2. Academic Validation
  3. Structures, NMR Spectroscopic Features, and Cytotoxic Properties of Oligomeric Hellinoyl (m-GO- m-GOG)-Type Ellagitannins from the Galls of Tamarix aphylla

Structures, NMR Spectroscopic Features, and Cytotoxic Properties of Oligomeric Hellinoyl (m-GO- m-GOG)-Type Ellagitannins from the Galls of Tamarix aphylla

  • J Nat Prod. 2019 Oct 25;82(10):2682-2695. doi: 10.1021/acs.jnatprod.9b00073.
Mohamed A A Orabi 1 2,  Esam A Orabi 3 4,  Shoko Taniguchi 5,  Hiroshi Sakagami 6,  Morio Yoshimura 7,  Yoshiaki Amakura 7,  Tsutomu Hatano 5
Affiliations

Affiliations

  • 1 Faculty of Pharmacy , Al-Azhar University , Assiut 71524 , Egypt.
  • 2 College of Pharmacy , Najran University , Najran 55461 , Kingdom of Saudi Arabia.
  • 3 Department of Chemistry , University of Manitoba , Winnipeg , Manitoba R3T 2N2 , Canada.
  • 4 Department of Chemistry, Faculty of Science , Assiut University , Assiut 71516 , Egypt.
  • 5 Graduate School of Medicine, Dentistry and Pharmaceutical Sciences , Okayama University , Tsushima , Okayama 700-8530 , Japan.
  • 6 Meikai University Research Institute of Odontology (M-RIO) , Meikai University School of Dentistry , 1-1 Keyakidai , Sakado-shi , Saitama 350-0283 , Japan.
  • 7 College of Pharmaceutical Sciences , Matsuyama University , Bunkyo-cho , Matsuyama 790-8578 , Japan.
PMID: 31532650 DOI: 10.1021/acs.jnatprod.9b00073
Abstract

Ellagitannin oligomers are large molecules habitually showing complex NMR spectra that are sometimes misinterpreted and lead to incorrect structures. Understanding the NMR spectroscopic features of a group of ellagitannins would overcome these inadequacies. In this study, investigation of the galls of Tamarix aphylla led to the isolation of three new ellagitannin oligomers, phyllagallins T1 (1), T2 (2), and Q1 (3), a known monomer nilotinin M4 (4), four known dimers, nilotinins D7 (5) and D8 (6), hirtellin B (7), and tamarixinin A (8), and a simple phenolic, dehydrotrigallic acid (9). 1D and 2D NMR, HRESI-TOFMS, and ECD experiments show that compounds 1-8 are hellinoyl-type ellagitannins. The NMR spectroscopic features of this type of ellagitannins and the reasons for the abnormal upfield shifts of glucose anomeric proton and hellinoyl moiety proton signals are established considering the experimental results as well as quantum chemical calculation on a simple hellinoyl-type monomer, phyllagallin M2. Based on these results, the NMR assignments reported previously by a different research group for bracteatinin T1 and hirtellin T3 are revised. A cytotoxicity study against human oral squamous cell carcinoma cell lines (Ca9-22, HSC-2, and HSC-4) and human mesenchymal normal oral cells (HGF, HPC, and HPLF) showed cytotoxic effects with tumor-specificity higher than 5.2, 3.0, 1.6, and 2.0 for compounds 5, 2, 9, and 3, respectively.

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