Akkarach Bumrungpert. Bioavailability and inhibitory effects on inflammation and insulin resistance of xanthones from Garcinia Mangostana L (Mangosteen) in human adipocyttes. Doctoral Degree(Nutrition ). Mahidol University. Mahidol University Library and Knowledge Center. : Mahidol University, 2009.
Bioavailability and inhibitory effects on inflammation and insulin resistance of xanthones from Garcinia Mangostana L (Mangosteen) in human adipocyttes
Abstract:
Obesity-associated inflammation in white adipose tissue (WAT) is strongly implicated in the
development of insulin resistance. α- and γ-Mangostin (MG) which are the most abundant
xanthones found in mangosteen have been reported to have anti-inflammatory properties. Thus, α-
and γ-MG have the potential to reduce inflammation in WAT which would be expected to
improve insulin sensitivity. However, the health-promoting benefits of mangosteen are dependent
on delivery of the xanthones to target tissues. The objective of this study was to evaluate the
bioavailability and inhibitory effects on inflammation and insulin resistance of xanthones from
mangosteen in the primary cultures of human adipocytes. Here, we used simulated digestion and
Caco-2 cells to investigate the digestive stability, bioaccessibility and intestinal cell transport of α-
and γ-MG. Recovery of α- and γ-MG after simulated digestion of pericarp and fruit pulp exceeded
90%. Transfer of α- and γ-MG to the aqueous fraction during simulated digestion was efficient
(65-74%) and dependent on bile salts suggesting that micellarization is required for optimal
bioaccessibility of xanthones. Cell uptake of xanthones from micelles was dose dependent and
intracellular concentrations were at the maximum by 1 h. Both free and phase II metabolites of α-
MG were transported in the basolateral compartment and metabolites also effluxed into the apical
compartment. Transepithelial transport of α-MG was increased during prandial-like conditions
compared to fasting conditions suggesting that absorption is enhanced by dietary fat. We
examined the efficacy of α- and γ-MG to prevent lipopolysaccharide (LPS)-mediated
inflammation and insulin resistance in human adipocytes. α- and γ-MG decreased LPS-inducted
inflammatory genes (i.e., TNF-α, IL-1β, IL-6, IL-8, MCP-1, TLR-2). Moreover, α- and γ-MG
attenuated LPS-activated MAPKs; JNK, ERK, and p38. α- and γ-MG also attenuated LPSactivated
c-Jun and AP-1 activity. γ-MG was more effective than α-MG on an equimolar basis. γ-
MG, but not α-MG, attenuated LPS-mediated IκB-α degradation and NF-κB activity. γ-MG
prevented LPS suppression of insulin-stimulated glucose uptake. Similarly, γ-MG attenuated LPS
suppression of PPAR-γ and adiponectin gene expression. Taken together, these data demonstrate
for the first time that MG attenuates LPS-mediated inflammation and insulin resistance in human
adipocytes by inhibiting the activation of MAPKs, NF-κB, and AP-1. These data suggest that MG
has the potential to be absorbed into the blood circulation and also prevents inflammation and
insulin resistance associated with obesity