Probing the molecular orientation of chemically polymerized polythiophene-polyrotaxane via solid state NMR

Averrhoa carambola Leaf Extract Induces Apoptosis-Like Death with Increased ROS Generation in Leishmania donovani

PURPOSE

The parasitic disease leishmaniasis is responsible for high mortality and morbidity rates worldwide. The visceral form is the most severe form of leishmaniasis (or leishmaniosis), which is caused predominantly by Leishmania donovani. Currently, clinically recommended antileishmanial drugs are not convenient because of several medical complications and resistance issues. Phytocompounds are the best candidates in this regard. The present study aimed to evaluate the antileishmanial activity of Averrhoa carambola leaf extract.

METHODS

The antipromastigote activity and cytotoxicity were assessed using the MTT assay. Morphological distortions were determined using phase contrast microscopy and scanning electron microscopy (SEM). Reactive oxygen species (ROS) production, nonprotein thiol depletion and apoptotic death in promastigotes were determined via flow cytometry. UV-visible spectroscopy and energy dispersive X-ray (EDX) spectroscopy was performed for elemental analysis. Fourier-transform infrared spectroscopy (FTIR) and liquid chromatography‒mass spectrometry (LCMS) were used to characterize the phytocomponent(s) present in the extract.

RESULTS

The chloroform extract of Averrhoa carambola leaf (ACCEX) (IC50 = 50.76 ± 1.7 µg/mL) exhibited the highest activity, followed by the ethyl acetate, hexane, and methanol extracts. ACCEX has also exhibited lower toxicity towards host macrophages. ACCEX also induced morphological distortions in promastigotes, with significant generation of ROS and the concomitant apoptosis initiation followed by a decrease in the nonprotein thiol level. The major phytometabolites present in ACCEX were identified from the National Institute of Standards and Technology (NIST) database and from a literature review.

CONCLUSIONS

This study suggested that Averrhoa carambola leaf extracts are rich in some classes of biologically active phytocompounds and exhibit good antileishmanial activity.

Optimization of the pre-tension and separation distance for measurement of the dynamic elastic modulus and macromolecular orientation of a polypropylene monofilament via the sonic velocity method

Using a fiber orientation degree measurement instrument (i.e., a dynamic modulus tester), 28 groups of averaged sonic pulse travel times in a polypropylene monofilament were measured and recorded under five pre-tensions across eight separation distances. The zero-time (or delay time) T₀, sonic velocity C, sonic modulus E, Hermans orientation factor F, and orientation angle θ were calculated via two- and multi-point methods. The good agreement observed between the scatter plots of calculated data and the regression lines shows that the multi-point method provides reliable, accurate determination of the sonic modulus (or the dynamic elastic modulus) and the orientation parameters. Surprisingly, the zero-time for sonic pulse propagation depends significantly on the separation distance in practice, although it does not in theory. For easy and rapid measurement or relative comparisons using the two-point method, the optimal range of pre-tension is 0.1 gf/den-0.2 gf/den, and the optimal separation distances are 200 mm and 400 mm. The two-point method is appropriate for industrial applications, while because of its greater accuracy, the multi-point method is preferred for scientific research.