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Articles by S. Ramanathan
Total Records ( 6 ) for S. Ramanathan
  R. Manivannan and S. Ramanathan
  The effect of hydrogen peroxide in chemical mechanical planarization slurries for shallow trench isolation was investigated. The various abrasives used in this study were ceria, silica, alumina, zirconia, titania, silicon carbide, and silicon nitride. Hydrogen peroxide suppresses the polishing of silicon dioxide and silicon nitride surfaces by ceria abrasives. The polishing performances of other abrasives were either unaffected or enhanced slightly with the addition of hydrogen peroxide. The ceria abrasives were treated with hydrogen peroxide, and the polishing of the work surfaces with the treated abrasive shows that the inhibiting action of hydrogen peroxide is reversible. It was found that the effect of hydrogen peroxide as an additive is a strong function of the nature of the abrasive particle.
  H.V. Annegowda , C. Ween Nee , M.N. Mordi , S. Ramanathan and S.M. Mansor
  The influence of acid and alkaline hydrolysis on the phenolic content and antioxidant activity of Terminalia catappa L. leaves were evaluated in this study. Polyphenolic content was determined using total phenolic, total flavonoid and total tannin assays. Four in vitro antioxidant assays such as DPPH, ABTS, Ferric Reducing Antioxidant Potency (FRAP) and total antioxidant capacity assays were followed to determine the antioxidant potency of the extracts and the values were expressed as mg vitamin C equivalent antioxidant capacity (VCEAC)/g extract. The results of this study indicated that acid hydrolysed and alkaline hydrolysed extracts possess fewer amounts of polyphenolic constituents in comparison with non hydrolysed extract. Even the VCEAC values of non hydrolysed extract in antioxidant assays were significantly higher (p<0.05) than acid and alkaline hydrolysed extracts. Moreover, the UV-visible spectral study also showed the absence of some of the absorption peaks of polyphenolic constituents in acid and alkaline hydrolysed extracts and hence, it supported our in vitro results. A strong correlation was observed for polyphenolic content and antioxidant activities of these extracts ensuring the involvement of polyphenolic content for the antioxidant activity. However, the results of this study may not be generalised for all plants as different plants possess different phytoconstituents in varying quantities.
  N. Krishnan , S. Ramanathan , S. Sasidharan , V. Murugaiyah and S.M. Mansor
  The aim of the present study was to characterize the antimicrobial properties of various crude extracts of the Cassia spectabilis leaf against bacteria and yeast. Acetone, n-hexane, dichloromethane, ethyl acetate and methanol extracts of C. spectabilis leaves were evaluated in vitro against Gram positive bacteria (Bacillus subtilis and Staphylococcus aureus), Gram negative bacteria (Escherichia coli, Salmonella typhi and Pseudomonas aeroginosa) and yeast (Candida albicans). The Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and Minimum Fungicidal Concentration (MFC) were determined using micro dilution assay. Methanol showed the highest yield (14.12%) followed by dichloromethane (8.37%), acetone (6.66%), ethyl acetate (4.76%) and n-hexane (1.80%). Acetone and methanol crude extracts showed a good antimicrobial activity with MIC values ranging from 0.625 to 2.5 mg mL-1 and MBC or MFC values ranging from 1.25 to 5 mg mL-1. The MIC, MFC and MBC values of these extracts were 10 to 80 times less potent than standard antimicrobial drugs, amoxilin and miconazole nitrate.
  F. Mustaffa , J. Indurkar , S. Ismail , M.N. Mordi , S. Ramanathan and S.M. Mansor
  This study investigated the antioxidant capacity and safety parameters (toxicity) of Cinnomomum iners standardized leaves methanolic extract (CSLE) to provide information regarding long term usage of this plant. CSLE exhibited high total phenolic (211.94±12.04 mg GAE g-1 plant material) and flavonoid (13.38±0.08 mg CE g-1 plant material) contents. The antioxidant activity of CSLE was evaluated using DPPH, H2O2 and reducing power assay. CSLE showed potent antioxidant activity with IC50 value of 0.5±0.26 mg mL-1 and 1.00±0.31 mg mL-1 in DPPH assay and H2O2 study, respectively. The electron donating capability (reducing power) of CSLE was found to be higher than standard antioxidant (vitamin E). The toxicity screening of CSLE was conducted using brine shrimp assay, acute toxicity screening and histopathologic study. An acute toxicity study was carried out by using OECD guideline 423. The LC50 and LD50 values of CSLE were found to be 2.59±0.3 mg mL-1 and > 5000 mg kg-1, respectively. The organ body weight of the CSLE treated mice shows no considerable difference with control group mice. This shows that CSLE does not affect the weight of the mice. No mortality or significant signs of acute toxicity was observed during the 14 days observation period. On the day 14, all the mice were dissected and organ as heart, liver, kidney, spleen and lung were withdrawn for the calculation of organ body index. The organ body index obtained showed that no significant difference with control. Withdrawn organ was subjected to histopathological study. Histopathological analysis of organs did not show any pathological changes. The results obtained in present study indicate that CSLE is very good antioxidant source with high margin of safety.
  H.V. Annegowda , M.N. Mordi , S. Ramanathan and S.M. Mansor
  The aim of the present study was to investigate the analgesic and antioxidant activities of ethanolic extract of Terminalia catappa (TCSE) leaves obtained by soxhlet extraction. The analgesic effects of TCSE extract was studied by formalin induced pain, hot plate and tail flick tests where as antioxidant activity was evaluated by ABTS radical scavenging and metal chelating assays. In formalin test, 80 mg kg-1 (p.o.) dose of TCSE extract inhibited both the phases (p<0.05) of animal’s nociception, but TCSE extracts (40 mg kg-1, p.o.) inhibited only late phase. TCSE extract (80 mg kg-1, p.o.) showed a significant (p<0.05) increase in the reaction time in hot plate test at the time interval of 60, 90 and 120 min. In contrast, both the doses of TCSE extracts did not show any analgesic effect in tail flick test, but morphine (5 mg kg-1, s.c.) shown significantly (p<0.05) higher analgesic effect at all time intervals. TCSE extracts showed moderate ABTS free radical scavenging activity compared to standard gallic acid and higher activity compared to BHT (88.07, 96.35 and 68.76% of inhibition, respectively) but shown less ability to chelate ferrous ion. It was concluded from our studies that TCSE extracts have analgesic and anti-inflammatory properties as well as better radical scavenging ability.
  H.V. Annegowda , T.S. Gooi , S.H.H. Awang , N.A. Alias , M.N. Mordi , S. Ramanathan and S.M. Mansor
  The multiple traditional uses with fewer scientific investigations about C. iners bark made imperative to further exploit this plant for the evaluation of its therapeutic value. Analgesic and antioxidant activities of ethanolic, aqueous and alkaloid extracts prepared from C. iners bark was studied using both in vivo and spectrometric experimental models. Results of hot plate and tail flick studies show that all the screened extracts are devoid of central analgesic activity. However, promising findings regarding the peripheral analgesic and anti-inflammatory activity was revealed from the formalin induced pain method with alkaloid extract possessing significant activity followed by ethanolic and aqueous extract. Moreover, the results of total phenolic content and antioxidant activity was also confirmed the presence of higher amount polyphenolic content in ethanolic extract with significant antioxidant activity. The observed peripheral analgesic activity by ethanolic and aqueous extract might be due to the presence of higher amount polyphenolic present in them. Results of this study also supported the traditional use of this plant in the treatment of pain. Hence, it was concluded from the study that C. iners bark extract can be utilized as new source of peripheral analgesic in the treatment of pain.
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