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A set of twenty one lupane derivatives (2-22) was prepared from the natural triterpenoid calenduladiol (1) by transformations on the hydroxyl groups at C-3 and C-16, and also on the isopropenyl moiety. The derivatives were tested for their inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and some structure-activity relationships were outlined with the aid of enzyme kinetic studies and docking modelization. The most active compound resulted to be 3,16,30-trioxolup-20(29)-ene (22), with an IC50 value of 21.5μM for butyrylcholinesterase, which revealed a selective inhibitor profile towards this enzyme., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Lupane triterpenoids 2 and 5-12 and oleanene derivatives 13 and 14 were prepared from lupeol (1), betulin (3), and germanicol (4). They were tested for anti-HIV activity, and some structure-activity relationships were outlined. The 20-(S) absolute configuration of epoxylupenone (8) was assessed by comparison of the observed and DFT-calculated vibrational circular dichroism spectra. The CompareVOA algorithm was employed to support the C-20 configuration assignment. The 20,29 double bond in lupenone (2) and 3-epilupeol (15) was stereoselectively epoxidized to produce 20-(S)-8 and 20-(S)-16, respectively, an assignment in agreement with their X-ray diffraction structures., (© 2012 American Chemical Society and American Society of Pharmacognosy)

Seven new triterpenoids (1-7) and 36 known compounds were isolated from the root bark of Maytenus retusa. Their structures were determined by 1D and 2D spectroscopic studies. Several compounds were evaluated for their cytotoxicity against the human tumor cell lines HL-60 and MCF-7. Some of them were cytotoxic, with IC(50) values ranging between 0.2 and 4.7 μM.

Five new triterpenes (1-5) and one new lignan (6) were isolated from the aerial parts of Maytenus apurimacensis. Their structures were determined on the basis of spectroscopic studies, including homonuclear and heteronuclear correlation NMR experiments (COSY, ROESY, HSQC, and HMBC).

Two new dammarane triterpenes have been isolated from the stem bark exudates of Maytenus macrocarpa. Their structures were determined by extensive 1D and 2D NMR spectroscopic studies as 24(Z)-3-oxodammara-20(21),24-dien-27-oic acid (1) and octa-nor-13-hydroxydammara-1-en-3,17-dione (2). These compounds were tested for antitumoral activity.

Cancer will be the major cause of death in the 21st century and natural products should provide novel and more effective anticancer agents. This review deals with new natural molecules liable to become anticancer drugs, as well as recent specific strategies for a selective treatment of cancer. The introduction presents the current state of the art on anticancer research. Beside, in the following subheadings we summarize our research on cytotoxic natural quinone methide-triperpenes and their analogues. We also discuss our results on the anti-tumour promoting activity of natural naphthoquinones and their derivatives.

Cucurbitacin F and the cyanogenetic compounds prunasin were isolated and identified from the seeds of Kageneckia angustifolia.

Parasite resistance to drugs has emerged as a major problem in current medicine, and therefore, there is great clinical interest in developing compounds that overcome these resistances. In an intensive study of South American medicinal plants, herein we report the isolation, structure elucidation, and biological activity of dihydro-beta-agarofuran sesquiterpenes from the roots of Maytenus magellanica (1-14) and M. chubutensis (14-17). This type of natural products may be considered as privileged structures. The structures of 10 new compounds, 1, 3, 6-9, and12-15, were determined by means of (1)H and (13)C NMR spectroscopic studies, including homonuclear (COSY and ROESY) and heteronuclear correlation experiments (HMQC and HMBC). The absolute configurations of eight hetero- and homochromophoric compounds, 1, 3,6-9, 12, and 13, were determined by means of CD studies. Fourteen compounds, 1-3 and 6-16, have been tested on a multidrug-resistant Leishmania tropica line overexpressing a P-glycoprotein-like transporter to determine their ability to revert the resistance phenotype and to modulate intracellular drug accumulation. From this series, 1, 2, 3, 14, and 15 showed potent activity, 1 being the most active compound. The structure-activity relationships of the different compounds are discussed.

Macrocarpins A (1), B (2), C (3) and D (4), four new nor-triterpenes, have been isolated from the roots of Maytenus macrocarpa. The structures were established by spectroscopic examinations. Natural compounds 1, 2, 4 and the acetyl derivative 1a are cytotoxic against four tumoral cell lines with IC50 values ranging between 0.4 and 5.2 microM.

Two novel trimers, triscutins A and B (1 and 2), based on pristimerin triterpene units, were isolated and characterized from Maytenus scutioides. Their structures were determined on the basis of spectroscopic evidence, including 1H-13C heteronuclear correlation (HMQC), long-range correlation with inverse detection (HMBC), and ROESY NMR experiments; and their absolute configurations, by means of CD studies. Compounds 1 and 2 were assayed for antimicrobial and cytotoxic activities, and their possible biosynthetic route is proposed.

The new nortriterpene methylene quinones amazoquinone (1) and (7S, 8S)-7-hydroxy-7,8-dihydro-tingenone (2), and the new norphenolic triterpenes 7,8-dihydro-6-oxo-tingenol (3), 23-nor-6-oxo-tingenol (4), and 23-oxo-iso-tingenone (5) were isolated from Maytenus amazonica. Their structures were elucidated by spectroscopic methods. Compounds 1, 2, 3, and 5 showed low antitumor activity against four cancer cell lines.

By antimicrobial and cytotoxic-guided fractionation, a bioactive norquinone-methide triterpene, 15 alpha-hydroxypristimerin, was isolated from a South American medicinal plant, Maytenus scutioides. Its structure was determined on the basis of spectroscopic evidence. Successful chemical transformation of pristimerin to netzahualcoyene indicates that the 15-hydroxy compounds seems to be a possible percursor of 14(15)-ene-quinone-methide-triterpenoids in the biogenetic pathway.

A set of friedelane triterpenoids has been isolated from the stem bark exudates of Maytenus macrocarpa. It includes a new friedelan triterpene (1), together with the known compounds friedelin, 3-oxo-29-hydroxyfriedelane, 3-oxofriedelan-25-al, and canophyllol. The structures of these compounds were elucidated by spectroscopic and chemical evidence. Complete 1H and 13C assignments were achieved by 2D NMR spectroscopy. The new compound showed weak activity against aldose reductase. It did not display antitumor activity against P-388 lymphoid neoplasm, A-549 human lung carcinoma, HT-29 human colon carcinoma, or MEL-28 human melanoma cell lines.

Scutione (1), a new norquinonemethide triterpene with a netzahualcoyene type skeleton, has been isolated from the root bark of Maytenus scutioides (Celastraceae) by bioactivity-directed fractionation. The structure of 1 has been elucidated by means of 1H and 13C NMR spectroscopic studies, including 1H-13C heteronuclear correlation (HETCOR), a long-range correlation spectrum with inverse detection (HMBC) and ROESY experiments. Compound 1 showed antibiotic activity against Gram-positive bacteria and modest cytotoxic activity against HeLa, Hep-2 and Vero cell lines. Fluoride derivatives 2-4 were prepared and assayed for bioactivity, where 2 showed slight improvement of the cytotoxic potency.

The activity of netzahualcoyone on Bacillus subtilis and Escherichia coli was studied. The product inhibited the respiration of intact cells of B. subtilis but had no effect on the respiration of E. coli. However, when preparations of sonically disrupted cells were examined, inhibitory activity on both bacteria was observed.

The cytostatic activity of several triterpenequinone methides isolated from Rzedowskia tolantonguensis and Maytenus horrida (Celastraceae) was evaluated against HeLa cell cultures. Their ID50 were determined and compared with those of other related compounds. A preliminary study of the antibacterial activity of the above triterpenequinone methides was also carried out.