Tegene Tesfaye Tole’s research while affiliated with Hawassa University and other places

The medicinal value of medicinal plants lies in some bioactive constituents that produce a definite physiological action on the human body. Heliotropium verdcourtii is a deciduous shrub or small tree traditionally used in the treatment of various diseases including fever, dry cough, measles, convulsions, epilepsy, diarrhea, and other ailments. The chemical constituents of the roots of the plant were not investigated to date. The aim of the study was to investigate the phytochemicals present in the roots of Heliotropium verdcourtii. The freshly collected root of the plant was chopped and air dried under shade. The dried and finely grounded plant root was extracted through maceration with n-hexane, chloroform/methanol (v/v 1:1), and methanol successively. The extracts were subjected to qualitative phytochemical tests for screening the classes of secondary metabolites present in the plant. Compound isolation of the chloroform/methanol (v/v 1:1) extract was performed through silica gel chromatographic separation. The structures of all isolated compounds were determined by spectroscopic methods as well as comparison with previous reports in the literature. The yields of n-hexane, chloroform/methanol (v/v 1:1), and methanol extracts were 2.2 g (0.4%), 25 g (5.0%), and 19.8 g (4.0%), respectively. The qualitative phytochemical test of the extracts revealed the presence of flavonoids, terpenoids, phenolics, saponins, glycosides and alkaloids. Silica gel chromatographic separation afforded a mixture of three isomeric triterpenoids identified as α-amyrin, β-amyrin, and bauerenol. To the best of our knowledge these bioactive compounds were isolated from the root of this plant, for the first time.

Four pyridinyl alcohols and the corresponding hemilabile pyridinyl alcoholato ligand containing ruthenium carbene complexes of the Grubbs second generation-type [RuCl(H2IMes)(O^N)(= CHPh)], where [O^N = 1-(2′-pyridinyl)-1,1-diphenyl-methanolato, 1-cyclopentyl-1-(2’-pyridinyl)-methanolato, 1-cyclohexyl-1-(2′-pyridinyl)-methanolato, and 1-cycloheptyl-1-(2’-pyridinyl)-methanolato] were synthesized with very good yield. The precatalysts were tested for their activity and selectivity (60–90 °C) and the stability of the precatalysts were compared in 1-octene metathesis reaction. The catalytic performances and stabilities of the precatalysts were also compared with Grubbs first and second generation precatalysts. The precatalysts showed very good selectivity and activity in the temperature range 60–80 °C, compared to the Grubbs first and second generation precatalysts, in 1-octene metathesis. The 1-cyclopentyl-1-(2’-pyridinyl)-methanolato and 1-(2’-pyridinyl)-1,1-diphenyl-methanolato ligand containing ruthenium precatalysts showed comparable catalyst activity on 1-octene metathesis reaction at 80 °C than the 1-cyclohexyl-, and 1-cycloheptyl–1-(2’-pyridinyl)-methanolato ligand containing precatalysts. The hemilabile 1-cycloalkyl-1-(2’-pyridinyl)-methanolato ligands improved the catalyst activity and selectivity for 1-octene metathesis significantly compared to the PCy3 ligand at 80 °C. The catalytic lifetime of the cyclopentyl pyridinyl alcoholato ligand containing precatalyst, however, was shorter than diphenyl, cyclohexyl and cycloheptyl pyridinyl alcoholato ligand containing ruthenium precatalyst.

This study was carried out to investigate the potential of water hyacinth as a source of alkali solution for soap making and also its utilization as a possible option for its control. The ash of water hyacinth was boiled with distilled water to prepare the alkali solution. Alkalinity (pH) the resulting solution was tested using chemical indicators and pH meter to assess its suitability for soap making, and it was found to be 10.85. The prepared alkali solution was heated with used cooking oils to prepare soap by a process known as saponification. The moisture content, total free alkali content, total fatty matter and the pH values of the prepared soap materials were found to be in the ranges of 24.3-37.8%, 0.46-0.77, 68.2-72.8 and 9.82-10.33%, respectively. These values are in acceptable ranges for good grade laundry soaps. The data also suggested that water hyacinth ash can be used as source of alkali solution for soap making. It is, therefore, possible to control environmental pollution caused by water hyacinth using its ash in soap making.

Croton macrostachyus is traditionally used in Ethiopia for treating diabetes, cancers, digestive problems, dysentery, wounds, fevers, constipation, diarrhea, intestinal worms, malaria, pain ulcers, and inflammation. The aim of the present work is investigating the chemical constituents of C. macrostachyus and Commiphora habessinica. The powdered stem bark of C. macrostachyus was successively extracted with n-hexane, chloroform and methanol yielding 1.2, 0.72 and 6.04% respectively. Phytochemical screenings of the extracts revealed the presence of flavonoids, tannins, saponins, phenols, terpenoids, glycosides, steroids and absence of anthraquinones. The methanol extract of C. macrostachyus subjected to chromatographic separation resulted in the antimalarial, antiprotozoal, antimicrobial, anti-inflammatory, antitumor and chemopreventive component lupeol (SED-1). The isolated compound was characterized using melting point, NMR and IR spectroscopy and by comparing experimentally obtained spectral data with previously reported literature. The essential oil of the resin from C. habessinica was isolated by hydro-distillation and a total of 21 components were identified by means of GC and GC/MS analysis. The main components of the essential oil were the medicinally important components α-copaene (27%), α-cadinol (25%), and trans-caryophyllene (15.3%).

The paper presents a comprehensive survey on the synthetic procedures of transition metal complexes of α-pyridinyl alcoholato, α-bipyridinyl alcoholato, α,α’-pyridinyl dialcoholato and α,α’-bipyridinyl dialcoholato ligands and their coordination chemistry. Greater emphasis is, however, given to the catalytic activity of the complexes in homogeneous and asymmetric chemical reactions. The multidentate character of the pyridinyl alcohols and/or bipyridinyl diols is of great importance in the complexation with a large number and type of transition metals. The transition metal complexes of pyridinyl alcoholato or bipyridinyl dialcoholato ligands in most cases, and a few pyridinyl alcohols alone, were used as catalysts in homogeneous and chemical asymmetric reactions. In most of the homogeneously catalysed enantioselective chemical reactions, limited numbers and types of pyridinyl alcohols and or bipyridinyl diols were used in the preparation of chiral catalysts that led to a few investigations on the catalytic importance of the pyridinyl alcohols.

Other than their valuable use as starting materials and intermediates in the synthesis of drugs and other important organic compounds, pyridinyl alcohols are largely used as hemilabile chiral chelating ligands in the development of homogeneous transition metal catalysts. The pyridinyl alcohols covered in this review are divided into four types based on the position of the alcohol group and number of the pyridine ring, namely alpha-pyridinyl alcohols alpha,alpha '-pyridine diols, alpha-bipyridinyl alcohols and alpha,alpha '-pyridine diols. Many synthetic procedures have been conducted by a number of research groups in order to obtain the best synthetic method for these alcohols in the past decades. Significant and remarkable efforts, by many chemists, have been made to synthesise enantiomerically pure pyridinyl alcohols in very good to excellent chemical and optical yields. In this article, a critical overview of the synthetic strategies of the aforementioned pyridinyl alcohols with detailed procedures is provided with the aim of giving a wide scope for the reader in this area.