Antioxidant and anti-tumor promoting activities of the methanol extract of heat-processed ginseng.

Heat treatment of Panax ginseng C.A. Meyer at a temperature higher than that applied to the conventional preparation of red ginseng yielded a mixture of saponins with potent antioxidative properties. Thus, the methanol extract of heat-processed neoginseng (designated as 'NGMe') attenuated lipid peroxidation in rat brain homogenates induced by ferric ion or ferric ion plus ascorbic acid. Furthermore, the extract protected against strand scission in phiX174 supercoiled DNA induced by UV photolysis of H2O2, and was also capable of scavenging superoxide generated by xanthine-xanthine oxidase or by 12-O-tetradecanoylphorbol-13-acetate (TPA) in differentiated human promyelocytic leukemia (HL-60) cells. Topical application of NGMe onto shaven backs of female ICR mice 10 min prior to TPA, significantly ameliorated skin papillomagenesis initiated by 7,12-dimethylbenz[a]anthracene. Moreover, TPA-induced enhancement of epidermal ornithine decarboxylase (ODC) activity and ODC mRNA expression was abolished by a topical dose (0.68 mg) of NGMe. Likewise, TPA-induced production of tumor necrosis factor- in mouse skin was inhibited by NGMe pretreatment.

Effect of UV-B phototherapy on plasma HIV type 1 RNA viral level: a self-controlled prospective study.

OBJECTIVE: To study the plasma human immunodeficiency virus type 1 (HIV-1) RNA levels of 12 patients seropositive for HIV who were undergoing UV-B phototherapy to determine if UV-B phototherapy upregulates HIV activity in humans. DESIGN: A self-controlled prospective cohort of HIV-infected patients seen for the treatment of a skin disorder responsive to UV-B phototherapy. Viral levels were measured weekly for 8 weeks of phototherapy. Follow-up viral levels were measured for patients who continued phototherapy beyond 8 weeks, those who had a significant change in their viral level, or both. SETTING: Outpatient clinic of an academic hospital. PATIENTS: Patients with HIV disease and a skin disorder responsive to UV-B phototherapy. Inclusion criteria for patients in this study were those receiving a stable antiviral regimen for at least 6 weeks and who had no major illness or immunization in the 2 months before starting phototherapy. Of 72 patient volunteers screened, 15 met the criteria, 2 declined to participate, and 13 entered the study. One patient was dropped from the study because an accurate baseline measurement could not be obtained. Twelve patients were analyzed, 2 of whom left the study early, 1 at 6 weeks and 1 at 7 weeks. INTERVENTIONS: Ultraviolet-B phototherapy. MAIN OUTCOME MEASURE: Plasma HIV-1 RNA viral level. RESULTS: Plasma HIV-1 RNA levels showed no significant increase or decrease in most of the patients, defined as a 3-fold change from baseline (mean fold change from baseline after 8 weeks of phototherapy, -1.1; 95% confidence interval, 2.9 to -5.0). Trend analysis indicated no significant pattern of change in viral levels (slope, -0.013 log; P > .25). The CD4+ cell counts also remained unchanged (mean before therapy, 277 x 10(9)/L; mean after therapy, 285 x 10(9)/L; P = .67). CONCLUSION: No significant effect of UV-B exposure was seen on plasma HIV-1 levels.

Photobiological activity of sulphur and selenium analogues of psoralen.

Eight psoralen analogues, in which sulphur or selenium replaces one or both intracyclic oxygen atoms, were synthesized. Photoreaction with M13mp19 RF DNA in the presence and absence of oxygen (wavelength, greater than 320 nm) was studied. The damaged viral DNA was transfected into Escherichia coli and scored for infectivity towards Ca-treated wild-type E. coli. This allowed a comparative evaluation to be made of the heteropsoralens in terms of the photoreaction with DNA and the photodynamic effect. Most of the seleno- and thio-psoralens show very high photoactivity towards DNA compared with psoralen and 8-methoxypsoralen (8-MOP). Their photoreactivity is due mainly to a [2 + 2] photoreaction, since only a minor influence of molecular oxygen could be detected. Some of the studied seleno- and thio-psoralens are very efficient DNA photoinactivating agents and show great promise in photochemotherapy.

DNA damage induced by furocoumarin hydroperoxides plus UV (360 nm).

When irradiated at 360 nm, furocoumarins with a hydroperoxide group in a side chain efficiently give rise to a type of DNA damage that can best be explained by a photo-induced generation of hydroxyl radicals from the excited photosensitizers. The observed DNA damage profiles, i.e. the ratios of single-strand breaks, sites of base loss (AP sites) and base modifications sensitive to formamidopyrimidine--DNA glycosylase (FPG protein) and endonuclease III, are similar to the DNA damage profile produced by hydroxyl radicals generated by ionizing radiation or by xanthine and xanthine oxidase in the presence of Fe(III)--EDTA. No such damage is observed with the corresponding furocoumarin alcohols or in the absence of near-UV radiation. The damage caused by the photo-excited hydroperoxides is not influenced by superoxide dismutase (SOD) or catalase or by D2O as solvent. The presence of t-butanol, however, reduces both the formation of single-strand breaks and of base modifications sensitive to FPG protein. The cytotoxicity caused by one of the hydroperoxides in L5178Y mouse lymphoma cells is found to be dependent on the near-UV irradiation and to be much higher than that of the corresponding alcohol. Therefore the new type of photo-induced damage occurs inside cells. Intercalating photosensitizers with an attached hydroperoxide group might represent a novel and versatile class of DNA damaging agents, e.g. for phototherapy.