4-Aryl Pyrrolidines as a Novel Class of Orally Efficacious Antimalarial Agents. Part 1: Evaluation of 4-Aryl- N-benzylpyrrolidine-3-carboxamides.

Identification of novel chemotypes with antimalarial efficacy is imperative to combat the rise of Plasmodium species resistant to current antimalarial drugs. We have used a hybrid target-phenotype approach to identify and evaluate novel chemotypes for malaria. In our search for drug-like aspartic protease inhibitors in publicly available phenotypic antimalarial databases, we identified GNF-Pf-4691, a 4-aryl- N-benzylpyrrolidine-3-carboxamide, as having a structure reminiscent of known inhibitors of aspartic proteases. Extensive profiling of the two terminal aryl rings revealed a structure-activity relationship in which relatively few substituents are tolerated at the benzylic position, but the 3-aryl position tolerates a range of hydrophobic groups and some heterocycles. Out of this effort, we identified (+)-54b (CWHM-1008) as a lead compound. 54b has EC50 values of 46 and 21 nM against drug-sensitive Plasmodium falciparum 3D7 and drug-resistant Dd2 strains, respectively. Furthermore, 54b has a long half-life in mice (4.4 h) and is orally efficacious in a mouse model of malaria (qd; ED99 ∼ 30 mg/kg/day). Thus, the 4-aryl- N-benzylpyrrolidine-3-carboxamide chemotype is a promising novel chemotype for malaria drug discovery.

Nucleoside and N-acetyldopamine derivatives from the insect Aspongopus chinensis.

Two new nucleoside derivatives, named asponguanosines A and B (1 and 2), three new N-acetyldopamine analogues, aspongamides C-E (3-5), one new sesquiterpene, aspongnoid D (6), and three known compounds were isolated from the medicinal insect Aspongopus chinensis. Their structures including absolute configurations were assigned by using spectroscopic methods and ECD and 13C NMR calculations. Biological activities of compounds 3-7 towards human cancer cells, COX-2, ROCK1, and JAK3 were evaluated.

Meroterpenoid dimers from Ganoderma cochlear and their cytotoxic and COX-2 inhibitory activities.

(+)- and (-)-Spirocochlealactones A-C (1-3), three pairs of new spiro meroterpenoidal dimeric enantiomers together with one known compound ganodilactone (4), were isolated from the fruiting bodies of Ganoderma cochlear. Their structures including absolute configurations were assigned by using spectroscopic methods and ECD calculations. All the isolated compounds were tested for their COX-2 inhibitory and cytotoxic activities toward human cancer lines (A549, K562, and Huh-7). The results show that all the compounds could inhibit COX-2 with IC50 values in the range of 1.29 to 3.63 µM. In addition, (+)-spirocochlealactone A and (+)-ganodilactone were found to be moderate activities against human cancer cell line A549 with the IC50 values of 7.14 and 9.47 µM, respectively.

Meroterpenoids from the fruiting bodies of Ganoderma theaecolum.

A series of new terminal cyclohexane-type meroterpenoids, ganotheaecoloids A-N (1-6, 8-13, 15, and 16), along with three known ones (7, 14, and 17), were isolated from the dried fruiting bodies of Ganoderma theaecolum. Their chemical structures were identified by using spectroscopic data and computational methods. Biological activity of all the new meroterpenoids against COX-2 was evaluated in vitro, only ganotheaecoloid J (11) was found to have COX-2 inhibitory activity with IC50 value of 9.96µM.

Vaccinols J-S, ten new salicyloid derivatives from the marine mangrove-derived endophytic fungus Pestalotiopsis vaccinii.

Ten new salicyloid derivatives, namely vaccinols J-S (1-10), along with five known compounds (11-15) were isolated from Pestalotiopsis vaccinii (cgmcc3.9199) endogenous with the mangrove plant Kandelia candel (L.) Druce (Rhizophoraceae). Their structures including absolute configurations were established on the basis of spectroscopic analysis, optical rotation, CD spectra, quantum ECD calculations. To the best of our knowledge, vaccinol J (1) is the first example of salicyloid derivatives containing 2-methylfuran moiety. All of the new compounds were tested for their anti-enterovirus 7l (EV71) and cytotoxic activities. Among them, vaccinol J (1) exhibited in vitro anti-EV71 with IC50 value of 30.7µM (IC50 177.0µM for the positive control ribavirin).

Phenolic derivatives from Blaps japanensis and their biological evaluation.

This study was designed to characterize compounds from two thousands of insects of Blaps japanensis. With this purpose, pipajiains A-C (1-3), three novel phenolic derivatives, pipajiains D (4) and E (5), two new natural occurring compounds, and four known substances were isolated thereof. Their structures were identified by spectroscopic methods. Biological activities of all these compounds towards EV71, tuberculosis, COX-2, ROCK1/2, and JAK3 kinases were evaluated.

Antituberculosis compounds from a deep-sea-derived fungus Aspergillus sp. SCSIO Ind09F01.

Eleven diketopiperazine and fumiquinazoline alkaloids (1-11) together with a tetracyclic triterpenoid helvolic acid (12) were obtained from the cultures of a deep-sea derived fungus Aspergillus sp. SCSIO Ind09F01. The structures of these compounds (1-12) were determined mainly by the extensive NMR, ESIMS spectra data and by comparison with previously described compounds. Besides, anti-tuberculosis, cytotoxic, antibacterial, COX-2 inhibitory and antiviral activities of these compounds were evaluated. Gliotoxin (3), 12,13-dihydroxy-fumitremorgin C (11) and helvolic acid (12) exhibited very strong anti-tuberculosis activity towards Mycobacterium tuberculosis with the prominent MIC50 values of <0.03, 2.41 and 0.894 µM, respectively, which was here reported for the first time. Meanwhile gliotoxin also displayed significant selective cytotoxicities against K562, A549 and Huh-7 cell lines with the IC50 values of 0.191, 0.015 and 95.4 µM, respectively.

Structurally diverse secondary metabolites from a deep-sea-derived fungus Penicillium chrysogenum SCSIO 41001 and their biological evaluation.

Five new compounds, including a cytotoxic dimeric isocoumarin, bipenicilisorin (1), a merosesquiterpenoid, yaminterritrem C (2), a citrinin dimer, penicitrinone F (3), a alkaloid, terremide D (4), and a δ-valerolacton, (E)-4-(propen-1-yl)-5,6-dihydro-2H-pyran-2-one (5), along with ten known compounds (6-15) were isolated from a deep-sea-derived fungus Penicillium chrysogenum SCSIO 41001. Their structures and absolute configurations were elucidated by NMR spectra, MS, CD, optical rotation, X-ray crystallography, and compared with literature data. Biological evaluation results revealed that 1 exhibited significant cytotoxic activities against K562, A549, and Huh-7 cell lines with IC50 values of 6.78, 6.94, and 2.59µM, respectively. Compound 3 exhibited moderate inhibitory activity against EV71 with IC50 value of 14.50µM. In addition, 13 and 14 showed specific COX-2 inhibitory activities with IC50 values of 1.09 and 1.97µM, respectively.

Compounds from Polyphaga plancyi and their inhibitory activities against JAK3 and DDR1 kinases.

Plancyamides A (1) and B (3), plancypyrazine A (2), and plancyols A (4) and B (5), five new compounds (1-5), and three known ones (6-8), were isolated from the whole bodies of Polyphaga plancyi Bolivar. Their structures were elucidated by a combination of spectroscopic analyses including 1D and 2D NMR, and HRESIMS. Among them, compound 3 is racemic, chiral HPLC separation afforded its respective enantiomers. The absolute configuration of 1 was assigned by computational methods. Biological evaluation of all the compounds with exception of 7 and 8 discloses that compounds 2 and 4 could inhibit JAK3 kinase with IC50 values of 12.6 and 5.0µM, respectively. In addition, compound 4 exhibit inhibitory activity towards DDR1 kinase with IC50 value of 4.87µM.

New phenyl derivatives from endophytic fungus Botryosphaeria sp. SCSIO KcF6 derived of mangrove plant Kandelia candel.

Two new phenyl derivatives (1 and 3), along with two new natural products (4 and 5), and three known compounds (2, 6 and 7), were isolated from an endophytic fungus Botryosphaeria sp. SCSIO KcF6. The structures of these compounds 1-7 were elucidated by the extensive 1D and 2D-NMR and HRESIMS Data analysis, and compared with those of reported data. The absolute configuration of the compounds 1 and 3 were assigned by optical rotation and CD data. The isolated compounds were evaluated for their cytotoxic, anti-inflammatory (COX-2) and antimicrobial activities. Compound 3 exhibited a specific COX-2 inhibitory activity with the IC50 value of 1.12 µM.

Five new compounds from the fungus Ganoderma petchii.

The fungal species of the genus Ganoderma attracted great interest in the last decades. Our recent investigation on Ganoderma petchii afforded five new compounds, (-)-petchioics A and B (1 and 2), petchiates A and B (3 and 4), petchine (5), and a known compound. The structures of the new compounds were elucidated on the basis of spectroscopic data. The absolute configurations of 1 and 2 were assigned by computational methods. Biological activities of these isolates towards human cancer cells, COX-1/2, and influenza virus were evaluated.

Cytotoxic cytochalasins from marine-derived fungus Arthrinium arundinis.

Four new cytochalasins, arthriniumnins A-D (1-4), a new natural product, ketocytochalasin (5), as well as five known cytochalasin analogues (6-10) were isolated and identified from the fungus Arthrinium arundinis ZSDS1-F3 from the sponge Phakellia fusca. Their structures were elucidated by NMR spectroscopic and mass spectrometric analyses, as well as single crystal X-ray diffraction. Compounds 6 and 9 showed cytotoxicity against K562, A549, Huh-7, H1975, MCF-7, U937, BGC823, HL60, Hela, and MOLT-4 cell lines, with IC50 values ranging from 1.13 to 47.4 µM.

Identification and optimization of new dual inhibitors of B-Raf and epidermal growth factor receptor kinases for overcoming resistance against vemurafenib.

Epidermal growth factor receptor (EGFR) amplification has been demonstrated to be critical for the inherent and/or acquired resistance against current B-Raf(V600E) inhibitor therapy for melanoma and colorectal cancer patients. We describe the discovery and structure-activity relationship study of a series of 1H-pyrazolo[3,4-b]pyridine-5-carboxamide analogues as novel dual inhibitors of EGFR and B-Raf(V600E) mutant. One of the most promising compounds, 6a, potently inhibited both of the kinases with IC50 values of 8.0 and 51 nM, respectively. The compound also strongly suppressed the proliferation of a panel of intrinsic and acquired resistant melanoma and/or colorectal cancer cells harboring overexpressed EGFR with submicromolar IC50 values. Further mechanism investigation revealed that 6a could sustainably inhibit the activation of the MAPK path way in the resistant SK-MEL-28 PR30 melanoma cancer cells and WiDr colorectal cancer cells with EGFR amplification. Our results support the hypothesis that the EGFR/B-Raf(V600E) dual inhibition might be a tractable strategy to overcome the intrinsic and acquired resistance of melanoma and/or colorectal cancers against the current B-Raf(V600E) inhibitor therapy.

Design, synthesis, and biological evaluation of novel histone deacetylase 1 inhibitors through click chemistry.

We report the design, synthesis, and biological evaluation of a new series of HDAC1 inhibitors using click chemistry. Compound 17 bearing a phenyl ring at meta-position was identified to show much better selectivity for HDAC1 over HDAC7 than SAHA. The compond 17 also showed better in vitro anticancer activities against several cancer cell lines than that of SAHA. This work could serve as a foundation for further exploration of selective HDAC inhibitors using the compound 17 molecular scaffold.