Study On The Chemical Constituents And Antiproliferative Activity Of Selaginella Doederleinii Hieron.

Cancer is the uncontrolled multiplication and abnormal growth of body cells that occurs when the normal control mechanism of the body stops working.It is among the top world’s killer diseases and has over 100 types.Lung,breast,prostate,and colorectum are the leading cancer types in both morbidity and mortality.Radiotherapy,chemotherapy and surgery are the main cancer treatment methods others include stem cell transplant and hormone therapy.Despite chemotherapy having strong side effects,it still plays an important role in cancer treatment and plant-derived anti-cancer agents having the advantage of fewer side effects have continuously increased in research.Selaginella doederleinii Hieron.,a traditional medicinal plant,has been used for decades to treat several diseases.In China,the plant has been used traditionally to treat several cancers including;lung,liver,gastric,cervical and esophageal cancer.It has also been used to treat sore throat,cardiovascular and rheumatoid arthritis.Previous pharmacological studies have revealed that S.doederleinii has antiproliferative,antioxidant,antimicrobial and anti-Alzheimers properties while phytochemical studies have revealed that its main compounds are biflavonoids that include amentoflavone,robustaflavone,delicaflavone,bilobetin among others.These biflavonoids exhibit strong antiproliferative activity against numerous cancer cell lines.Other classes of compounds like flavones,triflavonoids,sterols and alkaloids have also been reported.By comparing the phytochemical profile of S.doederleinii to those of other species in genus Selaginella,there could be other classes of compounds like diterpenoids,neolignans which were reported in S.moellenderffii.Therefore,the purpose of this study was to explore the phytochemical profile of S.doederleinii to isolate new compounds as well other compound classes that have not been previously reported.The soaking extraction method was employed for crude extraction with 75%ethanol.Liquid/liquid extraction using petroleum ether（PE）,dichloromethane（DCM）,ethyl acetate（EA）,and n-butanol（n-Bu OH）was performed.The total flavonoid content（TFC）for all the extracts was evaluated by colorimetric method and expressed in Rutin equivalent per gram of dry weight（mg RE/g dw）.MTT（3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide）assay was used to investigate the antiproliferative activity of the plant extracts and isolated compounds against three human cancer cell lines,A549（lung）,HeLa（cervical）,and HT-29（colon）.Column chromatography,high-performance liquid chromatography,and nuclear magnetic resonance were employed for the isolation and identification of compounds.The quantitative determination revealed that DCM and EA extracts possessed the highest flavonoid content levels of 340.77±1.00 and 310.29±3.05 mg RE/g sample respectively.On evaluating the antiproliferative activity of the extracts on the three cancer cell lines,EA extract exhibited the best activity on HT-29 and HeLa with IC₅₀ values of 55.59 and 69.19μg/m L respectively by inhibiting the growth of the tumor in a dose-dependent manner.DCM extract exhibited the best activity on cell line A549 with an IC₅₀ value of 55.96μg/m L.The TFC and antiproliferative results of extracts revealed that the DCM extract was the promising part hence was selected for,chemical constituents isolation and finally antiproliferative screening of the isolated compounds.33 compounds under classification of biflavonoids,apigenin derivatives,flavones,diterpenoids,anthraquinones,neolignan and an ester were isolated.Among the 7 classes mentioned,diterpenoids,anthraquinones,neolignan,and ester were reported for the first time in this species.Two new compounds,3-（5-hydroxy-7-methoxy-2-（4-methoxyphenyl）-4-oxo-4H-chromen-8-yl）-4-methoxybenzoic acid（1）and 8-（5-acetyl-2-hydroxyphenyl）-5,7-dihydroxy-2-（4-methoxyphenyl）-4H-chromen-4-one（2）were isolated.In total,21 compounds are reported for the first time in this species.Compound 7（4ˊ-methyl ether amentoflavone）exhibited the best activity on HeLa cancer cell line by inhibiting the cell growth in a dose-dependent manner with an IC₅₀value 19.17μM.Compound 22（7ˊˊ-methyl ether tetrahydrohinokiflavone）exhibited the best activity on cell lines HT-29 and A549 by inhibiting cell growth in a dose-dependent manner with IC₅₀ values of 27.97 and 20.71μM respectively.This study,therefore,reveals the cancer treatment properties of S.doederleinii as has been reportedly used traditionally and enriched the phytochemical profile of this species.