Composed of Ginsenoside Rg1 and Geniposide the herbal medicine TongLuoJiuNao (TLJN) injection liquid has anti-inflammatory properties and can improve learning and memory in mice. old. We found that TLJN significantly decreased Aβ production and deposition in the brain of APP23 mice. Furthermore we observed GDC-0449 that TLJN down-regulated the levels and activity of β-secretase 1 (BACE1) protein as well as the expression levels of γ-secretase complex components: PS1 nicastrin and anterior pharynx-defective 1 (APH1) but not presenilin enhancer 2 (PEN2). The results suggest GDC-0449 an inhibitory effect of TLJN on amyloidogenic APP processing by down-regulating the cleavage enzymes BACE1 and γ-secretase. Introduction TongLuoJiuNao (TLJN) injection liquid is an herbal medicine which is primarily composed of two active components: Ginsenoside Rg1 and Geniposide [1] [2]. Nowadays TLJN has been used in the treatment of patients with cerebral ischemic stroke and vascular dementia [3] [4]. Ginsenosides belong to the class of steroid glycosides and triterpene saponins in the JTK2 plant genus (ginseng) which can suppress inflammation by nuclear factor κB (NF-κB) pathway [5] [6] and tumor growth by inhibiting DNA polymerase activity [7] [8]. Recent studies showed GDC-0449 GDC-0449 that Ginsenoside Rg1 could improve spatial learning and memory in rat models of Alzheimer’s disease (AD) [9] [10]. Another compound Geniposide in TLJN is an iridoid glycoside with a variety of biological activities including neuroprotection anti-proliferation and anti-oxidative stress [11] [12]. Besides the beneficial roles of TLJN in acute ischemic stroke and vascular dementia [3] [4] whether this anti-stroke herbal medicine could also be applied in the prevention and therapy of other neurological disorders such as AD is unknown. AD is a neurodegenerative disease and pathologically characterized by excessive extracellular accumulation of amyloid β peptide (Aβ) in brains [13] [14]. Aβ is generated from the cleavage of amyloid precursor protein (APP) by two enzymes: β-secretase 1 (BACE1) and γ-secretase [15] [16]. Emerging evidence has shown that BACE1 expression levels and/or activities are increased in the brain of AD patients [17] [18] [19] [20]. Herbal medicines have been introduced to alleviate demented symptoms of AD patients [21] [22]. It has been suggested that Ginsenoside protects neurons against oxidative stress [23] and improves learning and memory functions [24] [25]. Experimental studies showed that administration of Ginsenoside significantly reduced Aβ levels in brains of Tg2576 mice an AD mouse model [26] and senescence-accerlerated mouse prone 8 (SAMP8) mice [10] [27]. Furthermore Ginsenoside is found to inhibit BACE1 activity by 80% in PC12 cells [28] and mouse neuroblastoma N2a cells expressing mutation human APP696 [29]. A recent report showed that TLJN increased the expression levels of IDE and NEP which both are involved in Aβ clearance [1]. In the present study we intraperitoneally injected herbal medicine TLJN once a day in amyloid precursor protein (APP) Swedish double mutation transgenic mice (APP23) for 6 months (a critical period for Aβ deposition) [30]. We found that chronic administration of TLJN significantly reduced Aβ production and deposition and down-regulated BACE1 expression and activity as well as the expression of γ-secretase complex. However Aβ degradation enzymes neprilysin (NEP) and insulin degradation enzyme (IDE) were not affected in the animal model. Materials and Methods Component Analysis of Herbal Medicine TongLuaoJiuNao TLJN was purchased from Kang Yuan Pharmaceutical Engineering Limited Company Neimenggu China (Catalog: 051125). In recent years the active components in TLJN were identified and widely applied GDC-0449 in clinic and experiments [1] [2] [31]. In brief the components are extracted from and test was used as a comparison of two groups. The level of significance was of BACE1 activity inhibition by the treatment of Ginsenoside Rg1 [28] [29]. The mechanism involved in BACE1 down-regulation by TLJN remains to be confirmed. It has been found that glucose reduction could possibly be involved in the early events of AD pathogenesis [54] [55]. It has been evidenced that glucose reduction as well as energy inhibition.