Hong-Tao Zhu

Cytotoxic bisbenzylisoquinoline alkaloids from Stephania epigaea.

Six new bisbenzylisoquinoline alkaloids (1-6) and seven known compounds (8-14) were isolated from the tubers of Stephania epigaea, in addition to the major alkaloid, cepharanthine (7). The structures of 1-6 were elucidated by combined spectroscopic data analysis and chemical methods, with their configurations determined from their optical rotation values and confirmed using circular dichroism. Compounds 1-6 belong to the oxyacanthine type of bisbenzylisoquinoline alkaloids and have a rare methylenedioxy substituent. Compound 1, a dimer composed of benzylisoquinoline and seco-aristolactam units, represents a new type of bisbenzylisoquinoline alkaloid, while compounds 3-6 are bisbenzylisoquinoline N-oxides. These compounds were evaluated for their in vitro cytotoxicities against six human cancer cell lines (A-549, ECA109, HL-60, MCF-7, SMMC-7721, and SW480). Cepharanthine (7), the major component of S. epigaea, exhibited cytotoxicity against all of these cancer cell lines except ECA109, while its known analogue, 10, displayed cytotoxicity against all six cancer cell lines.

A New Norisoprenoid and Other Compounds from Fuzhuan Brick Tea

Fuzhuan brick tea, a kind of dark tea consumed mainly in the border regions of Southwestern and Northwestern China since the 1860s, is produced from the leaves of Camellia sinensis var. sinensis by microbial fermentation. From this special fermented tea, a new norisoprenoid, 3R,9R-oxido-5-megastigmene, was isolated, together with α-linolenic acid, strictin, isovitexin, astragalin, (+)-catechin, (−)-epicatechin, (−)-epicatechin gallate, (+)-gallocatechin, (−)-epigallocatechin, (−)-epigallocatechin gallate and gallic acid. The structures of the compounds were identified by spectroscopic means. The new compound didn’t show any inhibition activity against the tested enteric pathogenic microorganisms at a concentration of 800 μg/mL by the hole plate diffusion method.

Anti-hepatitis B virus norbisabolane sesquiterpenoids from Phyllanthus acidus and the establishment of their absolute configurations using theoretical calculations.

Nineteen new highly oxygenated norbisabolane sesquiterpenoids, phyllanthacidoid acid methyl ester (1), and C-T (4-21), were isolated from Phyllanthus acidus Skeels, together with two known ones, phyllanthusols A (2) and B (3), whose sugar moiety was revised as glucosamine-N-acetate, rather than the previously assigned mannosamine-N-acetate. Compounds 2 and 3 were renamed respectively as phyllanthacidoids A (2) and B (3) to avoid confusion. All of the isolates except for 1 are glycosides, whose saccharide moieties possess a pentaoxy cyclohexane (scyllo quercitol) connecting with glucosamine-N-acetate or glucosyl moieties, which are first examples in natural products. Phyllanthacidoids N-R (15-19) with 8R configurations and/or 5,8-diketal skeleton, are unprecedented structures among norbisabolane sesquiterpenoids. Phyllanthacidoids S (20) and T (21) have the unusual tricyclo [3.1.1.1] oxygen bridge skeleton formed by a diketal system, of which the relative configurations of the aliphatic chain were assigned on the basis of heteronuclear coupling constants. The absolute configurations of compounds (1-21) were established by means of calculated electronic circular dichroism (ECD) and coupling constants. Compounds 1-5, 7-9, 10, and 14 displayed potential anti-hepatitis B virus (HBV) activities, with IC50 values of 0.8-36 μM against HBV surface antigen (HBsAg) and HBV excreted antigen (HBeAg), and the results indicated that the 5-ketal group and sugar moieties had contributions to the selectivity of HBsAg and HBeAg.

Chemical and morphological variations of Panax notoginseng and their relationship

A collection of 70 randomly selected three-year-old Panax notoginseng plants was analyzed to evaluate the germplasmic resources of cultivated notoginseng. The results obtained indicated that the individual plants of P. notoginseng were greatly diversified not only in saponin contents, but also in morphological features. It was further proven that, after hundreds years of cultivation, notoginseng has become a mixed farm cultivar with very large variations occurring. This high variance in saponin contents implies the possibility for breeding of this medicinal plant in order to obtain cultivars with higher saponin production. Statistic analysis of correlation between morphologic variation and chemical variation suggests that some morphological characters, such as root weight, plant height and peduncle length, can be correlated with saponin contents and can be used as important selective traits for selective breeding.

Lignans and aromatic glycosides from Piper wallichii and their antithrombotic activities.

ETHNOPHARMACOLOGICAL RELEVANCE Piper wallichii (Miq.) Hand.-Mazz. is a medicinal plant used widely for the treatment of rheumatoid arthritis, inflammatory diseases, cerebral infarction and angina in China. Previous study showed that lignans and neolignans from Piper spp. had potential inhibitory activities on platelet aggregation. In the present study, we investigated the chemical constituents of Piper wallichii and their antithrombotic activities, to support its traditional uses. MATERIALS AND METHODS The methanolic extract of the air-dried stems of Piper wallichii was separated and purified using various chromatographic methods, including semi-preparative HPLC. The chemical structures of the isolates were determined by detailed spectroscopic analysis, and acidic hydrolysis in case of the new glycoside 2. Determination of absolute configurations of the new compound 1 was facilitated by calculated electronic circular dichroism using time-dependent density-functional theory. All compounds were tested for their inhibitory effects on platelet aggregation induced by platelet activating factor (PAF) in rabbits׳ blood model, from which the active ones were further evaluated the in vivo antithrombotic activity in zebrafish model. RESULTS A new neolignan, piperwalliol A (1), and four new aromatic glycosides, piperwalliosides A-D (2-5) were isolated from the stems of Piper wallichii, along with 25 known compounds, including 13 lignans, six aromatic glycosides, two phenylpropyl aldehydes, and four biphenyls. Five known compounds (6-10) showed in vitro antiplatelet aggregation activities. Among them, (-)-syringaresinol (6) was the most active compound with an IC50 value of 0.52 mM. It is noted that in zebrafish model, the known lignan 6 showed good in vivo antithrombotic effect with a value of 37% at a concentration of 30 μM, compared with the positive control aspirin with the inhibitory value of 74% at a concentration of 125μM. CONCLUSION This study demonstrated that lignans, phenylpropanoid and biphenyl found in Piper wallichii may be responsible for antithrombotic effect of the titled plant.

Two New Highly Oxygenated and Rearranged Limonoids from Phyllanthus cochinchinensis

A new 6/6/5/6-fused limonoid, phyllanthoid A (1), possessing both 19/30 and 19/29 oxygen bridges was isolated from Phyllanthus cochinchinensis (Euphorbiaceae), together with a new related limonoid, phyllanthoid B (2). Their structures were determined by spectroscopic analysis and single-crystal X-ray diffraction in the case of 1. Compound 1 displayed moderate antifeedant against the generalist plant-feeding insect Spodoptera exigua and cytotoxicity against the MCF-7 cell line.

The chemical constituents from the roots of Gentiana crassicaulis and their inhibitory effects on inflammatory mediators NO and TNF-α

Chemical study on the roots of Gentiana crassicaulis Duthie ex Burk (Gentianaceae) afforded 15 compounds, including two new iridoid glycosides, qinjiaosides B (1) and C (2). Their structures were elucidated by spectroscopic methods and chemical evidence. The isolated iridoid glycosides 1, 4–6 and 8–11 were tested for their anti-inflammatory activity by the inhibitory effects on LPS-induced NO and TNF-α production in macrophage RAW264.7 cells. All of them showed inhibitory effects on inflammatory mediators NO at a concentration of 15 µM, while 5 and 9 displayed the most potential inhibitory effects on TNF-α with IC50 of 0.06 and 0.05 µM, respectively. The structure-activity relationships (SARs) of these iridoid derivatives were discussed.Graphical abstract

Review on “Long-Dan”, one of the traditional Chinese medicinal herbs recorded in Chinese pharmacopoeia.

Abstract“Long-Dan” is an important traditional Chinese medicinal (TCM) herb used widely for the treatment of inflammation, hepatitis, rheumatism, cholecystitis, and tuberculosis. In the Chinese Pharmacopoeia, the roots and rhizomes of four species from the genus Gentiana (Gentianaceae) are recorded as the original materials of “Long-Dan”, called Gentianae Radix et Rhizoma. The species included G. manshurica, G. scabra, G. triflora and G. rigescens, which are distributed in different areas of China. Though iridoid and secoiridoid glucosides were reported as the main constituents in “Long-Dan”, these four different species also resulted in different minor components, which may related to their pharmacological activities. Herein, we summarized the herbal textual study, distribution, chemical constituents, biological investigation and quality control of the recorded “Long-Dan” origins in Chinese Pharmacopoeia during the period 1960 to 2011.

Flavonoid oligomers from Chinese dragon’s blood, the red resins of Dracaena cochinchinensis.

A detailed chemical investigation of the red resins from Dracaena cochinchinensis (Chinese dragon’s blood) yielded five new flavonoid oligomers, named cochinchinenins D-H (1–5), together with a known biflavonoid, cinnabarone (6), and a mixture of two known biflavonoids, socotrin-4′-ol (7) and homoisosocotrin-4′-ol (8). Of these new compounds, 1–3 were biflavonoids and 4 and 5 were triflavonoids. Their structures were determined on the basis of spectroscopic analysis. The isolated compounds were tested for cytotoxicity (Cdc25), antibacterial (PEPT) and antifungal (YNG) activities.

Triterpenoids with Promoting Effects on the Differentiation of PC12 Cells from the Steamed Roots of Panax notoginseng.

The roots of Panax notoginseng, an important Chinese medicinal plant, have been used traditionally in both the raw and processed forms, due to the different chemical constituents and bioactivities found. Thirty-eight dammarane-type triterpenoid saponins were isolated from the steam-processed roots of P. notoginseng, including 18 new substances, namely, notoginsenosides SP1-SP18 (1-18). The structures of 1-18 were determined on the basis of spectroscopic analysis and acidic hydrolysis. The absolute configuration of the hydroxy group at C-24 in 1-4, 19, and 20 was determined in each case by Mo2(AcO)4-induced circular dichroism. The new compounds were found to feature a diversity of highly oxygenated side chains, formed by hydrolysis of the C-20 sugar moiety followed by dehydration, dehydrogenation, epoxidation, hydroxylation, or methoxylation of the main saponins in the raw roots. The new saponins 1, 2, 6-8, 14, and 17 and the known compounds 20-27 showed promoting effects on the differentiation of PC12 cells, at a concentration of 10 μM.