Department of Pharmacognosy, Faculty of Pharmacy, Srinakharinwirot University, Nakhon Nayok 26120, Thailand.
Melatonin Research Group, Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand.
Molecules. 2022 Aug 5;27(15):4979. doi: 10.3390/molecules27154979.
Mulberry ( L.) leaves from two cultivars, Yai-Burirum (YB) and Khunphai (KP), were prepared into green tea (GT) and black tea (BT). Compared to fresh leaf (FL) extract, GT and BT extracts were evaluated for their total phenolic and total flavonoid contents. Total phenolic content (TPCs) in all samples ranged between 129.93 and 390.89 mg GAE/g extract. The processing of tea decreased the levels of TPC when compared to FL extracts in both cultivars. The total flavonoid content (TFCs) in all samples was found in the range of 10.15-39.09 mg QE/g extract and TFCs in GT and BT extracts were higher than FL extracts. The change in tryptophan, melatonin, phenolic and flavonoid contents was investigated by liquid chromatography-mass spectroscopy (LC-MS). The results exhibited that tryptophan contents in all samples were detected in the range 29.54-673.72 µg/g extract. Both GT and BT extracts increased tryptophan content compared to FL extracts. BT extracts presented the highest amounts of tryptophan among others in both cultivars. Phenolic compounds were found in mulberry leaf extracts, including gallic acid, caffeic acid, gentisic acid, protocatechuic acid and chlorogenic acid. Chlorogenic acid presented the highest amount in all samples. Almost all phenolic acids were increased in the processed tea extracts except chlorogenic acid. Rutin was the only flavonoid that was detected in all extracts in the range 109.48-1009.75 mg/g extract. The change in phenolic and flavonoid compounds during tea processing resulted in the change in antioxidant capacities of the GT and BT extracts. All extracts presented acetylcholinesterase enzyme (AChE) inhibitory activity with IC in the range 146.53-165.24 µg/mL. The processing of tea slightly increased the AChE inhibitory effect of GT and BT extracts. In conclusion, processed tea from mulberry leaves could serve as a new alternative functional food for health-concerned consumers because it could be a promising source of tryptophan, phenolics and flavonoids. Moreover, the tea extracts also had antioxidative and anti-AChE activities.
两种桑（ Mulberry ）品种的叶 Yai-Burirum （YB ）和 Khunphai （KP ）被制成绿茶（ GT ）和红茶（ BT ）。与新鲜叶（ FL ）提取物相比，评估了 GT 和 BT 提取物的总酚和总类黄酮含量。两种品种的所有样品的总酚含量（ TPCs ）均在 129.93 至 390.89 mg GAE/g 提取物之间。与 FL 提取物相比，茶的加工过程降低了 TPC 水平。所有样品的总类黄酮含量（ TFCs ）在 10.15-39.09 mg QE/g 提取物范围内， GT 和 BT 提取物中的 TFCs 高于 FL 提取物。通过液相色谱-质谱联用（ LC-MS ）研究色氨酸、褪黑素、酚类和类黄酮含量的变化。结果表明，所有样品中的色氨酸含量均在 29.54-673.72 µg/g 提取物的范围内检测到。与 FL 提取物相比， GT 和 BT 提取物均增加了色氨酸含量。两种品种的 BT 提取物中色氨酸含量最高。在桑树叶提取物中发现了酚类化合物，包括没食子酸、咖啡酸、龙胆酸、原儿茶酸和绿原酸。所有样品中绿原酸含量最高。除绿原酸外，加工茶提取物中的几乎所有酚酸含量均增加。芦丁是所有提取物中唯一检测到的黄酮类化合物，含量在 109.48-1009.75 mg/g 提取物之间。茶加工过程中酚类和类黄酮化合物的变化导致 GT 和 BT 提取物抗氧化能力的变化。所有提取物均具有乙酰胆碱酯酶（ AChE ）抑制活性， IC 在 146.53-165.24 µg/mL 范围内。茶的加工稍微增加了 GT 和 BT 提取物的 AChE 抑制作用。总之，桑树叶加工成的茶可以作为一种新的功能性食品供关注健康的消费者选择，因为它可能是色氨酸、酚类和类黄酮的有前途的来源。此外，茶提取物还具有抗氧化和抗 AChE 活性。
