| Firstly, we compared the phytochemical profile and antioxidant activities of the whole leaves from seven cultivars of Aloe(A. ferox mill, A. vera var. chinensis, A. saponaria, A. mutabilis, A. vera, A. arborescens, A. greenii). Using 80% chilling acetone to extract the phytochmicals from Aloe, the Folin-Ciocalteu colorimetric method to detect the total phenolic content(TPC) and the Sodium borohydride/chloranil(SBC) method to determine the total flavonoids content(TFC). Two antioxidant methods in vitro to measure including peroxyl radical scavenging capacity(PSC), oxygen radical scavenging capacity(ORAC) and cellular antioxidant assay(CAA). The results showed that the TPC and TFC among different cultivars of Aloe were significantly different(p < 0.05). The TPC of A. vera, A. arborescens and A. greenii were similar and higher than other that of Aloe and their TPC were 69.10 ± 1.93, 68.10 ± 0.74 and 65.50 ± 3.22 mg GAE/100 g FW, respectively. The highest TFC was showed in A. vera and reached 121.1 ± 8.1 mg CE/100 g FW. Through the analysis by HPLC, five compounds have been specified, including aloin, aloenin, O-methylaloeresin A, 7-, chlorogenic acid and sinapic acid. Aloin and aloenin were major phytochemicals, and the extracts of A. greenii had the highest contents, respectively, were 42.2 ± 0.13 and 110.4 ± 2.6 mg/100 g FW. The results showed the antioxidant activity had a positive correlation with TPC and TFC(p < 0.05). A. arborescens had the highest ORAC value(2135.1 ± 35.1 μmol TE/100 g FW). And A. vera had the highest value of PSC(275.2 ± 9.8 μmol ASA equiv. /100 g FW). The highest CAA value in the no PBS wash protocal was found in A. arborescens(17.30 ± 2.40 μmol QE/100 g FW), and the highest CAA value in PBS wash protocal was observed in A. greenii(5.67 ± 0.74 μmol ASA equiv./100 g FW).Then, the impact of tissues on phytochemical profiles and antioxidant activities was investigated in four cultivars of Aloe(A. vera var. chinensis, A. ferox mill, A. vera, A. arborescens) from the seven. The results showed that the TPC and TFC of peel were significantly higher than gel(p < 0.05) regardless of different cultivars. The TPC of peel and gel in A. arborescens were the highest among the four cultivars which were 168.7 ± 1.2 and 27.57 ± 1.60 mg GAE/100 g FW, respectively. The peel of A. vera contained the highest flavonoids which was 306.6 ± 0.7 mg CE/100 g FW, and A. arborescens had the highest TFC of gel which was 24.88 ± 2.24 mg CE/100 g FW. Through the analysis of HPLC, A. arborescens had the highest content of aloin and aloenin which were 77.17 ± 0.22 and 182.4 ± 0.4 mg/100 g FW, respectively. There was a higher correlation between antioxidant activities using different methods and all of them had positive correlation with the TPC and TFC(p < 0.05). The peel of A. arborescens had the highest ORAC value, CAA value in no PBS wash and PBS wash protocals which were 422.8 ± 15.1 μmol TE/100 g FW, 22.56 ± 3.33 μmol QE/100 g FW and 7.68 ± 0.91 μmol QE/100 g FW respectively. The highest PSC value was found in A. vera which reached 3169.6 ± 145.0 μmol ASA equiv./100 g FW.Finally, the cytotoxicity, antiproliferation and anti-UV activity of Aloe extracts were analyzed using Hep G2 cell lines. The results showed the higher the content of phenolics and flavonoids, the more excellent the anti-UV activity in Aloe. The TPC and TFC of A. vera, A. arborescens and A. greenii were similar, so there were no significant difference in EC50 value(p ≥ 0.05), an evaluation index of anti-UV activity. The peel of A. arborescens had the highest TPC and anti-UV activity. Its EC50 was 17.51 ± 3.14 mg/m L. The characteristic phytochemical aloin showed potential anti-UV activity, and the EC50 was 571.8 ± 9.1 μM. The results of DNA-Ladder assay showed that the extract of Aloe can protect Hep G2 cells from UV radiation by inhibition of degradation from photoproducts. |
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