aplikasi UV pada senyawa flavonoid (2).pptx

aplikasi UV pada senyawa flavonoid

1. IDENTIFIKASI FLAVONOID DENGAN Spektroskopi UV-VIS

2. Aluminum chloride (AlCI3). Hydrochloric acid (HCl). Sodium methoxide ( NaOMe ). Asam borat (H3B O 3). Reagents and Procedures for the Ultraviolet Spectral Analysis of Flavonoids

3. The UV Spectra of Flavones and Flavonols in Methanol Spektrum metanol flavon dan flavonol menunjukkan dua puncak serapan utama di wilayah 240 - 400 nm . Kedua puncak ini biasa disebut sebagai Band I (biasanya 300 - 380 nm, dan Band II (biasanya 240 - 280 nm). Band I dianggap terkait dengan penyerapan karena B-ring cinnamoyl sistem, dan Band II dengan penyerapan yang melibatkan sistem cincin-benzoil (lihat III ).

4. On increasing the oxygenation of the B-ring in flavones and flavonols , a bathochromic shift in Band I occurs with each additional oxygen function (see Table V-3) Increasing hydroxylation of the A-ring in flavones and flavonols produces a notable bathochromic shift in Band II (see Table V-4) and a smaller effect on Band 1. 1a. The Effect of Oxidation Patterns on the UV Spectra of Flavones and Flavonols

5. terjadi pada  lebih panjang ( pergeseran merah / batokhromik ) Meningkatkan oksigenasi dari cincin – B pada flavon dan flavonol , terjadi pergeseran batokromik di Band I untuk setiap penambahan oksigen

6. If a 3-, 5- or 4'-hydroxyl group on the flavone or flavonol nucleus is methylated or glycosylated, hypsochromic shifts (i. e. to shorter wavelengths), especially in Band I , are observed. The shift associated with the substitution of the 3-hydroxyl group is usually of the order of 12 - 17 nm but reaches 22 - 25 nm in flavonols which do not contain a free 5-hydroxyl group. Methylation of the 5-hydroxyl group results in a 5-15 nm hypsochromic shift in both Band land II. And, Methylation or glycosylation of the 4'-hydroxyl group produces a 3-10 nm hypsochromic shift in Band I. Substitution of the hydroxyl groups at positions other than 3, 5 and 4' has little or no effect on the UV spectrum (in methanol). 1b. The Effect of Methylation and Glycosylation on the UV Spectra of Flavones and Flavonols

7. Acetylation of a phenolic hydroxyl group is known to nullify the effect of that group on the UV spectrum. This principle has been applied by Jurd [1] to locate methoxyl groups in polyhydroxyflavones . For example, diosmetin triacetate (IV) was shown to possess a UV spectrum ( max 257 and 320 nm) similar to that observed for 4'-methoxyflavone ( max 253 and 317 nm).   1c. The Effect of Acetylation on the UV Spectra of Flavones and Flavonols