Lyonensinols A - C, 24-Norursane-Type Triterpenoids from the Twigs and Leaves of Lyonia doyonensis and Their Potential Anti-inflammatory and PTP1B Inhibitory Activities

Lyonia doyonensis is a deciduous shrub native to high-altitude regions of Asia. So far, there is no report on any chemical and biological properties of L. doyonensis. An EtOH extract of L. doyonensis twigs and leaves showed inhibitory activities on protein tyrosine phosphatase 1B and lipopolysaccharide-induced inflammation in BV-2 microglial cells. A phytochemical investigation of this extract led to the isolation of a, so far only ambiguously described, 24-norursane-type triterpenoid, now named lyonensinol A (1: ), along with its two new derivatives, lyonensinols B and C (2: and 3: ), and six known triterpenoids (4 - 9: ). Their structures were elucidated by detailed analysis of spectroscopic data. A combination of chemical conversions, electronic circular dichroism, and Mo2(OAc)4-induced electronic circular dichroism was used to confirm their absolute configurations. Lyonensinols B (2: ) and C (3: ) represent the first examples of norursane-type triterpenoids acylated with a p-coumaroyl moiety. The potential anti-inflammatory and protein tyrosine phosphatase 1B inhibitory activities of all the isolates were evaluated. Compounds 3, 7: , and 8: at 10 µM showed potent inhibitory activities on lipopolysaccharide-induced nitric oxide production in BV-2 microglial cells, with nitric oxide levels decreasing to 31.5, 41.9, and 27.1%, respectively, while compounds 3, 4, 7: , and 8: exhibited notable inhibitory activities against protein tyrosine phosphatase 1B, with IC50 values ranging from 1.7 to 18.2 µM. Interestingly, compounds 3: and 8: , bearing a C-3 trans-p-coumaroyl group, showed not only more potent anti-inflammatory effects, but also exhibited stronger protein tyrosine phosphatase 1B inhibition than their respective stereoisomers (2: and 7: ) with a cis-p-coumaroyl group.

Triterpenoids

This review covers newly isolated triterpenoids that have been reported during 2015.

Isolation, characterization, and bioactivities of compounds from Fuscoporia torulosa mushroom

Chromatographic purification of Fuscoporia torulosa extracts resulted in the isolation and characterization of a new steroid, 5α,8α-epidioxyergosta-6,22-dien-3β-il-palmitate (1) and 10 known compounds (2-11). The structures of compounds were elucidated by IR, NMR, MS analyses, and comparison with literature data. Cytotoxic activities against MCF-7 (breast cancer), PC-3 (prostate cancer), and 3T3 (nontumor) of the extracts and cytotoxic, antioxidant, cholinesterase, and tyrosinase inhibitory activities of all isolated compounds were evaluated. The methanol extract and Compound 8 showed the best cytotoxicity against MCF-7, whereas the hexane extract and Compound 4 displayed the highest cytotoxicity against PC-3. Compounds 10 and 11 displayed higher antioxidant activity than α-tocopherol and butylated hydroxyanisole (BHA) which are used as standards in ABTS^•+ , DPPH^• , and cupric reducing antioxidant capacity (CUPRAC) assays. Also, cholinesterase inhibitory activity against acetylcholinesterase (AChE) and butrylcholinesterase (BChE), Compounds 4 and 8 were determined as the most active compounds. Among all isolated compounds, Compound 11 exhibited the highest tyrosinase inhibitory activity. PRACTICAL APPLICATIONS: Mushrooms have various important medicinal properties. A detailed study was made to identify the bioactive constituents of Fuscoporia torulosa mushroom and a new (1) and 10 known compounds (2-11) were isolated. Compounds 10 and 11 showed higher antioxidant activity than standards. The methanol extract and Compound 8 exhibited high cytotoxic activity against MCF-7. Compound 8 indicated potent BChE inhibitory activity. This study suggests that natural compounds isolated from F. torulosa mushroom could be used as promising anticancer, antioxidant, and anticholinesterase agents.

13,27-Cycloursane, ursane and oleanane triterpenoids from the leaves of Lucuma nervosa

One hitherto unknown 24-nor-13,27-cycloursane-type triterpenoid, lucumic acid A (1), one new 24-nor-ursane triterpenoid, lucumic acid B (2), along with six known triterpenoids were isolated from the ethanol extract of the leaves of Lucuma nervosa. Their structures were established on the basis of spectroscopic data interpretation. Lucumic acid A (1) is the first example of a 24-nor-triterpenoid with a 13,27-cyclopropane ring.

Cytotoxic Properties of the Stem Bark of Citrus reticulata Blanco (Rutaceae)

The bioassay-guided fractionation of the n-hexane extract of Citrus reticulata Blanco (Rutaceae) stem bark yielded scoparone (1), xanthyletin (2), lupeol (3), β-amyrin (4), stigmasterol (5), β-sitosterol (6) and palmitic acid. The structures of these compounds were determined by comprehensive spectroscopic analyses, i.e., 1D and 2D NMR and EI-MS, and by comparison with the reported data. Extracts, fractions and isolated compounds 1-6 were assessed for cytotoxicity by the 3-(4,5-dimethylthiazol-2-yl)-2,5-dphenyltetrazolium bromide (MTT) assay against three human cancer cell lines, i.e., human lung adenocarcinoma cell line A549, human breast adenocarcinoma cell line MCF7 and human Caucasian prostate adenocarcinoma cell line PC3. Significant activity of the n-hexane and the dichloromethane extracts was observed against the breast cancer cell line MCF7 with IC₅₀ s of 45.6 and 54.7 μg/mL, respectively. Moreover, the 70% ethyl acetate in n-hexane chromatographic fraction showed significant activity displaying IC₅₀ values of 53.0, 52.4 and 49.1 μg/mL against the cancer cell lines A549, MCF7 and PC3, respectively. Encouragingly, an IC₅₀ of 510.0 μg/mL against the human normal prostate cell line PNT2 indicated very low toxicity and hence favourable selectivity indices for the 70% ethyl acetate in n-hexane fraction in the range of 9.6-10.4 towards cell lines A549, MCF7 and PC3. Because compounds isolated from the above fraction only delivered IC₅₀ values in the range of 18.2-96.3, 9.2-34.1 and 7.5-97.2 μg/mL against A549, MCF7 and PC3 cell lines, respectively, synergistic action between compounds is suggested. Bioassay results valorize the anticancer effectivity of the stem bark of this plant in Cameroonian pharmacopoeia. Copyright © 2017 John Wiley & Sons, Ltd.