Research progress of Cassytha filiformis L

Zi-Bao Huang, Lu Zhang, Lin Dong, Xiao-Po Zhang, Li-Fang Han, Cai-Yun Zhang ✉

1. School of Pharmaceutical Science,Hainan Medical University,Haikou 571199,China

2. Research Center of Drug Safety Evaluation,Hainan Medical University,Haikou 571199,China

Keywords:Cassytha filiformis L Chemical composition Pharmacological activity Alkaloids

ABSTRACT Cassytha filiformis L, belonging to family Lauraceae, is widely distributed in subtropical and tropical regions. Cassytha filiformis L is a traditional plant medicine in China, it has proved that the plant showed anti-parasite, anti-tumor, anti-diabetic and anti-platelet aggregation activities,so far, the main pharmacological active components are alkaloids. In this paper, the chemical constituents and pharmacological effects of Cassytha filiformis L were reviewed by referring to databases such as CNKI, Vip and Pubmed, so as to lay a foundation for its development and utilization.

Cassytha filiformis L, belonging to family Lauraceae[1]. Cassytha filiformis L are mainly distributed in tropical and subtropical regions such as China, Africa and Australia, mainly distributed in Hainan, Guangxi, Taiwan, Guizhou, Fujian and other regions in China. Commonly found in hillside shrubs or sparse forests,parasitic entwining herbaceous plants, and clinging to host plants by disc-shaped suckers[2]. Cassytha filiformis L is a commonly used medicinal plant in our country, the whole herb is used as medicine,it has a sweet taste and cool nature and the effects of clearing heat and relieving cough, cooling blood and stopping bleeding.Traditional folk medicine is often used for many diseases such as diabetes, rheumatoid arthritis, nephritis and edema, urinary tract stones, etc[3]. Modern pharmacological research has found that Cassytha filiformis L has anti-diabetic, anti-tumor, anti-parasitic,anti-virus and other pharmacological activities. In terms of chemical composition research, Cassytha filiformis L mainly contains alkaloids, flavonoids, essential oils and other components, among which aporphine alkaloids are its characteristic components. This article systematically reviews the domestic and foreign research progress on the chemical constituents and pharmacological activities of Cassytha filiformis L in order to provide a reference for its indepth development and utilization.

1. Chemical composition

1.1 Alkaloids

As early as the middle of the twentieth century, scholars began to study the chemical constituents of Cassytha filiformis L and isolate alkaloids. After extracting with methanol or ethanol, extracting with dichloromethane or chloroform to obtain the extract, the extract is separated and purified by silica gel chromatography,gel chromatography, preparative thin layer chromatography and high performance liquid chromatography, and then the structure is identified by spectral analysis method, obtain a series of alkaloid compounds, most of which are aporphine alkaloids. The following are the aporphine alkaloids compounds 1-23 and their chemical structures (see Table 1 and Figure 1) isolated from Cassytha filiformis L by domestic and foreign scholars.

In addition to the characteristic components of aporphine alkaloids, there are many other types of alkaloids in the Cassytha filiformis L. In 1997, Wu et al[4], carried out methanol extraction,chloroform extraction, silica gel and TLC separation and purification experiments to obtain three alkaloid compounds in the Cassytha filiformis L, which were identified as compounds 24(cassameridine), 25 (cassamedine) and 26 (lysicamine) by spectral analysis method. Alkaloid compound 27 (thalicminine) was isolated from Cassytha filiformis L by Montenegro et al[12]. Chang et al[8], obtained the extracts by methanol extraction and chloroform extraction in the Cassytha filiformis L,

Table 1 Aporphine alkaloids isolated from Cassytha filiformis L

Figure1 Chemical structures of aporphine alkaloids 1-23 from Cassytha filiformis L

The extracts were separated and purified by silica gel, preparative thin layer chromatography and high performance liquid chromatography, and the structure was identified as 28 (filiformine),29 ( pronuciferine). Tsai et al[11], performed a series of extraction,separation and purification of Cassytha filiformis L to obtain alkaloids 30 (isofiliformine), 31 ((-)-O-methylflavinantine), 32((-)-salutaridine). Rios et al[13], isolated the alkaloid compound 33(stepharine) from Cassytha filiformis L. The structure of compound(24-33) is shown in Figure 2.

Figure2 Chemical structures of alkaloids from Cassytha filiformis L

T

o sum up, alkaloids are the main chemical component of Cassytha filiformis L, the research has not yet been completed, and the extraction and separation methods are basically similar, however,there are no research reports on the optimization of the extraction process of the alkaloids from Cassytha filiformis L, resulting in higher yields. Therefore, it is necessary to systematically separate and identify alkaloids in the Cassytha filiformis L. At present, most of the research in the Cassytha filiformis L comes from African countries and regions, and the research part is the whole grass of Cassytha filiformis L, the extraction and separation technology mostly uses methanol for extraction, and then according to the physical and chemical properties of the alkaloids, the total alkaloids are obtained by acid extraction and alkali precipitation, then, the total alkaloids are separated and purified through a series of column chromatography, and the structure is identified using nuclear magnetic resonance and other spectroscopy techniques. In China,Hainan, Guangxi, Guizhou and other places also have a large number of Cassytha filiformis L resources, which also have potential research and utilization values.

1.2 Essential oils

At present, there are few studies on essential oils components in the Cassytha filiformis L, according to the physical and chemical properties of essential oils components, most of them are extracted by steam distillation. Brophy et al[14], used gas chromatographymass spectrometry (GC-MS) analysis technology to identify the structure of the components extracted and separated from Cassytha filiformis L, and obtained the main essential oils components as bicyclogermacrene (12%–26%), spathulenol (27 %–36%) and β-caryophyllene (5%–10%). Ouattara et al[15], carried out the extraction and analysis of essential oils in the Cassytha filiformis L from five regions of Côte d’Ivoire, using steam distillation extraction,gas chromatography (GC)-mass spectrometry (MS)-chromatographic retention index (RI) combined use and Carbon Nuclear Magnetic Resonance Spectroscopy (13CNMR) and other analytical techniques for structural identification obtain 41 compounds (see Table 2),among them are mainly sesquiterpenes and their derivatiwves.

1.3 Flavonoids

There are many compounds with medicinal value in flavonoids,the research on flavonoids in the Cassytha filiformis L has not yet been fully studied, and these compounds also have potential research and development value. Chang et al[8], obtained the extracts by methanol extraction and chloroform extraction of the whole plant of Cassytha filiformis L. The flavonoids were separated and purified by a series of column chromatography, and the structure was identified as O-methylflavinantive by spectroscopic methodology.Tsai et al[11], isolated flavonoids from Cassytha filiformis L:isohamnetin, isohamnetin-3-O-β-glucoside, isohamnetin-3-Orutinoside, isohamnetin-3-O-robinobioside, quercetin-3-O-βgalactoside, quercetin-3-O-rutinoside, quercetin-3-Orobinobioside,kaemperferol-3-O-robinobioside.

1.4 Other components

The other components obtained from the research on Cassytha filiformis L include lignins: (+)-diasyringaresinol, (+)-yangambin,(+)-syringaresinol; aromatic aldehydes: vanillin and isovanillin;dulcitol, glycerolipids, sterols[8,16,17]; amino acids: 17 kinds of amino acids, mainly neutral amino acids and 8 essential amino acids[18];Phenolics and saponins[19].

2. Pharmacological activity

Cassytha filiformis L is a commonly used Chinese herbal medicine in the folk, especially in Africa, it is often used to fight parasites,ulcers and tumors[20]. In China, national medicine and local medicine chronicles record that it has multiple effects. For example,the Li Nationality Medicine Records records:"Decoction in water,appropriate amount for external use, cures diarrhea, dysentery and other diseases"[21]. The research on the pharmacological activity of Cassytha filiformis L is mainly anti-diabetic, anti-parasitic,anti-bacterial, anti-tumor, anti-platelet aggregation and antivasoconstriction.

Table 2 Essential oils isolated from Cassytha filiformis L

2.1 Anti-diabetic

Diabetes has become a major health problem that seriously endangers human health and social economic development[22,23].Natural products have gradually become an important source for the development of new drugs for the treatment of diabetes, especially the nine anti-diabetic drugs approved between 2015 and 2019 are all derived from natural products[24]. And in March 2020, china’s first anti-diabetic original natural drug-Sangzhi total alkaloid tablets was approved by the Food and Drug Administration[25], provide a reference for the development of natural medicines for the treatment of diabetes.

It is recorded in Fujian Medicine Records :"Treatment of diabetes,30 g of fresh Cassytha filiformis L, 9 g of Vigna umbellata and Dioscorea tokoro Makino. Decoction in water"[26]. This suggests that Cassytha filiformis L has anti-diabetic effects, but the specific active ingredients and mechanism of action have not been studied in depth.Chen et al[27], in the research and analysis of the plant resources for the prevention and treatment of diabetes in Chaoshan area showed that Cassytha filiformis L has anti-diabetic effects, but did not explain its active ingredients and mechanism. Ezuruike et al[28], studied the regulation of glibenclamide transport in the anti-diabetic effect of African plant extracts, suggesting that Cassytha filiformis L has an anti-diabetic effect, and also did not conduct in-depth research on its anti-diabetic mechanism. Ezeigbo et al[29], treated alloxan-induced diabetic mice with the methanol extract of Cassytha filiformis L, and the experimental results showed that the blood glucose of the mice was reduced by 46.8%. Oxidative stress is the main cause of diabetes and its complications. Therefore, effective behavioral intervention with antioxidant therapy can reduce the incidence of diabetes[30].Mythili et al[31], used the methanol extract of Cassytha filiformis L to determine the antioxidant activity and DPPH free radical scavenging test. Experiments show that the extract of Cassytha filiformis L has certain antioxidant activity, which is closely related to the treatment of diabetes. The research of Yuliandra et al[32], also showed that the ethanol extract of Cassytha filiformis L has antioxidant properties.

The aporphine alkaloids have anti-diabetic effects, for example,Zhang et al[33], found an anti-diabetic ingredient with independent intellectual property rights from Litsea glutinosa: Litsine A,which belongs to aporphine alkaloids[34]. In 2017, Liu et al[35],systematically reviewed the anti-diabetic effects of natural aporphine alkaloids and found that aporphine alkaloids can improve glucose metabolism, promote insulin secretion, and regulate small intestinal transporters. The current research shows that the main component of Cassytha filiformis L is aporphine alkaloids, therefore, Cassytha filiformis L has potential anti-diabetic research value, and its antidiabetic active ingredients and mechanism have not yet been systematically reported. This will become the research direction of future attention.

2.2 Antiparasitic

Cassytha filiformis L can be used to treat chyluria caused by filariasis in boiling water[36]. Atawodi et al[37], found that Cassytha filiformis L can be used to feed animals after they are ground and cooked to treat trypanosomiasis, but they have not further studied the mechanism of action. Hoet et al[7], carried out methanol extraction on Cassytha filiformis L to obtain the crude extracts, and then studied the inhibitory activity of Trypanosoma brucei through in vitro culture methods, the results showed that IC50=2.2 μg/mL. Furthermore, the extracts were separated and identified to obtain alkaloid components,and the inhibitory activity of seven alkaloids against Trypanosoma brucei was determined, among them, it is concluded that cassythine,actinodaphnine and dicentrine have good anti-trypanosomal activity in vitro. Quetin-Leclercq et al[38], carried out the in vitro culture test of three alkaloids (actinodaphnine, cassythine, dicentrine)obtained by extraction, separation and identification of Cassytha filiformis L. Studies have shown that the three have antitrypanosomal activity, with IC50values of 3.2 μg/mL, 6.0 μg/mL and 14.6 μg/mL,respectively. The results of this study again confirmed the conclusion of Hoet et al[7].

2.3 Antibacterial effect

Oli et al[39], used crude methanol extracts of Cassytha filiformis L to conduct antibacterial tests on Staphylococcus aureus, Salmonella,Shigella dysentery and Escherichia coli, the results showed that the extract of Cassytha filiformis L showed certain antibacterial activity against the four tested strains, and the minimum inhibitory concentrations were 6.25 mg/mL, 3.125 mg/mL, 6.25 mg/mL and 6.25 mg/mL, respectively. Adonu et al[40], used the methanol extract of Cassytha filiformis L to conduct in vitro antibacterial tests on Pseudomonas aeruginosa and Escherichia coli, studies have shown that Cassytha filiformis L extract has antibacterial activity against two kinds of bacteria, and the minimum inhibitory concentrations are(15.50 ± 3.00) mg/mL and (18.50 ± 5.37) mg/mL, respectively. Both of the above are only the research on the antibacterial effect of the crude extract of Cassytha filiformis L, without further exploration of the active ingredients and mechanism of action.

2.4 Antitumor

Stevigny et al[6], studied the in vitro inhibitory activity of four alkaloids (neolitsine, cassythine, dicentrine, and actinodaphnine)extracted and isolated from Cassytha filiformis L, the results show that neolitsine has the strongest inhibitory activity on Hela and 3T3 cells, with IC50values of 21.6 μg/mL and 21.4 μg/mL, respectively;cassythine and actinodaphnine have strong inhibitory effect on mouse erythroleukemia (Mel-5) and human promyelocytic leukemia(HL-60) cells. Hoet et al[7], studied the in vitro inhibitory effects of seven alkaloids (bulbocapnine, actinodaphnine, cassythine,dicentrine, glaucine, isocorydine, and boldine) on Hela cells, studies have shown that glaucine has the strongest inhibitory activity on Hela cells (IC50=8.2 μg/mL), using spectroscopy to study their mechanism of action, the results show that seven alkaloids can effectively bind to DNA, actinodaphnine, cassythine, and dicentrine can interfere with the catalytic activity of topoisomerase.

The above studies are only in vitro, and no in vivo studies have been conducted. Cheng[41] used Trypan blue staining method and MTT method to study the in vitro inhibitory effect of alkaloids of Cassytha filiformis L on mouse liver cancer cells (H22); the establishment of mouse liver cancer H22 ascites tumor model and solid tumor model were used to detect the in vivo inhibitory effect of alkaloids of Cassytha filiformis L on mouse liver cancer H22.The results show that the alkaloids of Cassytha filiformis L have significant inhibitory activity on the growth of mouse liver cancer H22 cells in vitro, and its inhibitory effect has a dose- and timedependent effect; alkaloids of Cassytha filiformis L can prolong the life of mouse liver cancer H22 ascites mice to a certain extent, and also have obvious inhibitory activity on mouse liver cancer H22 solid tumors. The research is conducted in vitro and in vivo, which has profound research significance, due to the numerous targets of anti-tumor effects, the possible mechanism of action of alkaloids of Cassytha filiformis L can be explored in multiple ways in the future.

2.5 Anti-platelet aggregation

Wu et al[16], found that the alkaloids (actinodaphnine, cathaformine,cassythicine, predicentrine, ocoteine and cathafiline) had significant inhibitory activity on rabbit platelet aggregation. The results showed that actinodaphnine (100 μg/mL) had a complete inhibitory effect on platelet aggregation induced by ADP (20 μg/mL), collagen (10 μg/mL), arachidonic acid (100 μg/mL) and platelet activating factor(3.6 μg/mL); among these isolated compounds, actinodaphnine is the strongest anti-platelet aggregation; cassythicine has a complete inhibitory effect on platelet aggregation induced by ADP, collagen,and arachidonic acid; cathafiline has a complete inhibitory effect on platelet aggregation induced by arachidonic acid. Chang et al[8], used EDTA-treated rabbit blood for anti-platelet aggregation test, it is also proved that these six alkaloids from Cassytha filiformis L have a significant inhibitory effect on platelet aggregation induced by ADP,arachidonic acid, collagen and platelet activating factor.

2.6 Anti-vasoconstriction

Tsai et al[11], tested the vascular relaxation effect of alkaloids from Cassytha filiformis L through a vascular tension test, and the results showed that cassythic acid, cassythine, neolitsine and dicentrine have significant vascular relaxation effects; 1, 1,2-methylenedioxy-3,10,11-trimethoxyaporphine, (-)-o-methylflavinantine and(-)-salutaridine have mild vascular relaxation effects. Wu et al[16], found that the alkaloids (actinodaphnine and cassythicine)isolated from Cassytha filiformis L had a strong inhibitory effect on vasoconstriction induced by high potassium (80 mg/mL) and norepinephrine (3 μg/mL). The study of Chang et al[9], proved that the alkaloid (ocoteine) isolated from Cassytha filiformis L has an inhibitory effect on the vasoconstriction caused by high potassium and norepinephrine. At present, many studies have focused on the inhibition of high potassium and norepinephrine induced vasoconstriction by alkaloids in Cassytha filiformis L.

3. Conclusion

The main chemical components of Cassytha filiformis L are aporphine alkaloids, as well as other components such as flavonoids and essential oils. However, the separation of the compounds in Cassytha filiformis L is not sufficient, some of the compounds isolated from Cassytha filiformis L are rare to continue the in-depth activity study and the elucidation of the mechanism of action. Although there are some reports in the literature that Cassytha filiformis L has antidiabetic, anti-tumor, and anti-platelet aggregation effects, however,there are still few studies on their mechanism of action, there are few studies on the use of extracts and compounds of Cassytha filiformis L in vitro cell experiments, animal experiments, and targets. Therefore,systematic research on the extracts and chemical components of Cassytha filiformis L still needs to be strengthened, it is worthwhile to apply modern molecular biology techniques to explore their ways and mechanisms of action, lay the foundation for its future in-depth development and utilization. Especially for more comprehensive and in-depth research on the alkaloids of Cassytha filiformis L, Promote the drug development and research of Cassytha filiformis L, and provide theoretical basis for the development of modern new drugs from Cassytha filiformis L.