The Scutellaria Flavone, Oroxylin A, Improves Attention-Deficit/Hyperactivity Disorder Related Behaviors in Spontaneously Hypertensive Rats

Effects of an Oroxylum indicum Extract (Sabroxy®) on Cognitive Function in Adults With Self-reported Mild Cognitive Impairment: A Randomized, Double-Blind, Placebo-Controlled Study

Background: Oroxylum indicum has been used in traditional Ayurvedic medicine for the prevention and treatment of several diseases and may have neuroprotective effects.

Purpose: Examine the effects of Oroxylum indicum on cognitive function in older adults with self-reported cognitive complaints.

Study Design: Two-arm, parallel-group, 12-week, randomized, double-blind, placebo-controlled trial.

Methods: Eighty-two volunteers received either 500 mg, twice daily of a standardized Oroxylum indicum extract or placebo. Outcome measures included several computer-based cognitive tasks, the Control, Autonomy, Self-Realization, and Pleasure scale (CASP-19), Cognitive Failures Questionnaire (CFQ), and the Montreal Cognitive Assessment (MoCA). Changes in the concentration of brain-derived neurotrophic factor (BDNF) were also examined.

Results: Compared to the placebo, Oroxylum indicum was associated with greater improvements in episodic memory, and on several computer-based cognitive tasks such as immediate word recall and numeric working memory, and a faster rate of learning on the location learning task. However, there were no other significant differences in performance on the other assessed cognitive tests, the MoCA total score, or other self-report questionnaires. BDNF concentrations increased significantly in both groups, with no statistically-significant between-group differences. Oroxylum indicum was well tolerated except for an increased tendency for mild digestive complaints and headaches.

Conclusion: The results of this first human trial on the cognitive-enhancing effects of Oroxylum indicum suggest that it is a promising herbal candidate for the improvement of cognitive function in older adults with self-reported cognitive complaints.

An unambiguous and practical synthesis of Oroxylin A: a commonly misidentified flavone

Oroxylin A, a major flavonoid in the extracts of Oroxylum indicum as well as Scutellaria baicalensis possesses useful medicinal properties. Many of the published routes claiming the synthesis of Oroxylin A (1) have in fact led to a regioisomer Negletein that was misinterpreted as Oroxylin A. In the present work, we describe a novel, straight-forward and scalable semi-synthetic approach for rapid access to the title compound, the structure of which is unambiguously secured by NMR and X-ray crystallographic analysis of a derivative. This work also encompasses the synthesis of a glycosylated derivative of Oroxylin A viz OAGME (2), which has marked pharmacological importance.

Systematic review and meta-analysis of the behavioral effects of methylphenidate in the spontaneously hypertensive rat model of attention-deficit/hyperactivity disorder

The spontaneously hypertensive rats (SHR) are the most widely used model for ADHD. While face and construct validity are consolidated, questions remain about the predictive validity of the SHR model. We aim at summarizing the evidence for the predictive validity of SHR by evaluating its ability to respond to methylphenidate (MPH), the most well documented treatment for ADHD. A systematic review was carried out to identify studies evaluating MPH effects on SHR behavior. Studies (n=36) were grouped into locomotion, attention, impulsivity or memory, and a meta-analysis was performed. Meta-regression, sensitivity, heterogeneity, and publication bias analyses were also conducted. MPH increased attentional and mnemonic performances in the SHR model and decreased impulsivity in a dose-dependent manner. However, MPH did not reduce hyperactivity in low and medium doses, while increased locomotor activity in high doses. Thus, since the paradoxical effect of stimulant in reducing hyperactivity was not observed in the SHR model, our study does not fully support the predictive validity of SHR, questioning their validity as an animal model for ADHD.

The Atxn7-overexpressing mice showed hyperactivity and impulsivity which were ameliorated by atomoxetine treatment: A possible animal model of the hyperactive-impulsive phenotype of ADHD

Attention-deficit/hyperactivity disorder (ADHD) is a heterogeneous neurodevelopmental disorder characterized by varying levels of hyperactivity, inattention, and impulsivity. Patients with ADHD are often classified as (1) predominantly hyperactive-impulsive, (2) predominantly inattentive, and (3) combined type. There is a growing interest in developing specific animal models that would recapitulate specific clinical forms of ADHD, with the goal of developing specific therapeutic strategies. In our previous study, we have identified Ataxin-7 (Atxn7) as a hyperactivity-associated gene. Here, we generated Atxn7 overexpressing (Atxn7 OE) mice to investigate whether the increased Atxn7 expression in the brain correlates with ADHD-like behaviors. Quantitative real-time polymerase chain reaction and immunofluorescence confirmed overexpression of the Atxn7 gene and protein in the prefrontal cortex (PFC) and striatum (STR) of the Atxn7 OE mice. The Atxn7 OE mice displayed hyperactivity and impulsivity, but not inattention. Interestingly, treatment with the ADHD drug, atomoxetine (3 mg/kg, intraperitoneal), attenuated ADHD-like behaviors and reduced Atxn7 gene expression in the PFC and STR of these mice. These findings suggest that Atxn7 plays a role in the pathophysiology of ADHD, and that the Atxn7 OE mice can be used as an animal model of the hyperactive-impulsive phenotype of this disorder. Although confirmatory studies are warranted, the present study provides valuable information regarding the potential genetic underpinnings of ADHD.

Oroxylin A improves attention deficit hyperactivity disorder-like behaviors in the spontaneously hypertensive rat and inhibits reuptake of dopamine in vitro

In previous studies we have demonstrated that the γ-aminobutryic acid-A (GABA-A) receptor antagonist oroxylin A has an awakening effect and it also represses ADHD-like behaviors (hyperactivity, impulsivity and inattention) in the spontaneously hypertensive rat (SHR) model of attention-deficit hyperactivity disorder (ADHD). We hypothesized that the effects of oroxylin A were exerted via the GABA-A receptor given the important role of the GABAergic system in ADHD. However, it is possible that aside from the GABAergic system, oroxylin A may influence other systems especially those implicated in ADHD (e.g. DAergic, etc.). To test this hypothesis, we evaluated the effects of GABA agonist, or dopamine (DA) antagonist in oroxylin A-induced alleviation of ADHD-like behaviors in SHR. SHR showed inattention and impulsivity as measured by the Y-maze and the electro-foot shock aversive water drinking tests, respectively. Oroxylin A significantly improved these behaviors, furthermore, its effect on SHR impulsivity was attenuated by haloperidol, a DA antagonist, but not by baicalein, an agonist of the GABA-A receptor. In vitro studies showed that oroxylin A inhibited DA uptake similar to methylphenidate, a dopamine transporter blocker, but did not influence norepinephrine uptake unlike atomoxetine, a selective NE reuptake inhibitor. Collectively, the present findings suggest that oroxylin A improves ADHD-like behaviors in SHR via enhancement of DA neurotransmission and not modulation of GABA pathway as previously reported. Importantly, the present study indicates the potential therapeutic value of oroxylin A in the treatment of ADHD.

5,7-Dihydroxy-6-methoxy-4'-phenoxyflavone, a derivative of oroxylin A improves attention-deficit/hyperactivity disorder (ADHD)-like behaviors in spontaneously hypertensive rats

Oroxylin A, a major flavonoid in Scutellaria baicalensis, has been shown to alleviate attention-deficit/hyperactivity disorder (ADHD)-like behaviors in the spontaneously hypertensive rat (SHR) model of ADHD. As part of our continuing effort to discover effective ADHD drug candidates, we synthesized a number of oroxylin A derivatives and characterized their biological activities. Among all oroxylin A analogs, compound 7-7 (5,7-dihydroxy-6-methoxy-4'-phenoxyflavone) showed the most remarkable inhibition of dopamine reuptake alike methylphenidate, a dopamine transporter (DAT) blocker and typical drug for ADHD, and oroxylin A. It did not influence norepinephrine reuptake unlike atomoxetine, a selective norepinephrine inhibitor. Moreover, compound 7-7 reduced hyperactivity, sustained inattention and impulsivity in the SHR as measured by the open field, Y-maze and electro-foot shock aversive water drinking tests, respectively. Most drugs that enhance brain dopamine levels (e.g. DAT blockers like cocaine and methylphenidate) produce behavioral effects like those of stimulants causing them to be abused. However, the repeated treatment of compound 7-7 failed to elicit locomotor sensitization in rats, and neither produced conditioned place preference response nor maintained self-administration behavior. Altogether, the present study suggests the promising therapeutic value of compound 7-7 as an ADHD drug. Furthermore, compound 7-7 may be considered as an alternative therapy to psychostimulant ADHD treatments (e.g. amphetamine and methylphenidate) for which use has been deemed controversial due to their abuse liability.

Oroxylin A analogs exhibited strong inhibitory activities against iNOS-mediated nitric oxide (NO) production

A number of oroxylin A analogs were prepared and evaluated for their inhibitory activities against iNOS-mediated nitric oxide (NO) production from LPS-stimulated BV2 cells. The analogs were synthesized from purchased 2'-hydroxy-4,5,6-trimethoxyacetophenone and aldehydes in 3 steps. Among the tested compounds, several analogs (3b, 3c, 3d, 3f) exhibited strong inhibitory activities. Especially, the analog with 4-nitrophenyl group (3b) showed stronger inhibitory activity (IC(50)=4.73 μM) than that of wogonin (IC(50)=7.80 μM).