Low targeting efficiency and fast metabolism of antineoplastic drugs are hindrances to effective chemotherapies and there is an ongoing search for better drugs, but also better carriers. Steroid derivatives, 3β-hydroxy-16-hydroxymino-androst-5-en-17-one (A) and 3β,17β-dihydroxy-16-hydroxymino-androst-5-ene (B) as cancer growth inhibitors were chemically synthesized and captured in a carrier composed of hydroxyapatite (HAp) nanoparticles coated with chitosan oligosaccharide lactate (ChOLS). The only difference between the two derivatives is that A has a carbonyl group at the C17 position of the five-membered ring and B has a hydroxyl. This small difference in the structure resulted not only in different physicochemical properties of the A- and B-loaded HAp/ChOSL, but also in different biological activities. The morphology of drug-loaded HAp/ChOSL particles was spherical, but the size depended on the drug identity: d₅₀ = 138 nm for A-loaded HAp/ChOSL and d₅₀ = 223 nm for B-loaded HAp/ChOSL. Cell-selective toxicity was tested against human breast carcinoma (MCF7 and MDA-MB-231), human lung carcinoma (A549) and human lung fibroblasts (MRC-5). The small selectivity of pure derivatives A and B toward breast cancer cells became drastically increased when they were delivered using HAp/ChOSL particles. Whereas the ratio of the cytotoxicity imposed onto breast cancer cells and the cytotoxicity imposed onto healthy MRC-5 fibroblasts ranged from 1.5 to 1.7 for pure A and from 1.5 to 2.3 for pure derivative B depending on the concentration, it increased to 5.4 for A-loaded HAp/ChOSL and 5.1 for B-loaded HAp/ChOSL. FACS analysis demonstrated poor uptake of HAp/ChOSL particles by MCF7 cells, suggesting that the drug release occurs extracellularly. The augmented activity of the drugs was most likely due to sustained release, although the favorable positive charge of the carrier, allowing it to adhere to the negatively charged plasma membrane and release the drugs steadily and directly to the hydrophobic cell membrane milieu, was delineated as a possible complementary mechanism.

Parasitic diseases affect millions of people and animals, predominantly in the tropics, in-cluding visitors to tropical countries and other areas. Efficient and low-cost treatments for infections caused by various parasites are not yet available. Antiparasitic drugs have some drawbacks, such as toxicity and the development of resistance by parasites. This has motivated many researchers to fo-cus on the discovery of safe, effective and affordable antiparasitic drugs, both among drugs already available for other diseases and new compounds synthesized or isolated from natural sources. Fur-thermore, steroid and triterpenoid compounds attract the attention of pharmacologists, chemists and biochemists owing to their broad application in the treatment of various diseases. Isolation of ster-oid and triterpenoid compounds from natural sources with antiparasitic efficacy is an attractive choice for scientists. On the other hand, these compounds can be transformed into more potent forms by modifying the basic skeleton. This review presents a collection of isolated and synthesized steroid and triterpenoid compounds from 2018 to 2021 that have been reported to be effective against certain parasitic protozoa and helminths. A total of 258 compounds have been identified with antimalarial, antitrypanosomal, antileishmanial, anti-Toxoplasma, and/or anthelmintic activity. The described investigations of antiparasitic compounds may be helpful for further drug develop-ment.