Photoprotective potential of lycopene, β-carotene, vitamin E, vitamin C and carnosic acid in UVA-irradiated human skin fibroblasts

The photoprotective potential of the dietary antioxidants vitamin C, vitamin E, lycopene, β-carotene, and the rosemary polyphenol, carnosic acid, was tested in human dermal fibroblasts exposed to ultraviolet-A (UVA) light. The carotenoids were prepared in special nanoparticle formulations together with vitamin C and/or vitamin E. Nanoparticle formulations, in contrast to dimethylsulphoxide, stablized lycopene in the cell culture medium and allowed efficient cellular uptake. The presence of vitamin E in the formulation further increased the stability and cellular uptake of lycopene. UVA irradiation of the human skin fibroblasts led to a 10–15-fold rise in metalloproteinase 1 (MMP-1) mRNA. This rise was suppressed in the presence of low μM concentrations of vitamin E, vitamin C, or carnosic acid but not with β-carotene or lycopene. Indeed, in the presence of 0.5–1.0 μM β-carotene or lycopene, the UVA-induced MMP-1 mRNA was further increased by 1.5–2-fold. This increase was totally suppressed when vitamin E was included in the nanoparticle formulation. Heme-oxygenase 1 (HO-1) mRNA expression was strongly induced by UVA irradiation but none of the antioxidants inhibited this effect at the concentrations used in this study. Indeed, β-carotene or lycopene (0.5–1.0 μM) led to a further 1.5-fold rise in the UVA-induced HO-1 mRNA levels. In conclusion, vitamin C, vitamin E, and carnosic acid showed photoprotective potential. Lycopene and β-carotene did not protect on their own but in the presence of vitamin E, their stability in culture was improved and the rise in MMP-1 mRNA expression was suppressed, suggesting a requirement for antioxidant protection of the carotenoids against formation of oxidative derivatives that can influence the cellular and molecular responses.     

Rapid high-performance liquid chromatographic method for the simultaneous determination of retinol, α-tocopherol and β-carotene in human plasma and low-density lipoproteins

A reversed-phase HPLC method with diode-array detection was used to simultaneously determine retinol, α-tocopherol and β-carotene in human plasma and low-density lipoproteins. An aliquot of sample was de-proteinized with ethanol containing α-tocopherol acetate as internal standard, and the analytes were extracted twice with hexane. The solvent was evaporated to dryness under a stream of nitrogen and the residue was redissolved in methanol to be injected directly into the HPLC system. A multiple solvent system based on methanol, butanol and water at a flow-rate of 2 ml/min and held at 45°C provided clear separation of these compounds in only 8 min. The method showed good linearity, precision and accuracy for all compounds. Owing to its simplicity, this method may be useful in routine clinical and epidemiological work.     

Prostaglandins E and F in uterine venous plasma in relation to peripheral plasma levels of progesterone and 20α-hydroxyprogesterone in the rat throughout pregnancy and parturition

Prostaglandins E and F in uterine venous plasma and progesterone (P) and 20α-hydroxyprogesterone (20α-OH-P) in peripheral plasma were measured by radioimmunoassays throughout pregnancy and parturition in the rat. E Prostaglandins are low (approx. 2 ng/ml) and maintain a more or less constant level throughout most of the pregnancy except just before parturition when they rise to 3.8 ng/ml on day 20. F Prostaglandin levels are always higher than E prostaglandins and show distinct peaks around day 5 (5 ng/ml), day 11 (7 ng/ml), and before parturition (8.4 ng/ml).Progesterone levels are higher than 20α-OH-P levels throughout most of the pregnancy (day 6–20); however, during early pregnancy (day 1–5) and before parturition more 20α-OH-P than P is present in peripheral blood.The possible role of uterine venous prostaglandin levels in altering the 20α-OH-P/P ratio during pregnancy and parturition is discussed.     

β-Carotene, vitamin C and vitamin E content of the marine microalga Dunaliella tertiolecta cultured with different nitrogen sources

Variations in the β-carotene, vitamin C and vitamin E content of D. tertiolecta have been shown to result from the nitrogen source used in the culture medium. Differences of 101%, 38% and 69% have been found in β-carotene, ascorbic acid and tocopherol content in mg/g of dry matter, respectively, and differences of 147%, 63% and 37% occurred in β-carotene, vitamin C and E concentrations in mg/litre of culture, respectively. Considering the β-carotene, vitamin C and vitamin E content in mg/g of chlorophyll a, maximum variations occurred in β-carotene content, with differences of 145% among the different nitrogen sources. Maximum β-carotene and vitamin C values were found in urea cultures, whereas urea cultures showed the minimum values for vitamin E.     

Influence of low plasma progesterone concentrations on the release of prostaglandin F2α during luteolysis and oestrus in heifers

A study was conducted to determine the effect of suprabasal plasma concentrations of progesterone on the release of prostaglandin F_2α (PGF_2α) at luteolysis and oestrus. Heifers received silicone implants containing 2.5 (n = 4), 5 (n = 4), 6 (n = 3), 7.5 (n = 3), 10 (n = 4), or 15 (n = 3) g of progesterone, or an empty implant (controls, n = 4) between Days 8 and 25 post ovulation. Blood was collected frequently between Days 14 and 28 and assayed for progesterone and 15-ketodihydroprostaglandin F_2α. Basal progesterone concentrations in control heifers did not differ from those in heifers with 2.5- or 5-g implants and remained around 0.4−0.5 nmol l⁻¹ until ovulation in all three groups. In the heifers treated with 6–15 g of progesterone, basal concentrations were maintained at higher (P < 0.05) levels compared with those in the controls, ranging from 0.8 to 1.6 nmol 1⁻¹. The effect of these elevated progesterone levels was to delay ovulation by prolonging the growth of the ovulatory follicle, which continued growing until the implant was removed. In all experimental groups, the first significant increase of the PGF_2α metabolite occurred between Days 15.3 and 16.3 (P > 0.05) and was associated with the onset of a decrease in progesterone concentrations, which had reached levels below 3 nmol 1⁻¹ by Days 17.4−19.1. PGF_2α metabolite peaks associated with luteolysis were frequent until Day 20. In the period from Day 20 until implant removal, sporadic peaks were observed, ranging in number from 1.0 ± 1.2 (mean ± SEM) in the control group to 3.0 ± 1.4 peaks in the heifers treated with 7.5 g of progesterone (P > 0.05). The number of PGF_2α metabolite peaks during that period was higher (P < 0.05) in heifers treated with 10 and 15 g than in controls. A positive correlation was found between the basal concentration of progesterone and the number of PGF_2α peaks after luteolysis (r = 0.54; P < 0.01). Plasma progesterone concentrations above approximately 1.4 nmol l⁻¹ were able to maintain the release of PGF_2α until the progesterone implants were removed and plasma levels decreased to basal values. These heifers had a preovulatory PGF_2α release pattern resembling that found in repeat breeder heifers.     

Temporal relationships between peripheral plasma concentrations of oxytocin, progesterone and 13, 14-dihydro-15-keto-prostaglandin F2α during the oestrous cycle and early pregnancy in the ewe

Peripheral plasma concentrations of oxytocin, 13,14-dihydro-15-keto-prostaglandin F_2α(PGFM), progesterone and LH were determined at 3 hourly intervals during the oesterous cycle (n = 3) and in early pregnancy (n = 4) in sheep. The progesterone and LH concentrations showed that the cycling ewes were samples during the periods of luteal regression (decreasing progesterone concentrations), the preovulatory gonadotrophin surge and the beginning of the next luteal phase (increasing progesterone concentrations). The pregnant ewes had basal LH concentrations and luteal phase concentrations of progesterone (>lng/ml afte day 5 following mating) throughout the whole of the sampling period. Oxytocin concentrations in the non-pregnant ewes decreased around the time of luteal regression to reach low concentrations (mean concentrations of approximately 18pg/ml) during the preovulatory period and then increased after the preovulatory surge. PGFM concentrations exhibited a pulsatile pattern with increasing concentrations as progesterone levels fell. In the pregnant ewes oxytocin concentrations gradually fell until approximately 16 days post-mating (approximately 7–8pg/ml). The magnitude of the pulses in PGFM concentrations were also lower than in the cycling ewes. These results demonstrate that the increased concentrations of PGFM which are found during the period of luteal regression are not caused by increased peripheral concentrations of oxytocin.