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Chemical constituents of Scurrula parasitica leaves from Loranthaceae family and some biological activities have been studied. Cold extractions were carried out using n-hexane, ethyl acetate and methanol to obtain the crude extracts. Purification of the extracts led to the isolation of quercetin 1, quercitrin 2, kaempferol 3-O--L-rhamnoside 3, (+)-catechin 4, lupeol 5, lupeol palmitate 6, -sitosterol 7, squalene 8, octacosane 9, octadecane 10 and eicosane 11. The in vitro antioxidant activity of the extracts and isolated compounds were evaluated. Compounds 1, 2, 3 and 4, together with ethyl acetate and methanol extracts exhibited effective antioxidant activities against DPPH, ABTS and FRAP assays, while n-hexane and other compounds were inactive. The ethyl acetate extract gave the highest tyrosinase percent inhibition value of 66.02%, while quercetin gave the best result with tyrosinase percent inhibition value of 79.09%. All extracts and isolated compounds showed weak activity on antimicrobial inhibition assay with the exception of quercetin which exhibited moderate activity against Pseudomonas aeruginosa with MIC and MBC value of 250 g/mL.
Ultrasonic assisted extraction (UAE) process increases the rate of extraction, the yield of extracted components and reduces extraction time. The high sensitivity of GC-MS/MS provides reliable identification of phytoconstituents present in a plant extract. This research is to develop an easy and effective method for the extraction and analysis of phytochemicals in C. singueana, C. sieberiana, C. tora and C. occidentalis using UAE and GC-MS/MS techniques. The crude extracts obtained from the four Cassia species under UAE conditions of 50 mins extraction time, 50 oC extraction temperature and 20 mL/g solvent to sample ratio were analyzed using GC-MS/MS. Thirty-four compounds were identified by comparison of their mass spectra with those in the National Institute of Standards and Technology library, requiring at least 80% similarity. These compounds comprise fatty acids, fatty alcohol, carboxylic acid, long-chain alkanes, diterpenes, triterpenes, sterols and anthraquinones. n-Hexadecanoic acid and phytol were identified in all the Cassia species while anthraquinone was detected only from the methanol extracts of C. tora and C. occidentalis. The bioactivities reported in the literature for these compounds corroborate with the phytoconstituents identified in these plants and support the ethnomedicinal uses of these Cassia species.
ABSTRACT. Herbal preparations of Globimetula braunii leaves are used in tropical African countries for the treatment of several illnesses. A preliminary study of the leaf extracts of Globimetula braunii has confirmed the antioxidant, antibacterial, biochemical and toxicological potency of the plant. The leaf extracts were subjected to bioactivity guided fractionation that led to the isolation of the active compounds. Antioxidant, antityrosinase and antimicrobial inhibitory activities of the isolated compounds were evaluated. Structural elucidations of the isolated compounds were carried out spectroscopically, including the use of 1D/2D nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopies and mass spectrometry. Results indicated that quercetin (15) isolated from ethyl acetate fraction exhibited the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) scavenging capacity and also showed the highest ferric reducing antioxidant potential (FRAP) equivalent value. Quercetin (15) and dodoneine (14) displayed the highest tyrosinase inhibition activity with IC50 value of 0.12±0.32 mM and 0.19±0.20 mM, respectively. All the isolated compounds showed weak to not active in the antimicrobial inhibition assay. The findings in this report have revealed the antioxidant and antityrosinase potential of Globimetula braunii and thus supporting their traditional uses. KEY WORDS: Globimetula braunii, Antioxidant, Antityrosinase, Antimicrobial, Triterpenoid esters, Dodoneine Bull. Chem. Soc. Ethiop. 2022, 36(2), 387-397. DOI: https://dx.doi.org/10.4314/bcse.v36i2.12
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