Polyunsaturated verses saturated index as a reference for determining the quality of edible seed oils extracted from locally cultivated oil seeds of Ethiopia

Consumption of edible oils is increasing tremendously regardless of their high prices. As a result, the global production of vegetable oils has also been growing constantly. This may be related to global population growth and associated increasing demands of the consumers. In this particular work, ten crude food seed oils of Ethiopian origin were extracted in our lab and analyzed for their chemical composition by gas chromatography mass spectroscopy (gc-ms). To check their food quality, P/S index of all laboratory extracted seed oils were compared. The fatty acids (fas) concentrations of the oils were determined using decanoic acid methyl ester as internal standard and linoleic acid ethyl ester as a reference. The analysis results indicate that the P/S index for standard crude oils were 8.19 for safflower (sff), 2.58 for sesame (ses), 4.37 for Niger (nig), 5.50 for Linseed (lns), 2.04 for peanut (pnt), 5.13 for Ethiopian mustard (etm) 4.25 for sunflower (suf), 0.09 for palm (pal), 3.14 for soybean (sob), and 1.56 for cotton (cot). The maximum and minimum P/S index were obtained for SFF oil (8.19) and pal oil (0.09), respectively. Analysis of the mixtures of commercial lns and pal oils indicate the improvement of the food quality of the pal seed oil by mixing them in an appropriate ratio

Chemical composition and antioxidant activities of the essential oils of Lippia adoensis Hochst ex. Walp and Ocimum sanctum Linn

ABSTRACT. Essential oils of Lippia adoensis Hochst ex. Walp leaf, Ocimum sanctum Linn leaf and stem and mixture of two plants from Bishoftu and Debre Berhan (Ethiopia) were analyzed using gas chromatography-mass spectrometry. The essential oil of O. sanctum from Bishoftu showed 12 compounds with major components being b-bisabolene (31.38%), 4-[(1Z)-1,5-dimethyl-1,4-hexadien-1-yl]-1-methylcyclo-hexen (25.56%), eucalyptol (17.12%). While that from Debre Berhan contained 20 compounds with major components being b-bisabolene (24.45%), 4-[(1Z)-1,5-dimethyl-1,4-hexadien-1-yl]-1-methylcyclohexen (19.61%) and eucalyptol (13.42%). The essential oil of the leaves of Lippia adoensis from Bishoftu showed 15 compounds with major components as linalool (66.60%), caryophyllene (4.28%) and that from Debre Berhan showed 12 compounds with linalool (86.11%) as major compound. The essential oil of the mixture of L. adoensis and O. sanctum from Bishoftu showed 18 compounds with major compound being linalool (62.54%) and that from Debre Berhan showed 21 compounds with major compounds being linalool (48.47%) and eicosane (9.42%), octadecane (5.47%). The essential oils of O. sanctum and L. adoensis and their mixture from the two places exhibited DPPH radical scavenging activity of 96.48% and 96.17%, 92.58% and 93.37%, and 95.25% and 96.42% at 100 µg/mL, respectively. The antioxidant activities of essential oils were comparable to that of ascorbic acid which exhibited 98.08% at the same concentration (100 µg/mL).                 KEY WORDS: Ocimum sanctum, Lippia adoensis, Essential oil, Antioxidant activity, DPPH assay Bull. Chem. Soc. Ethiop. 2022, 36(1), 95-108.                                                                   DOI: https://dx.doi.org/10.4314/bcse.v36i1.

Essential oil and smoke components of Carissa spinarum

ABSTRACT. Carissa spinarum Linn. is an incense plant traditionally used in Ethiopia and other countries for the treatment of numerous diseases. It also exhibits different biological activities, and different classes of natural compounds were previously reported from the plant. In this study, the essential oil from the roots of C. spinarum together with medicinal smoke obtained from burnt roots of C. spinarum were analyzed by GC-MS. The essential oil of C. spinarum roots was predominantly composed of 2-hydroxyacetophenone (82.97%). The dominant components in the n-hexane soluble fraction of the smoke derived from the roots of C. spinarum were 2,6-dimethoxyphenol (14.16%), 2-methoxyphenol (10.34%) and 2-hydroxyacetophenone (9.51%). On the other hand, the major components in the MeOH-soluble fraction were 2,6-dimethoxyphenol (17.51%), 2-methoxyphenol (13.02%) and 2-hydroxyacetophenone (10.98%). The smoke derived from the roots of C.  spinarum showed 92.60 ± 0.34% DPPH inhibition at concentration of 100 µg/mL. At the same concentration, standard ascorbic acid scavenged the DPPH radical by 96.09 ± 0.16%. This result supports the traditional medicinal use of the plant material as a skin-care and wound healing agent most likely due to the presence of simple phenols and other biologically active compounds.   KEY WORDS: Carissa spinarum Linn., Medicinal smoke, Essential oil, Antioxidant activity, Phenolic compounds Bull. Chem. Soc. Ethiop. 2022, 36(3), 641-649.                                                                DOI: https://dx.doi.org/10.4314/bcse.v36i3.1

Total phenolics and antioxidant capacity of the white and brown teff [Eragrostic tef (Zuccagni) trotter] varieties cultivated in different parts of Ethiopia

ABSTRACT. This study was aimed to determine the total phenolics contents and antioxidant capacity of white and brown teff grain samples. The free total polyphenolic content (TPPC), bound TPPC and total flavonoids content ranged from 62.1–129.9, 84.6–189.6 mg GAE/100 g and 84.4–195.1 mg QE/100 g, respectively, in white teff samples, and, 118.6–196.7, 141.1–195.1 mg GAE/100 g and 97.8–202.5 mg QE/100 g, respectively, in brown teff samples. Besides, the free 2,2-diphenyl-1-picrylhydrazyl (DPPH) and bound DPPH ranged from 74.8–98.3, 77.1–99.9 mg AAE/100 g, respectively, for white teff samples, and, 68.7–93.1 and 71.2–99.4 mg AAE/100 g, respectively, for brown teff samples. This study revealed that total phenolics content was higher in brown teff samples than white teff samples and is in agreement with other reports. However, their DPPH scavenging activities were nearly equal, indicating that both varieties of teff are relevant for human nutrition and health. Furthermore, the dendrogram has shown sharp separation of the samples based on their origin and variety related to the total phenolics parameters. Hence, findings of this study can help consumers appreciate the nutritional value of white and brown teff grains; provide them guidance for teff purchase and production.   KEY WORDS: Teff, Phenolics, Gallic acid, Ascorbic acid, Anti-oxidant, DPPH   Bull. Chem. Soc. Ethiop. 2022, 36(4), 749-766.                                                              DOI: https://dx.doi.org/10.4314/bcse.v36i4.3                                                       &nbsp

New analytical methods for the determination of ascorbic acid content in aqueous extracts of flesh, peel and seeds of pumpkin (Cucurbita maxima)

ABSTRACT. The main objective of this research was to develop a simple, rapid, cost-effective, and environmentally friendly methods for determining ascorbic acid in flesh, peel, and seeds of pumpkin. Ascorbic acid was extracted from the different parts of the pumpkin in water. The content of ascorbic acid in three parts of the pumpkin was determined using ATR-FTIR and UV-VIS methods. The ATR-FTIR method was validated to determine ascorbic acid at 1046 cm-1, and the results indicated a linear range of 5 to 50 g/L; R2, 0.999; LOD, 1.7 g/L; LOQ, 5.2 g/L; RSD, 0.09% to 0.65%, and %recovery of 95.86%. Ascorbic acid was also determined at 265 nm by the UV-VIS method that revealed a linear range of 1 to 12 mg/L; R2, 0.999; LOD, 0.25 mg/L; LOQ, 0.75 mg/L; RSD, 0.12% to 0.43%, and %recovery of 96.96%. Accordingly any of the two newly developed methods can easily be applied for quantitative determination of ascorbic acid in pumpkin flesh, peel, and seeds. Both methods yielded higher ascorbic acid content in pumpkin seeds than in pumpkin flesh and peel. Both ATR-FTIR and UV-VIS spectroscopic methods are green, low cost and rapid method. However, UV-VIS method showed higher sensitivity than the ATR-FTIR method.   KEY WORDS: Pumpkin, Cucurbita maxima, Ascorbic acid, ATR-FTIR spectroscopy, UV-VIS spectrophotometry   Bull. Chem. Soc. Ethiop. 2022, 36(2), 277-290.                                                             DOI:https://dx.doi.org/10.4314/bcse.v36i2.3                                                        &nbsp

In vitro antifungal, anti-inflammatory and cytotoxic activities of Rumex abyssinicus rhizome extract and bioassay-guided isolation of cytotoxic compounds from Rumex abyssinicus

  ABSTRACT. Rumex abyssinicus showed strong cytotoxicity against HeLa cells (IC50 = 22.25 μg/mL) and weak cytotoxicity against PC3 and BJ cells with percent inhibition of 58.6, 25.8 and 29.7% at 30.0 μg/mL. It showed moderate antifungal activity against Aspergillus niger with a percent growth inhibition of 55.5% at 3000 µg/mL. It also strongly inhibited oxidative burst with IC50 value of 24.8 μg/mL. DCM (100%) and DCM: EtOAc (1:1) fractions showed strong cytotoxicity against HeLa cells, whilst pet ether: DCM (1:1) fraction showed strong cytotoxicity against PC3 cells with IC50 values of 29.3, 26.3 and 24.3 μg/mL, respectively. Moreover, the DCM: EtOAc (1:1) fraction inhibited ROS production with IC50 value of 18.8 μg/mL. Cytotoxic fractions afforded chrysophanol (1), physicon (2), emodin (3), citreorosein (4) and β-sitosterol (5). Among the isolated compounds, emodin (3) showed strong cytotoxicity against HeLa cells, whilst chrysphanol (1) and physicon (2) showed strong cytotoxicity against PC3 cells with IC50 values of 8.94, 22.5, and 28.5 µM, respectively. In addition, emodin (3) and citreorosein (4) showed strong inhibition against ROS production with an IC50 value of 16.2 and 38.2 μg/mL. The findings of this study suggest R. abyssinicus as a good candidate for cancer and inflammation management.     KEY WORDS: Polygonaceae, Rumex abyssinicu Jacq., Cytotoxic, Antifungal, Anti-Inflammatory, Reactive oxygen species   Bull. Chem. Soc. Ethiop. 2022, 36(4), 879-892.                                                               DOI: https://dx.doi.org/10.4314/bcse.v36i4.13                                                     &nbsp