Xican Li

Hexadecanoic Acid from Buzhong Yiqi Decoction Induced Proliferation of Bone Marrow Mesenchymal Stem Cells

Buzhong Yiqi decoction (BYD) is a well-known ancient tonic prescription in traditional Chinese medicine (TCM). The purpose of this study is to identify active components of BYD involved in promoting proliferation of mesenchymal stem cells (MSCs) and to investigate its mechanism. BYD was extracted with petroleum ether, ethanol, and water. Evidence provided by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, bromodeoxyuridine, proliferation cell nuclear antigen immunoreactivity, cell cycle analysis, and gas chromatography-mass spectrometry indicated that hexadecanoic acid (HA) in BYD extracted with petroleum ether is the active compound responsible for increasing proliferation of MSCs. Western blot analysis show that HA significantly increase retinoic acid receptor (RAR) levels of MSCs, but not estrogen receptor, thyroid hormone receptor, vitamin D receptor, glucocorticoid receptor, and peroxisome proliferator-activated receptor. Reverse transcription-polymerase chain reaction revealed that HA significantly increased RAR mRNA levels. Furthermore, the mechanism of HA action depends on RAR pathway and up-regulates expression of mRNA for insulin-like growth factor-I, the target gene of RAR. Our findings have now allowed for a refinement in our understanding of TCM with respect to pharmacological regulation of stem cells and may be useful to stem cell biology and therapy.

Protective Effect of Sinapine against Hydroxyl Radical-Induced Damage to Mesenchymal Stem Cells and Possible Mechanisms

As a phenolic alkaloid occurring in Cruciferous plants, sinapine was observed to protect mesenchymal stem cells (MSCs) against ·OH-induced damage in this study. It was also found to prevent DNA from damage, to scavenge various free radicals (·OH, ·O2(-), 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid diammonium salt) (ABTS)(+·), and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·)), and to reduce Cu(2+) to Cu(+). To further explore the mechanism, the end-product of sinapine reaction with DPPH· was determined using HPLC-electrospray ionization (ESI)-MS/MS and HPLC-diode array detector (DAD). Four molecular ion peaks (m/z 701, 702, 703, and 351) in HPLC-ESI-MS/MS analysis indicated a radical adduct formation (RAF) pathway; while a bathochromic shift (λ(max) 334→475u2009nm) in HPLC-DAD indicated the formation of quinone as the oxidized product of the phenolic -OH group. Based on these results, it may be concluded that, (i) sinapine can effectively protect against ·OH-induced damage to DNA and MSCs; such protective effect may provide evidence for a potential role for sinapine in MSC transplantation therapy, and be responsible for the beneficial effects of Cruciferous plants. (ii) The possible mechanism for sinapine to protect against ·OH-induced oxidative damage is radical-scavenging, which is thought to be via hydrogen atom (H·) transfer (HAT) (or sequential electron (e) proton transfer (SEPT))→RAF pathways.

Lyophilized aqueous extracts of Mori Fructus and Mori Ramulus protect Mesenchymal stem cells from •OH–treated damage: bioassay and antioxidant mechanism

BackgroundMori Fructus and Mori Ramulus are two traditional Chinese herbal medicines from mulberries. The present work explores their beneficial effects on •OH–treated mesenchymal stem cells (MSCs) and discusses possible mechanisms.MethodsLyophilized aqueous extracts of Mori Fructus (LAMF) and Mori Ramulus (LAMR) were prepared and analyzed using HPLC. LAMF and LAMR (along with morin) were further investigated for their effects on •OH-treated MSCs using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl (MTT) assay. The direct antioxidation mechanisms were studied using 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO•)-scavenging, 2,2′-azino-bis (3-ethylbenzo-thiazoline-6-sulfonic acid (ABTS+•)-scavenging and 1,1-diphenyl-2-picryl-hydrazl (DPPH•)-scavenging, as well as Cu2+-reducing and Fe3+-reducing antioxidant power. Finally, the indirect antioxidant mechanism was investigated based on the UV-vis spectra of Fe2+-chelation.ResultsIn each LAMF and LAMR, seven phytophenols were successfully measured by HPLC, including five flavonoids (morin, rutin, astragalin, isoquercitrin and luteolin) and two non-flavonoids (chlorogenic acid and maclurin). MTT assays revealed that LAMF, LAMR and morin could effectively increase the survival of •OH-treated MSCs at 10–100xa0μg/mL, and could effectively scavenge PTIO• (IC 50 6609.7xa0±xa0756.6, 4286.9xa0±xa084.9 and 103.4xa0±xa00.9xa0μg/mL, respectively), DPPH• (IC 50 208.7xa0±xa03.0, 97.3xa0±xa03.1 and 8.2xa0±xa00.7xa0μg/mL, respectively) and ABTS+• (IC 50 73.5xa0±xa05.8, 34.4xa0±xa00.1 and 4.2xa0±xa00.2xa0μg/mL, respectively), and reduce Cu2+ (IC 50 212.5xa0±xa07.0, 123.2xa0±xa00.9 and 14.1xa0±xa00.04xa0μg/mL, respectively) & Fe3+ (IC 50 277.0xa0±xa03.1, 191.9xa0±xa05.2 and 5.0xa0±xa00.2xa0μg/mL, respectively). In the Fe2+-chelating assay, the five flavonoids produced much stronger shoulder-peaks than the two non-flavonoids within 420–850xa0nm.ConclusionMori Fructus and Mori Ramulus, can protect MSCs from •OH-induced damage. Such beneficial effects can mainly be attributed to the antioxidant action of phytophenols, which occurs via direct (ROS-scavenging) and indirect mechanism (Fe2+-chelating). The ROS-scavenging mechanism, however, include at least a H+-transfer and an electron-transfer (ET), and possibly includes a hydrogen-atom-transfer (HAT). In the Fe2+-chelating, flavonoids are more effective than non-flavonoids. This can be attributed to several adjacent planar chelating-sites between the 3-OH and 4-Cxa0=xa0O, between the 4-Cxa0=xa0O and 5-OH, or between the 3′-OH and 4′-OH in flavonoids. Such multiple-Fe2+-chelating reactions cause overlap in the UV-vis absorptions to deepen the complex color, enhance the peak strength, and form shoulder-peaks. By comparison, two non-flavonoids with catechol moiety produce only a weak single peak.

The mechanism of (+) taxifolin’s protective antioxidant effect for •OH-treated bone marrow-derived mesenchymal stem cells

The natural dihydroflavonol (+) taxifolin was investigated for its protective effect on Fenton reagent-treated bone marrow-derived mesenchymal stem cells (bmMSCs). Various antioxidant assays were used to determine the possible mechanism. These included •OH-scavenging, 2-phenyl-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide radical-scavenging (PTIO•-scavenging), 1, 1-diphenyl-2-picryl-hydrazl radical-scavenging (DPPH•-scavenging), 2, 2′-azino-bis (3-ethylbenzo-thiazoline-6-sulfonic acid) radical-scavenging (ABTS+•-scavenging), Fe3+-reducing, and Cu2+-reducing assays. The Fe2+-binding reaction was also investigated using UV-Vis spectra. The results revealed that cell viability was fully restored, even increasing to 142.9u2009±u20099.3% after treatment with (+) taxifolin. In the antioxidant assays, (+) taxifolin was observed to efficiently scavenge •OH, DPPH• and ABTS+• radicals, and to increase the relative Cu2+- and Fe3+-reducing levels. In the PTIO•-scavenging assay, its IC50 values varied with pH. In the Fe2+-binding reaction, (+) taxifolin was found to yield a green solution with two UV-Vis absorbance peaks: λmaxxa0=u2009433xa0nm (ε =5.2u2009×u2009102xa0L mol−1xa0cm −1) and λmaxxa0=u2009721xa0nm (εu2009=u20095.1u2009×u2009102xa0L mol−1xa0cm −1). These results indicate that (+) taxifolin can act as an effective •OH-scavenger, protecting bmMSCs from •OH-induced damage. Its •OH-scavenging action consists of direct and indirect antioxidant effects. Direct antioxidation occurs via multiple pathways, including ET, PCET or HAT. Indirect antioxidation involves binding to Fe2+.

Structure-Activity Relationship and Prediction of the Electron-Transfer Potential of the Xanthones Series

Abstract The structure–activity relationships of 31 xanthones were analyzed by using the ferric reducing antioxidant power (FRAP) assay to determine their electron‐transfer (ET) potential. It was proven that the ET potential of xanthones was dominated by four moieties (i.e. hydroquinone moiety, 5,6‐catechol moiety, 6,7‐catechol moiety, and 7,8‐catechol moiety) and was only slightly affected by other structural features, including a single phenolic OH group, the resorcinol moiety, the transannular dihydroxy moiety, a methoxy group, a sugar residue, an isoprenyl group, a cyclized isoprenyl group, and an isopentanol group. The results could be used to predict the ET potentials of other antioxidant xanthones.