METHODS: In the present study, L. indica leaf crude ethanol and its fractionated extracts (hexane, ethyl acetate and water) were firstly prepared prior to phenolic content, antioxidant effect and cytotoxic activity assessment. Folin-Ciocalteau's method was used for the measurement of total phenolic content of the extracts. The antioxidant activity was measured by employing three different established testing systems, such as scavenging activity on DPPH (1,1-diphenyl-2-picrylhydrazyl) radicals, reducing power assay and SOD (superoxide dismutase) activity assay. The cytotoxic activity of the extracts were evaluated against three colon cancer cell lines with varying molecular characteristics (HT-29, HCT-15 and HCT-116) by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay.
RESULTS: The total phenolic content and antioxidant capabilities differed significantly among the L. indica leaf extracts. A strong correlation between total phenolic content and antioxidant properties was found, indicating that phenolic compounds are the major contributor to the antioxidant properties of these extracts. Among the crude ethanol and its fractionated extracts, fractionated water extract showed significantly the highest total phenolic content and strongest antioxidant effect in all the antioxidant testing systems employed in this study. All the four extracts exert no damage to the selected colon cancer cells.
CONCLUSIONS: The data obtained in these testing systems clearly establish the antioxidant potency of the fractionated water extract of L. indica leaves. Additional studies should be carried out to isolate and identify the bioactive compounds in the fractionated water extract, in order to provide more convincing evidence.
MATERIAL AND METHOD: The total phenolic content (TPC), 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and ferric-ion reducing power (FRAP) were used to evaluate their antioxidant capacity. Tyrosinase inhibition effect was measured using mushroom tyrosinase inhibition assay.
RESULT: Ethyl acetate extract of P. macrocarpa's stem exhibited highest total phenolic content, DPPH free radical scavenging and ferric reducing power. Meanwhile, chloroform extracts of leaves and fruits demonstrated potent anti-tyrosinase activities as compared to a well-known tyrosinase inhibitor, kojic acid.
CONCLUSION: Since chloroform extracts of leaves and fruits have low antioxidant capacities, the tyrosinase inhibition effect observed are antioxidant independent. This study suggests direct tyrosinase inhibition by chloroform extracts of Phaleria macrocarpa.
METHODS: Twenty postmenopausal women with a mean age of 54.59 +/- 1.22 years participated in this randomized, crossover, double-blind, placebo-controlled clinical trial. All women received 400 IU of tocopherol daily for 10 weeks or a placebo capsule, before being crossed over for treatment. At intervals of 5 weeks, subjects attended sessions where measurements of arterial stiffness, blood pressure and plasma vitamin E level were taken. Pulse wave velocity measurement, using the automated Complior machine, was used as an index of arterial stiffness.
RESULTS: Plasma vitamin E level was 30.38 +/- 1.56 micromol/l at baseline, after treatment it was 59.01 +/- 3.30 micromol/l and 31.17 +/- 1.37 micromol/l with vitamin E and placebo, respectively (p < 0.001). There was no significant difference in pulse wave velocity after 10-week treatment with placebo and vitamin E (9.14 +/- 0.29 versus 9.04 +/- 0.29 m/s, respectively). Similarly, no difference in systolic and diastolic blood pressure was seen between placebo and vitamin E at the end of 10 weeks.
CONCLUSION: Supplementary vitamin E for 10 weeks at 400 IU daily has no effect on arterial stiffness in healthy postmenopausal women.