Design, Synthesis and Biological Evaluation of Steroidal Glycoconjugates as Potential Antiproliferative Agents

Synthesis and Pharmacological Properties of Modified A- and D-Ring in Dehydroepiandrosterone (DHEA): A Review

Dehydroepiandrosterone (3β-hydroxyandrost-5-en-17-one) (DHEA) is a naturally occurring steroid hormone primarily produced in the zona reticularis of the human adrenal glands. It serves as a crucial precursor for sex hormones, such as testosterone, estradiol, and androstenedione. Recent findings indicate that DHEA serves as the primary source of sex steroids in women during both pre- and postmenopausal stages. Additionally, a decline in DHEA levels with age is linked to various hormone-deficiency symptoms. Despite the wide array of biological activities that make DHEA a valuable polycyclic natural steroid, particularly for pharmaceutical and cosmetic applications, reports suggest that oral DHEA has limited clinical effect. Thus, A- and D-ring modified DHEA are synthesized and their biological activities are carried out by different research groups and enhanced biological activity reported in the literature. Here, in this review, we have tried to cover all of the synthetic routes and biological studies of modified A- and D-ring DHEA from 2015 to mid-2022.

Three new cardenolides from the fruits of Cascabela thevetia (L.) Lippold and their cytotoxic activities

Phytochemical investigations on the fruits of Cascabela thevetia (L.) Lippold led to obtain three new cardenolides (1-3) and five known analogues (4-7). Their structures were elucidated by means of UV, IR, HR-ESI-MS, 1D and 2D NMR spectroscopic data analysis. Compounds 1 and 2 represent the first examples of naturally occurring cardenolides with 19-nor-5(10)-ene group and α-l-3-demethyl-thevetose, respectively. Compound 3 is a rare C-nor-D-homocardenolide in nature. All isolated cardenolides (1-7) were evaluated for their cytotoxic activities against four human cancer cell lines (MCF-7, HCT-116, HeLa and HepG2), and the results indicated the compounds with sugar units (1, 2, 4, and 5) exhibited stronger cytotoxic activities with IC50 values ranging between 0.022 and 0.308 μM.

Synthesis and biological evaluation of 3β-O-neoglycosides of caudatin and its analogues as potential anticancer agents

In order to study the structure-activity relationship (SAR) of C₂₁-steroidal glycosides toward human cancer cell lines and explore more potential anticancer agents, a series of 3β-O-neoglycosides of caudatin and its analogues were synthesized. The results revealed that most of peracetylated 3β-O-monoglycosides demonstrated moderate to significant antiproliferative activities against four human cancer cell lines (MCF-7, HCT-116, HeLa, and HepG2). Among them, 3β-O-(2,3,4-tri-O-acetyl-β-L-glucopyranosyl)-caudatin (2k) exhibited the highest antiproliferative activity aganist HepG2 cells with an IC₅₀ value of 3.11 μM. Mechanical studies showed that compound 2k induced both apoptosis and cell cycle arrest at S phase in a dose dependent manner. Overall, these present findings suggested that glycosylation is a promising scaffold to improve anticancer activity for naturally occurring C₂₁-steroidal aglycones, and compound 2k represents a potential anticancer agent deserved further investigation.

Synthesis of MeON-Glycoside Derivatives of Oleanolic Acid by Neoglycosylation and Evaluation of Their Cytotoxicity Against Selected Cancer Cell Lines

A series of C-3 and C-28 MeON-neoglycosides of oleanolic acid were designed and synthesized by neoglycosylation as potential antiproliferative agents. Their cytotoxicity was evaluated in vitro against five human cancer cell lines: human non-small cell lung cancer cell line (A549), human melanoma cell line (A375), human colon cancer cell line (HCT116), human liver carcinoma cell line (HepG2), human breast adenocarcinoma cell line (MCF-7) by the Cell Counting Kit-8 (CCK-8) assay. Most of C-3 and C-28 MeON-neoglycosides of oleanolic acid exhibited notably inhibitory effects against the tested cancer cells and more sensitive to HepG2 cells than 5-Fluorouracil (5-FU). Structure-activities relationship (SAR) analysis revealed that sugar types and the d/l configuration of sugars would significantly affect their antiproliferative activities of neoglycosides. Among them, compound 8a (28-N-methoxyaminooleanane-β-d-glucoside) exhibited the most potent antiproliferative activities against HepG2 cells with IC₅₀ values of 2.1 µM. Further pharmacological experiments revealed that compound 8a could cause morphological changes and cell cycle arrest at G0/G1 phase and induce apoptosis in HepG2 cells. These results suggested that neoglycosylation could provide a rapid strategy for the discovery of potential antiproliferative agents and their possible pharmacological mechanisms need more further research.