxidation and myeloperoxidase activity, which measures the extent of inflammation was observed in the doxorubicin-control compared to the normal-control. The plant-treated group showed a significant decrease (p ˂ 0.05) in malondialdehyde concentration and myeloperoxidase activity compared to the doxorubicincontrol. Histological assessment of tissue damage was scored according to a scale developed by the authors and doxorubicin-treated group showed a significant damage to the myocardium showing the highest score among the five groups. Plant-treated group showed only a minor degree of damage and showed a significant reduction in the score compared to the doxorubicin control. In conclusion, C. zeylanicum Blum bark extract has the potential to significantly reduce doxorubicin induced cardiotoxicity in Wistar rats.

GSTM2-2 C Terminus Modulates the Contractility of Cultured Rat Ventricular Cardiomyocytes

2025-03-05T03:59:45Z

GSTM2-2 C Terminus Modulates the Contractility of Cultured Rat Ventricular Cardiomyocytes Hewawasam, R.P.; Casarotto, Marco G.; Board, Philip G.; Dulhunty, Angela F. The ryanodine receptor (RyR) functions as an ion channel that releases Ca 2+ from the sarcoplasmic reticulum and is essential for excitation-contraction coupling and contraction in striated muscle. In previous studies we have shown that the human muscle specific glutathione transferase M2-2 (GSTM2-2) is a high affinity inhibitor of cardiac muscle ryanodine receptors (RyR2) and a weak activator of skeletal muscle ryanodine receptors (RyR1) (Abdellatif et al., 2007). Excessively active RyR channels are partly responsible for lowstore Ca 2+ levels and defective release in heart failure. Therefore, inhibition of RyR2 is a potential strategy for the treatment of heart failure. GSTM2-2 is one of the fewselective inhibitors of RyR2 that does not influence skeletal muscle RyR activity.Single channel lipid bilayer experiments and Ca 2+ release assays conducted on the C-terminal half of GSTM2-2(GSTM2C) and the mutants, F157A and Y160A in the C terminal domain confirmed the importance of the helix 6 in the C-terminal fold for the inhibition of RyR2 (Hewawasam et al., 2010). It has been reported in a qualitative study that a glutathione transferase from Schistosoma japonicum (Sj.GST26) can be internalised from the medium into a variety of mammalian cell types (Namiki et al.,2 003). Morris et al. (2008) also reported that proteins including GSTM2-2 containing a GST fold structure are efficiently internalized by L-929 cells. Therefore, the objective oft his study was to confirm the fact that GSTM2C is capable of internalising into cultured cardiomyocytes and to determine the effect of GSTM2C on the cardiac function. The study was performed on primary cardiomyocyte cultures from neonatal rats. Cells were seeded at a density of 1×10 5 cells per 35mm dish and used 2-3 days after plating. 1µMGSTM2C tagged with oregon green dye was incubated with cultured cardiomyocytes for 24h and immunostained with anti α-actinin, which specifically stains α cardiac/skeletal actinin. Optical fields were randomly chosen and observed to ascertain the occurrence of spontaneous beats. Beating frequencyand number of beating cells were counted from the control and 1µMG STM2C treated cells. Cell beating was recorded in both control and GSTM2C treated cells using a JVC video camera KY/F550 attached to Nikon TE2000-U microscope. Images were analysed using Image Pro plus 6.2 software and percentage cell shortening measured. Confocal images of the cardiomyocytes stained with Oregon green-GSTM2C and anti α-actinin confirmed the uptakeo fG STM2C into the cultured cardiomyocytes. A preliminary study showed that the beating frequency(contractions per min) in the control group was reduced significantly from 42.5/min to 6.9/min in the GSTM2C treated cells (p<0.001). The number of spontaneously beating cells observed in the control group, 6.6%, was also significantly reduced to 1.9% (p<0.001) in the drug treated group. In order to determine whether the above result is due to action potential failure or GSTM2 C terminus affecting the contraction mechanism, the degree of shortening in each beat was measured. The percentage shortening was significantly reduced from 7.5±1.0% in the control group of cardiomyocytes to 2.9±0.6% after GSTM2C treatment (p<0.001), consistent with GSTM2C reducing Ca 2+ release from the SR. In conclusion, our results indicate that GSTM2 C terminus enters cardiomyocytes and alters the cardiac function by reducing Ca 2+ release through RyR2 in ventricular cardiomyocytes.

Expression of Antiradical Power of Pigmented and Non-pigmented Rice (Oryza sativa L.) Varieties in Relation to their Colour Strengths Before and After Polishing

2025-01-20T04:27:11Z

Expression of Antiradical Power of Pigmented and Non-pigmented Rice (Oryza sativa L.) Varieties in Relation to their Colour Strengths Before and After Polishing Harsha Kumara, K.H.C.; Hafeel, R.F.; Bulugahapitiya, V.P.; Bentota, A.P.; De Zoysa, G.E.D.; Herath, H.M.S. Natural antioxidants have potential to counterbalance the effect of anti-oxidative stress and the deleterious effect on human health caused due to the synthetic antioxidants. Rice is one of the rich sources for antioxidants. Therefore to explore the total natural antioxidants in de-husked (un-polished rice), polished and cooked rice of forty which included 20 pigmented (red) and 20 non-pigmented (white) rice varieties were selected. These varieties were represented by new improved, traditional and exotic rice. Eighty percent Methanolic extract of these varieties were analyzed for total antioxidant activity which was expressed as anti-radical power (ARP) the reciprocal of EC50 value. The reducing power of 2,2-diphenyl-1-picrylhydrazyl (DPPH) was used to identify the efficient concentration (EC50) required to decrease the initial DPPH concentration by 50%. Brown rice and milled rice pericarp colour were measured by CR-20 spectrophotometric method to determine lightness, redness, and yellowness. Antiradical power of forty rice varieties was found to be highly diverse. Pigmented rice of un-polished, polished and cooked contained more antioxidants than that of non-pigmented rice. Mean ARP values for pigmented un-polished, non-pigmented un-polished, pigmented polished, non-pigmented polished, pigmented cooked and non-pigmented cooked rice were 20.7±1.77, 1.8±0.10, 10.3±0.92, 1.4±0.08, 1.4±0.07and 0.2±0.02 mL/mg, respectively. Due to presence of colour pigments in red rice varieties, they have shown comparatively higher ARP values. Two of the traditional and improved rice varieties namely Masuran and Nonabokra and Ld 368 and Ld 408 recorded the highest antioxidant contents with an ARP value more than 27 mL/mg. A drastic decline (average 35 and 88 %) of antioxidant contents were observed after milling and cooking irrespective of the presence of colour pigments in the outermost layer of the rice grain. Milling followed by cooking reduces the antioxidant content to minimum of 24 % and maximum of 96 %. However, on the average, pigmented cooked rice contain 6 times more antioxidants than non- pigmented rice. Colour values (lightness, redness and yellowness) of these varieties were significantly different among un-polished as well as polished rice. There was a significant decline in redness of pigmented varieties after polishing process. The mean redness values ranged from 3.5 to 15.2 and from 2.1 to 11.6 in un-polished and polished rice, respectively. Mean redness values of pigmented rice varieties varied between 9.0 and 14.3. Therefore, comparatively higher antioxidant capacity was observed with red pigmentation of rice grain which is reduced by polishing and further reduced by cooking.

A Comparative Investigation on Agronomic Traits of Popularly Grown Improved and Traditional Varieties of Rice.

2025-01-28T04:17:13Z

A Comparative Investigation on Agronomic Traits of Popularly Grown Improved and Traditional Varieties of Rice. Hafeel, R.F.; Bulugahapitiya, V.P.; Bentota, A.P.; De Zoysa, G.E.D. Rice is the staple food of Sri Lankans and it is available mainly in different categories such as improved and traditional varieties. Presently, most cultivation (99%) are improved rice varieties,while about 1% of cultivation in the country are the traditional varieties. Since, nowadays, people in the country have an increased interest to consume traditional varieties as a measure to reduce non communicable diseases (NCDs), this study aimed to monitor the growth and yield performance of selected traditional varieties, with comparison to selected improved varieties. Agronomic traits of popularly grown improved (15) and traditional (15) rice varieties were evaluated at Rice Research Station, Ambalantota during the 2016/2107 mahaseason. Fourteen day old seedlings were transplanted in experimental plots (8x3m) with 2 replicates to randomized complete block design (RCBD). A quadrate (30x30 cm) was placed randomly in each plot thrice to count the number of plants and tillers at 4, 5, and 6 weeks after transplanting. At flowering, plant height (PH), panicle length and number of seeds per panicle (NSP), and at harvest, total and unfilled seeds per panicle (USP), grain shattering (GS), thousand grain weight (TGW), and plot yield were recorded. Significant differences among rice varieties were observed in PH, panicle length, NSP, GS, USP, TGW and grain yield. All the traditional varieties(PH 112- 174cm) were taller than improved (PH 84 - 107 cm). During grain filling most of the traditional rice varieties logged totally or partially in the field. The longest (28.8 cm) and shortest (20.6 cm) panicles were reported in Bw 272-6B and Ld 408 respectively. NSP was found to be significantly high in 2 improved varieties Bw 367 and Ld 368. With 4 exceptions, the improved varieties have given yields of more than 5 t/ha, whileyields were below 5 t/ha in traditional varieties. In conclusion, different agronomic traits have contributed favourably to achieve significantly high grain yield in the improved rice varieties. Although different traditional varieties inherit desirable traits for high yields, plant height accompanied by logging as well as grain shattering and unfilled seeds per panicle had affected the yield badly.