Cytotoxic activity of dietary lignan and its derivatives: structure-cytotoxic activity relationship of dihydroguaiaretic acid

Structure-Antifungal Activity Relationship of Fluorinated Dihydroguaiaretic Acid Derivatives and Preventive Activity against Alternaria alternata Japanese Pear Pathotype

The structure-activity relationship of the antifungal fluorinated dihydroguaiaretic acid derivatives was evaluated. Some of the newly synthesized lignan compounds were found to show higher antifungal activity against phytopathogenic fungi such as Alternaria alternata (Japanese pear and apple pathotypes) and A. citri than the lead compound, 3-fluoro-3'-methoxylignan-4'-ol (3). The broad antifungal spectrum of 3'-hydroxyphenyl derivative 16 was observed, and the 3'-fluoro-4'-hydroxyphenyl derivative 38 was found to show the highest activity against the A. alternata Japanese pear pathotype, with an EC₅₀ value of 11 μM. The preventive effect of the potent lignan on the infection of A. alternata in the Japanese pear's leaves was also shown.

Neuroprotective Lignans from the Fruits of Schisandra bicolor var. tuberculata

Nine new lignans (1-9) and ten known analogues (10-19) were isolated from the fruits of Schisandra bicolor var. tuberculata. The structures of compounds 1-9 were established on the basis of spectroscopic data analysis. The absolute configuration of compound 1 was determined by single-crystal X-ray diffraction analysis with Cu Kα irradiation techniques, and the absolute configurations of compounds 2-9 were deduced by comparing their experimental ECD spectra and optical rotations with those of compound 1 or similar compounds. All isolates were evaluated for their neuroprotective activities against CoCl₂, H₂O₂, and Aβ_25-35-induced SH-SY5Y cell injury, and were found to exhibit different degrees of neuroprotective effects. At a low concentration of 3.2 nM, compounds 3, 8, 9, and 14-19 in CoCl₂-induced, compounds 7, 8, 13, 17, and 18 in H₂O₂-induced, and compounds 2, 6, 7, 9, 10, and 12-19 in Aβ_25-35-induced SH-SY5Y cell injury models, showed statistically significant neuroprotective activities, when compared with each negative control group.

Enantioselective syntheses of both enantiomers of 9'-dehydroxyimperanene and 7,8-dihydro-9'-dehydroxyimperanene and the comparison of biological activity between 9-norlignans and dihydroguaiaretic acids

To estimate the effect of methyl group of dihydroguaiaretic acid, which shows many kinds of biological activities, on biological activity, both enantiomers of 9'-dehydroxyimperanene (5, 6) and 7,8-dihydro-9'-dehydroxyimperanene (7, 8) lacking one of the methyl groups of dihydroguaiaretic acid were synthesized. (S)-7,8-Dihydro-9'-dehydroxyimperanene (7) showed 4-6-fold higher cytotoxic activity than all stereoisomers of dihydroguaiaretic acid (2-4). The IC50 values of (S)-7,8-dihydro-9'-dehydroxyimperanene (7) against HL-60 and HeLa cells were 6.1μM and 5.6μM, respectively. Though only one of three stereoisomers of dihydroguaiaretic acid showed antibacterial activity against a gram negative bacterium, both enantiomers of 5-8 showed antibacterial activity against a gram negative bacterium. This is a Letter on biological activity of 9-norlignan, in which one of methyl groups of lignan is absent.

Effect of the structure of dietary epoxylignan on its cytotoxic activity: relationship between the structure and the activity of 7,7′-epoxylignan and the introduction of apoptosis by caspase 3/7

We compared the cytotoxic activities of dietary epoxylignans and their stereoisomers and found (−)-verrucosin, which is (7S,7′R,8R,8′R)-7,7′-epoxylignan, to be the most cytotoxic epoxylignan against HeLa cells (IC50 = 6.6 μM). On the other hand, the activity was about a factor of 10 less against HL-60. In this research on the relationship between the structure and cytotoxic activity of (−)-verrucosin 13, the 7-(4-methoxyphenyl)-7′-(3,4-dimethoxyphenyl) derivative 60, for which the activity (IC50 = 2.4 μM) is three times greater than (−)-verrucosin 13, was discovered. The induction of apoptosis by caspase 3/7 was observed upon treatment with the (−)-verrucosin derivative.

Revised stereochemistry of ficifolidione and its biological activities against insects and cells

Ficifolidione (1), a moderately active insecticidal compound from two species of Myrtaceae, and its derivatives were synthesized to evaluate their insecticidal activity. X-ray crystallographic analyses and specific rotation values of ficifolidione and its C-4 (2) demonstrated that the structure of ficifolidione differs from the reported absolute structure; that is, the C-4 configuration of ficifolidione should have an S configuration. The reported insecticidal activity of ficifolidione (1) and its C-4 epimer (2) against adult houseflies (Musca domestica), mosquito larvae (Culex pipiens), and cutworms (Spodoptera litura) was not observed. The cytotoxicities of ficifolidione and its derivatives (1-4) against four cell lines, Sf9, Colon26, HL60, and Vero, were also measured because ficifolidione has a phloroglucinol-derived moiety, a motif that is often present in the structure of cytotoxic chemicals. Compound 1 exhibited IC50 values of ca. 32, 9, 3, and 12 μM for Sf9, Colon26, HL60, and Vero cells, respectively, indicating that ficifolidione possesses selective cytotoxicity against the four cell lines. In HL60 cells treated with 1, DNA fragmentation and the activation of procaspase 3 were observed, suggesting that the cytotoxicity is induced by apoptosis.

Development of nordihydroguaiaretic acid derivatives as potential multidrug-resistant selective agents for cancer treatment

A new series of nordihydroguaiaretic acid (NDGA) derivatives have been synthesized for the research of multidrug resistance (MDR) in cancer.

Cytotoxic activity of butane type of 1,7-seco-2,7'-cyclolignanes and apoptosis induction by Caspase 9 and 3

All stereoisomers of methoxybutane and fluorobutane type of 1,7-seco-2,7'-cyclolignane were synthesized and cytotoxic activities of these compounds were compared with those of all stereoisomers of butane and butanol type compounds. Both enantiomers of butane type secocyclolignane showed higher cytotoxic activity (IC50=16-20 μM) than methoxy type compounds, whereas none was observed for all the stereoisomers of butanol type secocyclolignane, however, (-)-Kadangustin J showed stereospecific cytotoxic activity (IC50=47-67 μM). Since (R)-9'-fluoro derivative 23 was most potent (IC50=19 μM) among the corresponding fluoro stereoisomers, (R)-9'-alkyl derivatives were synthesized, hydrophobic 9'-heptyl derivative 27 showing highest activity (IC50=3.7 μM against HL-60, IC50=3.1 μM against HeLa) in this experiment. Apoptosis induction caused by Caspase 3 and 9 for (R)-9'-heptyl derivative 27 was observed in the research on the mechanism. A degradation of DNA into small fragments was also shown by DNA ladder assay.