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Dasiphora fruticosa L. (Rosaceae), also known as Potentilla fruticosa L. (syn.), is a hardy deciduous shrub widely distributed in the north temperate regions of the world. Three methylene bisflavan-3-ols ( 1 - 3 ), together with a procyanidin dimer, (-)-afzelechin-(4α→8)-(-)-afzelechin ( 4 ) were isolated for the first time from the branches and leaves of the titled plant, in addition to 11 known compounds ( 5 - 15 ). Their structures were elucidated by means of extensive spectroscopic analysis and by comparison with data reported in the literatures. Methylene 6,8-bis(7- O -glucosyl) catechin ( 1 ) was determined to be a new dimeric flavan-3-ol glycoside through a methylene linkage between C-8 and C-8 of two units. At a concentration of 128 μg/mL, the known compounds 9 - 13 exhibited antibacterial activities on Escherichia coli , Staphylococcus aureus subsp. aureus , Salmonella enterica subsp. enterica , and Pseudomonas aeruginosa . Compound 12 also showed certain glucose uptake stimulating activity.

Camellia sinensis var. pubilimba, one variety of the genus Camellia sect. Thea (Theaceae), has been used for producing green tea mainly by the local people of its growing areas of Guangxi province, China. Forty compounds, including eight C-8 N-ethyl-2-pyrrolidinone-substituted flavan-3-ols (1-8) and their substituted unit N-ethyl-5-hydroxy-2-pyrrolidinone (9), four flavan-3-ol monomers (10-13) and one dimer (14), nine flavonoids (15-23), three hydrolyzable tannins (24-26), two lignans (27-28), 11 simple phenolics (29-39), and caffeine (40), were first isolated and identified from the leaves. Their structures were determined by detailed spectroscopic analysis and comparison with the literature data and authentic samples. Both 1 and 4 were obtained as a mixture of the N-ethyl-2-pyrrolidinone C-5 enantiomers (1a and 1b and 4a and 4b), respectively, while the resolution of another three pairs of enantiomers (2 and 3, 5 and 6, and 7 and 8) was achieved. Among them, 1b is a new compound whose NMR data together with its enantiomer (1a) were reported for the first time, while 2 and 3 are two new natural products. Most of the isolates exhibited significant antioxidant activities, stronger than ascorbic acid and trolox, while parts of the isolates, particularly C-8 N-ethyl-2-pyrrolidinone-substituted flavan-3-ols, showed obvious inhibitory effects on acetylcholinesterase (AChE). The results indicated that C. sinensis var. pubilimba is a valuable plant resource for tea production.

Camellia fangchengensis Liang et Zhong, belonging to the genus Camellia sect. Thea (Theaceae), is an endemic tea species to the south and southwest areas of Guangxi province, People's Republic of China. Known as a wild tea plant, the leaves have been used for producing green tea or black tea by the local people of its growing area. HPLC and LC-MS analysis showed the leaves contain oligomeric catechins as major phenolic components. Further detailed phytochemical study led to the identification of five flavan-3-ol dimers (1-5) including two new ones, fangchengbisflavans A (1) and B (2) from the leaves of C. fangchengensis, together with six known monomers (6-11) and one glucoside (12), in addition to gallic acid (13). Their structures were determined by extensive spectroscopic analysis. Most of the isolates displayed significant antioxidant activities in 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS + ) radical scavenging assays. The results suggested that the leaves of C. fangchengensis, rich in flavan-3-ol oligomers and monomers as potent antioxidants, could be a valuable plant resource for the production of tea and natural beverages.

Pu-er ripe tea is a special microbial post-fermented tea made from Pu-er raw tea, a kind of green tea produced from the leaves of Camellia sinensis var. assamica. It is one of the most consumed teas in the past two decades in China, due to its special flavor, taste, and beneficial effects. This work aimed to obtain diverse catechin structures from Pu-er ripe tea, which led to the isolation of four new phenylpropanoid-substituted flavan-3-ols, puerins C-F (1-4), together with four known flavan-3-ols, (+)-catechin (5), (-)-epicatechin (6), (+/-)-gallocatechin (7), and (-)-epigallocatechin (8). Their structures were elucidated on the basis of detailed spectroscopic analysis, including 1D and 2D NMR, mass and CD spectra. Compounds 1-4, which could be formed in the post-fermentative process of Pu-er tea, were isolated for the first time from tea and Theaceae plant.

Camellia taliensis (W. W. Smith) Melchior, belonging to the genus Camellia sect. Thea (Theaceae), is an endemic species distributed from the west and southwest of Yunnan province, China, to the north of Myanmar. Known as a wild tea tree, its leaves have been used commonly for producing tea beverages by the local people of its growing area. One new flavan-3-ol dimer, talienbisflavan A (1), was isolated from green tea prepared from the leaves of C. taliensis collected from the east side of the Ai-Lao mountains, Yuanjiang county of Yunnan province, China. In addition, five hydrolyzable tannins (2-6), five flavonols and flavonol glycosides (9-13), three flavan-3-ols (14-16), nine simple phenolic compounds and glycosides (7, 8, and 17-23), and caffeine (24) were identified. Their structures were determined by detailed spectroscopic analysis. All of the isolated phenolic compounds were tested for their antioxidant activities by DPPH and ABTS(+) radical scavenging assays. The contents of its main chemical compositions were also compared with those collected from the Lincang area of Yunnan province by high-performance liquid chromatography analysis.

Eleven flavonoids including one new flavonol glycoside, quercetin-3-O-(2-α-L-rhamnopyranosyl)-β-D-glucuronopyranosyl methyl ester (1), were isolated for the first time from the fruits of Phyllanthus acidus (L.) Skeels (Phyllanthaceae). Their structures were determined by extensive spectroscopic data. The known flavonoids, quercetin-3-O-β-D-glucuronide methyl ester (3), quercetin-3-O-(2''-α-L-rhamnopyranosyl-6''-O-α-L-rhamno pyranosyl)-β-D-glucopyranoside (5), myricetin (9), and 6-methoxy-naringenin (11) were isolated for the first time from the genus Phyllanthus. Flavonoids 4, 6 and 9 (IC50 = 6.01, 6.32, and 7.84 μM, respectively) showed stronger α-glucosidase inhibitory activities than the positive control, acarbose (IC50 = 306.45 μM). The fruits of P. acidus might be further developed as an anti-diabetic food supplement. [ABSTRACT FROM AUTHOR]

Black tea, rich in various and complex polyphenols, is one of the most popular beverages in the world due to its pleasant aroma and health benefits, such as alleviate hyperglycemia and antioxidant. The extensive investigation on the chemical constituents of Yunnan black tea 'Jin-Ya', produced from the leaf buds of Camellia sinensis var. assamica , led to the isolation and identification of 16 flavonoids including three new flavan-3-ols, namely theaflavoids A-C (1 – 3). Most of the isolates displayed obvious inhibitory activity on α -glucosidase with IC 50 values ranging from 1.11 to 24.7 μM. Notably, the new theaflavoids 1 – 3 showed much stronger inhibitory activity (IC 50 = 1.34, 1.11, and 4.57 μM, respectively) than those of the positive controls (acarbose and quercetin, IC 50 = 228 and 9.38 μM, respectively). In addition, the isolated flavonol glycosides 5 – 16 were evaluated for their antioxidant activities by DPPH and ABTS + radical scavenging assays. Those with galloyl group in molecular exhibited comparable free radical scavenging activities to the positive controls (ascorbic acid and Trolox), while most of the flavonol glycosides showed only moderate activities. The results indicated that Yunnan black tea 'Jin-Ya' is an ideal drink with hypoglycemic and antioxidant property, and is worthy of regular consumption. [Display omitted] • Three new (theaflavoids A-C) and 13 known flavonoids were isolated from black tea 'Jin-Ya'. • 'Jin-Ya' is produced from the leaf buds of Camellia sinensis var. assamica. • 15 flavonoids were isolated from black tea for the first time. • Most of the isolates showed obvious α -glucosidase inhibitory activity. • Some flavonoids showed stronger DPPH and ABTS + radical scavenging activities. [ABSTRACT FROM AUTHOR]

• Two rare flavonoid-sulfonic acids complexed with calcium ions were obtained. • Their structures were elucidated by spectroscopic, single-crystal X-ray diffraction analyses. • The existence of calcium was confirmed by elemental analysis. • They are the first examples of sulfonic flavonoids coordinated with calcium ions from natural products. Two rare flavonoid-sulfonic acids complexed with calcium ions, Ca (II)-6‑methoxy-8- sulfonic acid-naringenin complexes and Ca (II)-8-sulfonic acid-isoprunetin complexes, were isolated from the fruits of Phyllanthus acidus (L.) Skeels (Phyllanthaceae). Their planar structures were unambiguously established by extensive interpretation of the HRESIMS, 1D and 2D NMR data, and comparison to the literature data. The single crystal X-ray diffraction analysis revealed the location of sulfonic acid group on flavonoid C-8 position and the existence of metal atom in molecules, which was confirmed further to be calcium by elemental analysis. The two molecules represent the first examples of sulfonic flavonoids coordinated with calcium ions from the natural products. This example enriched the variety of natural product structures. All the isolates were evaluated for their antioxidant and anti-inflammatory activity. [Display omitted] [ABSTRACT FROM AUTHOR]