Plants in lilium are famous for their edible and medicinal functions due to their chemical constituents and pharmacological effects. Chemical studies have shown that Lilium mainly contains steroidal saponins, polysaccharides, alkaloids and flavonoids. The pharmacological effects of lilium include antitumor, hypoglycemic, antibacterial, antioxidant, antidepressant and anti-inflammatory. Pengyu Wang, Fatma Alzahra K. Attia of Henan University and Jian Li of Hefei University of Technology summarized the chemical constituents and pharmacological effects of lilium in this review.

Introduction

Plants in lilium are distributed in China and cultivated as ornamental plants all over the world, which can be used as important edible plants and biomedical products. Lilium has the function of nourishing yin, moistening lung, relieving inflammation and tranquilizing mind. It can also act on persistent cough, hemoptysis, anxiety, insomnia, dreamful sleep and inability to concentrate caused by deficiency of Yin.

Bulbs of Lilium plants have high medicinal value, such as Lilium pumilum and Lilium lancifolium. There are many studies on the chemical constituents of Lilium, including saponins, sterols, alkaloids, polysaccharides, glycerides, phenylpropanes and flavonoids. Literature results show that Lilium plants have pharmacological effects of anti-tumor, hypoglycemic, antibacterial, anti-inflammatory, hypolipidemic, antidepressant, anti-fatigue and improving hypoxia tolerance. This review summarizes the latest studies on phytochemistry and pharmacology of Lilium, which can provide reference for further research and application of related strains.

Biological activities

Anti-cancer activity

The bulbs of Lilium brownii and Lilium lancifolium are often used as antineoplastic agents in traditional Chinese medicine. The antitumor activity of Lilium has been demonstrated in HepG2, K562, SGC-7901, A549, HGC-27 and SPCA-1 cells as well as S180, H22 and B16 mouse models. The results showed that the crude extracts and some active components of Lilium brownii, Lilium lancifolium and Lilium striatum exhibited potential antitumor activity. In vivo and in vitro experiments showed different mechanisms of action, which can be divided into two main categories:

(1) enhancing immune function to kill tumor cells;

(2) Inhibiting cell proliferation and blocking cells in G2/M phase.

Anti-inflammatory activity

The literature showed that the root extract of Lilium lancifolium can inhibit the number of macrophages and neutrophils in the model exposed to cigarette smoke, and reduce the protein secretion levels of TNF-α, IL-6, IL-1β and MCP-1, and the methanolic extract thereof has anti-inflammatory effect because it can significantly inhibit the contents of NO, PGE2, IL-6 and TNF-α induced by lipopolysaccharide; or inhibit iNOS and COX-2 to play anti-inflammatory effects in RAW264.7 cells. Therefore, its anti-inflammatory mechanism is to inhibit the production of inflammatory factors, to play an anti-inflammatory role.

Antioxidant activity

The polysaccharide from Lilium brownii has obvious vivo antioxidant activity in mice by reducing MDA levels in serum and tissues, enhancing the activity of SOD and improving the activity of CAT in liver and serum. The crude polysaccharide from Lilium brownii has the strongest scavenging ability against hydroxyl and nitrite. In addition, the phenolic compounds extracted from Lilium lancifolium showed strong antioxidant activity and free radical scavenging activity against DPPH, ABTS and hydroxyl in vitro. The bulb extracts of Lilium lancifolium have important antioxidant activity and may be a potential source of natural antioxidants.

Effects on the immune system

According to the literature, the medium and high doses of polysaccharide from Lilium brownii can improve the clearance rate of charcoal particles and the weight index of immune organs, indicating that polysaccharide from Lilium brownii can promote the phagocytic function of the reticuloendothelial system of mice and enhance the non-specific immune function. In addition, polysaccharide from Lilium brownii can increase the level of serum hemolysin in mice. These results indicated that Lilium brownii polysaccharide could enhance the humoral immune function of mice.

Hypoglycemic effect

Polysaccharide from Lilium brownii has obvious hypoglycemic effect induced by alloxan in mice. Lilium brownii polysaccharide can increase insulin secretion through enhancing the activity of antioxidant enzymes, improving the antioxidant function and inhibiting the damage to pancreatic islet β-cells by oxygen free radicals, thereby playing an active role in the hypoglycemic mechanism.

Antimicrobial activity

The antibacterial activities of Lilium davidii, Lilium leucanthum, Lilium regale, Lilium brownii and Lilium lancifolium were related to the active ingredients such as, alkaloids, flavonoids and saponins. There was a significant dose-effect relationship between the antibacterial activity and the content of extracts from lilium bulbs. The antibacterial activity increased proportionally with the increase of the content of extracts from lilium bulb.

Antidepressant effect

The depression model of mice is observed through chronic psychological stimulation to observe the influence of Lilium brownii saponin on blood COR and ACTH. The result showed that Lilium brownii saponin can reduce the COR and ACTH of the depression model of mice, indicating that dose-effect relationship exists between the antidepressant effect and the Lilium brownii saponin content.

Anti-fatigue and anti-hypoxia effects

The anti-fatigue pharmacological effects of Lilium lancifolium polysaccharide on mice were observed in the literature and it was found that Lilium lancifolium polysaccharide can prolong the swimming time of mice, enhance the activity of SOD and reduce the content of MDA. Therefore, the Lilium polysaccharide can enhance the anti-fatigue ability of mice.

Future perspectives

The literature showed that saponins, flavonoids and polysaccharides are the main active components of Lilium plants. The studies on the chemical constituents of lilium bulbs were mainly focused on, but little research has been done on their flowers. The pharmacological effects of the compounds isolated from Lilium plants have not been studied, and their mechanisms are still unclear.

Conclusion

In conclusion, the following points can be taken into consideration in the future research and reasonable development of Lilium:

(1) The chemical constituents of Lilium were identified by UPLC-Q-TOF-MS;

(2) To study the chemical constituents and pharmacological effects of Lilium plants systematically, including the flowers of Lilium plants, and to further explore their mechanism of action;

(3) It is of great significance for the in-depth research and development in food, health care products and related drugs.