Geniposide, a key component extracted from the fruit of Gardenia jasminoides Ellis, is a major iridoid glycoside considered to be responsible for various biological effects of the herbs, and its aglycon is genipin. Gardenia is a widely used Chinese herb for the treatment of hepatic disease, inflammation disorders, contusions and brain disorders. Increasing studies have focused on the neuroprotective effect of geniposide in brain diseases, especially neurodegenerative disorders. Its protective effect from memory impairment and the normalization of objection recognition has been shown in animal behavioral experiments. Using a high-throughput screen for GLP-1R agonists, geniposide was identified as an agonist for GLP-1R. It has been shown that the activation of GLP-1R by geniposide induces neurotrophic and neuroprotective effects in cells. Geniposide exerted anti-inflammatory effects by interfering with the expression of P2Y14 receptor, which subsequently inhibits the downstream ERK1/2 signaling pathways and the release of the pro-inflammatory cytokines IL-8, MCP-1, IL-1β.

Coptisine (COP), a protoberberine alkaloid, is widely found in Chinese medicinal plants (family Berberidaceae, Ranunculaceae and Papaveraceae). It is reported that COP has a wide range of pharmacological and biological activities, including antibacterial, hypoglycemic, anti-tumorigenic, and gastric-mucous membrane protection. Considerable attention has been focused on its activity against central nervous system disorders, such as improving the symptoms of Alzheimer’s disease and even preventing its onset, by exerting antidepressant effects as a potent type A monoamine oxidase inhibitor. Coptisine was found to be an efficient uncompetitive Indoleamine 2,3-dioxygenase inhibitor. Coptisine is a potent inhibitor of human organic cation transporters.

24S-hydroxycholesterol (24(S)-HC), the major cholesterol metabolite in the brain, is critical to brain cholesterol metabolism and turnover. This metabolite is a very potent, direct, and selective positive allosteric modulator of N-methyl-D-aspartate receptors (NMDARs) with a mechanism that does not overlap that of other allosteric modulators. NMDARs are glutamate-gated ion channels that are critical to the regulation of excitatory synaptic function in the CNS. It is known, that concentrations of 24(S)-HC in plasma and cerebrospinal fluid (CSF) are significantly higher in Alzheimer's disease and in mild cognitive impairment patients at early stages of the diseases compared to healthy subjects. It was suggested, that 24-hydroxycholesterol, could be a sensitive biomarker for the evaluation of these two diseases.

Methysticin is a kavalactone originally found in Piper methysticum (kava plant). Methysticin exhibits neuroprotective, neuromodulatory, and antifungal activities. Methysticin may also display anti-inflammatory benefit, inhibiting activation of NF-κB in lung adenocarcinoma tissue. Methysticin activates Nrf2 in neurons and astroglia, protecting against amyloid-β (Aβ)-induced neurotoxicity. This compound displays antimicrobial efficacy against species of Fusarium, Trichoderma, and Colletotrichum. Additionally, methysticin inhibits peak amplitude of voltage-gated Na+ channels in hippocampal neurons. Methysticin administration activates the Nrf2 pathway and reduces neuroinflammation, hippocampal oxidative damage and memory loss in a mouse model of AD. Therefore, kavalactones might be suitable candidates to serve as lead compounds for the development of a new class of neuroprotective drugs.

1,4-naphthoquinone is a chemical studied as a potential inhibitor of monoamine oxidase and DNA topoisomerase activities as well as acetyltransferase activity. 1,4-Naphthoquinone is a potent inhibitor of human cancer cell growth and angiogenesis.

Lycorine is a natural pyrrolo[de]phenanthridine ring-type alkaloid extracted from Amaryllidaceae. It has been reported to exhibit a wide range of physiological effects, including anti-viral, anti-malarial, anti-cancer and anti-inflammatory. Although a defined target or mechanism of action of lycorine is still unknown, it is a candidate anti-inflammatory and anti-cancer drug.

Trihydroxychalcone (Isoliquiritigenin, ISL) is a flavonoid found in licorice root and several other plants that displays antioxidant,anti-inflammatory,and antitumor activities as well as hepatoprotection against steatosis-induced oxidative stress. Trihydroxychalcone is a potent antimetastatic agent, which can markedly inhibit the metastatic and invasive capacity of prostate cancer cells. The inhibition of JNK/AP-1 signaling may be one of the mechanisms by which ISL inhibits cancer cell invasion and migration. Trihydroxychalcone has been shown to be a BACE1 inhibitor, which could ameliorate memory impairment in mice, and is expected to be potentially used as a lead compound for further anti-AD reagent development.

Acacetin is an O-methylated flavone that exhibits anti-inflammatory, anti-nociceptive, neuroprotective, and anti-aromatase properties. It is a naturally occurring plant metabolite which can be found in Robinia pseudoacacia, Turnera diffusa, Betula pendula, and Asplenium normale. Acacetin has been investigated in a number of in-vitro and animal models for various cancers, and neurological disorders including Alzheimer's disease.

Phenserine tartrate (phenserine), a phenylcarbamate analog of physostigmine, is a long-acting and centrally active inhibitor of acetylcholinesterase (AChE). In addition to being a potent inhibitor of AChE, it has been demonstrated that phenserine inhibits the formation of beta-APP, the source of neurotoxic beta-amyloid peptide which is a major component of the extraneuronal plaques that pathologically characterize Alzheimer’s disease (AD). Phenserine was developed as a potential therapy for AD by Axonyx, under license from the National Institutes of Health/National Institute on Aging. In March 2005, Axonyx suspended patient recruitment for the ongoing Phase III trials of phenserine, after the drug failed to meet the primary endpoints of the first of these trials.

SB-271046 is one of the first selective 5-HT6 receptor antagonists to be discovered. SB-271046 is a potent, selective and orally active 5-HT6 receptor antagonist with a pKi value of 8.9. This compound provides a useful tool for further elucidating the physiological function of 5-HT6 receptors in vivo. SB-271046 was found to increase levels of the excitatory amino acid neurotransmitters glutamate and aspartate, as well as dopamine and noradrenaline in the frontal cortex and hippocampus of rats, and 5-HT6 antagonists have been shown to produce nootropic effects in a variety of animal studies. Suggested applications of SB-271046 included treatment of schizophrenia and other psychiatric disorders. A phase I clinical development of SB-271046 by GlaxoSmithKline (GSK) was discontinued due to a poor BBB permeability.