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Antitumor agents, 129. Tannins and related compounds as selective cytotoxic agents
Y Kashiwada1, G Nonaka, I Nishioka
1Natural Products Laboratory, School of Pharmacy, University of North Carolina, Chapel Hill 27599.
Abstract:
Fifty-seven tannins and related compounds, including gallotannins, ellagitannins, and condensed and complex tannins, were evaluated for their cytotoxicities against human tumor cell lines, including malignant melanoma, lung carcinoma, ileocecal adenocarcinoma, epidermoid carcinoma, malignant melanoma, and medulloblastoma cell lines. Among them, chebulagic acid [1], geraniin [2], sanguiin H-11 [3], 4,5-di-O-galloylquinic acid [12], 1,3,4,5-tetra-O-galloylquinic acid [15], 1(beta)-O-galloylpedunculagin [24], furosin [29], castalagin [38], sanguiin H-2 [34], vescalagin [39], grandinin [40], phyllyraeoidin A [42], (-)-epicatechin 3-O-gallate [50], cinnamtannin B2 [55], and acutissimin A [56] exhibited moderate selective cytotoxicity against PRMI-7951 melanoma cells with ED50 values in the range of 0.1-0.8 microgram/ml. Selective cytotoxicities against the melanoma cells were also observed for strictinin [22], pedunculagin [23], eugeniin [25], elaeocarpusin [28], punicacortein C [37], casuarinin [41], sanguiin H-6 [43], procyanidin B-2 3,3'-di-O-gallate [51], procyanidin C-1 3,3',3"-tri-O-gallate [52], and cinnamtannin B1 [54] with ED50 values of 1-4 micrograms/ml. All of the tannins were found to be inactive (greater than 10 micrograms/ml) against lung carcinoma (A-549), ileocecal adenocarcinoma (HCT-8), epidermoid carcinoma of nasopharnyx (KB), and medulloblastoma (TE-671) tumor cells.
Insights
Certain tannins show selective cytotoxicity against melanoma cells, with some compounds like chebulagic acid and geraniin demonstrating potent effects. However, these tannins were inactive against other tested cancer cell lines, indicating specificity in their anti-cancer properties.
Area of Science:
- Natural Products Chemistry
- Pharmacology
- Cancer Research
Background:
- Tannins are a diverse group of polyphenolic secondary metabolites found in plants.
- Many tannins possess biological activities, including antioxidant, anti-inflammatory, and antimicrobial properties.
- The cytotoxic potential of various tannin classes against human cancer cell lines warrants investigation.
Purpose of the Study:
- To evaluate the cytotoxicities of 57 different tannins and related compounds.
- To identify specific tannins with selective cytotoxic activity against human tumor cell lines.
- To determine the efficacy of these compounds against melanoma and other cancer types.
Main Methods:
- Fifty-seven tannins were screened for cytotoxicity.
- Assays were performed against human tumor cell lines: malignant melanoma (PRMI-7951), lung carcinoma (A-549), ileocecal adenocarcinoma (HCT-8), epidermoid carcinoma (KB), and medulloblastoma (TE-671).
- Selective cytotoxicity was assessed by determining ED50 values.
Main Results:
- Several tannins, including chebulagic acid, geraniin, and sanguiin H-11, exhibited moderate selective cytotoxicity against PRMI-7951 melanoma cells (ED50: 0.1–0.8 µg/ml).
- Other tannins like strictinin and pedunculagin also showed selective cytotoxicity against melanoma cells (ED50: 1–4 µg/ml).
- All tested tannins were inactive against lung carcinoma, ileocecal adenocarcinoma, epidermoid carcinoma, and medulloblastoma cell lines (ED50 > 10 µg/ml).
Conclusions:
- Certain tannins possess selective cytotoxic activity against melanoma cells.
- The efficacy of these tannins is specific to melanoma and not observed in other tested cancer cell lines.
- These findings highlight the potential of specific tannins as leads for melanoma-targeted therapies.