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A carotenoid compound, crocetin, was used in two different types of tests involving animal tumors. These tests showed that crocetin both decreased the numbers of tumors as well as delaying onset.

a b s t r a c tFrom the reaction of 6-(p-methoxyphenyl) fulvene (1a), 6-(3,4-dimethoxyphenyl) fulvene (1b) and 6-(3,4,5-trimethoxyphenyl) fulvene (1c) with LiBEt 3 H, lithiated cyclopentadienide intermediates (2a-c) were synthesised. These intermediates were then transmetallated to vanadium with VCl 4 to yield the benzyl-substituted vanadocenes bis-[(p-methoxybenzyl)cyclopentadienyl] vanadium(IV) dichloride (3a), bis-[(3,4-dimethoxybenzyl)cyclopentadienyl] vanadium(IV) dichloride (3b), and bis-[(3,4,5-trimethoxybenzyl)cyclopentadienyl] vanadium(IV) dichloride (3c). The two vanadocenes 3a and 3c were characterised by single crystal X-ray diffraction. All three vanadocenes had their cytotoxicity investigated through MTT based preliminary in vitro testing on the LLC-PK (pig kidney epithelial) cell line in order to determine their IC50 values and compare them with the corresponding titanocene dichloride derivatives.Vanadocenes 3b-c were found to have IC50 values of 9.1 and 8.3 lM, while 3a showed a superior value of 3.0 lM, respectively.

From the reaction of 6‐(2‐fluoro‐4‐methoxyphenyl)fulvene (1a), 6‐(3‐fluoro‐4‐methoxyphenyl)fulvene (1b) and 6‐[4‐(trifluoromethoxy)phenyl]fulvene (1c) with LiBEt3H, lithiated cyclopentadienide intermediates (2a–c) were synthesised. These intermediates were then transmetallated to vanadium with VCl4 to yield the benzyl‐substituted vanadocenes bis[(2‐fluoro‐4‐methoxybenzyl)cyclopentadienyl]vanadium(IV) dichloride (3a), bis[(3‐fluoro‐4‐methoxybenzyl)cyclopentadienyl]vanadium(IV) dichloride (3b), and bis[(4‐trifluoromethoxybenzyl)cyclopentadienyl]vanadium(IV) dichloride (3c). The three vanadocenes 3a–c were characterised by single‐crystal X‐ray diffraction. All three vanadocenes had their cytotoxicity investigated through MTT‐based preliminary in‐vitro testing on the LLC‐PK and Caki‐1 cell lines in order to determine their IC50 values. Vanadocenes 3a–c were found to have IC50 values of 6.0 (+/–4), 35 (+/–7) and 13 (+/–3) μM on the LLC‐PK cell line and IC50 values of 78 (+/–11), 18 (+/–16) and 2.2 (+/–0.5) μM on the Caki‐1 cell line respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)