Cytotoxic and Apoptotic Effects of Luffa Cylindrica Leaves Extract against Acute Lymphoblastic Leukemic Stem Cells

BACKGROUND

Acute lymphoblastic leukemia (ALL) is an aggressive malignancy defined by accumulation of lymphoblasts in the bone marrow. Leukemic stem cells (LSCs) are the major cause of the recurrence and metastasis of ALL. This study aimed to develop an effective anti-cancer agent targeting these LSCs. Luffa Cylindrica (L.C.) leaves extract was selected to evaluate its effect on ALL via eradicating the LSCs as it contains many active anti-cancer flavonoids.

METHODS

Thirty-two bone marrow samples of ALL patients were used in this study. LSCs population was identified in the selected samples. Cell viability was measured by MTT assay and flow cytometry. Cell cycle, apoptosis, proliferation marker; ki-67 and colony forming assay were further analyzed.

RESULTS

This study revealed the expression of CD34+/CD38+ cells in addition to CD34+/CD38- population and the extract was effective against the two LSCs populations. MTT assay showed that treated leukemic cells exhibited significant reduction in the viable cells in a dose dependent manner with IC50 of 3 µg/µl which was then confirmed by flow cytometry. Cell cycle analysis results showed significant reduction in the percentage of cells treated with L.C. extract in both the S and G0/G1 phases, with concomitant increase in the G2/M phase. Also, L.C. extract could effectively induce apoptosis, inhibit proliferation and suppress colonogenecity of leukemic cells.

CONCLUSION

This study validated the medicinal potential of L.C. leaves extract as a promising anti-leukemic agent targeting both LSCs and blasts in ALL patients, which may be explained by the synergy found between its potent flavonoids especially apigenin, luteolin and kaempferol.

Effect of phenolic compounds from the leaves of Psidium guajava on the activity of three metabolism-related enzymes

Enzyme activity modulation by synthetic compounds provide strategies combining the inhibitory and therapeutic mode of action of the confirmed inhibitors. However, natural modulators could offer a valuable alternative for synthetic ones for the treatment of different chronic diseases (diabetes, hypertension, cancer); due to the numerous side effects of the latter. In vitro screening assays were conducted for Psidium guajava leaf methanolic extract against three metabolism-related enzymes; α-amylase, tyrosinase, and hyaluronidase. The obtained results showed that the examined extract retained weak and moderate multitarget inhibition against α-amylase, tyrosinase, and hyaluronidase, respectively; however, the leaf fractions exhibited stronger inhibitions for the three investigated enzymes. Fractionation of P. guajava leaf extract revealed that anthraquinones and ellagic acid are of the major active compounds with inhibitory activities for α-amylase, tyrosinase, and hyaluronidase. Kinetic studies showed that quinalizarin inhibition is competitive for both α-amylase and hyaluronidase, and ellagic acid inhibition for tyrosinase and hyaluronidase is competitive and un-competitive, respectively. The molecular docking studies of quinalizarin and ellagic acid with α-amylase, tyrosinase, and hyaluronidase showed high binding energies with different bonds stabilizing the ligand-protein complex. Compiling all obtained results led to conclude that both P. guajava leaf fractions, quinalizarin and ellagic acid, have multitarget activities with potential therapeutic applications in many metabolic disorders.

Effect of phenolic compounds from the rind of Punica granatum on the activity of three metabolism-related enzymes

Enzyme activity modulation by synthetic compounds provide strategies combining the inhibitory and therapeutic mode of action of the confirmed inhibitors. However, natural modulators could offer a valuable alternative for synthetic ones for the treatment of different chronic diseases (diabetes, hypertension, cancer) due to the numerous side effects of the latter. In vitro screening assays were conducted for Punica granatum rind methanolic extract against three metabolism-related enzymes: α-amylase, tyrosinase, and hyaluronidase. The obtained results showed that the examined extract retained high multitarget inhibition with inhibition percentages 31.5 ± 1.3%, 75.9 ± 4.7%, and 68.5 ± 5.3% against α-amylase, tyrosinase, and hyaluronidase, respectively. Bioguided fractionation of P. granatum rind extract revealed that quercetin is the major active compound with inhibitory activities: 54.3 ± 2.7%, 94.2 ± 3.5%, and 90.9 ± 2.7% against α-amylase, tyrosinase, and hyaluronidase, respectively. Kinetic studies of enzymes showed that quercetin inhibition was noncompetitive, uncompetitive, and competitive for α-amylase, tyrosinase, and hyaluronidase, respectively. The molecular docking of quercetin with α-amylase and hyaluronidase showed high binding energy with different bonds stabilizing the ligand-protein complex. Compiling all obtained results led to conclude that both P. granatum rind extract and quercetin have multitarget activities with potential therapeutic applications in many metabolic disorders.