Open Access proceedings Journal of Physics: Conference series
Figure 2. Structure of quercetin (left) and kaempferol (right). Figure 3
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BÀI TẬP THAM KHẢO KIỂM TRA CUỐI HỌC KÌ 1 SINH 8
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- 4. Conclusion
| Figure 2. Structure of quercetin (left) and kaempferol (right).
Figure 3. Chromatogram of extract and standard on UV 366 nm; from 1-14: quercetin standard, kaempferol standard, M1, M2, M3, Sn1, Sn2, Sn3, R1, R2, R3, S1, S2, and S3. In fgure 2 showed that the extract of M1, M2, Sn1, and Sn2 has many bands with high intensity. The reflux and Soxhlet from original leaf and residues of n-hexane (R1, R2, S1, S2) showed a smaller number of bands and lower intensity of bands, while all extracts derived from residues of ethyl acetate (M3, SN3, R3, S3) show the lowest number and intensity of bands. It can be concluded that more separation step before extraction may be causing the loss of other compounds. 5 ISS IOP Publishing IOP Conf. Series: Earth and Environmental Science 58 (2017) 012060 doi:10.1088/1755-1315/58/1/012060 Table 2. Kaempferol and quercetin content on selected extract Extract/standard name Concentration (%) Kaempferol Quercetin Sn1 0.02 b 2.15 c Sn2 0.02 b 1.97 b S1 0.03 b 1.98 b S3 0.01 a 1.14 a Difference letter means significantly different at p>0.05 Based on the fluorescent intensity on TLC, total phenolic content, tannin content, and flavonoid content, extract of Sn1, Sn2, S1 and S3 were selected to determine the kaempferol and quercetin content using HPLC. Selected extracts have high fluorescent intensity, low tannin and phenols content and high flavonoids content. Table 2 shows that the highest kaempferol content was found in extract of S1, while the highest quercetin content was found in Sn1 extract. Kaempferol content of the extract Sn1 is only small different with the S1, but has much higher LC 50 value. Extract Sn1 had LC 50 values of 41.21 ppm, whereas S1 extracts 1340.81 ppm. So Sn1 extract is considered better because it has a lower LC 50 value. The results showed that the guava leaf sonication using methanol-water (85:15) directly from the sample was the best extraction techniques for the isolation of kaempferol and quercetin in guava leaves. The kaempferol and quercetin content on guava leaf extract with the Tang et al (2001) methods on this study is higher (0.04 mg/g sample and 4.30 mg/g sample respectively) compared with Ginko biloba leaf extracts reported by Tang et al [12]. 4. Conclusion Best extraction techniques to isolate kaempferol and quercetin from guava leaves are sonication using methanol-water (85:15) with a content of 0.02% by kaempferol and quercetin at 2:15%. This technique had yield about 20.05% and BSLT LD50 of 41.21ppm. tải về 0.65 Mb. Chia sẻ với bạn bè của bạn:
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