Outlining In Vitro and In Silico Cholinesterase Inhibitory Activity of Twenty-Four Natural Products of Various Chemical Classes: Smilagenin, Kokusaginine, and Methyl Rosmarinate as Emboldening Inhibitors

Cholinesterase (ChE) inhibition is an important treatment strategy for Alzheimer’s disease (AD) as acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are involved in the pathology of AD. In the current work, ChE inhibitory potential of twenty-four natural products from different chemical classes (i.e., diosgenin, hecogenin, rockogenin, smilagenin, tigogenin, astrasieversianins II and X, astragalosides I, IV, and VI, cyclocanthosides E and G, macrophyllosaponins A-D, kokusaginin, lamiide, forsythoside B, verbascoside, alyssonoside, ipolamide, methyl rosmarinate, and luteolin-7-O-glucuronide) was examined using ELISA microtiter assay. Among them, only smilagenin and kokusaginine displayed inhibitory action against AChE (IC₅₀ = 43.29 ± 1.38 and 70.24 ± 2.87 µg/mL, respectively). BChE was inhibited by only methyl rosmarinate and kokusaginine (IC₅₀ = 41.46 ± 2.83 and 61.40 ± 3.67 µg/mL, respectively). IC₅₀ values for galantamine as the reference drug were 1.33 ± 0.11 µg/mL for AChE and 52.31 ± 3.04 µg/mL for BChE. Molecular docking experiments showed that the orientation of smilagenin and kokusaginine was mainly driven by the interactions with the peripheral anionic site (PAS) comprising residues of hAChE, while kokusaginine and methyl rosmarinate were able to access deeper into the active gorge in hBChE. Our data indicate that similagenin, kokusaginine, and methyl rosmarinate could be hit compounds for designing novel anti-Alzheimer agents.

Chemical constituents of the aerial parts of Salvia judaica Boiss. from Jordan

Investigation of the chemical constituents of Salvia judaica growing wild in Jordan led to the isolation and identification of 15 known compounds. These included: luteolin-3'-methyl ether (1), indole-3-carboxyaldehyde (2), p-hydroxybenzaldehyde (3), tricin (4), apigenin (5), methyl isoferuloyl-7-(3,4-dihydroxyphenyl) lactate (6), methyl rosmarinate (7), rosmarinic acid (8), salvigenin (9), β-sitosterol (10), 3β, 28-dihydroxyurs-12-ene (11), cirsilineol (12), 2,3-dihydroxyurs-12-en-28-oic acid (13), β-sitosteryl glucoside (14), and tormentic acid (15). Compounds 6 and 7 exhibited strong radical scavenging and chelating activities as compared to α-tocopherol and ascorbic acid, compound 7 showed a 2-fold greater antioxidant activity as compared to compound 6. Furthermore, low doses of compounds 6 and 7 were able to inhibit the growth of leukemic (HL-60, Jurkat, K562 and CCRF-SB) and solid tumor cells (MCF-7, MDA-MB-231 and Caco-2). Compound 7 showed a ca. 3-4-fold stronger cytotoxicity against the tested cells as compared to compound 6.