Integrated metabolic and transcriptomic profiles reveal the germination-associated dynamic changes for the seeds of Cassia obtusifolia L

INTRODUCTION

The seeds of Cassia obtusifolia L. (Cassiae [C.] semen) have been widely used as both food and traditional Chinese medicine in China.

OBJECTIVES

We aimed to analyze the metabolic mechanisms underlying C. semen germination.

MATERIALS AND METHODS

Different samples of C. semen at various germination stages were collected. These samples were subjected to ¹ H-NMR and UHPLC/Q-Orbitrap-MS-based untargeted metabolomics analysis together with transcriptomics analysis.

RESULTS

A total of 50 differential metabolites (mainly amino acids and sugars) and 20 key genes involved in multiple pathways were identified in two comparisons of different groups (36 h vs 12 h and 84 h vs 36 h). The metabolite-gene network for seed germination was depicted. In the germination of C. semen, fructose and mannose metabolism was activated in the testa rupture period, indicating more energy was needed (36 h). In the embryonic axis elongation period (84 h), the pentose and glucuronate interconversions pathway and the phenylpropanoid biosynthesis pathway were activated, which suggested some nutrient sources (nitrogen and sugar) were in demand. Furthermore, oxygen, energy, and nutrition should be supplied throughout the whole germination process. These global views open up an integrated perspective for understanding the complex biological regulatory mechanisms during the germination process of C. semen.

Potent and Selective Inhibition of CYP1A2 Enzyme by Obtusifolin and Its Chemopreventive Effects

Obtusifolin, a major anthraquinone component present in the seeds of Cassia tora, exhibits several biological activities, including the amelioration of memory impairment, prevention of breast cancer metastasis, and reduction of cartilage damage in osteoarthritis. We aimed to evaluate the inhibitory effects of obtusifolin and its analogs on CYP1A enzymes, which are responsible for activating procarcinogens, and investigate its inhibitory mechanism and chemopreventive effects. P450-selective substrates were incubated with human liver microsomes (HLMs) or recombinant CYP1A1 and CYP1A2 in the presence of obtusifolin and its four analogs. After incubation, the samples were analyzed using liquid chromatography-tandem mass spectrometry. Molecular docking simulations were performed using the crystal structure of CYP1A2 to identify the critical interactions between anthraquinones and human CYP1A2. Obtusifolin potently and selectively inhibited CYP1A2-mediated phenacetin O-deethylation (POD) with a Ki value of 0.031 µM in a competitive inhibitory manner in HLMs, whereas it exhibited negligible inhibitory effect against other P450s (IC50 > 28.6 µM). Obtusifolin also inhibited CYP1A1- and CYP1A2-mediated POD and ethoxyresorufin O-deethylation with IC50 values of <0.57 µM when using recombinant enzymes. Our molecular docking models suggested that the high CYP1A2 inhibitory activity of obtusifolin may be attributed to the combination of hydrophobic interactions and hydrogen bonding. This is the first report of selective and potent inhibitory effects of obtusifolin against CYP1A, indicating their potential chemopreventive effects.

Simultaneous determination of seven anthraquinones in Cassiae semen by natural deep eutectic solvent extraction

INTRODUCTION

Anthraquinones are considered to be an important class of bioactive substances in Cassiae semen, and the content of anthraquinones is an essential indicator of the quality of Cassiae semen raw herbal materials.

OBJECTIVES

The present study aimed to propose a novel, efficient and effective ultra-high-performance liquid chromatography (UHPLC) method for the simultaneous determination of aurantio-obtusin, aloe-emodin, rhein, obtusin, emodin, chrysophanol and physcion, with the help of natural deep eutectic solvents (NADESs) as extraction solvents.

METHODOLOGY

NADESs were introduced to the simultaneous extraction of anthraquinones from Cassiae semen samples. Several NADESs were designed by menthol, choline chloride, d-glucose as hydrogen bond acceptors, with nine different acids and appropriate water as hydrogen bond donors. The parameters affecting the extraction efficiency of seven anthraquinones were demonstrated in detail.

RESULTS

Among the obtained NADESs, the highest extraction efficiency was demonstrated by a solution consisting of d-glucose, lactic acid and water with a molar ratio of 1:5:4. The seven anthraquinones were separated on an ACQUITY UPLC® BEH C₁₈ column (2.1 mm × 100 mm, 1.8 μm) and detected within 12 min by a photodiode array (PDA) detector at 254 and 284 nm. The limits of detection and quantitation were from 1.00 to 7.26 μg/l and 3.29 to 24.22 μg/l, respectively. And Cassiae semen sample-based recoveries ranged from 81.13% to 113.78% with the relative standard deviation (RSD) (n = 6) of 1.4% to 10.1%.

CONCLUSION

The developed method demonstrated that NADESs were applied successfully to analyse the anthraquinones in Cassiae semen samples collected from different regions in China.

Predicting the potential toxicity of 26 components in Cassiae semen using in silico and in vitro approaches

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A combination of in silico and in vitro methods was applied.

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The potential toxicity of 26 components isolated from Cassiae semen is predicted.

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Six compounds were predicted toxic to liver & ten compounds toxic to kidney.

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Special anthraquinones and anthraquinone-glucosides are potential toxicants.

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Specific group of anthraquinones influences hepatic or renal cytotoxicity.

Cassiae semen are dried and ripe seeds of Cassia obtusifolia L. or Cassia tora L. (Fabaceae) and have been made into roasted tea or used as a traditional medicine in Asian countries. However, it was reported to result in liver and renal toxicity. The components of Cassiae semen that induce hepatotoxicity or nephrotoxicity remain unknown. In the present study, we evaluate the potential toxicity of 26 newly isolated compounds from Cassiae semen using quantitative structure–activity relationship (QSAR) methods and co-culture of hepatic and renal cell approaches, and we aim to illustrate the relationship between the structural characteristics and cytotoxicity by general linear models (GLMs). Both the QSAR models and co-culture of hepatic and renal cell systems predicted that 6 compounds were potentially hepatotoxic, 10 compounds were potentially nephrotoxic, and specific anthraquinones and anthraquinone-glucosides were potential toxicants in Cassiae semen. Specific groups such as –OH and –OCH₃ at the R1, R2, R3, and R7 positions influenced the cytotoxicity.

How does traditional knowledge of Cassiae semen shed light on weight management? - A classical and modern literature review

ETHNOPHARMACOLOGICAL RELEVANCE

The seed of Senna obtusifolia (L.) H. S. Irwin & Barneby (Cassiae semen, CS) also known as Jue ming zi in China, has been traditionally used for weight management by purging the liver and improving the liver functions to support digestion. In the past decades, it has been used for hepatoprotection and treatment of overweight and other metabolic disorders such as hyperlipidaemia and diabetes.

AIM OF THE REVIEW

This review aimed at providing comprehensive information on the traditional usages, pharmacology, phytochemistry and toxicology of CS and critically exploring its potential usage for clinical weight management from both traditional and modern application perspectives.

MATERIALS AND METHODS

In order to fully understand the properties, actions and indications of CS, two sets of Chinese classical texts were searched, namely: Zhong Hua Yi Dian (Encyclopedia of Traditional Chinese Medicine) and Zhong Guo Ben Cao Quan Shu (Complete Collection of Traditional Texts on Chinese Materia Medica). The purpose of studying these classical texts was to determine the traditional use of CS in weight management. Comprehensive searches were also performed on seven databases for publications on original randomised clinical trials (RCT), in vivo, in vitro or in silico studies related to pharmacological effects of CS. Detailed information about the phytochemistry of CS was collected from books, encyclopedia, online databases and journal literature.

FINDINGS

In classical literature review, 89 classic texts provided information of properties, actions and indications of CS. In modern literature review, 44 studies were included for analysis, including 5 RCTs, 7 in vivo studies, 14 in vitro studies, 2 in silico studies and 16 studies of mixed types. Chinese classic literature has provided traditional evidence of the usage of CS for weight management. Contemporary studies have revealed that CS has weight loss effects and possesses some other pharmacological activities supporting weight management. Some chemical compounds of CS have been hypothesised to have a direct or indirect contribution to weight control.

CONCLUSIONS

The relationships between chemical compounds and the corresponding weight-loss target proteins are not fully understood. Therefore, CS constituents should be further explored for the development of novel therapeutic or preventive agents for the treatment of overweight and obesity.

Anthraquinones in the aqueous extract of Cassiae semen cause liver injury in rats through lipid metabolism disorder

BACKGROUND

Cassiae semen has been used as the tea or medicine component to treat hyperlipidemia or for hepatoprotection. However, Cassiae semen was reported to be a potentially hepatotoxic herb, and the underlying hepatotoxicity mechanisms or specific hepatotoxic components of Cassiae semen are unknown.

PURPOSE

In this study, we aimed to explore the potential hepatotoxicity mechanisms and the hepatotoxic components of Cassiae semen.

METHODS

Both young adult male and female SD rats were orally administrated with the aqueous extract of the seeds of Senna obtusifolia (L.) H.S.Irwin & Barneby at doses of 4.73, 15.75, 47.30 g/kg for 28 days, and the body weight, liver coefficient, bile acids, histopathology, serum levels of TC, TG, LDL, HDL, ALP, ALT, AST, and LDH were examined. Lipidomic analysis of rat serum was performed by LC-MS to investigate the specifically changed lipids caused by the aqueous extract treatment. The components absorbed in plasma were detected by UHPLC-Q-Exactive-MS. MTT assay was used to evaluate the cytotoxicity of these components absorbed in plasma.

RESULTS

The serum levels of ALP, AST, ALT, LDH were increased on day 7 with some of which gradually dropped to normal level on day 28. In high dose of the aqueous extract treated group, the histopathological changes were observed based on the cytoplasmic vacuolation in the liver and the increase of bile acids, indicating the hepatotoxicity of the aqueous extract. The changes of TC, TG, LDL, HDL indicated the disorder of lipid metabolism. By comparing the difference in lipids between high dose group and control group, the results showed that the alterations were primarily focused on glycerophospholipid metabolism in both male and female rats. In addition, the glycerolipid metabolism in female rats also changed. Further analyses found that PC (18:2/20:4) and LysoPC 18:0 were significantly increased. Among these phytochemicals detected in plasma, nine components in the aqueous extract were considered to have the highest concentrations, particularly some types of anthraquinones (AQs) existing in Cassiae semen (AQs-in-CS), such as obtusifolin, aurantio-obtusin, and obtusin. The MTT assay showed that emodin, obtusifolin, rhein, aurantio-obtusin, and obtusin inhibited cell viability. Considering plasma concentrations and cytotoxicity of these components, our study indicates that the AQs-in-CS (obtusifolin, aurantio-obtusin and obtusin), emodin and rhein are the potential hepatotoxic phytochemicals in the aqueous extract.

Anthraquinones from Cassiae semen as thrombin inhibitors: in vitro and in silico studies

Thrombin inhibitor therapy is one of the most effective therapeutic strategies for the prevention and treatment of cardiovascular and thrombotic diseases. Although several marketed direct thrombin inhibitors (DTIs) have been widely used in clinic, the potentially serious complications of these DTIs prompted the researchers to find more DTIs with improved safety profiles. Herein, we report that natural anthraquinones in Cassiae semen (the seed of Cassia obtusifolia L. or C. tora L.), including obtusifolin, obtusin, aurantio-obtusin and chryso-obtusin, display strong to moderate inhibition on human thrombin, with the IC₅₀ values ranging from 9.08 μM to 27.88 μM. Further investigation on the inhibition kinetics demonstrates that these anthraquinones are mixed inhibitors against thrombin-mediated Z-GGRAMC acetate hydrolysis, while obtusifolin and aurantio-obtusin show strong thrombin inhibition capacity, with the K_i values of 9.63 μM and 10.30 μM, respectively. Docking simulations demonstrate that both obtusifolin and aurantio-obtusin can simultaneously bind on the catalytic cavity and the two anion binding exosites (ABE1 and ABE2), while the hydroxyl group at the C-7 site and the methoxyl group at the C-8 site can create key interactions with the amino acids surrounding the catalytic cavity via hydrogen bonding. All these findings suggest that obtusifolin and aurantio-obtusin are strong thrombin inhibitors possessing a unique anthraquinone skeleton, and could be used as lead compounds for the development of new thrombin inhibitors with improved properties.

Extract of Cassiae semen attenuates diabetic nephropathy via inhibition of advanced glycation end products accumulation in streptozotocin-induced diabetic rats

Chronic hyperglycemia leads to the formation of advanced glycation end products (AGEs), which accelerates the development of diabetic complications. Previous studies have shown that extract of Cassiae semen (CS), the seed of Cassia tora, has inhibitory activity on AGEs formation in vitro and reduces transforming growth factor-beta1 (TGF-β1) and extracellular matrix protein expression via inhibition of AGEs-mediated signaling in glomerular mesangial cells. In this study, to examine the preventive effects of CS extract on the development of diabetic nephropathy in vivo, streptozotocin (STZ)-injected diabetic rats were orally administered CS extract (200 mg/kg body weight/day) for 12 weeks. Serum glucose, triglycerides, and total cholesterol in diabetic rats were significantly higher compared to control rats. CS or aminoguanidine (AG) treatment significantly reduced these factors. Proteinuria and creatinine clearance were also significantly decreased in the CS-treated group compared with the untreated diabetic group. The CS-treated group had significantly inhibited COX-2 mRNA and protein, which mediates the symptoms of inflammation in the renal cortex of diabetic rats. Furthermore, histopathological studies of kidney tissue showed that in diabetic rats, AGEs, the receptor for AGEs, TGF-β1, and collagen IV were suppressed by CS treatment. Our data suggest that oral treatment of CS can inhibit the development of diabetic nephropathy via inhibition of AGEs accumulation in STZ-induced diabetic rats.