Guava leaf (Psidium guajava Linn.) is a common folk medicine in China. Modern pharmacological studies have confirmed its remarkable antioxidant and hypoglycemic activities, which has broad prospects in the development of natural antioxidants and hypoglycemic agents. The release of non-volatile active components of plants or herbs were greatly affected by extraction ways. The extraction effects on guava leaves of macerated extraction (ME), heat reflux extraction (HRE), ultrasound-assisted alcohol extraction (UAAE) and ultrasound-assisted deep eutectic solvents extraction (UADEE), microstructure were evaluated. The content of total saponins, total flavonoids, total phenols in the extract was respectively determined by vanillin-glacial acetic acid colorimetric method, NaNO2-Al(NO3)3 colorimetric method and folin phenol method. The content of flavonoid components was determined by high performance liquid chromatography (HPLC). The metabolites were analyzed by liquid chromatograph-mass spectrometer (LC-MS). In vitro antioxidant activity and α-glycosidase inhibitory ability of the extract were also evaluated. In UADEE group, internal structure of guava leaves was most completely damaged, the content of total saponins, total flavonoids, total phenols and guaijaverin, avicularin, reynoutrin was respectively determined to be 79.28 mg/g, 80.51 mg/g, 120.52 mg/g,7.96 mg/g, 7.74 mg/g and 3.99 mg/g, which significantly higher than those of the other three groups (P<0.05). Flavonoids, triterpenoids and phenols accounted for 9.830%, 27.267% and 1.013% of all metabolites in the extract, respectively. The IC50 value of scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and inhibiting α-glycosidase in UADEE group was 45.18 μg/mL and 904.67 μg/mL, respectively, significantly superior than those of the other three groups (P<0.05). In summary, UADEE has the best effect on the extraction of active components in the extract, attributed to the mechanical and chemical effects of ultrasound and the polarity tunability and solubilization of solvents. The results would provide experimental basis for the efficient extraction of effective components from guava leaves and the development of processed products.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |