Naringenin and Hesperetin Induce Growth Arrest, Apoptosis, and Cytoplasmic Fat Deposit in Human Preadipocytes

Abstract

Citrus flavonoids are reported to be promising bioactive compounds against hyperlipidemia and lipid biosynthesis. However, the mechanism of the lipid lowering effect by flavonoids remains unknown. The present study examines the effect of some flavanones on the adipocytic conversion of the human preadipocyte cell line, AML-I. Among four structure-related flavanones including naringenin, naringenin-7-rhamnoglucoside (naringin), hesperetin, and hesperetin-7-rhamnoglucoside (hesperidin), the aglycones such as naringenin and hesperetin exhibited the growth arrest of AML-I cells. When the cells were examined by Annexin V-FITC staining method, it was noticed that growth arrest was induced by apoptotic cell death. In the study of apoptosis-related protein in the naringenin-treated cells, anti-apoptotic proteins such as p-Akt, NF-kappaB, and Bcl-2 were decreased, and pro-apoptotic protein Bad was accumulated by Western blot analysis. Interestingly, exposure of AML-I cells to naringenin or hesperetin during short-term cultures increased cytoplasmic lipid droplets by Sudan Black B staining. Furthermore, expression of fatty acid synthase (FAS) and peroxisome proliferator activated receptor (PPAR)-gamma was enhanced in naringenin-treated cells. These data suggest that apoptosis by flavanones does not inhibit the adipocytic conversion of AML-I preadipocytes. The result also indicates that adipocyte may not be a direct target for the lipid-lowering activity of the flavanones.

Naringin inhibits matrix metalloproteinase‐9 expression and AKT phosphorylation in tumor necrosis factor‐α‐induced vascular smooth muscle cells

“…Naringin can accumulate in plasma after long-term intake, and they are distributed in tissues other than plasma [41]. Because of the limitation in detective analytical methods, distribution and accumulation of naringin in other tissues cannot be investigated [41,44]. Thus, we suggest that benefit health effects could ensue in individuals consuming orange or grapefruit products regularly if naringin actually has biological significances in vivo.…”

“…Previous studies showed that naringin and naringenin (less than 50 mM) treatment had no effect on cell viability in several cell lines, although there were differences of the inhibition of cell proliferation between naringin and naringenin (more than 100 mM) treatment in different cell lines [41][42][43]. We used the concentration of naringin at 25 mM in this experiment.…”

“…Pharmacokinetic study has suggested that plasma concentration of naringin was 7.3 mM, when 472 mM of naringin is administered in human [41,44]. The plasma concentration of the naringin was relatively high after ingestion of orange or grapefruit juice [44].…”

“…The plasma concentration of the naringin was relatively high after ingestion of orange or grapefruit juice [44]. Naringin can accumulate in plasma after long-term intake, and they are distributed in tissues other than plasma [41]. Because of the limitation in detective analytical methods, distribution and accumulation of naringin in other tissues cannot be investigated [41,44].…”

Instability of, and generation of hydrogen peroxide by, phenolic compounds in cell culture media

“…For example, apigenin can modulate Akt activity and trigger apoptosis in prostate cancer cells [4], naringenin and hesperetin alter fat metabolism and cause growth arrest [5] by mechanisms involving reactive oxygen species [6], the anthocyanin delphinidin causes apoptosis in PC3 cells [7], naringenin decreases the viability of colon cancer cells [8], hesperetin arrests the proliferation of vascular smooth muscle cells [9] and olive oil-derived phenolic compounds have a variety of reported effects on cells in culture [10,11]. Epigallocatechin gallate [1,[12][13][14] has been extensively studied and appears to have potential as an anti-cancer agent [1,15], rosmarinic acid promotes TNFa induced apoptosis [16], and resveratrol and curcumin have also attracted wide attention as possible health-maintaining and potential therapeutic agents [15,[17][18][19][20].…”