D-limonene: A multifunctional compound with potent therapeutic effects.

D-limonene or 4-isopropenyl-1-methylcyclohexene (C10 H16 ) is a monocyclic monoterpene abundant in citrus plants like lemon, orange, and grape. The application of D-limonene in the form of flavor and fragrance additive in perfumes, soaps, foods, and beverages is consistently increased due to its high-quality fragrance property. This review is intended to analyze and delineate every possible available evidence and details about D-limonene with the special focus on its therapeutic efficacy. Many studies have reported that D-limonene effectively plays a valuable role in the prevention of several chronic and degenerative diseases. This review provides worthy information about the beneficial effects of D-limonene such as antioxidant, antidiabetic, anticancer, anti-inflammatory, cardioprotective, gastroprotective, hepatoprotective, immune modulatory, anti-fibrotic, anti-genotoxic etc. This could in turn help in the application of D-limonene for clinical studies. PRACTICAL IMPLICATIONS: Various plant families contain Terpenes as their secondary metabolites. Monoterpenes constitute an important part of these secondary metabolites. D-limonene is a well-identified monoterpene that is commonly applied as a fragrance ingredient in essential oils. D-limonene is known to possess remarkable biological activities. It can be effectively used for treating various ailments and diseases. Due to its diverse functions, it can be efficiently utilized for human health.

The Anticancer Role of Capsaicin in Experimentallyinduced Lung Carcinogenesis.

OBJECTIVES: Capsaicin (CAP) is the chief pungent principle found in the hot red peppers and the chili peppers that have long been used as spices, food additives and drugs. This study investigated the anticancer potential of CAP through its ability to modify extracellular matrix components and proteases during mice lung carcinogenesis. METHODS: Swiss albino mice were treated with benzo(a) pyrene (50 mg/kg body weight dissolved in olive oil) orally twice a week for four successive weeks to induce lung cancer at the end of 14(th) week. CAP was administrated (10 mg/kg body weight dissolved in olive oil) intraperitoneally. Extracellular matrix components were assayed; Masson's trichome staining of lung tissues was performed. Western blot analyses of matrix metalloproteases 2 and 9 were also carried out. RESULTS: In comparison with the control animals, animals in which benzo(a)pyrene had induced lung cancer showed significant increases in extracellular matrix components such as collagen (hydroxy proline), elastin, uronic acid and hexosamine and in glycosaminoglycans such as hyaluronate, chondroitin sulfate, keratan sulfate and dermatan sulfate. The above alterations in extracellular matrix components were effectively counteracted in benzo(a)pyrene along with CAP supplemented animals when compared to benzo(a) pyrene alone supplemented animals. The results of Masson's trichome staining for collagen and of, immunoblotting analyses of matrix metalloproteases 2 and 9 further supported the biochemical findings. CONCLUSION: The apparent potential of CAP in modulating extracellular matrix components and proteases suggests that CAP plays a chemomodulatory and anti- cancer role working against experimentally induced lung carcinogenesis.

Potential preventive effect of carvacrol against diethylnitrosamine-induced hepatocellular carcinoma in rats.

Antioxidants are one of the key players in tumorigenesis, several natural and synthetic antioxidants were shown to have anticancer effects. The aim of the present study is to divulge the chemopreventive nature of carvacrol during diethylnitrosamine (DEN)-induced liver cancer in male wistar albino rats. Administration of DEN to rats resulted in increased relative liver weight and serum marker enzymes aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and gamma glutamyl transpeptidase (γGT). The levels of lipid peroxides elevated (in both serum and tissue) with subsequent decrease in the final body weight and tissue antioxidants like superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), glutathione peroxidase (GPx), and glutathione reductase (GR). Carvacrol supplementation (15 mg/kg body weight) significantly attenuated these alterations, thereby showing potent anticancer effect in liver cancer. Histological observations and transmission electron microscopy studies were also carried out, which added supports to the chemopreventive action of the carvacrol against DEN-induction during liver cancer progression. These findings suggest that carvacrol prevents lipid peroxidation, hepatic cell damage, and protects the antioxidant system in DEN-induced hepatocellular carcinogenesis.

Potent antitumor and antineoplastic efficacy of baicalein on benzo(a)pyrene-induced experimental pulmonary tumorigenesis.

Current study aims to evaluate the efficacy of baicalein (BE), a naturally occurring bioactive flavanoid (5,6,7-trihydroxy-flavone), at a dose of 12 mg/kg body wt in Swiss albino mice exposed to tobacco-specific carcinogen benzo(a)pyrene [B(a)P] (50 mg/kg body wt) for its ability to mitigate pulmonary adenoma formation and growth. Under coarse observation, B(a)P-administered mice, after 16 weeks, developed macroscopically detectable tumors, whereas oral treatment with BE to the lung cancer-induced mice significantly reduced tumor incidence in 16-week pre- and posttreated groups. A detailed histopathological examination of lung was conducted to determine the degree of cancer progression. Incidence of anaplasia, hyperplasia, dysplasia, severe dysplasia, and adenocarcinoma were evident in carcinogen-administrated group in 6, 10, 12, 14, and 16th weeks, respectively, whereas these anomalies were effectively reduced after pre- and posttreatment with BE. In the pretreatment group, BE significantly arrested tumor multiplicity by approximately 65% and tumor load by approximately 88%, while in the posttreatment, the compound significantly reduced the tumor multiplicity by approximately 48% and tumor load by approximately 61%. Further analysis of serum tumor markers like carcinoembryonic antigen, CK 19 fragments (CYFRA 21-1), and tissue marker enzymes like aryl hydrocarbon hydroxylase, adenosine deaminase, γ-glutamyl transpeptidase, 5'-nucleotidase, and lactate dehydrogenase in serum and lung homogenate was carried out to substantiate the anticarcinogenic effect of BE. The overall data from our experiments suggested that BE significantly inhibited pulmonary adenoma formation and growth, thus revealing its potent antitumorigenic effect.

Antiproliferative and antioxidant potential of beta-ionone against benzo(a)pyrene-induced lung carcinogenesis in Swiss albino mice.

Nowadays, in developing countries like India, incidence of lung cancer is increasing rapidly, and as a consequence it has become the most common cause of malignancy-associated death. This study is aimed to evaluate the therapeutic efficacy of beta-ionone (ION), a precursor for carotenoids against benzo(a)pyrene [B(a)P]-induced lung carcinogenesis. B(a)P (50 mg/kg body weight, orally twice a week for 4 successive weeks)-induced lung cancer in mice was assessed both in tissue and serum in terms of increase LPO and tissue marker enzymes, such as aryl hydrocarbon hydroxylase, γ-glutamyl transpeptidase, 5'-nucleotidase, and lactate dehydrogenase, and serum tumor markers such as carcinoembryonic antigen and neuron-specific enolase with concordant decrease in activities of tissue enzymic and non-enzymic antioxidants were observed on the treatment of ION (60 mg/kg body weight, orally twice a week for 16 weeks) significantly attenuated LPO and restored all cancer marker enzymes and antioxidants levels to near normal, which indicates the anticancer effect of ION. This was further confirmed by histological staining of argyrophilic nucleolar organizer region and histopathological analysis of lung tissue, immunohistochemical and immunoblot analysis of proliferating cell nuclear antigen. Overall findings suggested that the ION effectively ameliorated the lung carcinogenesis, which is attributed to the antiproliferative and antioxidant potential through free radical scavenging property.

The neuroblastoma ALK(I1250T) mutation is a kinase-dead RTK in vitro and in vivo.

Activating mutations in the kinase domain of anaplastic lymphoma kinase (ALK) have recently been shown to be an important determinant in the genetics of the childhood tumor neuroblastoma. Here we discuss an in-depth analysis of one of the reported gain-of-function ALK mutations-ALK(I1250T)-identified in the germ line DNA of one patient. Our analyses were performed in cell culture-based systems and subsequently confirmed in a Drosophila model. The results presented here indicate that the germ line ALK(I1250T) mutation is most probably not a determinant for tumor initiation or progression and, in contrast, seems to generate a kinase-dead mutation in the ALK receptor tyrosine kinase (RTK). Consistent with this, stimulation with agonist ALK antibodies fails to lead to stimulation of ALK(I1250T) and we were unable to detect tyrosine phosphorylation under any circumstances. In agreement, ALK(I1250T) is unable to activate downstream signaling pathways or to mediate neurite outgrowth, in contrast to the activated wild-type ALK receptor or the activating ALK(F1174S) mutant. Identical results were obtained when the ALK(I1250T) mutant was expressed in a Drosophila model, confirming the lack of activity of this mutant ALK RTK. We suggest that the ALK(I1250T) mutation leads to a kinase-dead ALK RTK, in stark contrast to assumed gain-of-function status, with significant implications for patients reported to carry this particular ALK mutation.

Hesperidin attenuates mitochondrial dysfunction during benzo(a)pyrene-induced lung carcinogenesis in mice.

The present study is designed to assess the mitochondrial status during benzo(a)pyrene (B(a)P)-induced lung carcinogenesis in Swiss albino mice and to reveal the modulatory effect of hesperidin over it. B(a)P (50 mg/kg body weight)-induced mitochondrial abnormalities was evident from alterations in mitochondrial lipid peroxides, antioxidant status (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, reduced glutathione, vitamin E, and vitamin C), major tricarboxylic acid (TCA) cycle enzyme activities (isocitrate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, alpha-ketoglutarate dehydrogenase), electron transport chain (ETC) complexes activities and ATP levels. Ultrastructural changes in lung mitochondria were also in accord with the above aberrations. Hesperidin (25 mg/kg body weight) supplementation effectively counteracted all the above changes and restored cellular normalcy, indicating its protective role during B(a)P-induced lung cancer.

Appearance of the novel activating F1174S ALK mutation in neuroblastoma correlates with aggressive tumor progression and unresponsiveness to therapy.

Mutations in the kinase domain of the ALK kinase have emerged recently as important players in the genetics of the childhood tumor neuroblastoma. Here, we report the appearance of a novel ALK mutation in neuroblastoma, correlating with aggressive tumor behavior. Analyses of genomic DNA from biopsy samples initially showed ALK sequence to be wild type. However, during disease progression, mutation of amino acid F1174 to a serine within the ALK kinase domain was observed, which correlated with aggressive neuroblastoma progression in the patient. We show that mutation of F1174 to serine generates a potent gain-of-function mutant, as observed in 2 independent systems. First, PC12 cell lines expressing ALK(F1174S) display ligand-independent activation of ALK and further downstream signaling activation. Second, analysis of ALK(F1174S) in Drosophila models confirms that the mutation mediates a strong, rough eye phenotype upon expression in the developing eye. Thus, we report a novel ALK(F1174S) mutation that displays ligand-independent activity in vivo, correlating with rapid and treatment-resistant tumor growth. The study also shows that initial screening in the first tumor biopsy of a patient may not be sufficient and that further molecular analysis, in particular in tumor progression and/or tumor relapse, is warranted for better understanding of the treatment of neuroblastoma patients.

Modulatory effect of hesperidin on benzo(a)pyrene induced experimental lung carcinogenesis with reference to COX-2, MMP-2 and MMP-9.

Hesperidin is a naturally occurring flavonoid that has been reported to possess anticancer effects. The purpose of this study is to evaluate the effect of hesperidin in modulating the expressions of cyclooxygenase-2 (COX-2), mast cells (MCs) and matrix metalloproteinases (MMPs) during benzo(a)pyrene (B(a)P) induced lung carcinogenesis in mice. B(a)P (50 mg/kg body weight) induced animals showed increased mast cell density (MCD) as revealed by toluidine blue staining and severe expression of COX-2 along with upregulated expression of MMP-2 and MMP-9 as revealed by Western blotting and immunohistochemistry. Supplementation of hesperidin (25 mg/kg body weight) to lung cancer bearing mice attenuated MCD and downregulated the expressions of COX-2, MMP-2 and MMP-9. These observations show that hesperidin exerts its anti-carcinogenic activity against lung cancer by altering the expressions of COX-2, MMP-2 and MMP-9.

Chemopreventive task of capsaicin against benzo(a)pyrene-induced lung cancer in Swiss albino mice.

A voluminous number of evidence suggests that an increased consumption of fruits and vegetables is a relatively easy and practical strategy to reduce significantly the incidence of cancer. The present study is an effort to identify the chemopreventive role of alkaloid capsaicin against benzo(a)pyrene-induced lung cancer in Swiss albino mice. Benzo(a)pyrene-induced lung cancer-bearing animals showed abnormal changes in body weight, lung weight, tumour incidence and alterations in the activities of marker enzymes adenosine deaminase, aryl hydrocarbon hydroxylase, gamma-glutamyl transpeptidase, 5'-nucleotidase and lactate dehydrogenase. On capsaicin pre-co-treatment, all the above alterations were returned to near normal. Immunohistochemical analysis of proliferating cell nuclear antigen together with lung histological examination further supported our biochemical findings that demonstrated the chemoprotective role of capsaicin against benzo(a)pyrene-induced experimental lung cancer.

Antioxidant and anticancer efficacy of hesperidin in benzo(a)pyrene induced lung carcinogenesis in mice.

Chemoprevention is regarded as one of the most promising and realistic approaches in the prevention of cancer. Several bioactive compounds present in fruits and vegetables have revealed their cancer curative potential on lung cancer. Hesperidin is one such naturally occurring flavonoid widely found in citrus fruits. The aim of the present study is to divulge the chemopreventive nature of hesperidin during benzo(a)pyrene (B(a)P) induced lung cancer in Swiss albino mice. Administration of B(a)P (50 mg/kg body weight) to mice resulted in increased lipid peroxides (LPO), lung specific tumor marker carcinoembryonic antigen (CEA) and serum marker enzymes aryl hydrocarbon hydroxylase (AHH), gamma glutamyl transpeptidase (GGT), 5'nucleotidase (5'ND) and lactate dehydrogenase (LDH) with concomitant decrease in the levels of tissue antioxidants like superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH), vitamin E and vitamin C. Hesperidin supplementation (25 mg/kg body weight) significantly attenuated these alterations thereby showing potent anticancer effect in lung cancer. Further the antiproliferative effect of hesperidin was confirmed by histopathological analysis and proliferating cell nuclear antigen (PCNA) immunostaining. Overall, these findings substantiate the chemopreventive potential of hesperidin against chemically induced lung cancer in mice.

Silymarin attenuated mast cell recruitment thereby decreased the expressions of matrix metalloproteinases-2 and 9 in rat liver carcinogenesis.

Liver cancer is the sixth most common cancer worldwide but because of very poor prognosis, it is the third most common cause of death from cancer. There are currently limited therapeutic regimens available for effective treatment of this cancer. Silymarin is a naturally derived polyphenolic antioxidant, is the active constituent in a widely consumed dietary supplement milk thistle (Silybum marianum) extract. Mast cells play an important role in the inflammatory component of a developing neoplasm; they are also a major source for matrix metalloproteinases (MMPs), which are involved in invasion and angiogenesis. In the present study, we investigated whether dietary supplementation of silymarin has any role in mast cell density (MCD) and in the expressions of MMP-2 and MMP-9 in N-nitrosodiethylamine induced (NDEA) liver cancer in Wistar albino male rats. NDEA administered rats showed increased MCD as revealed by toluidine blue staining along with upregulated expressions of MMP-2 and MMP-9. Silymarin treatment inhibited this increase in MCD and downregulated the expressions of MMP-2 and MMP-9 as revealed by Western blotting and immunohistochemistry. In conclusion, silymarin exerted beneficial effects on liver carcinogenesis by attenuating the recruitment of mast cells and thereby decreased the expressions of MMP-2 and MMP-9.

Antiproliferative potential of gallic acid against diethylnitrosamine-induced rat hepatocellular carcinoma.

One of the focuses in current cancer chemoprevention studies is the search for nontoxic chemopreventive agents that inhibit the initiation of malignant transformation. Cancer biomarkers are quantifiable molecules involved in the physiologic or pathologic events occurring between exposure to carcinogens and the development, progression of cancer. Biomarkers may be the consequence of a continuous process, such as increased cell mass, or a discrete event, such as genetic mutation. Analysis of tumor markers can be used as an indicator of tumor response to therapy. Gallic acid is a naturally available polyphenol, possess strong antioxidant activity with a capacity to inhibit the formation of tumors in several cancer models. In the present study, we investigated the antiproliferative effect of gallic acid during diethylnitrosamine (DEN)-induced hepatocellular carcinoma (HCC) in male wistar albino rats. DEN treatment resulted in increased levels of aspartate transaminase, alanine transaminase, alkaline phosphatase, acid phosphatase, lactate dehydrogenase, gamma-glutamyltransferase, 5'-nucleotidase, bilirubin, alpha-fetoprotein, carcinoembryonic antigen, argyophillic nucleolar organizing regions, and proliferating cell nuclear antigen. Gallic acid treatment significantly attenuated these alterations and decreased the levels of AgNORs and PCNA. These finding suggests that gallic acid is a potent antiproliferative agent against DEN-induced HCC.

Silymarin downregulates COX-2 expression and attenuates hyperlipidemia during NDEA-induced rat hepatocellular carcinoma.

Silymarin is a naturally available bioflavonoid and is a strong antioxidant with a capacity to inhibit the formation of tumors in several cancer models. In the present study, we investigated whether dietary supplementation of silymarin has any role in lipid components, lipid-metabolizing enzymes, free fatty acid profile, and expression of cyclooxygenase-2 (COX-2) in N-nitrosodiethylamine (NDEA)-induced hepatocellular carcinoma in rats. NDEA-induced rats showed severe hyperlipidemia along with upregulated expression of COX-2 as revealed by western blotting and immunohistochemistry. Dietary silymarin supplementation attenuated this hyperlipidemia and downregulated the expression of COX-2. Thus we conclude that compounds like silymarin with potent hypolipidemic effect are strong candidates as chemopreventive agents for the treatment of liver cancer.

The effects of quercetin on antioxidant status and tumor markers in the lung and serum of mice treated with benzo(a)pyrene.

Chemoprevention has emerged as a very effective preventive measure against carcinogenesis. Several bioactive compounds present in fruits and vegetables have revealed their cancer curative potential on benzo(a)pyrene (B(a)P) induced carcinogenesis. In the present study, the efficacy of quercetin on the level of lipid peroxides, activities of antioxidant enzymes and tumor marker enzymes in B(a)P induced experimental lung carcinogenesis in Swiss albino mice was assessed. In lung cancer bearing animals there was an increase in lung weight, lipid peroxidation and marker enzymes such as aryl hydrocarbon hydroxylase, gamma glutamyl transpeptidase, 5'-nucleotidase, lactate dehydrogenase and adenosine deaminase with subsequent decrease in body weight and antioxidant enzymes-superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, glutathione reductase, reduced glutathione, vitamin E and vitamin C. Quercetin supplementation (25 mg/kg body weight) attenuated all these alterations, which indicates the anticancer effect that was further confirmed by histopathological analysis. Overall, the above data shows that the anticancer effect of quercetin is more pronounced when used as an chemopreventive agent rather than as a chemotherapeutic agent against B(a)P induced lung carcinogenesis.