Rajendra Gyawali

Chemical Composition and Antiproliferative Activity of Supercritical Extract of Citrus grandis (L.) Osbeck Fruits from Korea

Abstract Constituents of supercritical CO2 extracts of peel and flesh from pummelo fruits (Citrus grandis Osbeck) were analyzed by gas chromatography-mass spectrometry (GC-MS). In total, 69 constituents were identified while 42 were common in both samples. The identified major constituents are 7-Methoxy-8- (2-oxo-3-methylbutyl) coumarin (11.4 %), (6E,8E,10E)-2,6,11,15-tetramethyl-2,6,8,10,14-hexadecapentaene (5.9 %) and γ-sitosterol (5.1 %) in peel and hexadecanoic acid (10.0 %), (E,E)-2,4-decadienal (6.3 %) and pentacosane (7.0 %) in flesh extracts. Antiproliferative activity, determined by cell viability assay and cellular morphology observation, revealed that 400 μg/ml concentration of peel extract possesses significant efficacy and potency for inhibition of human cervical carcinoma HeLa and gastric adenocarcinoma AGS cells.

Supercritical Fluid Extraction of Citrus iyo Hort. ex Tanaka Pericarp Inhibits Growth and Induces Apoptosis Through Abrogation of STAT3 Regulated Gene Products in Human Prostate Cancer Xenograft Mouse Model.

Activation of signal transducer and activator of transcription 3 (STAT3) is well known to play a major role in the cell growth, survival, proliferation, metastasis, and angiogenesis of various cancer cells. Most of the citrus species offer large quantities of phytochemicals that have beneficial effects attributed to their chemical components. Our study was carried out to evaluate the anticancer effects of the pericarp of Iyokan (Citrus iyo Hort. ex Tanaka), locally known as yeagam in Korea, through modulation of the STAT3 signaling pathway in both tumor cells and a nude mice model. The effect of supercritical extracts of yeagam peel (SEYG) on STAT3 activation, associated protein kinases, STAT3-regulated gene products, cellular proliferation, and apoptosis was examined. The in vivo effect of SEYG on the growth of DU145 human prostate xenograft tumors in athymic nu/nu male mice was also investigated. We found SEYG exerted substantial inhibitory effect on STAT3 activation in human prostate cancer DU145 cells as compared to other tumor cells analyzed. SEYG inhibited proliferation and downregulated the expression of various STAT3-regulated gene products such as bcl-2, bcl-xL, survivin, IAP-1/2, cyclin D1, cyclin E, COX-2, VEGF, and MMP-9. This correlated with an increase in apoptosis as indicated by an increase in the expression of p53 and p21 proteins, the sub-G1 arrest, and caspase-3-induced PARP cleavage. When administered intraperitoneally, SEYG reduced the growth of DU145 human prostate xenograft tumors through downmodulation of STAT3 activation in athymic nu/nu male mice. Overall, these results suggest that SEYG extract has the potential source of STAT3 inhibitors that may have a potential in chemoprevention of human prostate cancer cells.

Citrus unshiu leaf extract containing phytol as a major compound induces autophagic cell death in human gastric adenocarcinoma AGS cells

The pharmaceutical potential of the methanolic extract of Citrus unshiu leaves (MECL) was assessed through analysis of its inhibitory effect on cancer cells. The antiproliferative activities of the leaves were evaluated using several cancer cell lines and considerable cytotoxicity was observed in human gastric adenocarcinoma AGS cells. Inhibition of AGS cell viability was both time- and dose-dependent, and MECL induced non-apoptotic cell death. AGS cells treated with MECL increased the formation of acidic vesicular organelles and GFP-LC3 puncta. Pretreatment with an autophagy inhibitor, 3-methyladenine, inhibited MECL-induced cell death. These results indicated that the mechanism underlying the anticancer effects of MECL in AGS cells could be via the induction of autophagic cell death. The major compounds of MECL were identified as phytol, 4-ethenyl-2-methoxyphenol, hexadecanoic acid, 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one, and vitamin E using gas chromatography–mass spectrometry. These results indicate that C. unshiu leaves can be exploited for numerous pharmaceutical applications as a source of anticancer ingredients.