Discovery of nontriterpenoids from the rot roots of Panax notoginseng with cytotoxicity and their molecular docking study and experimental validation.

Panax notoginseng (PN) is a well-known traditional Chinese medicine, with dammarane-type triterpenoid saponins characterized as major component and active ingredients, together with amino acids, flavonoids, polysaccharides, and polyacetylenes. The roots of PN are susceptible to root rot disease, which causes a huge loss and changes in the chemical components of this precious resource. In this study, sub-fractions of rot PN root extracts were preliminarily found to have admirable cytotoxicity on two human cancer cells. Further bioassay-guided isolation discovered nine new non-triterpenoids, including two novel N-methylacetamido-1-oxotetrahydropyrimidine alkaloids (1, 2), five 2H-furanones or 2H-pyranones (3-7), and two polyacetylenic alcohols (8, 9). Their structures were illuminated by extensive spectroscopic data, calculated ECD, and X-ray diffraction analysis. Among them, 3-7 were considered to be transformed from panaxatriol through the intermediates (8, 9). The new alkaloids (1, 2) displayed noteworthy cytotoxicity against five human cancer cells with IC50 values ranging from 14 to 24 µM. In silico target prediction and molecular docking studies showed that 1 and 2 may interact with EGFR, and were verified by the experimental inhibitory effect on EGFR tyrosine kinase.

Multiple in vitro biological effects of phenolic compounds from Terminalia chebula var. tomentella.

ETHNOPHARMACOLOGICAL RELEVANCE: Terminalia chebula (TC), a well-known Indian Ayurvedic medicine introduced into China in the Sui and Tang Dynasties, has been recorded and used medicinally as Fructus Chebulae, together with its variety tomentella (TCT) in the Chinese Pharmacopoeia. They have been also used commonly for the treatment of diabetes mellitus by Tibetan medicine. AIM OF THE STUDY: To investigate the main bioactive and therapeutic principles in the fruits of TCT, based on the extensive evaluation of their anti-inflammatory and hypoglycemic activities. MATERIALS AND METHODS: The TCT fresh fruits were analyzed by HPLC and separated further by column chromatography and preparative HPLC. The isolated compounds were identified by extensive spectroscopic analyses, including 1D/2D NMR, MS, UV, IR and ECD. Anti-inflammatory activity was evaluated by inhibition of NO production in RAW264.7 cells. The specific iNOS (PDB ID: 3E7G) structure was prepared by Discovery Studio 4.0, and the molecular docking simulation was performed on GOLD (version 5.2.2). Hypoglycemic activity was measured using the substrate solution of 4-nitrophenyl-α-d-glucopyranoside enzyme and buffer solution. RESULTS: The HPLC analysis method of polyphenols in the fruits of TCT was established, and 13 main chromatographic peaks were identified, including six hydrolyzable tannins (2, 4-7, 10-11), three simple phenols (12-14), and one oleanane pentacyclic triterpene, arjungenin. Extensive chromatographic separation of TCT fresh fruits yielded 14 compounds, including one new natural hydrolyzable tannin, 2,3-(S)-HHDP-6-O-galloyl-d-glucose (1). The known compounds were identified as 10 hydrolyzable tannins (2-11) and three simple phenols (12-14). Compounds 10 (IC50 = 36.43 ± 0.21 µM), 11 (IC50 = 42.28 ± 0.09 µM) displayed stronger NO inhibitory activity than the positive control L-NMMA (IC50 = 42.34 ± 0.66 µM), while 2, 4, and 9 showed moderate inhibitory activity against NO production. Further molecular docking simulation of specific iNOS on 10 and 11, as well as five previously isolated lignans 15-19 showed that there were no obvious rules between docking results and the in vitro NO inhibitory activity for hydrolyzable tannins (10 and 11), while the mechanism of anti-inflammatory activity for lignans was related to the substitution of conjugated aldehyde groups. Moreover, most of the hydrolyzable tannins (1-2, 4-5, 9-11) and simple phenol (12) displayed stronger inhibitory effects on α-glucosidase than the positive control, quercetin (IC50 = 6.118 ± 0.071 µM), with IC50 values ranging from 0.079 to 16.494 µM. Among these bioactive isolates, the hydrolyzable tannins 2, 4-5, and 9-11, and simple phenol 12 are major chemical components in TCT fruit. CONCLUSIONS: The results showed that lignans and hydrolyzed tannins are the main active ingredients of TCT fruits, responsible for the traditional treatment of sore throat and cough. Moreover, hydrolyzed tannins and simple phenolic compounds with potential hypoglycemic activity are closely related to the ethno-pharmacological uses of TCT fruits on diabetes in Tibetan medicine.

Allelochemicals of Panax notoginseng and their effects on various plants and rhizosphere microorganisms.

Panax notoginseng (Araliaceae) is an important ginseng herb with various health benefits and a history of cultivation in southwestern China over 400 years. In recent years P. notoginseng has faced serious continuous-cropping obstacles due to its large-scale cultivation. In this study, we aim to explore the allelochemicals of P. notoginseng and their interactions with various plants and rhizosphere microorganisms. The chemical constituents of the soil cultivated with 3-year-old P. notoginseng were studied by column chromatography, spectroscopic and GC-MS analyses. We identified 13 volatile components and isolated six triterpenes (1-4, 6-7) and one anthraquinone (5). Compounds 1-7 were tested for their effects on seed germination and root elongation in P. notoginseng, corn, wheat, turnip, water spinach and Arabidopsis thaliana. We also examined the effect of compounds 1-7 on the growth of ten rhizosphere microorganisms of P. notoginseng. At a concentration of 1.0 µg mL-1, compounds 3 and 5-7 caused the death of P. notoginseng root cells and compounds 2, 6 and 7 induced the death of root cells of A. thaliana. Compounds 1-5 and 7 inhibited elongation of A. thaliana root tip cells at a concentration of 10.0 µg mL-1. Moreover, at a concentration of 0.1 mg mL-1, compounds 3, 4, 6 and 7 inhibited the growth of probiotics and promoted the growth of pathogens of P. notoginseng. These results suggest that these isolated ursane-type triterpenoid acids and anthraquinone are potential allelochemicals that contribute to continuous-cropping obstacles of P. notoginseng.

Albocycline-type Macrolides with Antibacterial Activities from Streptomyces sp. 4205.

The actinomycete genus Streptomyces is characterized by producing bioactive secondary metabolites, including antibiotics. In this study, chemical and biological investigations were carried out on Streptomyces strain 4205 isolated from the paddy soil, leading to the identification and characterization of 10 albocycline-type macrolides, among which 4 compounds were new, namely albocyclines A-D (1-4). The structures of 1-10 were identified according to the 1D- and 2D-NMR spectroscopic data. Furthermore, compounds 1-10 were evaluated for antimicrobial activity. Compounds 5-7 displayed antimicrobial activities against Candidaalbicans ATCC 90028 with the same MIC value of 10.0 mg/mL and the IC50 values of 1.5, 1.0, and 1.0 mg/mL, respectively. Thus, the research on Streptomyces sp. is of vital significance for developing new antibiotic agents.

GC-MS-based identification and statistical analysis of liposoluble components in the rhizosphere soils of Panax notoginseng.

Continuous cropping obstacle, mainly caused by microorganisms and organic components in soil, has become a serious problem for the plantation of Panax notoginseng (Araliaceae) due to the rapidly increased demands of this famous herbal medicine in recent decades. The rhizosphere soils cultivated with 3-year-old healthy and ill notoginseng were chemically investigated by gas chromatography-mass spectrometry (GC-MS) and compared with the corresponding soils without the plantation of notoginseng. Totally 47 liposoluble components were identified. Furthermore, the multiple statistical analysis showed that these constituents were qualitatively and quantitatively associated with the differences between the cultivated soil with P. notoginseng and the uncultivated soil. Among them, neophytadiene (4), d-α-tocopherol (38), (3ß,22E,24S)-ergosta-5,22-dien-3-ol (39), (3ß,24R)-ergost-5-en-3-ol (40), stigmasta-5,22-dien-3-ol (41), stigmast-4-en-3-one (44) and (5α)-stigmastane-3,6-dione (47) contributed most to the significant differences between the cultivated and uncultivated soils, whereas cyclopentadecane (3), octadecanoic acid methyl ester (16), docosanoic acid ethyl ester (31), nonacosane (34), 38 and 39 were found in much higher amount in the soils with ill P. notoginseng as compared to the case of those with the healthy P. notoginseng. On the other hand, liposoluble components in different cultivation areas were of great diversity; however, they were able to remain relatively consistent across the overall trend of differential substances.

Research of Panax spp. in Kunming Institute of Botany, CAS.

Panax, a genus of the Araliaceae family, is an important herbal group in traditional Chinese medicine (TCM). Nine species and three varieties are included in the genus of Panax, in which nearly all species have been used for medicinal purposes. Among them, Panax notoginseng (Burk) F. H. Chen, Panax ginseng C. A. Meyer and Panax quinquefolius L. are the most representative and valuable herbs world-wide, with a long history of cultivation. As the main bioactive chemical constituents, saponins with different aglycones are the major components in various Panax spp., and their pharmacological activities are mainly reflected in the effects on blood system, cardio- and cerebro-vascular systems, nervous system, metabolism, and immune regulation. Researchers of Kunming Institute of Botany (KIB), Chinese Academy of Sciences (CAS), have put many efforts into conducting the investigations on Panax species. Herein, we reviewed the research progress on Panax spp. in KIB, CAS, over the past few decades, from the aspects of history and origin, phytochemistry and pharmacological activities.

New triterpenoid saponins from the steaming treated roots of Panax notoginseng.

Further phytochemical investigation of the steaming treated roots of Panax notoginseng (Araliaceae) led to the identification of two new dammarane-type triterpenoid saponins, notoginsenoside SP20 (1) and SP21 (2). In addition, a pair of new phenolic glycosides (3a and 3b) was also isolated together with two known compounds. Their structures were elucidated by HRESIMS, 1D- and 2D-NMR spectra. Compounds 1 and 2 showed no in vitro cytotoxicity against five human cancer cell lines (HL-60, SMMC-7712, A-549, MCF-9 and SW480).

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.