Donglei Yu

Antitumor agents. 272. Structure-activity relationships and in vivo selective anti-breast cancer activity of novel neo-tanshinlactone analogues.

Neo-tanshinlactone (1) and its previously reported analogues, such as 2, are potent and selective in vitro antibreast cancer agents. The synthetic pathway to 2 was optimized from seven to five steps, with a better overall yield. Structure-activity relationships studies on these compounds revealed some key molecular determinants for this family of antibreast agents. Several derivatives (19-21 and 24) exerted potent and selective antibreast cancer activity with IC(50) values of 0.3, 0.2, 0.1, and 0.1 microg/mL, respectively, against the ZR-75-1 cell lines. Compound 24 was 2- to 3-fold more potent than 1 against SK-BR-3 and ZR-75-1. Importantly, 21 exhibited high selectivity; it was 23 times more active against ZR-75-1 than MCF-7. Compound 20 had an approximately 12-fold ratio of SK-BR-3/MCF-7 selectivity. In addition, analogue 2 showed potent activity against a ZR-75-1 xenograft model, but not PC-3 and MDA-MB-231 xenografts, as well as high selectivity against breast cancer cell line compared with normal breast tissue-derived cell lines. Further development of lead compounds 19-21 and 24 as clinical trial candidates is warranted.

Cytotoxic phenanthrenequinones and 9,10-dihydrophenanthrenes from Calanthe arisanensis.

Two new phenanthrenequinones, calanquinones B and C (2 and 3) and four new 9,10-dihydrophenanthrenes, calanhydroquinones A-C (4-6) and calanphenanthrene A (7), along with five known compounds (1 and 8-11), were isolated from an EtOAc-soluble extract of Calanthe arisanensis through bioassay-guided fractionation. Their structures were identified from spectroscopic data, and the compounds were tested for in vitro cytotoxic activity against human lung (A549), prostate (PC-3 and DU145), colon (HCT-8), breast (MCF-7), nasopharyngeal (KB), and vincristine-resistant nasopharyngeal (KBVIN) cancer cell lines. Compound 1 showed the highest potency (EC(50) < 0.5 microg/mL) against all seven cancer cell lines, with the greatest activity against breast cancer MCF-7 cells (EC(50) < 0.02 microg/mL). Generally, except for 7, compounds 2-11 also showed significant cytotoxic activity (EC(50) < 4 microg/mL) against some cell lines (especially PC-3 and MCF-7) in the panel.

Synthesis and proteasome inhibition of glycyrrhetinic acid derivatives

This study discovered that glycyrrhetinic acid inhibited the human 20S proteasome at 22.3microM. Esterification of the C-3 hydroxyl group on glycyrrhetinic acid with various carboxylic acid reagents yielded a series of analogs with marked improved potency. Among the derivatives, glycyrrhetinic acid 3-O-isophthalate (17) was the most potent compound with IC(50) of 0.22microM, which was approximately 100-fold more potent than glycyrrhetinic acid.

Antitumor agents. Part 218: Cappamensin A, a new In vitro anticancer principle, from Capparis sikkimensis.

A new inhibitor of in vitro tumor cell replication, cappamensin A (1) (2H-1,4-benzoxazin-3(4H)-one, 6-methoxy-2-methyl-4-carbaldehyde), was isolated from the roots of Capparis sikkimensis subsp. formosana using bioactivity-guided fractionation. The structure of 1 was established by spectroscopic methods, including 2D NMR analyses. Compound 1 displayed significant in vitro anticancer activity against ovarian (1A9), lung (A549), ileocecal (HCT-8), breast (MCF-7), nasopharyngeal (KB), and vincristine resistant (KB-VIN) human tumor cell lines with ED(50) values </=4 microgram/mL (mean GI(50) value of 15.1 microM).

Cytotoxic calanquinone A from Calanthe arisanensis and its first total synthesis

Calanquinone A (1) was isolated from an EtOAc-soluble extract of Calanthe arisanensis through bioassay-guided fractionation. Its structure was identified by spectroscopic methods. Compound 1 showed potent cytotoxicity (EC(50)<0.5microg/mL) against lung (A549), prostate (PC-3 and DU145), colon (HCT-8), breast (MCF7), nasopharyngeal (KB), and vincristine-resistant nasopharyngeal (KB-VIN) cancer cell lines, and interestingly, showed an improved drug resistance profile compared to paclitaxel. The total synthesis of 1 was also achieved and is reported herein.

Synthesis and Anti-HIV Activity of Bi-Functional Triterpene Derivatives

We previously reported a bi-functional betulinic acid derivative, A12-2 (4), containing an optimized C-28 side chain that exhibits potent anti-HIV activity by inhibiting both HIV-1 entry and maturation. Compound 4 contains C-3 and C-28 side chains that are pharmacophores for anti-HIV maturation and entry activity, respectively. The betulinic acid core, which serves as a molecular scaffold for compound 4, is also important for anti-HIV activity. The main purposes of the present study were to investigate the structure-activity relationships (SAR) of both the C-3 side chain and scaffold of 4. Further modification of the C-3 side chain of 4 suggested that both bulkier and smaller C-3 substituents negatively impacted the anti-HIV-1 activity. SAR study of the scaffold indicated that the betulinic acid moiety of 4 could be replaced with other scaffolds while still remaining active against HIV-1 replication. Among the synthesized compounds, the most effective molecular scaffold for anti-HIV activity remained to be betulinic acid (0.0026 μM), followed by moronic acid, ursolic acid, and oleanolic acid. On the other hand, substitution of the betulinic acid moiety of 4 with glycyrrhetinic acid or lithocholic acid completely abolished anti-HIV activity. Mechanism of action studies indicated that all active terpenoid analogs of 4 retained both anti-HIV-1 entry and anti-HIV-1 maturation activities.

Anti-AIDS agents 82: Synthesis of seco-(3′R,4′R)-3′,4′-di-O-(S)-camphanoyl-(+)-cis-khellactone (DCK) derivatives as novel anti-HIV agents

Thirteen novel seco-DCK analogs (4-16) with several new skeletons were designed, synthesized and screened for in vitro anti-HIV-1 activity. Among them, three compounds (5, 13, and 16) showed moderate activity, and compound 9 exhibited the best activity with an EC(50) value of 0.058 microM and a therapeutic index (TI) of 1000. The activity of 9 was better than that of 4-methyl DCK (2, EC(50): 0.126 microM, TI: 301.2) in the same assay. Additionally, 9 also showed antiviral activity against a multi-RT inhibitor-resistant strain (RTMDR), which is insensitive to most DCK analogs. Compared with 2, compound 9 has a less complex structure, fewer hydrogen-bond acceptors, and a reduced log P value. Therefore, it is likely to exhibit better ADME, and appears to be a promising new lead for further development as an anti-HIV candidate.

Chapter 13:From Natural Product to Clinical Trials: Bevirimat, a Plant-Derived Anti-AIDS Drug

Theoretically, any of the multiple steps in the life-cycle of human immunodeficiency virus (HIV) such as viral attachment, co-receptor binding, fusion, reverse transcription, integration, translation, proteolytic cleavage, glycosylation, assembly, budding and release can be attacked chemotherapeutic...