Sterols and Triterpenes from Dobera glabra Growing in Saudi Arabia and Their Cytotoxic Activity.

ABSTRACT: A new lupane caffeoyl ester, lup-20(29)-ene 3?-caffeate-30-al (7), and a new oleanane-type triterpene, 3?-hydroxyolean-13(18)-en-12-one (17), were isolated from the aerial parts of Dobera glabra (Forssk), along with ten known triterpenes, including seven lupane-type lupeol (1), 30-nor-lup-3?-ol-20-one (2), ?¹-lupenone (3), lup-20(29)-en-3?,30-diol (4), lupeol caffeate (5), 30-hydroxy lup-20(29)-ene 3?-caffeate (6), and betunaldehyde (8); three oleanane-type compounds were also identified, comprising ?-amyrone (15), ?-amyrin (16), and 11-oxo-?-amyrin (18); together with six sterols, comprising ?-sitosterol (9), stigmasterol (10), 7?-hydroxy-?-sitosterol (11), 7?-hydroxy-stigmasterol (12), 7-keto-?-sitosterol (13), and 7-keto-stigmasterol (14). Their structures were elucidated using a variety of spectroscopic techniques, including 1D (¹H, ¹³C, and DEPT-135 ¹³C) and 2D (¹H-¹H COSY, ¹H-¹³C HSQC, and ¹H-¹³C HMBC) nuclear magnetic resonance (NMR) and accurate mass spectroscopy. Subsequently, the different plant extracts and some of the isolated compounds (1-9, 11 and 13) were investigated for their possible cytotoxic activity in comparison to cisplatin against a wide array of aggressive cancer cell lines, such as colorectal cancer (HCT-116), hepatocellular carcinoma (HepG-2), and prostate cancer (PC-3) cell lines. Compound 11 displayed broad cytotoxicity against all of the tested cell lines (IC₅₀ ? 8 µg/mL in all cases), and a high safety margin against normal Vero cells (IC₅₀ = 70 µg/mL), suggesting that 11 may be a highly selective and effective anticancer agent candidate. Notably, the evidence indicated that the mode of action of compound 11 could possibly consist of the inhibition of phosphodiesterase I (80.2% enzyme inhibition observed at 2 µM compound concentration).

SUBMITTER: Abdel-Mageed WM 

PROVIDER: S-EPMC7827382 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature