Maria De Mieri

A library of extracts from plants used in Chinese Traditional Medicine was screened for inhibition of T lymphocyte proliferation. An ethyl acetate extract from aerial parts of Artemisia argyi showed promising activity and was submitted to HPLC-based activity profiling to track the active compounds. From the most active time window, three guaianolides (1, 2, and 5) and two seco-tanapartholides (3 and 4) were identified and, in a less active time window, five new sesquiterpene lactones (8–11, 17), along with six known sesquiterpene lactones and two known flavonoids. The absolute configurations of compounds 1, 2, 5–10, 13–15, 17, and 18 were established by comparison of experimental with calculated electronic circular dichroism (ECD) spectra. For seco-tanapartholides B (3) and A (4), ECD yielded ambiguous results, and their absolute configurations were determined by comparing experimental and calculated vibrational circular dichroism (VCD) spectra. Compounds 1–5 showed significant, noncytotoxic inhibition of T lymphocyte proliferation, with IC₅₀ values between 1.0 and 3.7 μM.

Plant pollens are strong airborne elicitors of asthma. Their proteinaceous allergens have been studied intensively, but little is known about a possible contribution of pollen secondary metabolites to the nonallergic exacerbation of asthma. Pollen samples originating from 30 plant species were analyzed by HPLC coupled to PDA, ESIMS, and ELSD detectors and off-line NMR spectroscopy. Polyamine conjugates, flavonoids, and sesquiterpene lactones were identified. Polyamine conjugates were characteristic of all Asteraceae species. The presence of sesquiterpene lactones in Asteraceae pollen varied between species and pollen lots. All plant pollen, including those from non-Asteraceae species, contained to some extent electrophiles as determined by their reaction with N-acetyl-l-cysteine. Selected pollen extracts and pure compounds were tested in murine afferent neurons and in murine tracheal preparations. Tetrahydrofuran extracts of Ambrosia artemisiifolia and Ambrosia psilostachya pollen and a mixture of sesquiterpene lactones coronopilin/parthenin increased the intracellular Ca²⁺ concentration in 15%, 32%, and 37% of cinnamaldehyde-responsive neurons, respectively. In organ bath experiments, only the sesquiterpene lactones tested induced a weak dilatation of naïve tracheas and strongly lowered the maximal methacholine-induced tracheal constriction. A tetrahydrofuran extract of A. psilostachya and coronopilin/parthenin led to a time-dependent relaxation of the methacholine-preconstricted trachea. These results provide the first evidence for a potential role of pollen secondary metabolites in the modulation of the tracheal tone.

A surface extract of the aerial parts of Salvia chamaedryoides afforded 13 diterpenes (1–13), with seven compounds (1, 3, 4, 7–9, 12) described for the first time. The structures of the new compounds were established using 1D and 2D NMR spectroscopic methods, HRESIMS, and ECD data. The potential hypoglycemic effects of the crude extract, fractions, and pure compounds from S. chamaedryoides were investigated by inhibition of α-glucosidase and α-amylase enzymes. The extract and its fractions showed a moderate dose-dependent inhibition; the pure compounds exhibited differential inhibitory activity against these two enzymes. Molecular modeling studies were also performed to suggest the interaction mode of compound 3 in the α-glucosidase enzyme active site. The antimicrobial activity of the purified compounds was investigated against 26 clinical pathogens. No activity was detected for the Gram-negative species tested nor on Candida albicans and C. glabrata, while variable susceptibilities were observed using Gram-positive staphylococcal and enterococcal species.

A dichlomethane extract of Anthemis nobilis flower cones showed promising in vitro antiprotozoal activity against Trypanosoma brucei rhodesiense and Leishmania donovani, with IC₅₀ values of 1.43 ± 0.50 and 1.40 ± 0.07 μg/mL, respectively. A comprehensive profiling of the most active fractions afforded 19 sesquiterpene lactones, including 15 germacranolides, two seco-sesquiterpenes, one guaianolide sesquiterpene lactone, and one cadinane acid. Of these, 13 compounds were found to be new natural products. The compounds were characterized by extensive spectroscopic data analysis (1D and 2D NMR, HRMS, circular dichroism) and computational methods, and their in vitro antiprotozoal activity was evaluated. The furanoheliangolide derivative 15 showed high potency and selectivity in vitro against T. b. rhodesiense bloodstream forms (IC₅₀ 0.08 ± 0.01 μM; SI 63). In silico calculations were consistent with the drug-like properties of 15.

Thirteen acylated flavonoid glycosides, 1–13, including eleven new congeners, 3–13, were isolated from the aerial parts of Pritzelago alpina (Brassicaceae) by a combination of column chromatography on Sephadex LH-20, and preparative and semi-preparative HPLC. The structures were established by extensive NMR and MS experiments in combination with acid hydrolysis and sugar analysis by GC/MS. The new compounds were shown to be kaempferol and quercetin glycosides acylated for most of them by a branched short chain fatty acid or a hydroxycinnamic acid residue on the sugar portion. As shown by a HPLC-DAD analysis of a MeOH extract, these compounds are the main phenolic constituents in the aerial parts of the plant.

Patients with overactive bladder syndrome (OAB) suffer from urgency with/without incontinence, frequency, and nocturia [1]. Antimuscarinic agents are used as a first-line therapy with clinical benefits, but exhibit anticholinergic side effects [2]. Here we investigated the inhibitory effect of Bryophyllum pinnatum leaf press juice on porcine detrusor contractility in vitro. To characterize the active compounds in B. pinnatum, we tested the effects of a flavonoid and a bufadienolide fraction on the contractility of the porcine bladder strips in comparison to a highly polar fraction and oxybutynin. The methanolic leaf extract of B. pinnatum [3] was partitioned between CH₂Cl₂/H₂O to yield a fraction of lipophilic bufadienolides. The aqueous phase was separated on a Diaion HP-20 column in a flavonoid fraction, and a fraction of highly polar constituents. Detrusor muscle strips used for the contractility experiments were prepared from porcine bladders. The effect of the separated 3 fractions and oxybutynin on detrusor muscle contractility was investigated in an organ bath chamber. Muscle contractions were induced by electric field stimulation (EFS). The flavonoid fraction (1 mg/mL) showed a significant reduction of the contractility to 21.3 ± 5.2% after 77 min. The bufadienolide fraction had no inhibitory effect at the test concentrations. The polar fraction reduced the contractility in a pH-dependent manner, and oxybutynin (10^-6 M) reduced the contractility to 21.9 ± 4.7% of the contraction measured before treatment (100%). The flavonoid fraction of B. pinnatum reduced the porcine detrusor contractility in a dose- and time-dependent manner. Bryophyllum pinnatum may be a new pharmacological option for the treatment of OAB. Keywords: Kalanchoe pinnata, flavonoids, overactive bladder, detrusor contractility, detrusor relaxation References: [1] Haylen BT, de Ridder D, et al. An International Urogynecological Association (IUGA)/International Continence Society (ICS) joint report on the terminology for female pelvic floor dysfunction. Neurourol Urodyn 2010; 29: 4 – 20 [2] Veenboer P, Bosch JL. Long-term adherence to antimuscarinic therapy in everyday practice: a systematic review. J Urol 2014; 191: 1003 – 1008 [3] B. pinnatum leaves were harvested in Schwäbisch Gmünd, Germany, by Weleda AG. A voucher specimen (ZSS 29715) has been deposited at The Zurich Succulent Plant Collection.

Sesquiterpene lactones (STLs) are natural products that have potent antitrypanosomal activity in vitro and, in the case of cynaropicrin, also reduce parasitemia in the murine model of trypanosomiasis. To explore their structure-antitrypanosomal activity relationships, a set of 34 natural and semi-synthetic STLs and amino-STLs was tested in vitro against T. b. rhodesiense (which causes East African sleeping sickness) and mammalian cancer cells (rat bone myoblast L6 cells). It was found that the α-methylene-γ-lactone moiety is necessary for both antitrypanosomal effects and cytotoxicity. Antitrypanosomal selectivity is facilitated by 2-(hydroxymethyl)acrylate or 3,4-dihydroxy-2-methylenebutylate side chains, and by the presence of cyclopentenone rings. Semi-synthetic STL amines with morpholino and dimethylamino groups showed improved in vitro activity over the native STLs. The dimethylamino derivative of cynaropicrin was prepared and tested orally in the T. b. rhodesiense acute mouse model, where it showed reduced toxicity over cynaropicrin, but also lost antitrypanosomal activity.