Cynanchum atratum, commonly known as Bai Wei or black swallow-wort, is a perennial herbaceous plant native to East Asia, particularly found in China, Korea, and Japan. This plant belongs to the Apocynaceae family and is known for its medicinal properties, which have been utilized in traditional Chinese medicine to treat various ailments.

Botanical Classification

Kingdom: Plantae
Clade: Angiosperms
Class: Eudicots
Order: Gentianales
Family: Apocynaceae
Genus: Cynanchum
Species: C. atratum

Plant Characteristics

Cynanchum atratum is a vine that can grow several meters in length, using other plants or structures for support. It has simple, opposite leaves which are broad and oval-shaped. The plant produces small, inconspicuous flowers that are greenish-white, followed by slender, pod-like fruits containing seeds with silky tufts, which aid in wind dispersal.

Chemical Composition and Structure

The roots of Cynanchum atratum contain several bioactive compounds including pregnane glycosides, flavonoids, and phenolic acids. These compounds are believed to confer anti-inflammatory, immunomodulatory, and antitumor properties, making the plant a subject of interest in pharmacological research.

How to Cultivate It

1. Soil: Prefers well-drained, fertile soil with moderate moisture.
2. Light: Grows best in partial shade but can tolerate full sun if adequately watered.
3. Water: Requires regular watering but is drought-tolerant once established.
4. Temperature: Thrives in temperate climates and can tolerate a range of temperatures but is not frost-hardy.

Uses and Benefits

Traditionally, Cynanchum atratum has been used in Chinese medicine to treat conditions such as sore throat, tonsillitis, rheumatoid arthritis, and various skin diseases. It is also reputed to have diuretic and detoxifying effects.

Applications

• Medicinal: The roots are primarily used to prepare decoctions or extracts which are incorporated into various traditional medicine formulations.
• Research: Modern pharmacological studies focus on its potential anti-cancer and immune-boosting effects.
• Horticultural: While not typically grown for ornamental purposes, it can be used in gardens to cover trellises or fences due to its climbing nature.

Environmental and Safety Considerations

Cynanchum atratum should be cultivated with care as it can become invasive under certain conditions, particularly in North America where it is considered a weed in some regions. Managing its spread is crucial to prevent it from overtaking native flora. Generally, the plant is safe for use under traditional medicine guidelines, but it should be used with caution due to the potent nature of its bioactive compounds. Pregnant and breastfeeding women should avoid using this herb, as there is insufficient data on its safety in these populations.

References__________________________________________________________________________

Fleitas MMD, Kim SS, Kim NK, Seo SR. Cynanoside F Controls Skin Inflammation by Suppressing Mitogen-Activated Protein Kinase Activation. Antioxidants (Basel). 2022 Sep 1;11(9):1740. doi: 10.3390/antiox11091740. 

Abstract. Atopic dermatitis (AD) is a chronic inflammatory skin disease accompanied by severe itching and dry skin. Currently, the incidence of AD due to excessive activation of immune cells by various environmental factors is increasing worldwide, and research on inflammatory response inhibitors with fewer side effects is continuously needed. Cynanoside F (CF) is one of the pregnane-type compounds in the root of Cynanchum atratum, an oriental medicinal herb that has been shown to have antioxidant, antitumor, and anti-inflammatory effects. Although CF has been isolated as a component in Cynanchum atratum, the scientific role of CF has not yet been explored. In this study, we evaluated the effect of CF on AD and revealed the mechanism using in vitro and in vivo experimental models. CF significantly reduced lipopolysaccharide (LPS)-induced protein expression levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), and cyclooxygenase-2 (COX-2), which are important proinflammatory mediators in the RAW264.7 macrophage cell line. CF did not inhibit the nuclear factor-kappa B (NF-κB) signaling activated by LPS but significantly reduced the phosphorylation of mitogen-activated protein kinases (MAPKs), such as p38 MAPK, JNK, and ERK. CF consistently inhibited the activity of the activator protein-1 (AP-1) transcription factor, a downstream molecule of MAPK signaling. In addition, in an experiment using an oxazolone-induced AD mouse model, the CF-treated group showed a marked decrease in epidermal thickness, the number of infiltrated mast cells, and the amount of histamine. The mRNA levels of IL-1β, interleukin-4 (IL-4), and thymic stromal lymphopoietin (TSLP) were consistently lowered in the group treated with CF. Moreover, the phosphorylation of c-Jun and c-Fos protein levels, which are the AP-1 components, were lowered in the skin tissues of CF-treated mice. These results provide the first evidence that CF has an inhibitory effect on AD and suggest the possibility of CF being developed as a potential therapeutic agent for AD.

Kim YY, Lee S, Jang HJ, Hur G, Lee SW, Jung K, Lee SJ, Kim SH, Rho MC. Cynanchum atratum Ameliorates Airway Inflammation via Maintaining Alveolar Barrier and Regulating Mast Cell-Mediated Inflammatory Responses. Am J Chin Med. 2019;47(8):1795-1814. doi: 10.1142/S0192415X19500915. 

Abstract. Asthma is a common allergic airway inflammatory disease, characterized by abnormal breathing due to bronchial inflammation. Asthma aggravates the patient's quality of life and needs continuous pharmacological treatment. Therefore, discovery of drugs for the treatment of asthma is an important area of human health. The aim of the present study was to evaluate whether Cynanchum atratum extract (CAE) modulates the asthma-like allergic airway inflammation and to study its possible mechanism of action using ovalbumin (OVA)-induced airway inflammation and lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice, as well as a mast cell-based in vitro model. The histological analysis showed that CAE reduced the airway constriction and immune cell infiltration. CAE also inhibited release of β-hexosaminidase and expression of inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-4, and IL-5 in bronchoalveolar lavage fluid and lung tissues. In addition, CAE reduced the OVA-specific immunoglobulin (Ig) E, total IgE, IgG1, and IgG2a levels in the serum. In the LPS-induced ALI model, CAE suppressed the LPS-induced lung barrier dysfunction and the release of proinflammatory cytokines. Because allergic airway inflammatory responses are associated with the activation of mast cells, RBL-2H3 cells were used to evaluate the underlying mechanism of CAE effects. In RBL-2H3 cells, CAE down-regulated release of β-hexosaminidase and histamine by reducing the intracellular calcium influx. In addition, CAE suppressed the expression of proinflammatory cytokines by inhibiting nuclear translocation of nuclear factor-κB. Taken together, our findings suggest that CAE may help in the prevention or treatment of airway inflammatory diseases.

Bai H, Li W, Koike K. Pregnane glycosides from Cynanchum atratum. Steroids. 2008 Jan;73(1):96-103. doi: 10.1016/j.steroids.2007.09.004. 

Abstract. Five new pregnane glycosides, cynanosides K-O (1-5) with a 14,15-seco-pregnane-type skeleton as the aglycon, together with five known compounds, cynascyroside C, sublanceoside E(1), sublanceoside I(1), atratoside A and atratoside B, were isolated from the roots of Cynanchum atratum. Their structures were determined on the basis of spectroscopic analysis and chemical evidence.

Yang J, Wang B, Zhang CF, Xu XH, Zhang M. A C21-Steroidal Glycoside from Cynanchum atratum Attenuates Concanavalin A-Induced Liver Injury in Mice. Molecules. 2019 Mar 19;24(6):1087. doi: 10.3390/molecules24061087. 

Abstract. Cynatratoside A (CyA) is a C21 Steroidal glycoside with pregnane skeleton isolated from the root of Cynanchum atratum Bunge (Asclepiadaceae). This study aimed to investigate the effects of CyA on concanavalin A (Con A)-induced autoimmune hepatitis (AIH) and the underlying mechanism. CyA was orally administered to mice at 10 and 40 mg/kg 8 h before and 1 h after Con A treatment. The effects of CyA on Con A-induced spleen and liver in mice were assessed via histopathological changes, T lymphocyte amounts and the expressions of IL-1β and ICAM-1. Con A-induced L-02 hepatocytes were used to evaluate whether CyA (0.1⁻10 μM) can directly protect hepatocytes from cytotoxicity and the possible mechanism. The results revealed that CyA treatment could significantly improve the histopathological changes of spleen and liver, reduce the proliferation of splenic T lymphocytes, and decrease the expressions of IL-1β and ICAM-1 in liver. The experiment in vitro showed that CyA inhibited Con A-induced hepatotoxicity in a concentration-dependent manner. CyA (10 μM) significantly increased/decreased the expression of Bcl-2/Bax and reduced the levels of cleaved caspases-9 and -3. Our study demonstrated for the first time that CyA has a significant protective effect on Con A-induced AIH by inhibiting the activation and adhesion of T lymphocytes and blocking hepatocyte apoptosis.

Fu YW, Zhang QZ, Xu DH, Liang JH, Wang B. Antiparasitic effect of cynatratoside-C from Cynanchum atratum against Ichthyophthirius multifiliis on grass carp. J Agric Food Chem. 2014 Jul 23;62(29):7183-9. doi: 10.1021/jf5018675. 

Abstract. Ichthyophthirius multifiliis (Ich), a fish ectoparasite, comprises an important challenge in the aquaculture industry. In this study, a steroidal glycoside, cynatratoside-C, isolated from Cynanchum atratum roots by bioassay-guided fractionation was used to treat I. multifiliis. The cynatratoside-C at 0.25 mg/L demonstrated a 100% mortality of I. multifiliis in vitro after 5 h exposure. The 5 h median effective concentration (EC50) of cynatratoside-C to nonencysted tomonts was 0.083 mg/L. In addition, cynatratoside-C at concentrations of 0.125 and 0.06 mg/L could completely terminate the reproduction of encysted tomonts. The cynatratoside-C at 2 mg/L could cure the infected grass carp within 48 h. The exact mechanism of cynatratoside-C for killing I. multifiliis is unknown, but it manifests itself microscopically through loss of membrane integrity of nonencysted tomonts or through releasing immature theronts from encysted tomonts. The immature theronts finally died before infecting fish. On the basis of these results, cynatratoside-C could be used as a natural anti-I. multifiliis agent.

Day SH, Wang JP, Won SJ, Lin CN. Bioactive constituents of the roots of Cynanchum atratum. J Nat Prod. 2001 May;64(5):608-11. doi: 10.1021/np000428b.

Abstract. A novel biphenylneolignan, 2,6,2',6'-tetramethoxy-4,4'-bis(2,3-epoxy-1-hydroxypropyl)biphenyl (1), and two new glycosides named atratoglaucosides A (2) and B (3), were isolated from the roots of Cynanchum atratum, and their structures were determined on the basis of chemical and spectroscopic evidence. The aglycons of 2 and 3 were identified as glaucogenin C and 7-desoxyneocynapanogenin A, a new disecopregnane. A known compound, glaucogenin C 3-O-beta-D-cymaropyranosyl-(1-->4)-alpha-L-diginopyranosyl-(1-->4)-beta-D-thevetopyranoside (4), isolated from the same source, showed a significant cytotoxic effect against 212 cells. This substance also gave a significant inhibitory effect on TNF-alpha (tumor necrosis factor-alpha) formation from the RAW 264.7 mouse macrophage-like cell line stimulated with LPS (lipopolysaccharide) and on the N9 microglial cell line stimulated with LPS/IFN-gamma (interferon-gamma).