Guo-Wei Qin

Luteolin from Purple Perilla mitigates ROS insult particularly in primary neurons

Increased attention has been paid to the role of oxidant/antioxidant imbalance in neurodegenerative process and pharmaceutical neuroprotective interventions. Food-derived compound luteolin possesses multitarget actions including reactive oxygen species (ROS)-scavenging activity in cultured human endothelial cells or permanent immature rat oligodendrocytes. This study aims to elucidate whether luteolin has a neuroprotective tendency toward ROS-insulted neural cells. The present results showed that luteolin, isolated from the ripe seed of Perilla frutescens (L.) Britt., markedly reversed hydrogen peroxide-induced cytotoxicity in primary culture cortical neurons but not in cultured human neuroblastoma cells. Upon the ROS-insulted primary neurons, luteolin concentration-dependently enhanced neuronal cell survival with efficacy higher than and potency similar to vitamin E. Additionally, luteolin significantly attenuated the increase in ROS production and prevented the decreases in activities of mitochondria, catalase, and glutathione in ROS-insulted primary neurons. Thus, luteolin functions by neuroprotection possibly through a rebalancing of pro-oxidant-antioxidant status. This agent points to possible interventions for preventing neurodegenerative diseases such as cerebral ischemia, Parkinsons disease, and Alzheimers disease, as well as for improving brain aging.

Functional activation of monoamine transporters by luteolin and apigenin isolated from the fruit of Perilla frutescens (L.) Britt.

Monoamine transporters playing major roles in regulating normal and abnormal synaptic activity are associated with various neuropsychological disorders. In spite of the discovery of a series of structurally different monoamine transporter antagonists for the therapy approach, no practical pharmaceutical can act as a transporter activator. Here, we isolated luteolin and apigenin from the fruit of Perilla frutescens (L.) Britt by using an activity-guided extraction technique, and proved that the two compounds possess actions of enhancing monoamine uptake either upon monoamine-transporter transgenic Chinese hamster ovary (CHO) cells or upon wild dopaminergic cell lines, with higher specificity for dopamine (DA) uptake than for norepinephrine (NE)- and serotonin (5HT)-uptake, as well as with more potency and greater efficacy for luteolin than for apigenin. Further, in the transgenic cells, the principal NE/DA uptake activation by luteolin was significantly prevented by respective transporter inhibitor, and the transmitter-uptake-enhancing action was independent of its ligands, which is in support of the compounds as monoamine transporter activators. Furthermore, luteolin evoked a marked disinhibition of cocaine-targeted effect in CHO cells overexpressing dopamine transporter. Thus, luteolin and apigenin function as monoamine transporter activators, which would improve several hypermonoaminergic neuropsychological disorders, especially cocaine dependence, through up-regulating monoamine transporter activity.

Postischemic administration of liposome-encapsulated luteolin prevents against ischemia-reperfusion injury in a rat middle cerebral artery occlusion model

Oxidative stress-induced neuronal cell death has been implicated in neurodegenerative diseases; one such disease is ischemic stroke. Using reactive oxygen species (ROS)-insulted primary neurons, we screened neuroprotectants with clinical potential and then, using ischemia/reperfusion (I/R) model, investigated the anti-ischemic potential of candidate neuroprotectants. Here, we showed that luteolin, isolated from the ripe fruit of Perilla frutescens (L.) Britt, exhibited a neuroprotective action upon the in vitro platform, thus serving as candidate for in vivo pharmacological evaluation. Liposome-encapsulated luteolin produced dramatic preventing effects on I/R-induced behavioral and histological injuries after a 13-day post-ischemic treatment. Furthermore, this phytochemical not only lowered the increased level of mitochondrial ROS but also substantially up-regulated the decreased activity of catalase and glutathione in I/R rat brains. Collectively, luteolin as a neuroprotectant acts by anti-ischemic activity likely through a rebalancing of pro-oxidant/antioxidant status. Its multitarget mechanisms implicate potential effectiveness for clinically treating ischemia stroke.

A novel compound N1,N5-(Z)-N10-(E)-tri-p-coumaroylspermidine isolated from Carthamus tinctorius L. and acting by serotonin transporter inhibition

Safflower, the dry flower of Carthamus tinctorius L., has long been applied for empirically treating cerebral ischemia and depression in traditional Chinese medicine. Pathogenesis of major depression involves monoaminergic transmission. The present study assessed whether safflower or its isolate would be effective in functionally regulating monoamine transporter using in vitro screening cell lines. We discovered that safflower insoluble fraction significantly inhibited serotonin uptake in Chinese hamster ovary cells stably expressing serotonin transporter (i.e. S6 cells). This fraction went through an activity-guided isolation and an active ingredient was obtained, which was subsequently elucidated as a novel coumaroylspermidine analog N(1),N(5)-(Z)-N(10)-(E)-tri-p-coumaroylspermidine using NMR techniques. Pharmacologically, this compound potently and selectively inhibited serotonin uptake in S6 cells or in synaptosomes, with IC(50) of 0.74+/-0.15 microM for S6 cells or 1.07+/-0.23 microM for synaptosomes and with a reversible competitive property for the 5HT-uptake inhibition. The potency of it for 5HT uptake was weaker than that of fluoxetine whereas efficacy generally similar for both. Animals treated with this testing compound showed a significant decrease in synaptosomal 5HT uptake capacity. Thus, N(1),N(5)-(Z)-N(10)-(E)-tri-p-coumaroylspermidine is a novel serotonin transporter inhibitor, which could improve neuropsychological disorders through regulating serotoninergic transmission.

Safflower extracts functionally regulate monoamine transporters

Safflower (HH), the dry flower of Carthamus tinctorius L., has long been used to empirically treat neuropsychological disorders such as stroke and major depression in traditional Chinese medicine, and recently been proven effective for regulating levels of dopamine and serotonin in new-born rat brain. The present study assessed whether HH would be bioactive for functionally regulating monoamine transporters using in vitro drug-screening cell lines. Our current results showed that all solvent-extracted HH fractions, in different degrees, markedly increased both dopamine uptake by Chinese hamster ovary (CHO) cells stably expressing dopamine transporter (DAT) and norepinephrine uptake by CHO cells expressing norepinephrine transporter (NET), and also showed that chloroform (HC), ethyl acetate (HE), and n-butyl alcohol extract strikingly depressed serotonin uptake by CHO cells expressing serotonin transporter (SERT); wherein, the potencies of ethanol extract, HC, HE, and aqueous extract to up-regulate dopamine/norepinephrine uptake and potency of HE to inhibit serotonin uptake were relatively stronger. Further investigation revealed that the enhancement of dopamine/norepinephrine uptake by HC and HE was dependent of DAT/NET activity, and the HE-induced inhibition of serotonin uptake was typical of competition. Thus, HH extracts are novel monoamine transporter modulators functioning as DAT/NET activators and/or SERT inhibitors, and would likely improve neuropsychological disorders through regulating monoamine-transporter activity.

Cynomorium songaricum Extracts Functionally Modulate Transporters of γ-Aminobutyric Acid and Monoamine

Cynomorium songaricum Rupr. (SY) is a central nervous system-oriented herb material that has actions of anti-dementia, anti-epilepsy, and anti-stress. It is unclear whether SY would be biologically active in functionally regulating neurotransmitter transporters. Here, we assessed these potential actions using Chinese hamster ovary cells expressing γ-aminobutyric acid (GABA) transporter (GAT-1), dopamine transporter (DAT), norepinephrine transporter (NET), or serotonin transporter (SERT) (i.e. G1, D8, N1, or S6 cells, respectively). It was shown that SY extracts, such as SYw, SYa, SYp, SYc, SYe, and SYb (SY water, ethanol, petroleum ether, chloroform, ethyl acetate, and n-butyl alcohol extract, respectively) increased dopamine/norepinephrine (DA/NE) uptake by corresponding D8/N1 cells and decreased γ-aminobutyric acid/serotoin (GABA/5HT) uptake by corresponding G1/S6 cells; wherein, the potency or efficacy of SYc for up-regulating DA/NE uptake and that of SYb for inhibiting GABA/5HT uptake were relatively stronger. Additionally, GABA/5HT-uptake inhibition by SY extracts were also seen in cortical synaptosomes, and DA/NE-uptake enhancement by SYc was dependent on the activity of DAT and NET. Thus, SY extracts especially SYc and SYb are novel neurotransmitter-transporter modulators functioning as DAT/NET activators and/or GAT-1/SERT inhibitors.

Caulis Sinomenii Extracts Activate DA/NE Transporter and Inhibit 5HT Transporter:

Caulis Sinomenii (QFT) has analgesic, sedative, and anxiolytic-like actions, and is proven effective for improving drug dependence that is known to be associated with abnormal monoaminergic transmission. We assessed whether QFT would be biologically active in functionally regulating monoamine transporters using CHO cells expressing dopamine transporter (DAT), norepinephrine transporter (NET), or serotonin transporter (SERT) (i.e. D8, N1, or S6 cells, respectively). Here, we showed that its primary extracts, such as QA, QC, QE, QD, and QB (QFT ethanol, chloroform, ethyl acetate, alkaloid-free chloroform, and alkaloid-containing chloroform extract, respectively), and secondary extracts, such as QE-2, − 3, − 5, − 7, QD-1, − 2, − 3, − 4, − 5, and QB-1, − 2, − 3, − 4, − 5 (fractioned from QE, QD, and QB, respectively), in differing degrees, either increased DA/ NE uptake by corresponding D8/N1 cells or decreased 5HT uptake by S6 cells; wherein, QE-2, QD-3, and QE-7 were potent DA/NE uptake activators while both QE-7 and QB-5 were potent 5HT uptake inhibitors. Furthermore, the enhancement of DA/NE uptake was dependent of DAT/NET activity, and the inhibition of 5HT uptake was typical of competition. Thus, QFT extracts, especially QE-2 and QE-7 (both with stronger potencies), are novel monoamine transporter modulators functioning as DAT/ NET activators and/or SERT inhibitors, and would likely improve neuropsychological disorders through regulating monoamine transporters.