Chemical composition, antioxidant activity and cytotoxicity on tumour cells of the essential oil from flowers of <i>Magnolia grandiflora</i> cultivated in Iran

<p><i>Magnolia grandiflora</i> (Magnoliaceae) is an evergreen tree with fragrant and showy flowers native to southeastern USA but widely cultivated all over the world and used in cosmetics industry in treatment of skin diseases. Here, we report on the chemical analysis of the essential oil obtained from flowers of plants cultivated in Iran, together with the evaluation of its antioxidant and cytotoxic activities. The essential oil composition was dominated by bioactive sesquiterpenes, namely <i>β</i>-elemene, bicyclogermacrene, germacrene D and (<i>E</i>)-caryophyllene. The oil exhibited moderate radical scavenging activity towards the radical, and mild non-selective inhibitory effects against A375, MDA-MB 231 and T98 G tumour cell lines. The latter were influenced by the presence of the anticancer <i>β</i>-elemene. These results provided new insights for potential application of <i>M. grandiflora</i> volatile oil in the pharmaceutical and cosmetics industry where only the non-volatile magnolol and honokiol have hitherto been fully exploited.</p

Efficiency of singlet oxygen generation by photoactivated C14 porphyrin.

<p>Effect of the irradiation time on the fluorescence properties of a DMA solution (initial absorbance around 1 at 380 nm) and porphyrin solution (initial absorbance around 0.4 at 420 nm) in N,N-dimethyl-formamide (DMF), which was exposed to white light (400–800 nm) at a fluence rate of 100 mW/cm². The spectra taken at 1, 3, 5, 10 and 15 s were overlapping, and the corresponding coloured lines have been omitted from the legend, for clarity.</p

Larvicidal photosensitizing effect of C14 porphyrin.

<p>Mortality of <i>Ae. aegypti</i> larvae (n = 50) incubated with C14 at 28±2°C in the dark for 12 h, and then exposed to light (fluence rate 1.0–4.0 mW/cm²) for 1 or 6 h. After irradiation, larvae were kept in the dark and larval mortality was monitored daily for 6 days. Arithmetic means of % dead larvae. Error bars represent standard deviation (n = 3 replicates of 50 larvae each).</p

Influence of irradiation time on C14 porphyrin LC₅₀ on <i>Ae. aegypti</i> larvae.

<p>Error bars represent 95% confidence interval (n = 3 replicates of 100 larvae each). The shaded area in the graph indicates the period of incubation without light (night).</p

Effect of concentration on the absorbance of C14 porphyrin solutions.

<p>Solutions were prepared in PBS. <b>A:</b> absorbance of solutions at the maximum of the Soret band (424 nm); <b>B:</b> absorbance at a wavelength characterized by a lower molar extinction coefficient (404 nm).</p

Median lethal concentrations (LC₅₀) of C14 porphyrin.

<p>C14 solutions at 7 increasing concentrations (range 0.03–4.3 µM) were incubated with 6 mg PFP at 28±2°C in the dark for 48 h. <i>Ae. aegypti</i> larvae (3^rd–early 4^th instar, n = 100, 3 replicates) were introduced 12 hours before the beginning of the irradiation (1.0–4.0 mW/cm²).</p

Larvicidal activities of C14 porphyrin-incubated and non incubated PFP.

<p>5 µM C14 porphyrin solutions were used. PFP (70 mg), either pre-incubated with C14 or untreated, was added at the time of introduction of <i>Ae. aegypti</i> larvae (n = 50, see <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0001434#s2" target="_blank">methods</a> for details on preparation). Arithmetic means of percent dead, dying and living larvae after within 3 hours irradiation (intensity 1.0–4.0 mW/cm²). Error bars represent standard deviations, (n = 3 replicates of 50 larvae each). Lowercase letters above bars represent the results of LSD tests carried out independently for each category of larvae (see <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0001434#s2" target="_blank">methods</a>). Different letters above bars indicate statistically different means.</p

Chemical structure of C14 porphyrin: meso-tri(N-methylpyridyl),meso-mono(N-tetradecylpyridyl)porphine.

<p>Chemical structure of C14 porphyrin: meso-tri(N-methylpyridyl),meso-mono(N-tetradecylpyridyl)porphine.</p

Residual activity of C14 solutions and formulates on <i>Ae. aegypti</i> larvae.

<p>Mortality was assessed after 12 h irradiation (1.0–4.0 mW/cm²).</p><p>*time elapsed between the preparation of the trays and the introduction of 3^rd–4^th instar larvae (n = 100 larvae; 3 replicates). During this period, trays were incubated in the climatic chamber (12 h photoperiod; 28±2°C; >90% RH). Numbers in parentheses indicate standard deviations.</p>†<p>trays contained 6 mg of untreated larval food in C14 porphyrin solutions at the indicated concentration.</p>‡<p>trays contained 6 mg of the indicated formulation in spring water.</p>§<p>one surviving larva was found in the tray. Such larvae were negative for C14 fluorescence at the microscope, therefore they hadn't fed during the experiment.</p

Survival of <i>Ae. aegypti</i> larvae exposed to C14 in the dark.

a<p>incubation was carried out with 5 µM C14 in the dark at 28±2°C; control larvae were incubated for 24 h.</p>b<p>surviving larvae at the end of the incubation period (n = 3 replicates of ∼50 larvae each). Numbers in parentheses indicate standard deviations.</p>c<p>Emerged adults/total pupae; pooled data from the three replications.</p>d<p>12 h-long irradiation (1.0–4.0 mW/cm²).</p