Computational design, synthesis and biological evaluation of PDE5 inhibitors based on N2,N4-diaminoquinazoline and N2,N6-diaminopurine scaffolds.

We report the synthesis, and characterization of twenty-nine new inhibitors of PDE5. Structure-based design was employed to modify to our previously reported 2,4-diaminoquinazoline series. Modification include scaffold hopping to 2,6-diaminopurine core as well as incorporation of ionizable groups to improve both activity and solubility. The prospective binding mode of the compounds was determined using 3D ligand-based similarity methods to inhibitors of known binding mode, combined with a PDE5 docking and molecular dynamics based-protocol, each of which pointed to the same binding mode. Chemical modifications were then designed to both increase potency and solubility as well as validate the binding mode prediction. Compounds containing a quinazoline core displayed IC50s ranging from 0.10 to 9.39 µM while those consisting of a purine scaffold ranging from 0.29 to 43.16 µM. We identified 25 with a PDE5 IC50 of 0.15 µM, and much improved solubility (1.77 mg/mL) over the starting lead. Furthermore, it was found that the predicted binding mode was consistent with the observed SAR validating our computationally driven approach.

Phosphodiesterase-5 Inhibitory Activity of Canthin-6-One Alkaloids and the Roots of Eurycoma longifolia and Eurycoma harmandiana.

Eurycoma longifolia (EL) and Eurycoma harmandiana (EH) are natural medicinal plants belonging to the Simaroubaceae family, and are well-known for their ability to enhance male sexual performance. The present study investigated the phosphodiesterase-5 (PDE-5) inhibitory activity of intact roots of EL and EH. Additionally, canthin-6-one alkaloids, ß-carboline alkaloids, and quassinoids were also screened for PDE-5 inhibitory activity. We developed in vitro root and callus cultures of EL and EH to determine their PDE-5 inhibitory activity. Our results indicated that canthin-6-one alkaloids, which include canthin-6-one-9-O-ß-D-glucopyranoside, 9-methoxycanthin-6-one, canthin-6-one, and 9-hydroxycanthin-6-one, exhibited PDE-5 enzymatic inhibitory activity, with IC50 values of 2.86±0.23, 3.30±1.03, 4.31±0.52, and 4.66±1.13 µM, respectively. The ethanolic extract of the intact roots of EL and EH, and the in vitro root culture of EH had large amounts of canthin-6-one alkaloids (1.50±0.04, 2.12±0.03, and 3.48±0.08 mg/g dry weight, respectively), and showed potent PDE-5 inhibition. Our findings indicate that in vitro root cultures of EH may be used to replace intact plants, and canthin-6-one-9-O-ß-D-glucopyranoside should be further investigated for development as a health supplement.

Effects of Acanthus ebracteatus Vahl. extract and verbascoside on human dermal papilla and murine macrophage.

Androgenic alopecia is a common type of hair loss, usually caused by testosterone metabolism generating dihydrotestosterone and hair follicular micro-inflammation. These processes induce dermal papilla cells to undergo apoptosis. Currently approved effective medications for alopecia are Finasteride, an oral 5α-reductase inhibitor, Minoxidil, a topical hair growth promoter, and Diclofenac, an anti-inflammatory agent, all of which, however, have several adverse side effects. In our study, we showed the bioactivity of Acanthus ebracteatus Vahl. (AE) extract performed by 95% ethanol, and verbascoside (VB), a biomarker of AE extract. Both AE extract and VB were studied for their effects on dermal papilla cell viability and the cell cycle by using MTT assay and flow cytometry. The effect of an anti-inflammatory activity of AE extract and VB on IL-1ß, NO, and TNF-α, released from LPS induced RAW 264.7 cells, and IL-1α and IL-6 released from irradiated dermal papilla cells were detected using ELISA technique. The preventive effect on dermal papilla cell apoptosis induced by testosterone was determined by MTT assay. In controlled in vitro assays it was found that AE extract and VB at various concentrations induced dermal papilla cell proliferation which was indicated by an increase in the number of cells in the S and G2/M phases of the cell cycle. AE extract at 250 µg/mL concentration or VB at 62.50 µg/mL concentration prevented cell apoptosis induced by testosterone at a statistically significant level. In addition, both AE extract and VB greatly inhibited the release of pro-inflammatory cytokines from RAW 264.7 and dermal papilla cells. The release of IL-1ß, TNF-α, and NO from RAW 264.7 cells, as well as IL-1α and IL-6 from dermal papilla cells, was also diminished by AE extract 250 µg/mL and VB 125 µg/mL. Our results indicate that AE extract and VB are promising ingredients for anti-hair loss applications. However, further clinical study is necessary to evaluate the effectiveness of AE extract and VB as treatment for actual hair loss.

Quintaquinone, a Merosesquiterpene from the Yellow Sponge Verongula cf. rigida Esper.

A chemical investigation of the sponge Verongula cf. rigida led to the isolation of 13 merosesquiterpenes, among which quintaquinone (2), 5-epi-nakijiquinone L (3), and 3-farnesyl-2-hydroxy-5-methoxyquinone (4) were isolated and reported here for the first time. Particularly, compound 2 is the first member of merosesquiterpenes with a polyketide side chain substituted on C-19. All of the isolated compounds were examined for steroid 5α-reductase inhibitory activity. Cyclospongiaquinone 1 (5) showed a strong activity in the same range as that of standard finasteride.