Hydrolyzable Tannins of Tamaricaceous Plants. V. Structures of Monomeric–Trimeric Tannins and Cytotoxicity of Macrocyclic-Type Tannins Isolated from Tamarix nilotica

• Published in: Journal of natural products (Washington, D.C.) Vol. 76; no. 5; pp. 947 - 956
• Main Authors: Orabi, Mohamed A. A, Taniguchi, Shoko, Sakagami, Hiroshi, Yoshimura, Morio, Yoshida, Takashi, Hatano, Tsutomu
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society and American Society of Pharmacognosy 24.05.2013; Amer Chemical Soc
• Subjects: Antineoplastic Agents, Phytogenic - chemistry; Antineoplastic Agents, Phytogenic - isolation & purification; Antineoplastic Agents, Phytogenic - pharmacology; Chemistry, Medicinal; Drug Screening Assays, Antitumor; Egypt; Fluorouracil - pharmacology; Humans; Hydrolyzable Tannins - chemistry; Hydrolyzable Tannins - isolation & purification; Hydrolyzable Tannins - pharmacology; Life Sciences & Biomedicine; Melphalan - pharmacology; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular; Pharmacology & Pharmacy; Plant Leaves - chemistry; Plant Sciences; Polyphenols - pharmacology; Science & Technology; Tamaricaceae - chemistry; Egypt; TUMOR-CELL LINES; REAUMURIA-HIRTELLA; POLYPHENOLS; INHIBITION; ELLAGITANNINS
• ISSN: 0163-3864; 1520-6025
• DOI: 10.1021/np4001625

Three new ellagitannin monomers, nilotinins M5–M7 (1–3), a dimer, nilotinin D10 (4), and a trimer, nilotinin T1 (5), together with three known dimers, hirtellin D (7) and tamarixinins B (8) and C (9), and a trimer, hirtellin T2 (6), were isolated from Tamarix nilotica dried leaves. The structures of the tannins were elucidated by intensive spectroscopic methods and chemical conversions into known tannins. The new trimer (5) is a unique macrocyclic type whose monomeric units are linked together by an isodehydrodigalloyl and two dehydrodigalloyl moieties. Additionally, dimeric and trimeric macrocyclic-type tannins isolated from T. nilotica in this study were assessed for possible cytotoxic activity against four human tumor cell lines. Tumor-selective cytotoxicities of the tested compounds were higher than those of synthetic and natural potent cytotoxic compounds, including polyphenols, and comparable with those of 5-fluorouracil and melphalan.