3.beta-3-[2-(Diethylamino)ethoxy]androst-5-en-17-one hydrochloride or U18666A, an amphipathic cationic amine, is a cell permeable research tool drug that inhibits cholesterol synthesis and trafficking, and also a weak inhibitor of hedgehog (Hh) signaling. U18666A had been used in several models both in vivo and in vitro to mimic Niemann-Pick type C disease (NPC) and for assessing the importance of molecular trafficking through the lysosomal pathway in other conditions such as atherosclerosis, Alzheimer's disease, and prion infections. U18666A also provided animal models for such disorders as petite mal (absence) epilepsy and cataracts. U18666A inhibits the enzyme desmosterol reductase responsible for reducing the desmosterol in cholesterol biosynthesis, and also blocks LDL-(low density lipoprotein) cholesterol transport from the lysosomes into the endoplasmic reticulum thereby increasing the level of caveolina-1 located within the plasma membrane caveolae. U18666A was shown to be a potent antagonist of alpha4beta2 neuronal nicotinic acetylcholine receptors and may be useful as a tool in the functional characterization and pharmacological profiling of nAChRs.

Betonicine (trans-2-carboxy-4-hydroxy-1,1,-dimethylpyrrolidinium hydroxide, inner salt) and its cis isomer, turicine, are naturally occurring substituted pyrrolidines. Betonicine was used as an analgesic 1000 years ago and is still available commercially from herbalists today. Betonicine has been isolated from Achillea millefolium L. (Compositae) and probably from A. atrata L. (Compositae); it is an alkaloid. Proline betaine and Betonicine were identified as metabolically inert cell protectants against extremes in osmolarity and growth temperatures.

Pifithrin-alpha is a small molecule p53 functional inhibitor reported to behave like an antiapoptotic agent in neurodegenerative models. Pifithrin-alpha is a prodrug that under physiological conditions spontaneously undergoes ring closure to yield pifithrin-beta. Pifithrin-beta demonstrated antiproliferative and neuroprotective effects in vitro. Pifithrin-beta is able to activate the aryl hydrocarbon receptor (AhR) in a complete independent way of the p53 inhibition.

Sinapic acid is one of the most common hydroxycinnamic acids and is widespread in the plant kingdom. It has been identified in various fruits, vegetables, cereal grains, oilseed crops, some spices, and medicinal plants. Sinapic acid and its derivatives possess antimicrobial, antioxidant, anti-inflammatory, anticancer and anti-anxiety activities.

Tomatidine is a steroidal alkaloid derived from green tomato. Tomatitidine has been identified as a potential therapeutic agent or lead compound for the treatment of skeletal muscle atrophy. It has been shown to increase skeletal muscle mTORC1 signaling, reduce skeletal muscle atrophy, enhance recovery from skeletal muscle atrophy, stimulate skeletal muscle hypertrophy, and increase strength and exercise capacity. In addition, tomatidine has been identified as a potential therapeutic agent or lead compound for reducing the activity of Activating Transcription Factor 4 (ATF4).

Veratridine (VTD), an alkaloid derived from the Liliaceae plant shows anti-tumor effects. Veratridine is also an agent that opens voltage dependent Na+ channels, blocks Na+ channel activation, and induces Ca2+ influx. The compound has been observed to be an alkaloid neurotoxin used to amplify sodium permeability. Studies report that Veratridine can trigger exocytosis and induce Ca2+ oscillations. Furthermore, Veratridine has been shown to effect the mitochondrial respiratory chain complexes, induce release of noradrenaline, and increase superoxide anion production. Veratridine competes with BTX binding in a mutually exclusive manner. However, the pharmacological effects of veratridine on Na+ channels are quite different from those of BTX. First, veratridine reduces the single Na+ channel conductance drastically whereas BTX does not. Veratridine therefore is regarded as a partial agonist and BTX as a full agonist of Na+ channels. Second, under voltage clamp conditions BTX binds practically irreversibly to Na+ channels whereas veratridine readily dissociates from its binding site. Both of these drugs, however, bind preferentially to the open state of Na+ channels. The BTX resistant Na+ channels in Phyllobates frogs remain sensitive to veratridine. The ceveratrum alkaloids, including Veratridine, have a characteristic hypotensive effect not directly involving the CNS. They slow the heart and lower arterial blood pressure by reflexly stimulating medullary vasomotor centers without decreasing cardiac output (Bezold–Jarisch effect). These agents were introduced in the 1950s as antihypertensive agents; however, they were found to have a narrow therapeutic index and their use was discontinued.

Levovirin is a guanosine nucleoside analog and the L-enantiomer of ribavirin. It is an investigational drug for the treatment of hepatitis C virus-mediated diseases. Levovirin has a similar immunomodulatory potency to ribavirin in vitro without accumulating in red blood cells or causing hemolytic anemia, a known side effect of ribavirin. Levovirin has been shown to stimulate host immune responses (enhanced Th1 and reduced Th2 cytokine expression). Significantly improved oral absorption of levovirin was achieved following administration of a valine ester prodrug of levovirin R1518. Levovirin was found more potent to inhibit Tick-borne encephalitis virus (TBEV) on the basis of robust binding affinity between protein-drug interactions. This finding may help to understand the nature of helicase and development of specific anti-TBEV therapies.