Beta-glucan

From Wikipedia, the free encyclopedia

β-Glucans (or beta-glucans) are natural gum polysaccharides occurring in the bran of cereal grains, most abundantly in barley and oats and to a much lesser degree in rye and wheat. They are useful in human nutrition as texturing agents and as soluble fiber supplements, but problematic in brewing as excessive levels make the wort too viscous.

[edit] Medical applications

Beta-glucans found in certain fungi are thought to have anticancer properties. In Japan, mushroom derived extracts rich in beta-glucans have been used for over 20 years in intravenous forms and are approved for use as adjuncts to chemotherapy. There are phase III trial in the U.S. using beta-glucans with other cancer drugs. No forms of beta-glucans have been approved by the FDA to treat cancer.

Other beta-glucans, such as beta-D-glucan, can play an important role in the diagnosis of toxic mycosis caused by fungi that contain such compounds, such as Candida and Aspergillus species.

Beta-glucan is also promoted as dietary supplement for weight loss. These claims are not well supported by research although beta-glucan (like other soluble fibers) has some effect on effective glycemic index and insulin response.

[edit] Beta-D-glucan

β-D-glucan (properly known as (1→3)β-D-glucan, but also incorrectly called 1,3-β-D-glucan or even just glucan) forms part of the cell wall of certain medically important fungi, especially Aspergillus species. An assay to detect the presence of (1→3)β-D-glucan in the blood has been produced by Fungitell and is marketed as a means of diagnosing invasive fungal infection in patients.^[1][2][3]

One of the limitations of the assay is the presence of fungal contaminants in amoxicillin-clavulanate^[4] and piperacillin-tazobactam^[5] which may result in false-positive results in those patients receiving these antibiotics.

[edit] References

1. ^ Obayashi T, Yoshida M, Mori T, et al. (1995). "Plasma (13)-beta-D-glucan measurement in diagnosis of invasive deep mycosis and fungal febrile episodes". Lancet 345: 17–20. 
2. ^ Ostrosky-Zeichner L, Alexander BD, Kett DH, et al. (2005). "Multicenter clinical evaluation of the (1→3)β-D-glucan assay as an aid to diagnosis of fungal infections in humans". Clin Infect Dis 41: 654–659. 
3. ^ Odabasi Z, Mattiuzzi G, Estey E, et al. (2004). "Beta-D-glucan as a diagnostic adjunct for invasive fungal infections: validation, cutoff development, and performance in patients with acute myelogenous leukemia and myelodysplastic syndrome". Clin Infect Dis 39: 199–205. 
4. ^ Mennink-Kersten MASH, Warris A, Verweij PE (2006). "1,3-β-D-Glucan in patients receiving intravenous amoxicillin–clavulanic acid" 354 (26): 2834–2835. 
5. ^ Sulahian A, Touratier S, Ribaud P (2003). "False positive test for aspergillus antigenemia related to concomitant administration of piperacillin and tazobactam". N Engl J Med 349: 2366–2367.