Phytochemicals from a range of medicinal herbs are gaining broad attention for their anticancer properties. Many researchers have found that plant bioactive ingredients can improve the efficiency of chemotherapy and ameliorate the side-effect of chemical drugs utilized as chemotherapeutic agents [17–19]. Thus, we evaluated the efficacy of L. nummularifolia, L. ledebourii, C. radicans, and P. quinquefolia extracts on cell cycle arrest, apoptosis, and cytotoxicity induction in the skin, bone, and oral cancer cells.
From the MTT assay, four extracts significantly enhanced the cell death in the cancer cell lines when compared to the HGF-1 cell line. The high toxicity levels in the cancer cell lines were recorded for Le on G292 and A431, Pe on KB and A431, Ce on A431, as well as Lm on G292 and KB. Similarly, Farboodniay-Jahromi et al., (2020) demonstrated that alkaloids, flavonoids, and phenols can justify clearly the biological activity of L. nummularifolia on cell lines .
As our observations revealed, the Methanolic extract of L. ledebourii bulbs (Le) could induce the programmed cell death and enhanced the cell accumulation in subG1 step and the arrest of the cell cycle in the G0/G1 step. L. ledebourii has been proved as an herb containing lectin as carbohydrate-binding proteins . Several researches demonstrated the anticancer efficacy of these proteins in apoptosis induction, cell accumulation in G0/G1 and/or G2/M phases, and ribosomal attachment .
From previous reports, it was well-known that the BH3 interacting-domain death agonist (BID) gene is up-regulated via p53 tumor suppressor and is involved in p53-induced apoptosis . Moreover, apoptotic motivators induce caspase8 and its substrate, BH3 interacting-domain death agonist, in a death receptor-independent way . Our observations are in line with these reports, suggesting the L. ledebourii extract can increase BID and subsequent P53 genes expression, thereby makes help to induce apoptosis in the KB cell line, A431 cell line, and G292 cell line.
Map Kinase 14, a crucial member of the MAPK family P38, play a dual function in some tumors . Several researchers have indicated that Map Kinase 14 can promote the onset and progress of breast tumors via inducing its downstream genes . In addition, Map Kinase 14 has also been exhibited to play as an inhibitor in lung, colon, liver, and cancer . Given the inhibitory role of MAPK14 in skin cancer , it seems that the increased level of MAPK14 transcript derived by Le extract can be effective in controlling cell growth through apoptosis.
Cancer cells enhance the MYC gene expression, usually as a consequence of tonic WNT signaling, MYC gene amplification, and/or chromosomal translocation . By gain of prosurvival signals (e.g., NF-κB and BCL2) and/or by loss of surveillance mechanism (e.g., MDM2 and P53), cancer cells can tolerate the enhanced MYC level and thereby avoid programmed cell death . As proved in this study, the L. ledebourii Methanolic extract decreased the transcript level of MYC. Thus, it seems that L. ledebourii induces negative auto-regulation that in turn decreases MYC expression.
It is well-known that the MDM2/BCL2 dual repression makes an opportunity for a bioactive compound to act as an antitumor agent [22, 23]. These statements are in line with our findings when the L. ledebourii Methanolic declined the transcript levels of BCL2 and MDM2. It has been presented the evidence on the activating role of Le extract on p53 expression. Since the induction of p53 tumor suppressor indirectly decreases several cell cycle genes and eventually result in cell cycle arrest , the L. ledebourii extract regulates a plethora of genes involved in cell cycle by MDM2/BCL2 and p53 pathways and can contribute to cell cycle arrest.
Based on the results of Triple-Quad LC/MS connected to the UHPLC analysis for L. ledebourii methanolic extract, it was determined that anti-cancer substance is a phenolic compound. The phenolic compounds are secondary metabolites of plants, which have a wide range of biological activities, such as anti-inflammatory, antioxidant, anti-aging, and antidepressant properties . According to the report of Luo et al. , the phenolic compounds in L. brownii are mainly phenylpropanoids, which have significant antioxidant activity.
The results of identifying the sample structure of fraction 8 showed that was mainly composed of coumarin acid, Catechin, caffeic and ferulic acid, Kaempferol and Apigenin which are connected by one molecule of glycerol, and the glycerol group are formed by para/ortho substitution or glucose substitution/acetylation. Hence, these compounds belong to phenolic glycerides/glycosides (phenylpropanoid compounds), and are called “regalosides” in some studies. coumaric acid, a Phenolic Compounds with anti-cancer effects. They can downregulate amyloid β-induced the overexpression of COX-2 and iNOS in PC12 cells through inhibiting MAPK signaling pathway and NF-κB activity . Coumarin was capable of down-regulating MDM2 and the anti-apoptosis proteins Bcl-2 and Bcl-xL, up-regulating the level of P53 and the pro-apoptosis protein BAX, causing cell cycle arrest at G2/M phase and activating Caspase-9 to induce apoptosis . catechin can neutralize reactive oxygen species (ROS) present in the cell and also can reduce abnormal cell replication by altering cell signaling pathways (ex. MAP kinase pathway). catechin is effectively used as a preventative agent in cancer therapy. For better outcome catechin can be used as an adjunct therapy with radiation and chemotherapy during cancer treatment . Research results of Serafim et al., showed that results show that the new caffeic and ferulic acid lipophilic derivatives show increased cytotoxicity toward human breast cancer cell lines . Kaempferol and apigenin were investigated as their anti-SIRTs potential. Sharma et al., showed in their paper, KMP and API inhibits cellular proliferation by DNA damage and S-phase cell cycle arrest in TNBC Cells. KMP and API inhibited SIRT3 and SIRT6 proteins, and as promising candidates to be further developed as sirtuin modulators against TNBCs .