Influence of side chain structure changes on antioxidant potency of the [6]-gingerol related compounds.

[6]-Gingerol and [6]-shogaol are the major pungent components in ginger with a variety of biological activities including antioxidant activity. To explore their structure determinants for antioxidant activity, we synthesized eight compounds differentiated by their side chains which are characteristic of the C1-C2 double bond, the C4-C5 double bond or the 5-OH, and the six- or twelve-carbon unbranched alkyl chain. Our results show that their antioxidant activity depends significantly on the side chain structure, the reaction mediums and substrates. Noticeably, existence of the 5-OH decreases their formal hydrogen-transfer and electron-donating abilities, but increases their DNA damage- and lipid peroxidation-protecting abilities. Additionally, despite significantly reducing their DNA strand breakage-inhibiting activity, extension of the chain length from six to twelve carbons enhances their anti-haemolysis activity.

Synthesis and biological evaluation of hydroxylated 3-phenylcoumarins as antioxidants and antiproliferative agents.

Based on the observed biological activities of coumarins and resveratrol, we synthesized fourteen hydroxylated 3-phenylcoumarins (stilbene-coumarin hybrids) including six novel ortho-hydroxy-methoxy substituted derivatives, 1-14, by Perkin reaction. We characterized these compounds concerning their antioxidant activity against 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH)-induced pBR322 DNA strand breakage, and their antiproliferative effects on human promyelocytic leukemia HL-60 and human lung adenocarcinoma epithelial A549 cells. Structure-activity relationship information suggests that the introduction of ortho-hydroxy-methoxy groups and ortho-dihydroxy groups on the aromatic A ring could efficiently improve antiproliferative activity. Interestingly, a new derivative, 6-methoxy-7-hydroxy-3-(4'-hydroxyphenyl)coumarin, 9, behaved as a poor antioxidant but appeared to be the most potent antiproliferative agent among the compounds examined, and this activity was mediated by deregulation in cell cycle and induction of apoptosis.

Two novel ent-kauranoid diterpenoids from Isodon japonica leaves.

Two novel ent-kaurane diterpenoids, taihangjaponicain A (1), and taihangjaponicain B ( 2), and nine known diterpenoids, epinodosin (3), oridonin (4), epinodosinol (5), lasiokaurin ( 6), 1alpha- O-beta- D-glucopyranosylenmenol (7), lasiodonin (8), rabdosichuanin D ( 9), shikokianin (10) and rabdoternin A (11) were isolated from I. japonica leaves. The structures of the two new compounds were elucidated using 1-D and 2-D NMR spectroscopy. Compounds 1 and 3 - 11 were tested against HL-60, HO-8910 and A-549 human tumor cells. Compounds 4, 6 and 10 showed significant cytotoxicity against HL-60 cells with IC (50) values of 4.6, 2.0 and 3.4 microM, respectively, and against A-549 cells with IC (50) values of 17.5, 11.4 and 18.8 microM, respectively. Compound 6 exhibited moderate cytotoxicity against HO-8910 cells with an IC (50) value of 17.9 microM.