Flavonoids were extracted by solid phase extraction (SPE) from seven floral honey samples of different botanical origin from different regions of Sudan. The flavonoids were determined by high performance liquid chromatography (HPLC) technique using photo diode array detector (PDA). An isocratic and gradient systems for the resolution, identification and quantification of five flavonoids, namely; quercetin, kaempferol, apigenin, hesperetin and isorhamnetin, were developed. Although the isocratic system resolved the five compounds, however it suffered from interference by the complex mixture of honey samples. The gradient system resolved three of five flavonoids, namely, quercetin, kaempferol, and isorhamnetin, without interference by the complex honey matrix. Two flavonoids, apigenin and hesperetin, were observed to elute at close retention times, which lead to their interference with each other when injected in a mixture; however, absorption wavelength selection was found indicative of the presence or absence of either compound. The quantification of these flavonoids was done through the calibration curves of their standards. The obtained results were compared with reported results.

This study came with the objective to compare the effect of extraction method and solvents on yield and antioxidant activity of certain Sudanese medicinal plant extracts, used in traditional medicine for treating various illnesses. The effect of maceration and Soxhlet successive extraction with n-hexane, chloroform and methanol were investigated on the antioxidant activity of five Sudanese medicinal plants. The antioxidant activities were assessed via DPPH (2, 2-Di (4-tert-octylphenyl)-1-picryl-hydrazyl) free radical scavenging activity and Propyl Gallate as standard antioxidants. Maceration was more effective than successive Soxhlet extraction with the same solvents.

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The ethyl acetate extracts of fruits and bark of Acacia nilotica (L.) Willd. ex Del subsp. nilotica, fomentosa and asrringens. showed the highest rnolluscicidal activity against snail species Bulinus truncatus and Biomphalaria pfeifferi. This was due mainly to the flavanol derivatives isolated from the tannin extracts and characterized as (-)-epigallocatechin-7-gallate and (-)-epigallocatechin-5,7-digallate. It was found also that the ethyl acetate extracts of 20Acacia species and subspecies growing in the Sudan were active against the snails, which was due to the presence of the above mentioned (-)-epigallocatechin derivatives.