Abstract
Squalene is a precursor of steroids with diverse bioactivities. Tea was previously found to contain squalene, but its variation between tea cultivars remains unknown. In this study, tea leaf squalene sample preparation was optimized and the squalene variation among 30 tea cultivars was investigated. It shows that squalene in the unsaponified tea leaf extracts was well separated on gas chromatography profile. Saponification led to a partial loss of squalene in tea leaf extract and so it is not an essential step for preparing squalene samples from tea leaves. The tea leaf squalene content increased with the maturity of tea leaf and the old leaves grown in the previous year had the highest level of squalene among the tested samples. The squalene levels in the old leaves of the 30 tested cultivars differentiated greatly, ranging from 0.289 to 3.682 mg/g, in which cultivar “Pingyun” had the highest level of squalene. The old tea leaves and pruned littering, which are not used in tea production, are an alternative source for natural squalene extraction.
Highlights
Squalene is a triterpene with molecular formula C30H50 [(6E,10E,14E,18E)-2,6,10,15,19,23hexamethyl-2,6,10,14,18,22-tetracosahexaene], in which there are six isoprene units
It is concluded that saponification is not an essential process for preparing squalene samples from tea leaves with low-level oil through saponification is essential for separating the unsaponifiable fraction from the saponifiable fraction when squalene was isolated from fish livers and vegetable seeds containing a high level of oil
This study shows that though the saponification of the extracts of freshly harvested tea leaves induced an increase in β-amyrin, accompanied with the decrease in squalene (Figures 1B,C and Table 1), the decrease in squalene was not the direct cause of the increase in βamyrin because the content of β-amyrin was increased in the saponified extract of Liupao tea which contained no squalene, and β-amyrin was not detected in the squalene solution after saponification (AS) (Table 1)
Summary
Squalene is a triterpene with molecular formula C30H50 [(6E,10E,14E,18E)-2,6,10,15,19,23hexamethyl-2,6,10,14,18,22-tetracosahexaene], in which there are six isoprene units. Squalene was first identified in shark liver extract in 1903 [1, 12] and late was found in the other tissues of shark and vegetable oils such as olive oil [13]. The liver of deep-sea sharks is an abundant natural source of squalene, excessive hunting endangered the shark species. The amaranth seed oil production is far less than olive oil These suggest that olive and amaranth oils are not available in sufficient quantities for squalene extraction. Kuntze] is widely planted in many Asian and African countries and, tea leaves were found to contain squalene [21, 22] and it might be a source for extracting natural squalene. This study was set to investigate the difference in squalene content between leaves with various maturities and from various tea cultivars, which will be helpful to target the optimum source of tea materials for extracting natural squalene
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