Abstract

Extracts of the herbs Oldenlandia diffusa (OD) and Scutellaria barbata (SB) have been used in traditional Chinese medicine for treating liver, lung and rectal tumors while extracts of Astragalus membranaceus (AM) and Ligustrum lucidum (LL) are often used as adjuncts in cancer therapy. In this study, we determined the effects of aqueous extracts of these four herbs on aflatoxin B1 (AFB1) benzo[a]pyrene (BaP), benzo[a]pyrene 7,8-dihydrodiol (BaP 7,8-DHD) and benzo[a]pyrene 7,8-dihydrodiol-9,10-epoxide (BPDE)-induced mutagenesis, mediated by enzymes in rat hepatic 9000 x g supernatant (S9), in Salmonella typhimurium TA100. We also studied the effects of these four herbs on AFB1 and BaP binding to calf thymus DNA and the effects of OD and SB on BaP 7,8-DHD and BPDE binding to calf thymus DNA. After incubation with rat hepatic S9, organosoluble metabolites of AFB1, BaP, and BaP 7,8-DHD were analyzed by reverse phase high performance liquid chromatography (HPLC), and water-soluble conjugates of BaP, BaP 7,8-DHD and BPDE were analyzed by alumina column liquid chromatography. Water-soluble conjugates of AFB1 were determined by passing through C18-Sep-pak cartridge and analyzed by HPLC. Mutagenesis assays showed that aqueous extracts of the herbs we tested produced a concentration-dependent inhibition of histidine-independent revertant (His+) colonies induced by AFB1, BaP, BaP 7,8-DHD, and BPDE. LL, OD, and SB inhibited AFB1 metabolite binding to calf thymus DNA, formation of AFB1-DNA adducts and metabolism of AFB1. These three herbs also inhibited the binding of BaP metabolites to calf thymus DNA. LL and SB decreased BaP-DNA adduct formation and SB inhibited the metabolism of BaP. OD and SB significantly inhibited the metabolism of BaP 7,8-DHD and the formation of water-soluble conjugates of BaP 7,8-DHD and BPDE. Both OD and SB modified the distribution of conjugates within the water-soluble fraction. SB inhibited BaP 7,8- DHD and BPDE binding to DNA and decreased the formation of adducts. Our results therefore suggest that the Chinese medicinal herbs LL, OD and SB possess antimutagenic and anticarcinogenic properties. OD and SB may possess these properties because they are able to scavenge the reactive metabolites and thus prevent their interaction with DNA.

LLU Discipline

Biology

Department

Biology

School

Graduate School

First Advisor

Benjamin H. S. Lau

Second Advisor

Ronald L. Carter

Third Advisor

David L. Cowles

Fourth Advisor

E. Clifford Herrmann

Fifth Advisor

Robert W. Teel

Degree Name

Doctor of Philosophy (PhD)

Degree Level

Ph.D.

Year Degree Awarded

1992

Date (Title Page)

6-1992

Language

English

Library of Congress/MESH Subject Headings

Herbs -- drug effects Medicine; Chinese Traditional Aflatoxin B1 -- metabolism; Benzo(a)pyrene -- metabolism; Antimutagenic Agents -- analysis; Anticarcinogenic Agents -- analysis

Type

Dissertation

Page Count

vi; 92

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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