Sweetcorn
4.4.1
Introduction
The diet of the younger generation in Japan is rapidly becoming Westernized, in-
cluding items such as bread, soup, coffee, or tea taken at meals. Consumption of
corn soup is increasing and it is available in every supermarket throughout the
country. Hokkaido at the northern end of Japan is a principal corn-producing area,
and provides a wide range of species to the nation.
One of aims of my laboratory is to search out more effective antitumor substanc-
es from natural resources. Our previous findings were that glycogen or glycogen-
like substances extracted from scallops possessed strong antitumor activity against
mouse tumors [23]; however, other researchers could not agree with our results.
Also, a highly purified glycogen as a chemical reagent did not show any antitumor
activity.
This discrepancy led us to carry out further experiments to confirm our results
(hypothesis) in collaboration with the Kewpie Institute in Tokyo by using the phy-
toglycogen prepared from sweetcorn.
Biological Effects
4.4.2.1 Antitumor Activity of Sweetcorn
Native sweetcorn powder and three types of phytoglycogen extracted from sweet-
corn powder (PG, PG-S, PG-LS) were tested for antitumor activity in a mouse mod-
el. The phytoglycogen PG-S revealed antitumor activity and gave a cure rate of 40%
(2/5) when administered by intratumor injection (Table 4.13) [24]. Oral administra-
tion, before or after tumor transplantation, was adopted for the evaluation of its
activity.
92 4 Bioactive Phytocompounds and Products Traditionally Used in Japan
Table 4.13 Antitumor activity of sweetcorn’s phytoglycogen by intratumor injection.
Sample Cured mice Tumor size in noncured mice (mm2)
PG, 1 mg 0/5 521 (59.9%)
Control 0/5 869
PG-S, 1 mg 2/5 358 (56.4%)
PG-S, 5 mg 0/5 438 (69.0%)
Control 0/4 634
PG-LS, 5 mg 0/5 570 (108.4%)
Control 0/5 692
Tumor-bearing mice were treated by test sample on days 2, 4, and 6 after tumor
transplantation.
Oral administration of sweet corn powder before tumor transplantation (pre-oral
administration) was very effective to prevent growth of tumor, and mice at eighty
percent (4/5) completely inhibited the growth of tumor (Table 4.14). The antitumor
effectiveness by oral administration of sweetcorn powder was better than that by
intratumor treatment, as shown in Table 4.13. It is possible that tumor at a very ear-
ly stage can be preventable and eradicable by regularly intake of sweetcorn powder.
4.4 Sweetcorn 93
Table 4.14 Tumor growth inhibition by pre-oral administration of sweetcorn powder.
Dosage Cured mice Tumor size in noncured mice (mm2)
200 μg 1/ 66 ± 32 (19.4%)
1 mg 4/5 96 ± 0 (27.8%)
5 mg 0/5 214 ± 42 (62.3%)
Control 0/4 345 ± 248
Sweetcorn powder in water was orally given by catheter once daily for a week, then tumor cells were
transplanted intradermally.
The phytoglycogen PG-S weakly increased the number of CD8+ T cells and NK
cells in the peripheral blood of mice, and weakly enhanced phagocytic activity of
macrophages, but these data are not enough to explain the antitumor mechanism
of sweetcorn (Table 4.15).
Table 4.15 Profile of lymphocyte subsets in blood of mice injected with intraperitoneal
phytoglycogen (PG-S).
Group CD4+ T cells (%) CD8+ T cells (%) Natural killer cells (%)
PG-S injected 69.5±1.3 13.0±0.4 6.7±0.04
Control (saline) 66.9±1.3 10.6±0.03 5.5±0.3
The phytoglycogen contained 45% corn powder as a major constituent, which
probably played an important role in healing the tumors. In a structural analysis of
scallop glycogen in relation to antitumor activity, it became clear that the glycogen
with antitumor potency was highly branched with a shorter chain than the glyco-
gen with no antitumor activity. These results suggest that short and highly
branched saccharide chains with nonreducing terminals are essential to maintain
antitumor activity [16].
The biological functions of glycogen or glycogen-related compounds still remain
obscure and research in this field should be carried out to answer these questions
in the near future.
4.5
4.4.1
Introduction
The diet of the younger generation in Japan is rapidly becoming Westernized, in-
cluding items such as bread, soup, coffee, or tea taken at meals. Consumption of
corn soup is increasing and it is available in every supermarket throughout the
country. Hokkaido at the northern end of Japan is a principal corn-producing area,
and provides a wide range of species to the nation.
One of aims of my laboratory is to search out more effective antitumor substanc-
es from natural resources. Our previous findings were that glycogen or glycogen-
like substances extracted from scallops possessed strong antitumor activity against
mouse tumors [23]; however, other researchers could not agree with our results.
Also, a highly purified glycogen as a chemical reagent did not show any antitumor
activity.
This discrepancy led us to carry out further experiments to confirm our results
(hypothesis) in collaboration with the Kewpie Institute in Tokyo by using the phy-
toglycogen prepared from sweetcorn.
Biological Effects
4.4.2.1 Antitumor Activity of Sweetcorn
Native sweetcorn powder and three types of phytoglycogen extracted from sweet-
corn powder (PG, PG-S, PG-LS) were tested for antitumor activity in a mouse mod-
el. The phytoglycogen PG-S revealed antitumor activity and gave a cure rate of 40%
(2/5) when administered by intratumor injection (Table 4.13) [24]. Oral administra-
tion, before or after tumor transplantation, was adopted for the evaluation of its
activity.
92 4 Bioactive Phytocompounds and Products Traditionally Used in Japan
Table 4.13 Antitumor activity of sweetcorn’s phytoglycogen by intratumor injection.
Sample Cured mice Tumor size in noncured mice (mm2)
PG, 1 mg 0/5 521 (59.9%)
Control 0/5 869
PG-S, 1 mg 2/5 358 (56.4%)
PG-S, 5 mg 0/5 438 (69.0%)
Control 0/4 634
PG-LS, 5 mg 0/5 570 (108.4%)
Control 0/5 692
Tumor-bearing mice were treated by test sample on days 2, 4, and 6 after tumor
transplantation.
Oral administration of sweet corn powder before tumor transplantation (pre-oral
administration) was very effective to prevent growth of tumor, and mice at eighty
percent (4/5) completely inhibited the growth of tumor (Table 4.14). The antitumor
effectiveness by oral administration of sweetcorn powder was better than that by
intratumor treatment, as shown in Table 4.13. It is possible that tumor at a very ear-
ly stage can be preventable and eradicable by regularly intake of sweetcorn powder.
4.4 Sweetcorn 93
Table 4.14 Tumor growth inhibition by pre-oral administration of sweetcorn powder.
Dosage Cured mice Tumor size in noncured mice (mm2)
200 μg 1/ 66 ± 32 (19.4%)
1 mg 4/5 96 ± 0 (27.8%)
5 mg 0/5 214 ± 42 (62.3%)
Control 0/4 345 ± 248
Sweetcorn powder in water was orally given by catheter once daily for a week, then tumor cells were
transplanted intradermally.
The phytoglycogen PG-S weakly increased the number of CD8+ T cells and NK
cells in the peripheral blood of mice, and weakly enhanced phagocytic activity of
macrophages, but these data are not enough to explain the antitumor mechanism
of sweetcorn (Table 4.15).
Table 4.15 Profile of lymphocyte subsets in blood of mice injected with intraperitoneal
phytoglycogen (PG-S).
Group CD4+ T cells (%) CD8+ T cells (%) Natural killer cells (%)
PG-S injected 69.5±1.3 13.0±0.4 6.7±0.04
Control (saline) 66.9±1.3 10.6±0.03 5.5±0.3
The phytoglycogen contained 45% corn powder as a major constituent, which
probably played an important role in healing the tumors. In a structural analysis of
scallop glycogen in relation to antitumor activity, it became clear that the glycogen
with antitumor potency was highly branched with a shorter chain than the glyco-
gen with no antitumor activity. These results suggest that short and highly
branched saccharide chains with nonreducing terminals are essential to maintain
antitumor activity [16].
The biological functions of glycogen or glycogen-related compounds still remain
obscure and research in this field should be carried out to answer these questions
in the near future.
4.5
إرسال تعليق