Aloin A

Aloin(Aloin-A; Barbaloin-A) is a natural antitumor anthraquinone glycoside with iron chelating and non-atherogenic activities. IC50 value: Target: in vitro: Aloin significantly inhibited HUVECs proliferation, migration and tube formation in vitro. suppressed activation of VEGF receptor (VEGFR) 2 and STAT3 phosphorylation in endothelial cells. In addition, the constitutively activated STAT3 protein, and the expression of STAT3-regulated antiapoptotic (Bcl-xL), proliferative (c-Myc), and angiogenic (VEGF) proteins were also down-regulated in response to AL in human SW620 cancer cells [1]. aloin exerted inhibition of cell proliferation, adhesion and invasion abilities of B16-F10 melanoma cells under non-cytotoxic concentrations. Furthermore, aloin induced melanoma cell differentiation through the enhancement of melanogenesis and transglutaminase activity [2]. in vivo: Aloin substantially reduced tumor volumes and weight in vivo mouse xenografts, without obviously toxicity [1]. Aloin (10, 30 mg/kg bw) or vehicle was given by gavage to mice after each alcohol administration. Alcohol elevated the serum transaminases alanine aminotransferase, aspartate aminotransferase, total cholesterol and triglyceride levels which were significantly attenuated by the co-administration of aloin (p < 0.05) [3].

References:
[1]. Pan Q, et al. Inhibition of the angiogenesis and growth of Aloin in human colorectal cancer in vitro and in vivo. Cancer Cell Int. 2013 Jul 12;13(1):69. [2]. Tabolacci C, et al. Aloin enhances cisplatin antineoplastic activity in B16-F10 melanoma cells by transglutaminase-induced differentiation. Amino Acids. 2013 Jan;44(1):293-300. [3]. Cui Y, et al. Aloin protects against chronic alcoholic liver injury via attenuating lipid accumulation, oxidative stress and inflammation in mice. Arch Pharm Res. 2014 Dec;37(12):1624-33.

A new antimicrobial anthrone from the leaf latex of Aloe trichosantha.[Pubmed:25230501]

Nat Prod Commun. 2014 Jul;9(7):949-52.

Phytochemical investigation of the leaf latex of Aloe trichosantha by preparative TLC gave two closely related anthrones, Aloin A/B (1) and aloin-6'-O-acetate A/B (2). The identity of the compounds was established from HRESI-MS, 1H, 13C, DEPT, HMQC and HMBC spectral and chemical data. Whilst Aloin A/B occurs in several Aloe species, aloin-6'-O-acetate A/B was isolated for the first time. The isolated compounds inhibited growth of several bacterial and fungal pathogens with minimum inhibitory concentration (MIC) from 10 to 400 microg/mL and 800 to 1000 microg/mL, respectively.

Determination of Aloin A and Aloin B in Aloe vera Raw Materials and Finished Products by High-Performance Liquid Chromatography: Single-Laboratory Validation.[Pubmed:25902982]

J AOAC Int. 2014 Sep-Oct;97(5):1323-8.

A single-laboratory validation (SLV) was conducted on an HPLC method for the detection and quantification of Aloin A and aloin B in Aloe vera raw materials and finished products. An extraction procedure using sonication with an acidified solvent was used for solid test materials while liquid test materials only required dilution, if necessary, prior to filtration and analysis. Separation was achieved using a fused core C18 column in 18 min under isocratic elution conditions allowing for a single analyte (Aloin A) calibration curve to quantify both aloins. Adequate chromatographic resolution (Rs >/= 1) was achieved for Aloin A and aloin B. The calibration curves for Aloin A exhibited coefficients of determination (r(2)) of >/= 99.9% over the linear range of 0.3-50 mug/mL. The LOD values were 0.092 and 0.087 mug/mL, and LOQ 0.23 and 0.21 mug/mL for Aloin A and aloin B, respectively. Repeatability studies were performed on nine test materials on each of 3 separate days, with five of the test materials determined to be above the LOQ having repeatability RSD (RSDr) values ranging from 0.61 to 6.30%. Method accuracy was determined through a spike recovery study on both liquid and solid matrixes at three different levels: low, medium, and high. For both aloins, the recovery in the liquid matrix ranged from 92.7 to 106.3% with an RSDr of 0.15 to 4.30%, while for the solid matrix, the recovery ranged from 84.4 to 108.9% with an RSDr of 0.23 to 3.84%. Based on the results of the SLV study, it is recommended that this method be evaluated for reproducibility through a collaborative study.

In vitro studies on the photobiological properties of aloe emodin and aloin A.[Pubmed:12521605]

Free Radic Biol Med. 2003 Jan 15;34(2):233-42.

Plants containing Aloin A, aloe emodin, and structurally related anthraquinones have long been used as traditional medicines and in the formulation of retail products such as laxatives, dietary supplements, and cosmetics. Since a recent study indicated that topically applied aloe emodin increases the sensitivity of skin to UV light, we examined the events following photoexcitation of Aloin A and aloe emodin. We determined that incubation of human skin fibroblasts with 20 microM aloe emodin for 18 h followed by irradiation with UV or visible light resulted in significant photocytotoxicity. This photocytotoxicity was accompanied by oxidative damage in both cellular DNA and RNA. In contrast, no photocytotoxicity was observed following incubation with up to 500 microM Aloin A and irradiation with UVA light. In an attempt to explain the different photobiological properties of Aloin A and aloe emodin, laser flash photolysis experiments were performed. We determined that the triplet state of aloe emodin was readily formed following photoexcitation. However, no transient intermediates were formed following photoexcitation of Aloin A. Therefore, generation of reactive oxygen species and oxidative damage after irradiation of Aloin A is unlikely. Although Aloin A was not directly photocytotoxic, we found that human skin fibroblasts can metabolize Aloin A to aloe emodin.