Biological signatures of the cognitive effects of Centella asiatica

Centella asiatica（CA）是一种植物药，被认为可以增强记忆力和大脑功能。认知效果 在啮齿类动物和人类中已经报道了CA。在我们的临床前研究中，CA水提取物（CAW） 在阿尔茨海默病（AD）的Tg 2576小鼠模型和野生型（WT）小鼠中改善认知。 CAW上调多个脑区线粒体电子传递链（ETC）基因表达， 治疗小鼠。在体外，CAW增加ETC基因表达，ATP水平和氧化磷酸化， 人神经母细胞瘤细胞和小鼠原代神经元。CAW还上调抗氧化反应元件 在这些体内和体外模型中的基因表达。由于线粒体功能障碍和氧化应激是 与AD的疾病进展密切相关，我们假设CA将减少AD的认知下降 通过增加脑线粒体生物发生和/或功能以及减少氧化应激来治疗患者。活性 CA中的化合物包括三萜和咖啡酰奎宁酸（CQA）。我们的最终目标是开发一个CA 产品标准化为这些活性物质，作为植物制剂，以减缓AD的认知能力下降。为了实现这一目标， 目前的建议旨在：（a）确定CA在人体中靶向作用的生物学特征（R61 阶段）和（B）证明了这些标记与对认知的临床作用（R33阶段）的关联。 R61项目将首先检查CA三萜和CQA的药代动力学，以及血浆中CA三萜和CQA的变化。 总抗氧化能力，口服摄入CA产品（已知三萜和CQA含量）后，在10 认知正常的老年受试者（年龄65-85岁）。这将证实CA化合物的生物利用度，并告知 剂量决定。然后将以三次递增剂量给予CA产品，每次持续四周， 认知功能正常的老年受试者（n=16）和患有遗忘性轻度认知功能障碍的其他受试者（n=16） (MCI)或轻度AD。将记录每个CA产品剂量的耐受性和不良事件。脑线粒体 活性将通过使用1H测量N-乙酰天冬氨酸和高能磷酸代谢物来评估， 31 P磁共振波谱成像（MRSI）。抗氧化状态将测量为血浆和 尿8-羟基-2-脱氧鸟苷水平。MRSI信号和/或氧化应激信号较基线的显著变化 状态将被视为CA活动的生物特征。随后的R33项目将比较CA 在MCI/轻度AD受试者中，产品和安慰剂（每个治疗组n=24）。受试者将接受 在R61研究（或安慰剂）中给予生物信号的最大耐受剂量24周。认知 除R61外，还将评价F2-异前列烷评估和血浆F2-异前列烷水平（抗氧化状态） 生物特征我们将比较CA产品与安慰剂诱导的生物学特征的变化， 并确定它们与观察到的任何认知效应的关联强度。R61和R33阶段将 包括相同数量的男性和女性受试者，以评估CA的性别依赖性效应。如果成功， 该项目将导致对CA产品在MCI或AD受试者中的认知效果进行更大规模的临床试验。

Centella asiatica (CA) is a botanical remedy, reputed to enhance memory and brain function. Cognitive effects of CA have been reported in rodents and in humans. In our preclinical studies, CA water extract (CAW) improved cognition in both the Tg2576 mouse model of Alzheimer's Disease (AD) and in wild type (WT) mice. CAW upregulated mitochondrial electron transport chain (ETC) gene expression in multiple brain regions of treated mice. In vitro, CAW increased ETC gene expression, ATP levels and oxidative phosphorylation in human neuroblastoma cells and mouse primary neurons. CAW also upregulated antioxidant response element gene expression in these in vivo and in vitro models. Since mitochondrial dysfunction and oxidative stress are strongly associated with disease progression in AD, we hypothesize that CA will reduce cognitive decline in AD patients by increasing brain mitochondrial biogenesis and/or function, and reducing oxidative stress. Active compounds in CA include triterpenes and caffeoylquinic acids (CQAs). Our ultimate goal is to develop a CA product standardized to these actives, as a botanical agent to slow cognitive decline in AD. Towards this goal, the present proposal seeks to (a) identify biological signatures of target engagement by CA in humans (R61 phase) and (b) demonstrate an association of these signatures with a clinical effect on cognition (R33 phase). The R61 project will first examine the pharmacokinetics of CA triterpenes and CQAs, and changes in plasma total antioxidant capacity, following oral intake of a CA product (with known triterpene and CQA content) in 10 cognitively normal, elderly subjects (age 65-85). This will confirm bioavailability of CA compounds and inform dosage decisions. CA product will then be administered, at three escalating doses for four weeks each, to elderly subjects with normal cognition (n=16) and others (n=16) with either amnesic mild cognitive impairment (MCI) or mild AD. Tolerability and adverse events at each CA product dose will be noted. Brain mitochondrial activity will be assessed by measuring N-acetylaspartate and high energy phosphate metabolites using 1H and 31P magnetic resonance spectroscopic imaging (MRSI). Antioxidant status will be measured as plasma and urine 8-hydroxy-2-deoxyguanosine levels. Significant changes from baseline in MRSI signals and/or oxidative status will be considered a biological signature of CA's activity. The subsequent R33 project will compare CA product and placebo, in subjects with MCI/mild AD (n=24 per treatment group). Subjects will receive the maximum tolerated dose giving a biological signal in the R61 study (or placebo) for 24 weeks. Cognitive assessments and plasma F2-isoprostane levels (for antioxidant status) will be evaluated in addition to the R61 biological signatures. We will compare changes in biological signatures induced by CA product versus placebo, and determine their strength of association with any cognitive effects observed. The R61 and R33 phases will include equal numbers of male and female subjects, to assess gender dependent effects of CA. If successful, this project will lead to a larger clinical trial of the cognitive effects of the CA product in MCI or AD subjects.