2 research outputs found
Putative Cationic Cell-Wall-Bound Peroxidase Homologues in Arabidopsis, AtPrx2, AtPrx25, and AtPrx71, Are Involved in Lignification
The
final step of lignin biosynthesis, which is catalyzed by a
plant peroxidase, is the oxidative coupling of the monolignols to
growing lignin polymers. Cationic cell-wall-bound peroxidase (CWPO-C)
from poplar callus is a unique enzyme that has oxidative activity
for both monolignols and synthetic lignin polymers. This study shows
that putative CWPO-C homologues in Arabidopsis, AtPrx2, AtPrx25, and AtPrx71, are involved in lignin biosynthesis.
Analysis of stem tissue using the acetyl bromide method and derivatization
followed by the reductive cleavage method revealed a significant decrease
in the total lignin content of <i>ATPRX2</i> and <i>ATPRX25</i> deficient mutants and altered lignin structures
in <i>ATPRX2</i>, <i>ATPRX25</i>, and <i>ATPRX71</i> deficient mutants. Among <i>Arabidopsis</i> peroxidases, AtPrx2 and AtPrx25 conserve a tyrosine residue on the
protein surface, and this tyrosine may act as a substrate oxidation
site as in the case of CWPO-C. AtPrx71 has the highest amino acid
identity with CWPO-C. The results suggest a role for CWPO-C and CWPO-C-like
peroxidases in the lignification of vascular plant cell walls
Inhibitory Effects of the Leaves of Loquat (Eriobotrya japonica) on Bone Mineral Density Loss in Ovariectomized Mice and Osteoclast Differentiation
The loquat, Eriobotrya
japonica Lindl.
(Rosaceae), is a small tree native to Japan and China that is widely
cultivated for its succulent fruit. Its leaves are used as an ingredient
of a tasty tea called “Biwa cha” in Japanese. The anti-osteoporosis
effects of the leaves of loquat in vitro and in vivo have been investigated.
After 15 days of feeding normal diet or diet supplemented with 5%
loquat leaves, the body weight, viscera weights, and bone mineral
density (BMD) of both groups of eight ovariectomized (OVX) mice were
compared. The result showed that the loss of BMD in loquat-fed mice
was significantly prevented in three parts of the body, especially
in the trabecular bone of the head (<i>P</i> < 0.05),
abdomen (<i>P</i> < 0.01), and lumbar (<i>P</i> < 0.05) compared to the control group. No hypertrophy in the
uterus by the loquat leaves diet was observed. The effect of the extract
(447.25 g) prepared from the dried leaves of loquat (2.36 kg) was
further studied on RANKL-induced osteoclast differentiation and cell
viability. The extract suppressed the differentiation of osteoclasts
under 50, 125, 250, and 500 μg/mL. Through bioactivity-guided
fractionation, ursolic acid (<b>1</b>) was isolated and inhibited
osteoclast differentiation under 4 and 10 μg/mL. It was concluded
that loquat leaves possess the potential to suppress ovariectomy-induced
bone mineral density deterioration