Dihydrostreptomycin is an aminoglycoside antibiotic targeting gram-positive bacteria and Mycobacterium species. It is a derivative of streptomycin and commonly used to study aminoglycoside uptake. Dihydrostreptomycin sulfate is freely soluble in aqueous solution.

Dihydrotanshinone I is a compound extracted from the plant Salvie miltorrhiza Bunge. It is used as a gram positive antibacterial and anti-cancer compound. In both in vivo and in vitro research, dihydrotanshinone I generated reactive oxygen species which trigger apoptosis in bacteria and cancer cells.

Dihydrotanshinone I triggers apoptosis by directly damaging DNA and preventing further replication or by activating p38 mitogen-activated protein kinases (p38 MAPK). This class of protein kinase engages apoptosis by activating caspases which are proteases that induce cell death. Dihydrotanshinone I has also been shown to inhibit cell growth past the G1 stage and prevent blood vessel formation by inhibiting hypoxia-inducible factor (HIF-1) activity.

Dimethyl 1,4-Cubanedicarboxylate is a reagent used in chemical synthesis.

Dimetridazole is a nitroimidazole antibiotic useful against protozoa and bacteria. It has shown great efficacy against Campylobacter species. Dimetridazole has been useful in studying nitroimidazole mechanisms and is slightly soluble.

Dirithromycin is a lipid soluble prodrug derivative of the macrolide antibiotic 9S-erythromycyclamine. It has a sizeable antibiotic activity range, being effective against gram positive and gram negative bacteria. It is highly insoluble in acidic and alkaline conditions and will spontaneously hydrolyze into the active erythromycyclamine form.

Macrolide antibiotics are composed of a macrocyclic lactone ring attached to one or more deoxy sugars. They inhibit bacterial protein synthesis by irreversibly binding the P site of the 50s ribosome, preventing peptide bond formation and translocation.

Antibiotics are often used in clinical in vitro tests known as antimicrobial susceptibility tests or ASTs to determine their efficacy against certain bacterial species. They are tested against gram-negative and gram-positive bacteria using panels, discs, and MIC strips by medical microbiologists. ASTs decrease the risk of using an antibiotic against bacteria exhibiting resistance to it, and the results are used in clinical settings to determine which antibiotic(s) to prescribe for various infections.

DL-3-Tyrosine has a hypotensive effect on blood pressure and is converted to dopamine in rats. It can also be used as a reagent for chemical synthesis.

DL-Arginine is an alpha amino-acid and can be found as a metabolite and as a reagent for biological molecules.

DL-ethionine changes behavior of hepatic functions by working as a carcinogenic agent that induces cholangiocarcinogensis in vivo and can be used to induce oxidative stress on the liver to measure antioxidant enzymatic activity. In the pancreas it destroys acinar cells and eventually induces pancreatitis in rats. DL-ethionine also inhibits incorporation of amino acids, like methionine and glycine, into rat protein in vivo and interferes with the use of adenosine triphosphate (ATP) in cells.

DL-Glyceraldehyde is a substrate for the enzyme aldose reductase.