Bioavailability and Pharmacokinetics Studies of Gamma Oryzanol
Rice bran oil was extracted from rice bran collected after four milling breaks that were used to process rice in Bernas factory, Sekinchan, Malaysia. Two organic solvents were used, a non-polar solvent that was hexane and a mixture of non-polar and polar, which were chloroform-methanol. Gamma ory...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2004
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/6294/1/FPSK%28M%29_2004_6.pdf |
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| Summary: | Rice bran oil was extracted from rice bran collected after four milling breaks that were
used to process rice in Bernas factory, Sekinchan, Malaysia. Two organic solvents were
used, a non-polar solvent that was hexane and a mixture of non-polar and polar, which
were chloroform-methanol. Gamma oryzanol content of rice bran oil was then
quantified, and the total antioxidant activity (TAA) was determined using FTC and TBA
methods. After oil extraction, dietary fiber content was quantified in the four phases of
defatted rice bran. Results showed that rice bran contained around 20 % lipid in the
extracts of the two solvents used. Unlike oil yield, y-oryzanol content was affected by
rice milling and the type of solvent used for extraction. For chloroform-methanol
extract, phase 2 of rice milling contained the highest amount of y-oryzanol (5280 * 120
pprn), followed by phase 3 (3820 * 60 pprn), phase 4 (3400 * 100 pprn), and phase 1
(3000 * 80 pprn). The four phases of hexane extracts contained lower amount of yoryzanol
than chloroform-methanol extracts. Phase 2 of rice milling contained the
highest y-oryzanol content (4560 100 pprn), followed by phase 3 (2400 * 40 pprn),.
phase 4 (2080 * 40 pprn), and phase 1 (1600 * 60 pprn). TAA studies showed that rice
bran oil extracted from phase 2 of rice milling had significantly higher antioxidant
activity than phase 1 (pc0.05). However, no significant differences were found among
other phases (p0.05). It was found that rice bran is a good source of dietary fiber.
However, fiber distribution was affected also by milling systems. Phase 2 of rice milling
contained the highest amount of TDF which was 5 1.2 * 0.9 %, followed by phases 3, 1
and 4 that contained 45.2 * 1.0 %, 37.6 * 0.1 % and 35.5 * 0.8 % respectively.
Caco-2 cell line was used as in vitro model to study y-oryzanol bioavailability from
different formulations that were triolein solution, emulsion, tocotrienol rich fraction
(TRF)-y-oryzanol emulsion, and microspheres. By day 9, cell line showed polarized
monolayer properties as was detected from transepithelial electrical resistance (TEER)
value (247.2 * 25.0 &m2) and phenol red diffusion (4.2 + 0.1 %). However, all
experiments were conducted at day 18, to ensure that cells were fully polarized. In vitro
digestion of 100 mg dose from each formulation resulted in low micellarization
concentrations of y-oryzanol from both triolein solution and microspheres, that were 2 1
* 2 pglml digestate, and 20 * 2 pgml respectively. Nevertheless, micellarization
concentrations were greatly improved to 5087 * 147 pglml and 5 160 + 228 pglml, from
emulsion and TRF- y-oryzanol emulsion, respectively. After 10 h of incubation, only
0.43 * 0.02 pg (2.03 +_ 0.09 %) y-oryzanol was transported to the lower compartments
from triolein solution. Cellular uptake of y-oryzanol from microspheres after the same
period of incubation, increased to 1.25 * 0.09 pg (6.33 f 0.44 %). Gamma oryzanol
absorption increased further to 1 14.94 * 2.02 pg (2.3 1 f 0.04 %) and 1 15.82 * 4.52 pg
(2.24 + 0.05 %) from emulsion and TRF- y-oryzanol emulsion, respectively.
Phannacokinetics of y-oryzanol was studied using rabbits. Gamma oryzanol emulsion
was given as a single intravenous dose. Plasma level of y-oryzanol was quantified using
HPLC. Plasma clearance of y-oryzanol followed two compartments model, indicating
that y-oryzanol was distributed to the internal tissues. Elimination constant was 0.086 *
0.004 pg/ml.h, and the half-life was 8.040 * 0.360 h.
Rabbits were used as in vivo model to study the bioavailability of y-oryzanol from
triolein solution, microspheres, emulsion and TRF- y-oryzanol emulsion. The maximum
concentration of y-oryzanol from triolein solution was 6.37 * 1.48 pg/ml, and improved
to 130.30 * 30.40 pglml upon loading y-oryzanol in microspheres. However, in both
formulations, the maximum concentrations were achieved after 2 h of ingestion. Where
as the maximum concentrations of y-oryzanol from emulsion and TRF- y-oryzanol
emulsion were 555 * 100 pglml and 525 * 95 pglml respectively and the t max. was 2 h.
The absolute bioavailability of y-oryzanol emulsion was 6.61 * 0.86 %. The oral
emulsion was used as a standard, so that the relative bioavailabilitiy (F relative) values
of the other formulations were calculated. While F( relative) for y-oryzanol from triolein
solution was only 0.51 * 0.06 %, it was significantly ('<0.05) increased to 16.63 * 1.71
% upon loading y-oryzanol in microspheres. Addition of TRF to y-oryzanol emulsion
resulted in an increase of F (relative) to 109.60 * 13.83 %. However, this increase could
be due to the preservative effect of TRF antioxidants.
In conclusion, the bioavailability of y-oryzanol was low. However, its absorption
increased around 200 times after emulsification and 33 times upon loading in
microspheres. |
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