Enantioselective Total Syntheses of the Cephalotaxus Alkaloids (-)-Fortuneicyclidins A and B and (-)-Cephalotine B

Fortuneicyclidins A and B are a pair of recently isolated Cephalotaxus alkaloids with an unprecedented rearranged polycyclic skeleton possessing multiple complex stereocenters and functionalization. In this work, highly stereocontrolled asymmetric total syntheses for title alkaloids were outlined. Key features include an underexplored Ir-catalyzed α-allylation of aldehyde to strategically install a vicinal N-substituted quaternary center and a tertiary stereocenter, Heck and RCM reactions to construct the critical polycyclic framework rapidly, two different tandem oxidation-transannular aldol cyclization processes, one through ozonolysis and another via Swern oxidation, to forge the last ring for fortuneicyclidins A and B, respectively. In this approach, the challenging C-2 hydroxyl group can be installed stereospecifically.

Comparison of efficacy between homoharringtonine, aclarubicin, cytarabine (HAA) and idarubicin, cytarabine (IA) regimens as induction therapy in patients with de novo core binding factor acute myeloid leukemia

To compare efficacy between homoharringtonine combined with cytarabine and aclarubicin (HAA) and idarubicin and cytarabine (IA) regimens as first induction chemotherapy in patients with core binding factor acute myeloid leukemia (CBF-AML). Cox regression model and propensity score matching (PSM) were used to identify the regimen associated with a better remission rate and outcomes. In total, 374 patients with CBF-AML (243 with RUNX1::RUXN1T1 and 131 with CBFB::MYH11) were included in this study. The patients received the HAA or IA regimen (187 each) as the first induction therapy. For patients with RUNX1::RUXN1T1, multivariate analyses showed that the HAA regimen was significantly associated with a higher CR/CRi rate after the first induction (hazard ratio [HR] = 5.3 [95% CI 2.3, 12.2]; p < 0.001) and more favorable relapse-free survival (RFS) (HR = 0.5 [0.3, 0.8], p = 0.01). In PSM analysis, the HAA regimen also had a higher CR/CRi rate (96% vs. 77%, p < 0.001), especially for those harboring wild-type KIT (KITWT) (96% vs. 83%, p = 0.02) or non-D816 KIT mutation (100% vs. 63%, p = 0.002), as well as more favorable RFS (p = 0.01), compared with the IA regimen. However, there was no difference in the remission rate or outcomes between the two regimens for patients with CBFB::MYH11. The HAA regimen as first induction chemotherapy resulted in a higher CR/CRi rate in AML patients with RUNX1::RUNX1T1, especially those harboring KITWT and non-D816 KIT mutation, and a more favorable RFS compared with the IA regimen. The efficacy between the two regimens did not differ in those with CBFB::MYH11.

Harringtonine: A more effective antagonist for Omicron variant

Fusion with host cell membrane is the main mechanism of infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here, we propose that a new strategy to screen small-molecule antagonists blocking SARS-CoV-2 membrane fusion. Using cell membrane chromatography (CMC), we found that harringtonine (HT) simultaneously targeted SARS-CoV-2 S protein and host cell surface TMPRSS2 expressed by the host cell, and subsequently confirmed that HT can inhibit membrane fusion. HT effectively blocked SARS-CoV-2 original strain entry with the IC50 of 0.217 μM, while the IC50 in delta variant decreased to 0.101 μM, the IC50 in Omicron BA.1 variant was 0.042 μM. Due to high transmissibility and immune escape, Omicron subvariant BA.5 has become the dominant strain of the SARS-CoV-2 virus and led to escalating COVID-19 cases, however, against BA.5, HT showed a surprising effectiveness. The IC50 in Omicron BA.5 was even lower than 0.0019 μM. The above results revealed the effect of HT on Omicron is very significant. In summary, we characterize HT as a small-molecule antagonist by direct targeting on the Spike protein and TMPRSS2.

[Preliminary study of DA or HA regimen chemotherapy for the treatment of refractory and relapsed paroxysmal nocturnal hemoglobinuria]

OBJECTIVE

To observe the efficacy and side effect of DA/HA regimen chemotherapy for the treatment of refractory and relapsed paroxysmal nocturnal hemoglobinuria (PNH).

METHODS

Eight patients with refractory and relapsed PNH were treated with DA/HA regimen chemotherapy. Three patients were treated with DA (DNR 40 mg/d, i.v.drip, the first and the second day; 20 mg/d, i.v.drip, the third day; Ara-C 100 mg/d, i.v.drip, for 5 days) and 5 patients with HA (HHT 2 - 3 mg/d, i.v.drip, for 5 days; Ara-C 100 mg/d, i.v.drip, for 5 days).

RESULTS

All the 8 patients responded well: the PNH clone was diminished in five patients. Hemolysis was remitted in 6 cases. Five patients showed improvement in hematological parameters. The dosage of corticosteroid was decreased in all of them. No serious side effect was revealed.

CONCLUSION

DA/HA regimen chemotherapy was safe and effective for refractory and relapsed PNH patients.

Reduction of doxorubicin resistance by tetrandrine and dauricine in harringtonine-resistant human leukemia (HL60) cells

AIM

To study whether tetrandrine (Tet) and dauricine (Dau) can reduce doxorubicin (Dox) resistance in the harringtonine (Har)-resistant human leukemia cells.

METHODS

The drug cytotoxities were determined by counting cell numbers and colony formation. Cell cycle phases were assayed by flow cytometry, Dox contents were quantified by Dox fluorescence.

RESULTS

The non-cytotoxic concentrations of Tet and Dau potentiated the growth-inhibitory actions of Dox in the Har-resistant HL60 cells. The colony formation effiencies were reduced from 60% by Dox to 0.2% by Tet + Dox and 9.2% by Dau + Dox. Retardation of the G2M phase cells was increased. But Tet and Dau did not potentiate Dox cytotoxities in the sensitive HL60 cells. Dox accumulation in the Har-resistant HL60 cells treated by Tet was increased.

CONCLUSION

Dox resistance in the Har-resistant HL60 cells treated by Tet or Dau was reduced, due to the increase of Dox accumulation in the cells. One of the mechanisms of multidrug resistance in tumor cells is overexpression of cell membrane glycoproteins, termed P-glycoprotein (PGP). PGP pumps antitumor drugs out of tumor cells, causing drug resistance. Calcium antagonists and some calmodulin inhibitors such as verapamil, nifedepine, trifluorapine have effect on reversion of drug resistance, binding directly to PGP, but side effect of them is intolerable in clinical use. So searching for other potentiators to overcome drug resistance may be another avenue. Tetrandrine (Tet) effectively circumvented the resistance of Chinese hamster ovary cells to doxorubicin (Dox). Dauricine (Dau) is a bisbenzylisoquinoline alkaloid from Stephaia tetrandra. In this paper we studied whether Tet and Dau could reduce Dox resistance in the harringtonine (Har)-resistant human leukemia 60 (HL60) cells.