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1.
Plant Physiol Biochem ; 106: 141-8, 2016 Sep.
Article in English | MEDLINE | ID: mdl-27161580

ABSTRACT

Aloe vera L. is one of the most important medicinal plants in the world. In order to determine the effects of light intensity and water deficit stress on chlorophyll (Chl) fluorescence and pigments of A. vera, a split-plot in time experiment was laid out in a randomized complete block design with four replications in a research greenhouse. The factorial combination of three light intensities (50, 75 and 100% of sunlight) and four irrigation regimes (irrigation after depleting 20, 40, 60 and 80% of soil water content) were considered as main factors. Sampling time was considered as sub factor. The first, second and third samplings were performed 90, 180 and 270 days after imposing the treatments, respectively. The results demonstrated that the highest light intensity and the severe water stress decreased maximum fluorescence (Fm), variable fluorescence (Fv)/Fm, quantum yield of PSII photochemistry (ФPSII), Chl and photochemical quenching (qP) but increased non-photochemical quenching (NPQ), minimum fluorescence (F0) and Anthocyanin (Anth). Additionally, the highest Fm, Fv/Fm, ФPSII and qP and the lowest NPQ and F0 were observed when 50% of sunlight was blocked and irrigation was done after 40% soil water depletion. Irradiance of full sunlight and water deficit stress let to the photoinhibition of photosynthesis, as indicated by a reduced quantum yield of PSII, ФPSII, and qP, as well as higher NPQ. Thus, chlorophyll florescence measurements provide valuable physiological data. Close to half of total solar radiation and irrigation after depleting 40% of soil water content were selected as the most efficient treatments.


Subject(s)
Aloe/metabolism , Aloe/radiation effects , Chlorophyll/metabolism , Light , Agricultural Irrigation , Aloe/growth & development , Analysis of Variance , Anthocyanins/metabolism , Dehydration , Fluorescence , Photochemical Processes/radiation effects
2.
J Agric Food Chem ; 61(9): 2165-70, 2013 Mar 06.
Article in English | MEDLINE | ID: mdl-23406252

ABSTRACT

In this paper, the effects of ultraviolet (UV) treatments on the aloin content of Aloe vera L. gel have been analyzed. UV-A treatment to A. vera plants for 36 days led to an increase in the aloin concentration in gel, rind tissue, and latex, while a decrease in chlorophylls a and b occurred in the photosynthetic tissue as a consequence of UV treatment. The growth of Penicillium digitatum and Botrytis cinerea (artificially inoculated on the leaf surface) was drastically decreased in UV-A-treated leaves, which could be attributed to the increase in the aloin concentration by the UV-A treatment. In addition, UV-C treatment to detached leaves also led to an increase in the gel aloin concentration, at higher levels than occurred with UV-A treatment, although leaves showed severe lesions after 48 h of treatment.


Subject(s)
Aloe/chemistry , Aloe/radiation effects , Emodin/analogs & derivatives , Plant Leaves/chemistry , Ultraviolet Rays , Botrytis/growth & development , Chlorophyll/analysis , Emodin/analysis , Emodin/metabolism , Emodin/pharmacology , Fungicides, Industrial , Penicillium/growth & development , Plant Leaves/microbiology
3.
Ying Yong Sheng Tai Xue Bao ; 21(1): 260-4, 2010 Jan.
Article in Chinese | MEDLINE | ID: mdl-20387453

ABSTRACT

By using transmission electron microscopy and high performance liquid chromatography, this paper studied the effects of enhanced UV-B radiation on the leaf anthraquinones content and cell ultrastructure of Aloe vera L. After treated with enhanced UV-B radiation 6 hours per day for 20 days, the total anthraquinone content, barbaloin content, and aloe-emondin content in A. vera leaves increased by 31.8%, 11.3%, and 22.0%, respectively, chloroplast envelope membrane was slightly damaged, but the structure of other organelles had no significant change. It was suggested that UV-B radiation could promote the accumulation of anthraquinone in A. vera leaves, but had less effects on the leaf cell ultrastructure.


Subject(s)
Aloe/radiation effects , Anthraquinones/metabolism , Plant Leaves/metabolism , Ultraviolet Rays , Aloe/metabolism , Aloe/ultrastructure , Anthracenes/metabolism , Plant Leaves/ultrastructure
4.
Toxicol Lett ; 168(2): 165-75, 2007 Jan 30.
Article in English | MEDLINE | ID: mdl-17197137

ABSTRACT

Aloe vera whole leaf extracts are incorporated into a wide variety of topically applied commercial products. Aloe vera whole leaf extracts may contain anthraquinones, which have been shown to generate reactive oxygen species in the presence of ultraviolet A (UVA) light. Exposure to UVA light alone can also generate reactive oxygen species and is associated with photo-damaged and photo-aged skin in humans. This paper examines the photochemical properties of two Aloe vera whole leaf extracts that differed in their anthraquinone content. In the presence of methyl linoleate, the UVA irradiation of Aloe vera leaf extracts induced lipid peroxidation. The amounts of lipid peroxides formed were higher in the Aloe vera leaf extract that contained lower amounts of anthraquinones. Superoxide dismutase and sodium azide inhibited and deuterium oxide enhanced the formation of lipid peroxides, suggesting that singlet oxygen and superoxide were involved in the mechanism. Spin trapping electron spin resonance (ESR) spectroscopy was used to investigate the generation of free radicals by the UVA photo-irradiated Aloe vera plant extracts. ESR measurements indicated that the UVA photo-irradiation of Aloe vera plant extracts produced carbon-centered free radicals. These results suggest that humans exposed to products that contain Aloe vera whole leaf extracts may have enhanced sensitivity to ultraviolet light.


Subject(s)
Aloe/metabolism , Aloe/radiation effects , Free Radicals/chemistry , Lipid Peroxidation/radiation effects , Reactive Oxygen Species/chemistry , Superoxides/chemistry , Electron Spin Resonance Spectroscopy , Emodin/analogs & derivatives , Emodin/chemistry , Emodin/radiation effects , Free Radical Scavengers/chemistry , Linoleic Acids/chemistry , Plant Extracts/analysis , Plant Extracts/radiation effects , Ultraviolet Rays
5.
Photochem Photobiol Sci ; 4(4): 333-40, 2005 Apr.
Article in English | MEDLINE | ID: mdl-15803203

ABSTRACT

In Aloe arborescens Mill. leaves, strong sunlight or its combination with drought induces the accumulation of the red keto-carotenoid, rhodoxanthin. Simultaneously, the transformation of chloroplasts into chromoplasts accompanied by degradation of thylakoid membranes and formation of plastoglobuli, large in size and number, takes place. Depending on stress conditions the build up of rhodoxantin occurred along with the loss of chlorophyll or on the background of relatively high content of the pigment in the leaves. Microspectrophotometrical measurements showed the presence of chlorophyll-free plastids and retention of carotenoids during leaf adaptation to strong sunlight. The plastid spectra contained absorption bands of common for higher plants carotenoids together with those of rhodoxantin, with absorption maxima situated in the blue (440-480 nm) and the green ranges of the spectrum, respectively. The studies of whole-leaf optical properties revealed a broad band of rhodoxanthin absorption in the blue-green range peaking near 540-550 nm. Within this spectral band the accumulation of rhodoxanthin occurring, probably, in plastoglobuli considerably increased light absorption by stressed Aloe leaves. A possible photoprotective function of rhodoxanthin and other carotenoids as an internal light trap analogous to that accomplished by anthocyanins in other plant species is discussed.


Subject(s)
Aloe/chemistry , Aloe/radiation effects , Light/adverse effects , Plant Leaves/chemistry , Plant Leaves/radiation effects , Xanthophylls/analysis , Aloe/ultrastructure , Plant Leaves/ultrastructure
6.
Pharmazie ; 57(6): 399-404, 2002 Jun.
Article in English | MEDLINE | ID: mdl-12116877

ABSTRACT

Aloe-emodin (1), emodin (2) and rhein (3) were found to be photolabile by visible (390-500 nm) light under aerobic conditions. The drugs 1, 2 and 3 were phototoxic in vitro when examined by the photohemolysis test under both oxygen and argon atmospheres, although the photohemolysis rate was markedly lower under anaerobic conditions. The experiments were also carried out in the presence of butylated hydroxyanisole (BHA), reduced glutathione (GSH), sodium azide (NaN3) and superoxide dismutase (SOD). Based on the inhibition of this process on addition of BHA, GSH, SOD and NaN3, there would seem to be involvement of free radicals (type I mechanism) and singlet oxygen in the process (type II mechanism). The in vitro phototoxicity of this anthraquinone series was also verified in a lipid-photoperoxidation test with linoleic acid. In summary, this anthraquinone series is phototoxic in vitro. This behavior can be explained through the involvement of singlet oxygen and stable photoproducts.


Subject(s)
Aloe/chemistry , Anthraquinones/chemistry , Dermatitis, Phototoxic/pathology , Emodin/chemistry , Acetylcholinesterase/blood , Aloe/radiation effects , Anthraquinones/pharmacology , Anthraquinones/radiation effects , Drug Stability , Emodin/pharmacology , Emodin/radiation effects , Erythrocytes/drug effects , Erythrocytes/enzymology , Hemolysis/drug effects , Humans , In Vitro Techniques , Linoleic Acid/chemistry , Lipid Peroxidation/drug effects , Photochemistry , Reactive Oxygen Species/metabolism , Ultraviolet Rays
7.
J Am Podiatr Med Assoc ; 79(8): 395-7, 1989 Aug.
Article in English | MEDLINE | ID: mdl-2810076

ABSTRACT

Aloe vera preparations were evaluated for topical anti-inflammatory activity using the croton oil-induced edema assay. The results show that small amounts of A. vera given topically will inhibit inflammation induced by a moderate amount of irritant. In general, the decolorized Aloe was more effective than the colorized Aloe (with anthraquinone). A 47.1% inhibition of inflammation was obtained by 5% decolorized irradiated Aloe. These results may be used as a baseline to assess the biologic activity of A. vera in the treatment of inflammation by podiatric physicians.


Subject(s)
Aloe , Anti-Inflammatory Agents/therapeutic use , Plants, Medicinal , Administration, Topical , Aloe/radiation effects , Animals , Croton Oil , Evaluation Studies as Topic , Female , Inflammation/chemically induced , Inflammation/drug therapy , Mice , Mice, Inbred ICR , Plant Extracts/therapeutic use , Plants, Medicinal/radiation effects
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