In vitro chemopreventive effects of plant polysaccharides (Aloe barbadensis miller, Lentinus edodes, Ganoderma lucidum and Coriolus versicolor).
A plant polysaccharide, Aloe gel extract, was reported to have an inhibitory effect on benzo[a]pyrene (B[a]P)-DNA adduct formation in vitro and in vivo. Hence, chemopreventive effects of plant polysaccharides [Aloe barbadensis Miller (APS), Lentinus edodes (LPS), Ganoderma lucidum (GPS) and Coriolus versicolor (CPS)] were compared using in vitro short-term screening methods associated with both initiation and promotion processes in carcinogenesis. In B[a]P-DNA adduct formation, APS (180 micrograms/ml) was the most effective in inhibition of B[a]P binding to DNA in mouse liver cells. Oxidative DNA damage (by 8-hydroxydeoxyguanosine) was significantly decreased by APS (180 micrograms/ml) and CPS (180 micrograms/ml). In induction of glutathione S-transferase activity, GPS was found to be the most effective among plant polysaccharides. In screening anti-tumor promoting effects, APS (180 micrograms/ml) significantly inhibited phorbol myristic acetate (PMA)-induced ornithine decarboxylase activity in Balb/3T3 cells. In addition, APS significantly inhibited PMA-induced tyrosine kinase activity in human leukemic cells. APS and CPS significantly inhibited superoxide anion formation. These results suggest that some plant polysaccharides produced both anti-genotoxic and anti-tumor promoting activities in in vitro models and, therefore, might be considered as potential agents for cancer chemoprevention. (+info)
Characterization of the genotoxicity of anthraquinones in mammalian cells.
Naturally occurring 1,8-dihydroxyanthraquinones are under consideration as possible carcinogens. Here we wanted to elucidate a possible mechanism of their genotoxicity. All three tested anthraquinones, emodin, aloe-emodin, and danthron, showed capabilities to inhibit the non-covalent binding of bisbenzimide Hoechst 33342 to isolated DNA and in mouse lymphoma L5178Y cells comparable to the topoisomerase II inhibitor and intercalator m-amsacrine. In a cell-free decatenation assay, emodin exerted a stronger, danthron a similar and aloe-emodin a weaker inhibition of topoisomerase II activity than m-amsacrine. Analysis of the chromosomal extent of DNA damage induced by these anthraquinones was performed in mouse lymphoma L5178Y cells. Anthraquinone-induced mutant cell clones showed similar chromosomal lesions when compared to the topoisomerase II inhibitors etoposide and m-amsacrine, but were different from mutants induced by the DNA alkylator ethyl methanesulfonate. These data support the idea that inhibition of the catalytic activity of topoisomerase II contributes to anthraquinone-induced genotoxicity and mutagenicity. (+info)
Purification and characterization of two lectins from Aloe arborescens Mill.
Two lectins have been isolated from leaves of Aloe arborescens Mill by salt precipitation, pH-dependent fractionation and gel filtration. One lectin (P-2) has a molecular weight of approximately 18,000, consists of two subunits (alphabeta) and contains more than 18% by weight of neutral carbohydrate. The smaller subunit (alpha) has a molecular weight of approximately 7,500 and the larger subunit (beta) a molecular weight of approximately 10,500. The other lectin (S-1) has a molecular weight of approximately 24,000, consists of two subunits (gamma2) with a molecular weight of approximately 12,000 and contains more than 50% by weight of neutral carbohydrate. An interesting feature of the amino acid compositions of these lectins is the high proportion of acidic amino acids, such as aspartic acid and glutamic acid, and the low proportion of methionine and histidine. S-1 has a strong hemagglutinating activity. On the other hand, P-2 has not only hemagglutinating activity but also mitogenic activity on lymphocytes, precipitate-forming reactivity with serum proteins, one of which is alpha2-macroglobulin, and complement C3 activating activity via the alternate pathway. (+info)
Inhibitory mechanism of aloe single component (alprogen) on mediator release in guinea pig lung mast cells activated with specific antigen-antibody reactions.
We previously reported that the glycoprotein extracted from aloe strongly inhibited the mediator releases caused by the activation of guinea pig lung mast cells. Therefore, this study aimed to purify a single component that has an antiallergic effect from crude aloe extract and then to assess the effects of aloe single component (alprogen) on the mechanism of mediator releases caused by the mast cell activation. We purified aloe extracts by using various columns. We also purified mast cells from guinea pig lung tissues by using enzyme digestion, rough and discontinuous density Percoll gradient. Mast cells were sensitized with IgG(1) (anti-ovalbumin) and challenged with ovalbumin. Histamine was assayed by using a fluorometric analyzer and leukotrienes by radioimmunoassay. [Ca(2+)](i) level was analyzed by using a confocal laser scanning microscope. Protein kinase activity was determined by the protein phosphorylated with [gamma-(32)P]ATP. The phospholipase D activity was assessed by the labeled phosphatidylalcohol. The amount of mass 1,2-diacylglycerol (DAG) was measured by the [(3)H]DAG produced when prelabeled with [(3)H]myristic acid. Phospholipase A(2) activity was determined by measuring the lyso-phosphatidylcholine released from the labeled phospholipids. Alprogen significantly decreased histamine and leukotriene releases and blocked completely Ca(2+) influx during mast cell activation. The protein kinase C and phospholipase D activities were decreased by alprogen in dose-dependent manner. Alprogen inhibited mass DAG formation and the phospholipase A(2) activity during mast cell activation. The data suggest that alprogen purified from aloe inhibits multiple signals as well as blocking Ca(2+) influx caused by mast cells activated with specific antigen-antibody reactions and that then the inhibition of histamine and leukotriene release follows. (+info)
Aloe vera: a systematic review of its clinical effectiveness.
BACKGROUND: The use of aloe vera is being promoted for a large variety of conditions. Often general practitioners seem to know less than their patients about its alleged benefits. AIM: To define the clinical effectiveness of aloe vera, a popular herbal remedy in the United Kingdom. METHOD: Four independent literature searches were conducted in MEDLINE, EMBASE, Biosis, and the Cochrane Library. Only controlled clinical trials (on any indication) were included. There were no restrictions on the language of publication. All trials were read by both authors and data were extracted in a standardized, pre-defined manner. RESULTS: Ten studies were located. They suggest that oral administration of aloe vera might be a useful adjunct for lowering blood glucose in diabetic patients as well as for reducing blood lipid levels in patients with hyperlipidaemia. Topical application of aloe vera is not an effective preventative for radiation-induced injuries. It might be effective for genital herpes and psoriasis. Whether it promotes wound healing is unclear. There are major caveats associated with all of these statements. CONCLUSION: Even though there are some promising results, clinical effectiveness of oral or topical aloe vera is not sufficiently defined at present. (+info)
Status of certain additional over-the-counter drug category II and III active ingredients. Final rule.
The Food and Drug Administration (FDA) is issuing a final rule stating that the stimulant laxative ingredients aloe (including aloe extract and aloe flower extract) and cascara sagrada (including casanthranol, cascara fluidextract aromatic, cascara sagrada bark, cascara sagrada extract, and cascara sagrada fluidextract) in over-the- counter (OTC) drug products are not generally recognized as safe and effective or are misbranded. This final rule is part of FDA's ongoing OTC drug product review. (+info)
Biopharmaceutical assessment of eye drops containing aloe (Aloe arborescens Mill.) and neomycin sulphate.
The subject of the studies was eye drops made of aloe, containing the group of aloe chemical substances of anti-inflammatory use and neomycin sulphate. The aim of the studies was to evaluate the permeability of biologically active aloe substances, determined as aloenin, through synthetic lipophilic and hydrophilic membranes in a standard perfusion apparatus and in vitro verification of the transport possibilities of these substances through the isolated cornea of pig's eye. The permeability process of biologically active aloe substances determined as aloenin, through synthetic lipophilic and hydrophilic membranes, was analyzed using the first-order kinetics. Estimated quotas of permeability rate constant show that the investigated chemical compounds of aloe, included in the eye drops, diffused through the applied membranes. The studies of permeability through isolated pig's cornea proved that biologically active aloe substances could not overcome this biological barrier. On the basis of biopharmaceutical studies it can be concluded that the eye drops containing aloe and neomycin sulphate, due to the lack of permeating abilities through the eye cornea, should be particularly useful in the treatment of inflammations and infections of external parts of the eye, such as conjuctiva, eyelid edges, lacrimal sac and cornea. (+info)
In vitro susceptibilities of Shigella flexneri and Streptococcus pyogenes to inner gel of Aloe barbadensis Miller.
Aloe barbadensis Miller (or Aloe vera) has widespread use in health products, and despite numerous reports on the whole plant, little work has been performed on the inner gel, which has been used extensively in these products. This report describes the in vitro susceptibilities of two bacteria to this component. (+info)