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Antitumor-promoting effects of gallotannins extracted from various sources in mouse skin in vivo
H U Gali1, E M Perchellet, X M Gao
1Anti-Cancer Drug Laboratory, Kansas State University, Manhattan 66506-4901.
Abstract:
Sumach leaf, Aleppo gall, Tara pod and commercial tannic acids (TAs) were tested topically for their ability to inhibit the biochemical and biological effects of 12-0-tetradecanoylphorbol-13-acetate (TPA) in mouse epidermis in vivo. These TAs all inhibit to various degrees ornithine decarboxylase (ODC) induction, hydroperoxide (HPx) production and the sequential stimulation of RNA, protein and DNA synthesis linked to TPA promotion. When applied before each promotion treatment, these TAs all inhibit complete tumor promotion by TPA. Sumach leaf TA is the most effective. TAs applied 24h after TPA inhibit HPx production but not tumor promotion, since ODC activity and DNA synthesis have already been stimulated. However, these TA post-treatments enhance the antioxidant and antitumor-promoting effects of TA pretreatments. TAs inhibit the 2nd rather than the 1st stage of tumor promotion. Plant TAs, therefore, may be valuable against tumor propagation but their efficacy may vary considerably depending on their origin.
Insights
Plant-derived tannic acids (TAs) effectively inhibit tumor promotion by blocking key biochemical effects. Sumach leaf tannic acid demonstrated the highest efficacy in preventing tumor development in mouse skin.
Area of Science:
- Biochemistry
- Dermatology
- Pharmacology
Background:
- 12-O-tetradecanoylphorbol-13-acetate (TPA) is a known promoter of skin tumor development.
- Tannic acids (TAs) are phenolic compounds with potential chemopreventive properties.
Purpose of the Study:
- To evaluate the topical efficacy of various plant-derived tannic acids (TAs) in inhibiting TPA-induced biochemical and biological effects in mouse epidermis.
- To determine the optimal timing for TA application in relation to TPA treatment for maximum tumor inhibition.
Main Methods:
- Topical application of Sumach leaf, Aleppo gall, Tara pod, and commercial tannic acids (TAs) to mouse epidermis.
- Assessment of ornithine decarboxylase (ODC) induction, hydroperoxide (HPx) production, and nucleic acid synthesis following TPA treatment.
- Evaluation of complete tumor promotion inhibition by TAs applied before or after TPA treatment.
Main Results:
- All tested TAs inhibited TPA-induced ODC induction, HPx production, and nucleic acid synthesis to varying degrees.
- Pre-treatment with TAs significantly inhibited complete tumor promotion, with Sumach leaf TA being the most effective.
- Post-treatment with TAs inhibited HPx production but not tumor promotion, though it enhanced the effects of TA pre-treatments.
- TAs primarily inhibit the second stage of tumor promotion.
Conclusions:
- Plant-derived tannic acids possess significant antitumor-promoting properties by interfering with key TPA-induced biochemical pathways.
- Sumach leaf tannic acid exhibits superior efficacy in inhibiting TPA-induced tumor promotion.
- The efficacy of plant TAs can vary based on their botanical origin, suggesting the importance of source selection for chemopreventive applications.