Centipeda minima and 6-O-angeloylplenolin enhance the efficacy of immune checkpoint inhibitors in non-small cell lung cancer.

BACKGROUND: Chemotherapeutic agents including cisplatin, gemcitabine, and pemetrexed, significantly enhance the efficacy of immune checkpoint inhibitors (ICIs) in non-small cell lung cancer (NSCLC) by increasing PD-L1 expression and potentiating T cell cytotoxicity. However, the low response rate and adverse effects limit the application of chemotherapy/ICI combinations in patients. METHODS: We screened for medicinal herbs that could perturb PD-L1 expression and enhance T cell cytotoxicity in the presence of anti-PD-L1 antibody, and investigated the underlying mechanisms. RESULTS: We found that the aqueous extracts of Centipeda minima (CM) significantly enhanced the cancer cell-killing activity and granzyme B expression level of CD8+ T cells, in the presence of anti-PD-L1 antibody. Both CM and its active component 6-O-angeloylplenolin (6-OAP) upregulated PD-L1 expression by suppressing GSK-3ß-ß-TRCP-mediated ubiquitination and degradation. CM and 6-OAP significantly enhanced ICI-induced reduction of tumor burden and prolongation of overall survival of mice bearing NSCLC cells, accompanied by upregulation of PD-L1 and increase of CD8+ T cell infiltration. CM also exhibited anti-NSCLC activity in cells and in a patient-derived xenograft mouse model. CONCLUSIONS: These data demonstrated that the induced expression of PD-L1 and enhancement of CD8+ T cell cytotoxicity underlay the beneficial effects of 6-OAP-rich CM in NSCLCs, providing a clinically available and safe medicinal herb for combined use with ICIs to treat this deadly disease.

Two pairs of phenolic enantiomers from the leaves of Eucommia ulmoides Oliver.

Two pairs of new phenolic enantiomers, (+)-eucophenolic A (1a), (-)-eucophenolic B (1b), (-)-eucophenolic C (2a), (+)-eucophenolic D (2b) were isolated from the leaves of Eucommia ulmodies Oliver by chiral enantiomeric resolution. Their structures were elucidated based on extensive spectroscopic analysis. The absolute configurations of 1a/1b and 2a/2b were determined by empirical method and the calculated ECD and OR. All compounds were tested for Hep G2 tumour cell lines. However, no compounds showed potential cytotoxic activities against Hep G2 in vitro.

Two pairs of phenylpropanoid enantiomers from the leaves of Eucommia ulmoides.

Two pairs of phenylpropanoid enantiomers, (+)-(7S,8S)-alatusol D (1a), (-)-(7R,8R)-alatusol D (1b), (-)-(7S,8R)-alatusol D (2a) and (+)-(7R,8S)-alatusol D (2b) were isolated from the leaves of Eucommia ulmoides Oliver. Among them, 1a and 2b were firstly obtained by chiral enantiomeric resolution. Their structures were elucidated based on extensive spectroscopic analysis and the induced CD (ICD) spectrum caused by adding Mo2(AcO)4 in DMSO. All compounds were tested on Hep G2 tumor cell lines. However, none of the compounds showed potential cytotoxic activity against Hep G2 in vitro.

Withapubesides A-D: natural inducible nitric oxide synthase (iNOS) inhibitors from Physalis pubescens.

Four new steroid glycosides, withapubesides A-D (1-4), were isolated from the stems of Physalis pubescens L. Their structures were elucidated primarily by NMR experiments. The absolute configurations of 1 and 2 were deduced by single-crystal X-ray diffraction and ECD data analysis, respectively. Compound 3 has shown significant inhibitory activity against LPS-induced nitric oxide production in RAW 264.7 macrophages with an IC50 value of 12.8 µM and moderate cytostatic activity against human carcinoma cells (786-O, C4-2B, 22Rvl, A375 and A375S2) with IC50 values in the range of 3.05-9.47 µM. Molecular docking simulation demonstrated that 3 is bound in the inducible nitric oxide synthase (iNOS) active site heme pocket very well, which suggests that 3 might be a candidate for the development of iNOS inhibitors.

(+)/(-)-Phaeocaulin A-D, four pairs of new enantiomeric germacrane-type sesquiterpenes from Curcuma phaeocaulis as natural nitric oxide inhibitors.

Germacrane-type sesquiterpenes, with a flexible 10-membered ring unit as the structural and conformational features, play a central role in the biosynthesis and synthesis of other sesquiterpenes. In this report, two pairs of new sesquiterpene alkaloids, (+)/(-)-phaeocaulin A [(+)-1/(-)-1] and B [(+)-2/(-)-2], and two pairs of new sesquiterpenes, (+)/(-)-phaeocaulin C [(+)-3/(-)-3] and D [(+)-4/(-)-4], along with one related known analog (5), were isolated from the rhizomes of Curcuma phaeocaulis. The absolute configurations of (+)-1/(-)-1, (+)-2/(-)-2, (+)-3/(-)-3 and (+)-4/(-)-4 were unambiguously determined by analysis of single-crystal X-ray diffractions and quantum chemical electronic circular dichroism (ECD) method. It is noteworthy that (+)/(-)-phaeocaulin A [(+)-1/(-)-1] and B [(+)-2/(-)-2] are two pairs of rare N-containing germacrane-type sesquiterpenes. A possible biogenetic pathway for 1-5 was postulated. All of the isolated compounds were tested for their inhibitory activity against LPS-induced nitric oxide production in RAW 264.7 macrophages.

Antiproliferative and Anti-inflammatory Withanolides from Physalis angulata.

Sixteen new withanolides, physangulatins A-N (1-14) and withaphysalins Y and Z (15 and 16), as well as 12 known analogues, were isolated from the stems and leaves of Physalis angulata L. Their structures were established using extensive spectroscopic data analyses. The absolute configurations of 1 and 9 were assigned via X-ray crystallography. The isolated compounds were tested for their antiproliferative effects against human prostate cancer cells (C4-2B and 22Rvl), human renal carcinoma cells (786-O, A-498, and ACHN), and human melanoma cells (A375-S2), as well as inhibitory effects on NO production induced by LPS in macrophages. Compounds 9, 17, 20, 21, 25, and 27 showed antiproliferative effects against all tested cancer cells, with IC50 values of 0.18-7.43 µM. Compounds 3-5, 9-11, 17, 20-22, 24, 25, and 27 displayed inhibitory effects against NO production, with IC50 values of 1.36-11.59 µM.

Two pairs of farnesyl phenolic enantiomers as natural nitric oxide inhibitors from Ganoderma sinense.

Four new farnesyl phenolic compounds, ganosinensols A-D (1-4) were isolated from the 95% EtOH extract of the fruiting bodies of Ganoderma sinense. Two pairs of enantiomers, 1/2, and 3/4 were isolated by HPLC using a Daicel Chiralpak IE column. Their structures were elucidated from extensive spectroscopic analyses and comparison with literature data. The absolute configurations of 1-4 were assigned by ECD spectra. All of these isolated compounds showed potent inhibitory activity against LPS-induced nitric oxide production in RAW 264.7 macrophages, with IC50 values from 1.15 to 2.26µM.

Natural nitric oxide (NO) inhibitors from the rhizomes of Curcuma phaeocaulis.

An exploration we carried out for isolating nitric oxide (NO) inhibitors from the rhizomes of Curcuma phaeocaulis afforded one new salvialane-type sesquiterpene, phasalvione (1), two novel nor-sesquiterpenes, phaeocaudione (2) and phaeocauone (3), one aromatic acid 3-methyl-4-(3-oxo-butyl)-benzoic acid (4), two γ-elemene-type sesquiterpenes, 8ß(H)-elema-1,3,7(11)-trien-8,12-lactam (5) and 8ß-methoxy-isogermafurenolide (6), one eudesmane-type sesquiterpene, phaeusmane I (7), and one cyclic diarylheptanoid, phaeoheptanoxide (8). Their structures were established based on extensive spectroscopic analysis. The absolute configurations of compounds 1 and 2 were assigned using the circular dichroism data of the [Rh2(OCOCF3)4] complex, and the absolute configuration of 1 was further established by single crystal X-ray crystallography. It is noteworthy that compounds 5­7 were racemates analyzed by chiral HPLC. Furthermore, the inhibitory effects of the isolated compounds on nitric oxide production in LPS-activated macrophages were evaluated. Compounds 1, 3 and 4 showed strong inhibitory activities on NO production with IC50 values of 7.46 ± 0.69, 2.35 ± 0.17 and 3.49 ± 0.31 µM, respectively. A plausible biosynthetic pathway for 1­4 in C. phaeocaulis was also discussed.

Four new sesquiterpenes from the rhizomes of Curcuma phaeocaulis and their iNOS inhibitory activities.

Three new guaiane-type sesquiterpenes named phaeocaulisins K-M (1-3), and one germacrane-type sesquiterpenoid with new ring system of 1,5- and 1,8-ether groups named phagermadiol (4), were isolated from rhizomes of Curcuma phaeocaulis. Their structures were established based on extensive spectroscopic analysis. Compound 1, the first example of norsesquiterpene with tropone backbone, and compound 3 with a novel 1,2-dioxolane sesquiterpene alcohol were isolated from the genus Curcuma. All of the isolated compounds were tested for inhibitory activity against lipopolysaccharide-induced nitric oxide (NO) production in RAW 264.7 macrophages. Compound 3 inhibited NO production with IC50 value of 6.05 ± 0.43 µM. The plausible biosynthetic pathway for compounds 3 and 4 in C. phaeocaulis was also discussed.

Biotransformation of Curcumenol by Mucor polymorphosporus.

Biocatalysis of curcumenol (1) was performed by Mucor polymorphosporus AS 3.3443. Six metabolites including five new compounds were obtained, and their structures were elucidated as 10ß-hydroxy-9,10-dihydrocurcumenol (2), 2ß-hydroxycurcumenol (3), 15-hydroxycurcumenol (4), 12-hydroxycurcumenol (5), 1-hydroxy-4αH-guai-1,6,9-triene-2,8-dione (6), and 5-hydroxycarbonyl-1-oxo-3,7-dimethylindane (7) by spectroscopic analysis. M. polymorphosporus catalyzed unusual degradation and rearrangement reactions to generate a ring-contracted metabolite (7) of curcumenol (1). Curcumenol (1) and metabolites 4-7 exhibited inhibitory activities against lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophages, with 7 exhibiting more potent activity than curcumenol.

A New Triterpenoid from the Aerial Parts of Agrimonia pilosa.

(1S,3R,17R,18R,19R,20R,22R)-1,3,19,22-tetrahydroxy-28-norurs-12-en-2-one (1), along with 5 known triterpenoids (2-6), were isolated from the aerial parts of Agrimonia pilosa Ledeb. Their structures were established based on extensive spectroscopic and MS analysis. The absolute configuration of compound 1 was deduced by circular dichroism (CD). Compound 1 was the first example of a 28-norursene backbone isolated from the genus Agrimonia. Compounds 2-6 were tested for anti-inflammatory activities against RAW 264.7 macrophages. A plausible biosynthetic pathway for compound 1 in A. pilosa was also proposed.

Nitric oxide induces apoptosis and autophagy; autophagy down-regulates NO synthesis in physalin A-treated A375-S2 human melanoma cells.

Physalin A is an active withanolide isolated from Physalis alkekengi var. franchetii, a traditional Chinese herbal medicine named Jindenglong, which has been used for the treatment of sore throat, hepatitis, eczema and tumors in China. Our previous study demonstrated that physalin A induced apoptosis and cyto-protective autophagy in A375-S2 human melanoma cells. Induction of reactive oxygen species (ROS) with physalin A triggered apoptosis. In this study, NO generated by physalin A induced apoptosis and autophagy in A375-S2 cells, since physalin A induced the expression of inducible nitric oxide synthase (iNOS) in the cells. Generation of NO partially promoted both apoptosis and autophagy in A375-S2 cells. NO suppressed mTOR expression, which led to autophagy induction. An autophagic inhibitor, 3-methyladenine (3MA) promoted NO production, while acceleration of autophagy with an autophagic agonist rapamycin repressed NO production, suggesting that autophagy and NO production form a negative feedback loop that eventually protects the cells from apoptosis. The results together with the previous study indicate apoptosis and autophagy induced by physalin A in A375-S2 cells; the autophagy, repressing production of reactive nitrogen species (RNS) and ROS, protects the cells from apoptosis.