Comparisons of the active components in four unripe raspberry extracts and their activites

Abstract

Dried unripe raspberry of Rubus chingii, were prepared as the following four extracts: unpurified raspberry extract (URE), purified raspberry extract (PRE), URE after high temperature-high pressure (UPE-H, HTHP), and PRE after HTHP (PRE-H). The total polyphenolic contents (TPCs) and total flavonoid contents (TFCs) of the four extracts, as assessed by colorimetry, significantly increased in the following order: URE < URE-H < PRE < PRE-H. The antioxidant capacity and antibacterial activity were as follows: PRE-H > PRE ≈ URE-H > URE. Moreover, 11 typical polyphenols were quantified using a HPLC-MS analysis showed that HTHP treatments were conducive to releasing more (+)-catechin, (−)-epicatechin, proanthocyanidin B1 and ellagic acid, reaching ~70%-1,100%, but decreased the rutin, quercetin-3-D-glucuronide, kaempferol-3-D-rutinoside and kaempferol-3-D-glucoside levels by ~10%-20%. The purification of macroporous resin was beneficial to the enrichment of all polyphenols, by ~30%-300%. Ellagic acid was the main polyphenol found in the extracts, accounting for ~67%-74%. The study indicated that changes in the polyphenols of raspberry extracts after resin purification and/or HTHP treatment were correlated with the extract's antioxidant capacity and antibacterial activity. Further evaluations of the correlation between bioactive ingredients and treatments should reveal that HTHP and resin purification methods are effective means of preparing extracts.

Comprehensive Utilization of Thinned Unripe Fruits from Horticultural Crops

“…Sun et al [ 46 ] identified and individually quantified 102 individual polyphenols grouped in five major classes of phenolic compounds such as phenolic acids, phenol glycosides, flavanols and flavone alcohols, using ultra-performance liquid chromatography coupled with electrospray ionization triple quadrupole mass spectrometry (UPLC-Q TRAP-MS/MS) in thinned unripe pears. Other researchers detected a variety of monomeric phenolic compounds in unripe fruits such as pomegranate, kiwi, sweet orange peels, chinotto citrus and raspberry [ 19 , 37 , 40 , 47 , 48 ], as is shown in Table 2 .…”

Synergistic effects of unripe raspberry extracts (Rubus chingii) and antibiotics against three bacteria

“…Therefore, the synergistic effects between two unripe raspberry extracts (R. chingii) and four antibiotics against bacteria were evaluated using checkerboard microdilution and time-kill curves. Firstly, unripe raspberry extracts (URE) by ethanol extraction, and purified raspberry extract (PRE) by macroporous resin were prepared according to Yang et al(2019). Secondly, the MICs of two extracts and four antibiotics against E. coli, S. aureus and S. enterica were investigated respectively.…”

“…The extracts were prepared according to Yang et al(2019). Briefly, dried unripe raspberry powder was extracted using the ultrasonic-assisted ethanol method, in which 10 mg/mL of powder was extracted in 52% ethanol at 360 W for 45 min, twice, using a JOYN-15AL Ultrasonic apparatus (Shanghaiqiaoyue Co.).…”

“…The unripe (green) raspberry of Rubus chingii Hu, containing high medicinal ingredients e.g. polyphenols, terpenoids, saponins, polysaccharides, alkaloids, and essential oils, exhibits antioxidant, anti-bacteria, anti-complement and anticancer activities (Yang et al, 2019;Yu et al, 2019). It is the only plant of Rubus species included in The Chinese Pharmacopoeia and used to improve kidney functions, such as enuresis and urinary frequency, in Traditional Chinese Medicine for many years (Chinese Pharmacopoeia Commission, 2015).…”

“…Our previous study on four R. Chingii extracts found that ellagic acid, brevifolin carboxylic acid and kaempferol-3-rutinoside were the highest proportion of 11 tested phenolic compounds. Their MICs against Escherichia coli, Staphylococcus aureus and Salmonella enterica ranged from 2-20 mg/mL (Yang et al, 2019).…”