Enhancement of radiation effect by Ginkgo biloba extract in C3H mouse fibrosarcoma.
OBJECTIVE
Ginkgo biloba leaf extract (GBE) is known to increase peripheral blood circulation. The hypothesis that GBE may be able to enhance radiosensitivity of tumor by improving tumor blood flow and thus decreasing hypoxic fraction was tested.


METHODS
Fibrosarcoma (FSaII) growing in C3H mouse leg muscle was used as a tumor model. GBE was given i.p. 1 h before irradiation with or without priming dose given 1 day earlier. Effect on tumor and normal tissue radiation reaction was investigated.


RESULTS
Tumor growth delay by radiation was more elongated after two doses (1-day interval) of GBE than after a single dose. Radiation dose for 3-day tumor growth delay was decreased from 12.45 (10.97-13.93) Gy to 6.06 (3.89-8.22) Gy by two doses of GBE [enhancement ratio = 2.06 (1.32-2.79)]. Hypoxic cell fraction was 10.6% (6.3-18.2%) for control, 7.2% (3.8-14.0%) after a single dose (P = 0.18) and 2.7% (1.5-5.0%) after two doses (P < 0.001). Radiation effect on normal tissue, estimated by acute skin reaction and jejunal crypt assay, was not affected by GBE.


CONCLUSIONS
Ginkgo biloba extract enhances radiation effect on tumor without increasing acute normal tissue radiation damage in this model system probably by increasing tumor blood flow and further investigation for this possible radiosensitizer is needed.
Ha
S W
SW
Laboratory of Radiation Biology, Seoul National University Medical College, South Korea.
Yi
C J
CJ
Cho
C K
CK
Cho
M J
MJ
Shin
K H
KH
Park
C I
CI
D000818:Animals; D015687:Cell Hypoxia; D005260:Female; D005354:Fibrosarcoma / Q000532:radiotherapy*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D019042:Muscle Neoplasms / Q000532:radiotherapy*; D009368:Neoplasm Transplantation; D010936:Plant Extracts / Q000627:therapeutic use*; D011829:Radiation Dosage; D011838:Radiation-Sensitizing Agents / Q000627:therapeutic use*
D010936:Plant Extracts; D011838:Radiation-Sensitizing Agents