Flavonol profiles and resveratrol contents were analyzed in seed, leaves and exocarps from the various grape cultivars by HPLC and compared them according to the harvesting times (June - September), collecting locations (five regions on August) and dr...
Flavonol profiles and resveratrol contents were analyzed in seed, leaves and exocarps from the various grape cultivars by HPLC and compared them according to the harvesting times (June - September), collecting locations (five regions on August) and drying methods (freeze vs. air).
Resveratrol analysis: The overall mean of resveratrol contents in the leaves of 36 grapevines cultivars was 2.0 mg/g, and the cultivars with high level more than 3.0 mg/g were 'Cheongsoo' (3.1 mg/g) and ‘High Bailey’ (3.0 mg/g).
In addition to the cultivar's variation, resveratrol contents were affected by regional population of 'Kyoho' and 'Campbell Early'. It's content in the leaves of 'Kyoho' (Suwon, Senggeo and Mokcheon) and 'Campbell Early' (Senggeo, Onyang and Yeongdong) on August by localities was found the highest in those of ‘Senggeo’ population in both cultivars, as 1.5 and 1.1 mg/gDW, respectively.
The resveratrol content of exocarps of ‘Kyoho’ according to the harvesting times showed higher level on June (0.3 mg/gDW) than those of July-September, but this value of 0.3 mg/gDW represents only one-fifth of the amount in leaves. The resveratrol content was also different by organs, and revealed higher level in leaves than exocarps or seeds. In addition, its content in leaves was influenced by drying methods, with higher level by freeze drying (1.5 mg/gDW) than air drying (0.9 mg/gDW) in ‘Kyoho’.
Flavonoid analysis : Three kinds of conjugated flavonols were detected: kaempferol, quercetin, isorhamnetin. And, total nineteen compounds of sugar conjugated flavonols were identified from 30 grapevines cultivars. Among them, the most abundant flavonol was quercetin 3-O-glucoside 7-O-glucuronide. These results suggest that the kinds of flavonols are present differently among grape species or cultivars.
Flavonoid in callus : I identified two major flavonols, isorhamnetin 3-O-glucoside and quercetin 3-O-glucoside in calli induced from exocarps of grape 'Kyoho'.
The contents of flavonoid compounds in grape calli varied with the kinds of phytohormones in B5 medium. In summary, the relative amount of flavonols (isorhamnetin 3-O-glucoside plus quercetin 3-O-glucoside) in calli was the highest in TDZ medium by 200% increase of control, and the addition of kinetin led to decrease to 20% level of control which included 0.1 mg/L 2,4-D and 0.2 mg/L BA in same medium.
The wavelengths also influenced the flavonoid metabolism in cultured grape cells. Among the light sources treated, flavonoid contents decreased under blue light, but increased under red or green light.
From above results, the information of flavonoid profiles could provide chemical indicator for the identification of grapes at cultivar levels and consequently, 'Cheongsoo' or 'High Bailey' could be selected as parent lines for improving grape qualities in breeding program.
In the future research, the availability of abandoned grape leaves in the vineyards will be focused as potentially valuable resources on medicinal areas.