Nanoencapsulation of triterpene 3ß,6ß,16ß-trihydroxylup-20(29)-ene from Combretum leprosum as strategy to improve its cytotoxicity against cancer cell lines.

The pentacyclic triterpene 3ß,6ß,16ß-tri-hydroxilup-20(29)-ene is a natural product produced by the Brazilian medicinal plant Combretum leprosum. Its cytotoxicity has been previously reported against breast cancer cell lines. The low water solubility of this natural product, that hampers its bioavailability, motivated the investigation of a new nanoparticle formulation containing the triterpene in order to improve its bioactivity. The triterpene was encapsulated in polycaprolactone (PCL) polymer by nanoprecipitation, producing homogenic nanoparticles with nanometer sizes (122.7 ± 2.06 nm), which were characterized by FT-IR, SEM imaging and DSC. The cytotoxicity (MTT method) of the nanoparticle containing the triterpene 1, besides the free natural product and the nanoparticle control (without 1), was assayed against three human tumor cell lines [human colon carcinoma line (HCT116), prostate (PC3) and glioblastoma (SNB19)] and the normal epithelial embryo kidney human cell line (Hek293T). The nanocarrier produced a significative effect in the cytotoxicity of the natural product in the nanoformulation (IC50 0.11-0.26 µg mL-1) when compared with its free form (IC50 1.07-1.44 µg mL-1). Additionally, higher selectivity of the triterpene to the tumor cells was found when it was encapsulated (SI 1.92-4.54) than in its free form (SI 0.42-0.56). In this case, the nanoencapsulated triterpene was more selective to PC3 (SI 3.33) and SNB19 (SI 4.54) tumor cells.

Whole cells of recombinant CYP153A6-E. coli as biocatalyst for regioselective hydroxylation of monoterpenes.

Optimized recombinant whole cells of E. coli bearing CYP153A6 were employed for catalyzing the hydroxylation of different monoterpene derivatives. In most cases, high selectivity was observed with exclusive hydroxylation of the allylic methyl group bound to the aliphatic ring. In the case of (R)- and (S)-carvone, hydroxylation occurred also on the other allylic methyl group, although to a lesser extent. Biotransformations carried out in fed-batch mode on (S)-limonene and α-terpineol showed that recombinant whole cells retained activity for at least 24 h, allowing for the recovery of 3.25 mg mL-1 of (S)-perillyl alcohol and 5.45 mg mL-1 of 7-hydroxy-α-terpineol, respectively.

Stereo and regioselective microbial reduction of the clerodane diterpene 3,12-dioxo-15,16-epoxy-4-hydroxycleroda-13(16),14-diene.

The biotransformation of the clerodane diterpene, 3,12-dioxo-15,16-epoxy-4-hydroxy-cleroda-13(16),14-diene (1), obtained from Croton micans var. argyroglossum (Baill.) Mill., was investigated for the first time. Whole cells of Cunninghamella echinulata and Rhizopus stolonifer were used as enzymatic systems, and with both fungi the only biotransformation product obtained was the new ent-neo-clerodane diterpene (3R,4S,5S,8S,9R,10S)-3,4-dihydroxy-15,16-epoxy-12-oxo-cleroda-13(16),14-diene (2a). The absolute stereochemistry of 2a was inferred by comparison of its optical rotation with those of the chemical reduction product of 1 and its quasienantiomer 2c.

Secondary metabolite production by the basidiomycete, Lentinus strigellus, under different culture conditions.

The basidiomycete Lentinus strigellus was cultivated in three different culture media and the secondary metabolites produced under different culture conditions were isolated and identified. When cultivated in a liquid medium with peptone, L. strigellus afforded the benzopyrans, 2,2-dimethyl-6-methoxychroman-4-one, 4-hydroxy-2,2-dimethyl-6-methoxychromane and (3R,4S)-3,4-dihydroxy-2,2-dimethyl-6-methoxychromane. The indole alkaloid echinuline and the anthraquinone fiscione, both unprecedented for the genus Lentinus, were isolated from the mycelium of the fungus. When cultured in Czapek medium enriched with potato broth, the fungus afforded the same benzopyrans except (3S,4S)-3,4-dihydroxy-2,2-dimethyl-6-methoxychromane. Panepoxydone and isopanepoxydone were also isolated when the microorganism was grown in Czapek medium.