Novel bioactive maloyl glucans from aloe vera gel: isolation, structure elucidation and in vitro bioassays.
In this study, three novel maloyl glucans were isolated at temperatures below 15 degrees C from aloe vera gel (Aloe barbadensis Miller). These compounds were characterized using NMR spectroscopy, ESIMS, MALDITOF-MS and capillary electrophoresis. The compounds were characterized as 6-O-(1-L-maloyl)-alpha-,beta-D-Glcp (veracylglucan A), alpha-D-Glcp-(1-->4)-6-O-(1-L-maloyl)-alpha,-beta,-D-Glcp (veracylglucan B) and alpha-D-Glcp-(1-->4)-tetra-[6-O-(1-L-maloyl)-alpha-D-Glcp-(1-->4)]-6-O-(1-L-maloyl)-alpha,-beta-D-Glcp (veracylglucan C). These unusual malic acid acylated carbohydrates were then tested in vitro for effects on cell proliferation and gene expression of proinflammatory cytokines, IL-6, IL-8 and ICAM-1, using RT-PCR. Veracylglucan B demonstrated potent anti-inflammatory and anti-proliferative effects, while Veracylglucan C, on the other hand, exhibited significant cell proliferative and anti-inflammatory activities. Veracylglucan A could only be isolated in smaller quantities, and it proved to be very unstable. Thus no biological effects could be observed in this respect. The in vitro bioassays also indicated that Veracylglucan B and C are antagonistic and competitive in their effects on cell proliferation. The results of this work represent a major step forward in the research on aloe vera gel. This is the first time that two fully chemically characterized compounds are shown to be responsible for known biological activities of aloe vera gel.
Esua
Macniell F
MF
Wolfenbuetteler Strasse 25c, 30519 Hannover, and University of Leipzig, Institute of Pharmacy, Leipzig, Germany. mcesua@hotmail.com
Rauwald
Johann-Wilhelm
JW
D000215:Acylation; D000504:Aloe / Q000737:chemistry*; D001681:Biological Assay; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000737:chemistry; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects; D019075:Electrophoresis, Capillary; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D005936:Glucans / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects; D009682:Magnetic Resonance Spectroscopy; D008293:Malates / Q000737:chemistry; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D002241:Carbohydrates; D005936:Glucans; D015850:Interleukin-6; D016209:Interleukin-8; D008293:Malates; D018799:Intercellular Adhesion Molecule-1; C030298:malic acid