Investigation of the tannin constituents of Tamarix nilotica (Tamaricaceae) has resulted in the isolation of one new (1) and the three known trimeric ellagitannins hirrtellins T1 (4), T2 (2) and T3 (3). On the basis of spectroscopic and chemical experiments, the new tannin (1) was assigned a unique macrocyclic structure consisting of three tatally acylated glucose cores connected together by a p-dehydrodigalloyl (p-GOG) and two m-dehydrodigalloyl (m-GOG) moieties in the mode shown by the formula 1. Major T. nilotica dimers, hirtellins A (5) and B (6) and tamarixinin A (7), together with some related tannins, remurins A (8) and B (9), milotinins M4 (10) and D8 (11), with good abundance in the plant, were tested for their possible direct cytotoxic activity on human oral squamous cell carcinoma (HSC-2, HSC-3, anc HSC-4) and promyelocytic leukemia (HL-60) cell lines compared with their effects on human oral normal cells (HGF, HPC and HPLF), and all of the tested tannins were potently cytotoxic against HL-60 cells. Among all of the tested tannins, hirtellin A (5) and nilotinin D8 (11) showed potent cytotoxic effects and elevated tumor specificity (TS) values against all tested tumor cell lines. Upon oujr effort to find an alternative source for the stable production of these tannins through a biotechnological approach we established shoot cultures of T. tetrandra capable of producting ellagitannins. Chromatographic separations of an extract of cultured tissues, afforded 14 known monomeric-tetrameric together with new monomeric (12) and trimeric (13) ellagitannins, belonging to the different type of the tamaricaceous tannins. Known tannins were identified as 4 monomers, tellimagrandins I (14) and II (15), nilotinin M2 (16), remurin A (8), 8 dimers, hirtellins A (5), B (6) and C (19), isohirtellin C (20), milotinin D3 (17), tamarixinins A (7), B (21) and C (18), a trimer, hirtellin T1 (4) and a tetramer, hirtellin Q1 (22). The structure where O-1 of a glucose core of hirtellin T1 (4) was deacylated was assigned for the new trimer 13. The new monomer (12) was determined as methyl (2,3-di-O-galloyl-4,6-hexahydroxydiphenoyl)-β-D-glucoside. The influences of light, and manipulating nutrients in the culture medium on the growth and tannin production in cultured shoots of T. tetrandra were examined. Tamaricaceous plants produce unique class of hydrolysable tannins, which could be candidates for developing low-toxocity antitumor agents. T. tetrandra cultured tissues produce monomeric-tetrameric ellagitannins common to tamaricaceous plants. Although the intact plant produce high amoung of hirtellin B (6), the cultured tissues of T. tetrandra accumulalte high amoung of hirtellin A (5), which has been shown to have significant host-mediated antitumor activity in a previous study, and prominent selective cytotosic effects against broad specrum of tumor cell lines in our present investigation.
