Bisabololoxide A, one of the main constituents in German chamomile extract, induces apoptosis in rat thymocytes

Antiproliferative potential and phenolic compounds of infusions and essential oil of chamomile cultivated with homeopathy

ETHNOPHARMACOLOGICAL RELEVANCE

Chamomilla recutita (Asteraceae) is used worldwide as a soothing, anti-inflammatory and aromatherapy. In Brazil, it is one of the most cultivated medicinal species. However, the cultivation form may alter the production of compounds in the secondary metabolism and compromise the therapeutic purpose of this species.

AIM OF THE STUDY

Evaluation of antiproliferative and genotoxic effects of infusions and essential oil of chamomile, cultivated with homeopathy, on the cell cycle of Allium cepa, as well as the determination of the phenolic compounds present in the infusions of the chamomile inflorescences.

MATERIAL AND METHODS

For the Allium cepa test, two concentrations of 10 and 40 g L^-1 of inflorescences of chamomile were used for the preparation of the infusions and essential oil diluted to 0.10%, referring to the six treatments obtained in field cultivation, in which were carried out the applications of homeopathy from the emergence to the harvest of the plants. Distilled water and ethanol were used as negative control and glyphosate 2% as a positive control. The determination of phenolic compounds present in the infusions was carried by liquid chromatography in a UHPLC apparatus.

RESULTS

Chamomile infusions at concentrations of 10 and 40 g L^-1 of inflorescence reduced mitotic index and emphasized antiproliferative activity on the cell cycle of Allium cepa. However, the treatments related to essential oil diluted to 0.10% showed a response variation dependent on the dynamization used, as well as for apigenin concentration.

CONCLUSIONS

Therefore, cultivation with homeopathy does not induce a genotoxic effect in the use of infusions and essential oil of chamomile and it emphasize antiproliferative activity on the cell cycle of Allium cepa, favoring the sustainable cultivation and the safe use of this medicinal species when cultivated with homeopathy.

Bisabololoxide A, one of the constituents in German chamomile extract, attenuates cell death induced by calcium overload

Bisabololoxide A (BSBO), main constituents in German chamomile extract, is responsible for antipruritic effect. In previous study, the incubation with 30-100 μM BSBO for 24 h exerted cytotoxic and proapoptotic effects on rat thymocytes. To further characterize BSBO cytotoxicity, the effect on the cells suffering from calcium overload by calcium ionophore A23187 was examined. A23187 induced Ca(2+) -dependent cell death. Contrary to our expectation, 1-10 μM BSBO inhibited A23187-induced increase in cell lethality of rat thymocytes. BSBO attenuated A23187-induced increases in populations of shrunken living cells, phosphatidylserine-exposed living cells, and dead cells, without affecting the increase in intracellular Ca(2+) concentration and the Ca(2+) -dependent hyperpolarization. The effect of BSBO on A23187-treated cells may be unique because the activation of Ca(2+) -dependent K(+) channels is required for cell shrinkage, externalization of phosphatidylserine, and cell death in some cells. The cell death induced by A23187 was not inhibited by Z-VAD-FMK, a pan-inhibitor of caspases. Thus, the cell death may be a necrosis with some features observed during an early stage of apoptosis. These results suggest that BSBO at low micromolar concentrations is cytoprotective against calcium overload.

Bisabololoxide derivatives from Artemisia persica, and determination of their absolute configurations by ECD

Five antiplasmodial bisabololoxide sesquiterpene diesters were isolated from an EtOAc extract of the aerial parts of Artemisia persica following an HPLC-time-based activity profiling of the extract. Structure elucidation was achieved by 1D and 2D NMR experiments. Relative configurations of cyclohexenone/cyclohexene and tetrahydropyran moieties of 1-5 were established on the basis of ³J(H-H) coupling constants and NOE difference spectra. Stereochemical correlation of the two rings, and assignment of absolute configuration of 1-5 were achieved by comparison of experimental ECD spectra with simulated ECD data for possible stereoisomers, by using time dependent density function theory (TDDFT). Bisaboloids 1-4 exhibited in vitro antimalarial activity against Plasmodium falciparum, with IC₅₀ values ranging from 2.8 to 20.1 μM, and selectivity indices (SI) in L-6 cells of 3.7-11.9.

Apoptosis and mutagenicity induction by a characterized aqueous extract of Baccharis articulata (Lam.) Pers. (Asteraceae) on normal cells

In a previous study we have demonstrated that cold aqueous extract of Baccharis articulata (Ba-CAE) induced the death of human peripheral blood mononuclear cells (PBMCs) and exerted low mutagenic effects on mice at 6h after administration. The aim of this work was to investigate whether the PBMCs death induced by Ba-CAE is due to apoptosis, and whether this extract exerts mutagenic effects on mice at 24 and 48h after administration. In addition, Ba-CAE was chemically characterized. PBMCs from healthy volunteers were exposed to extract (10, 20, 40, 80, 160, 320, 640 and 1280μg/mL) for 18-24h. Cell viability was determined by staining of trypan blue dye exclusion method. Apoptosis was determined by Hoechst 33258 staining, TUNEL, and DNA fragmentation analysis by agarose gel electrophoresis. BALB/c mice were injected with extract (1800, 900 and 450mg/kg) and sacrificed at 24 and 48h postinjection. Bone marrow samples were used to assess chromosome mutations by the micronucleus test. The extract induced PBMCs death by apoptosis and increased the frequency of micronuclei in bone marrow. The phytochemical study of Ba-CAE showed the presence of flavones as luteolin and acacetin, caffeoylquinic acids as chlorogenic acid, and tannins.

Cytotoxic action of bisabololoxide A of German chamomile on human leukemia K562 cells in combination with 5-fluorouracil

German chamomile (Matricaria recutita L.) is a popular ingredient in herbal teas. In previous study, micromolar bisabololoxide A, one of main constituents in German chamomile, exerted cytotoxic action on rat thymocyte, a normal non-proliferative cell. This result prompted us to study the effect of bisabololoxide A on proliferative cancer cells and to seek the possibility of its use with 5-fluorouracil, an anticancer agent. In this study, the effect of micromolar bisabololoxide A on human leukemia K562 cells was cytometrically examined. Although the incubation of K562 cells with 10 μM bisabololoxide A for 72h did not significantly increase the percentage populations of dead cells and shrunken cells, the inhibitory action on the growth was obviously observed. It was not the case for the concentrations of less than 5 μM. The threshold concentration of bisabololoxide A to exert the cytotoxic action on K562 cells was ascertained to be 5-10 μM. Bisabololoxide A at 5-10 μM did not exert cytotoxic action on normal non-proliferative cells (rat thymocytes) in our previous study. Since the antiproliferative action of micromolar bisabololoxide A on cancerous cells was expected to be beneficial to cancer treatment, the modification of antiproliferative action of 5-fluorouracil (3-30 μM) by bisabololoxide A was studied. The combination of 5-fluorouracil and bisabololoxide further inhibited the growth of K562 cells although the additive inhibition of growth by bisabololoxide A became smaller as the concentration of 5-fluorouracil increased. Therefore, it is suggested that the simultaneous application of German chamomile containing bisabololoxide A may reduce the dose of 5-fluorouracil.