A study on the photodynamic properties of chlorophyll derivatives using human hepatocellular carcinoma cells

Abstract

Photodynamic therapy (PDT) is an alternative anticancer treatment in which direct tumor-cell killing results from selective accumulation of photosensitizers in the tumor sites and phototoxicity occurs when light-activated photosensitizers transfer the energy to oxygen nearby to produce singlet oxygen. The objective of this study was to investigate the effects of PDT using chlorophyll derivatives such as pheophytin a (phe a), pheophytin b (phe b), pheophorbide a (pho a) and pheophorbide b (pho b) as the photosensitizers, and the 660 nm light-emitting diodes (LEDs) irradiation on human hepatocellular carcinoma cells (HuH-7). The drug concentration-dependent inhibition of HuH-7 cell viability was studied under LEDs irradiation (10 mW cm(-2)) at radiant exposure of 5.1 and 10.2 J cm(-2) by MTT assay. Significant inhibition of the survival of HuH-7 cells (<10%) was observed when an irradiation dose of 10.2 J cm(-2) combined with the concentration of 0.5 microg ml(-1) of phe a, 0.125 microg ml(-1) of pho a, 0.25 microg ml(-1) of phe b, and 0.125 microg ml(-1) of pho b were applied. The results from Annexin V-propidium iodide staining revealed that phe a, phe b, pho a and pho b could induce cell death in HuH-7 cells predominantly via a necrotic process. The results from immunoblot analyses exhibited that chlorophyll derivative-mediated PDT initiated cytochrome c release, caspase-9 and caspase-3 activation, followed by poly ADP-ribose polymerase (PARP) cleavage. Thus, apoptosis also occurred in HuH-7 cells after PDT treatment, and the execution of the apoptotic process may be initiated from the loss of mitochondrial function. Our findings demonstrate that both apoptosis and necrosis can be induced in HuH-7 cells after PDT using phe a, phe b, pho a and pho b and LEDs.

Photo-activated pheophorbide-a, an active component of Scutellaria barbata, enhances apoptosis via the suppression of ERK-mediated autophagy in the estrogen receptor-negative human breast adenocarcinoma cells MDA-MB-231

“…PDT was reported to inhibit cancers through different cell death pathways and its effectiveness is dependent on the types of cancer cell lines and photosensitizers (Buytaert et al, 2007;Zuluaga and Lange, 2008). Previous studies on the potential of Pa as a photosensitizer have suggested that Pa is effective to inhibit cancer growth by the induction of apoptosis (Inanami et al, 1999;Hajri et al, 1999;Hajri et al, 2002;Lee et al, 2004;Lim et al, 2004;Tang et al, 2006;Li et al, 2007;Radestock et al, 2007;Kishino et al, 2008;Rapozzi et al, 2009;Tang et al, in press-a,b). We speculated that the apoptosis is a general anti-tumor mechanism of Pa-PDT on human cancers.…”

“…Pa has been commercial available as it can be purified from a number of traditional medicine sources such as Scutellaria barbata, Psychotria acuminata, as well as silkworm excreta (Glinski et al, 1995;Lim et al, 2002;Chan et al, 2006). Previous studies have suggested that the therapeutic potential of Pa-mediated photodynamic therapy (Pa-PDT) on leukaemia, pigmented melanoma, colonic cancer, hepatoma and uterine carcinosarcoma (Hajri et al, 2002;Lee et al, 2004;Lim et al, 2004;Tang et al, 2006;Li et al, 2007;Tang et al, in press-a).…”

The c-MET/PI3K Signaling Is Associated with Cancer Resistance to Doxorubicin and Photodynamic Therapy by Elevating BCRP/ABCG2 Expression

“…Pba was shown to cause mitochondria-dependent apoptosis in cultured cancer cells (Tang et al, 2009). In vivo animal models also demonstrated that Pba impedes tumor growth in colon carcinoma and hepatoma xenograft models (Hajri et al, 2002;Li et al, 2007). However, the development of PDT resistance has been displayed: colon cancer cells repeatedly exposed to PDT agents developed resistance to PDT (Singh et al, 2001).…”

Steroids from the Whole Plants of Leucaena Leucocephala

“…Investigation on the MeOH extract of the plants has led to the isolation of 14 compounds, four steroids: 5α, 8α-epidioxy-(24ξ)-ergosta-6,22-dien-3β-ol (1) (Figure 1) [3], β-sitosterol (2) (Figure 2) [4], β-sitostenone (3) (Figure 3) and stigmastenone (4) (Figure 4) [5] ; one terpenoid: lupeol (5) [6]; one glyceride: 1,3-dipalmitoyl-2-oleoylglycerol (6) [7]; one alkanoid: linoleic acid (7) [8]; two benzenoids:  methylparabene (8) [9] and isovanillic acid (9) [10]; and five chlorophylls: pheophytin-a (10) [11], pheophorbide a methyl ester (11) [12], methyl-13 2 -hydroxy-(13 enriched with acetone to furnish 10 fractions (1-1 to 1-10). Fraction 1-1 (1.72 g) was re-subjected to Si gel chromatography, eluting with n-hexane/acetone (80:1) to obtain linoleic acid (7) (58 mg, 0.0357%).…”