Biological effects of essential oils - A review

Screening of medicinal plant extracts for antioxidant activity

In vitro antioxidant activity and scavenging effects of Cinnamomum verum leaf extract assayed by different methodologies.

Historically, herbs and spices have enjoyed a rich tradition of use for their flavor enhancement characteristics and for their medicinal properties. The rising prevalence of chronic diseases worldwide and the corresponding rise in health care costs is propelling interest among researchers and the public for multiple health benefits related to these food items, including a reduction in cancer risk and modification of tumor behavior. A growing body of epidemiological and preclinical evidence points to culinary herbs and spices as minor dietary constituents with multiple anticancer characteristics. This review focuses on the antimicrobial, antioxidant, and antitumorigenic properties of herbs and spices; their ability to influence carcinogen bioactivation; and likely anticancer contributions. While culinary herbs and spices present intriguing possibilities for health promotion, more complete information is needed about the actual exposures to dietary components that are needed to bring about a response and the molecular target(s) for specific herbs and spices. Only after this information is obtained will it be possible to define appropriate intervention strategies to achieve maximum benefits from herbs and spices without eliciting ill consequences.

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The role of herbs and spices in cancer prevention

Dietary antioxidants protect laboratory animals against the induction of tumours by a variety of chemical carcinogens. Among possible mechanism of protection against chemical carcinogenesis could be mediated via-antioxidant-dependent induction of detoxifying enzymes. Curcumin, a yellow pigment from Curcuma longa, is a major component of turmeric and is commonly used as a spice and food colouring material and exhibits antiinflammatory antitumour, and antioxidant properties. In this study we therefore investigated the effect of dietary supplementation of curcumin on the activities of antioxidant and phase II-metabolizing enzymes involved in detoxification, and production of reactive oxygen species were quantified in ddY male mice. Dietary supplementation of curcumin (2%, w/v) to male ddY mice for 30 days significantly increased the activities of glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase and catalase to 189%, 179%, 189%, and 181% in liver and 143%, 134%, 167% and 115% in kidney respectively as compared with corresponding normal diet fed control (P<0.05-0.001). Parallel to these changes, curcumin feeding to mice also resulted in a considerable enhancement in the activity of phase II-metabolizing enzymes viz. glutathione S-transferase and quinone reductase to 1.7 and 1.8 times in liver and 1.1 and 1.3 times in kidney respectively as compared with corresponding normal diet fed control (P<0.05-0.01). In general, the increase in activities of antioxidant and phase II-metabolizing enzymes was more pronounced in liver as compared to kidney. The induction of such detoxifying enzymes by curcumin suggest the potential value of this compound as protective agent against chemical carcinogenesis and other forms of electrophilic toxicity. The significance of these results can be implicated in relation to cancer chemopreventive effects of curcumin against the induction of tumours in various target organs.

Dietary supplementation of curcumin enhances antioxidant and phase II metabolizing enzymes in ddY male mice: possible role in protection against chemical carcinogenesis and toxicity.

Cinnamomum cassia is used as a flavoring spice with some established medicinal properties. In this study, we evaluated the antimutagenic effect of C. cassia against two mutagens, viz. benzo[a]pyrene (B[a]P) and cyclophosphamide (CP). The antimutagenic properties of C. cassia were examined by the Ames test. In vivo chromosomal aberration (CA) and micronuclei tests were also employed to assess the antimutagenic effect of C. cassia in mice after pretreatment with the extract orally for seven consecutive days. To elucidate the mechanism by which C. cassia exerts its antimutagenic effect, certain key enzymes involved in bioactivation and detoxification processes were also investigated. Changes in liver cytochrome P450 (Cyt P450), glutathione content (GSH), glutathione S-transferase (GST), glutathione reductase (GR), and glutathione peroxidase (GPX) were evaluated in pretreated animals. It was observed in the Ames test, bone marrow chromosomal aberration assay, and micronucleus test that C. cassia exerted significant antimutagenic effects against B[a]P and CP in animals treated with the plant extract. C. cassia pretreatment decreased Cyt P450 content but increased GSH content and the activity of glutathione-dependent antioxidant enzymes, viz. GST, GR, and GPX. The present findings demonstrate that the antimutagenic potential of C. cassia could be attributed to its modulatory effect on the xenobiotic bioactivation and detoxification processes.

Inhibition of benzo[a]pyrene- and cyclophoshamide-induced mutagenicity by Cinnamomum cassia.

Benzo [α] pyrene (B[α]P) and cyclophosphamide (CP) are potent carcinogens/mutagens. Effect of Emblica officinalis extract administration on the in vivo genotoxi-city of B[α]P and CP was studied using bone marrow chromosomal aberration and micronucleus induction tests in mice.Three doses (50,250 and 500mg/kgbodyweight) oftheplant extractwere administered orallyfor 7 consecutive days prior to the administration of single dose of mutagens (B[α]P 125 mg/kg oral; CP 40 mg/kg i.p.).It was found that administration of 250 and 500 mg/kg of E. officinalis extract significantly inhibited the genotoxi-city of B [α] P as well as CP in both the assay systems. Administration of 50 mg/kg of the plant extract had no inhibitory effect.Vitamin C, a major constituent of E. officinalis when administered at dose level of 9 mg/kg b.w. (the approx-imate estimated amount present in the highest dose of plant extract, i.e. 500 mg) for 7 days did inhibit chromosomal aberrations and micronuclei induction, but not in a significant ma...

Inhibitory effect of Emblica officinalis on the in vivo clastogenicity of benzo[a]pyrene and cyclophosphamide in mice.

Aqueous extracts of Cassia occidentalis Linn. (Leguminoceae) and Emblica officinalis Gaertn. (Euphorbiaceae) were screened for effectiveness in inhibiting mutagenicity of aflatoxin B1 (AFB1) and benzo[a]-pyrene (B[a]P) in the Ames test. Antimutagenicity was evaluated using Salmonella typhimurium strains TA 98 and TA 100. In the assay, metabolic activation of AFB1 (0.5 μg/plate) and B[a]P (1 μg/plate) was mediated by rat liver S9 preparation. Although both plants inhibited mutagenicity, E. officinalis had more inhibitory effect than C. occidentalis. Their action is possibly mediated through interactions with micro somal activating enzymes. Their inhibitory action on chromosomal aberrations together with present results suggest that these plants have potent antimutagenic and anticarcinogenic activities against mutagens requiring metabolic activation.

In vitro inhibition of carcinogen-induced mutagenicity by Cassia occidentalis and Emblica officinalis.

Evidence that ferric nitrilotriacetate mediates oxidative stress by down-regulating DT-diaphorase activity: implications for carcinogenesis.

This study was conducted to determine the antimutagenic potential of aqueous extract of Cassia occidentalis against the chromosomal aberrations (CA) produced in vivo by benzo[a] pyrene (B[a]P) and cyclophosphamide (CP) in mice. Animals (male mice) were treated with three doses of plant extract (50mg/kg, 250mg/kg and 500mgAg) for 7 days prior to the administration of single dose of mutagens (B[a]P 125mg/kg oral; CP 40mg/kg i.p). The results indicated that C. occidentalis was not genotoxic per se and exerted no other toxic signs and symptoms in treated animals. The chromosomal aberrations produced by B[a]P and CP were significantly reduced (p < 0.001) by C. occidentalis pre-treatment. Furthermore, animals treated with plant extract showed a reduced level of cytochrome P 450 (Cyt P 450) and elevated levels of glutathione S-transferase (GST) activity and glutathione content in the liver. It seems that C. occidentalis exerts its antimutagenic activity by modulating the xenobiotic activation and detoxif...

Prashant Trikha

Papers

Inhibition of benzo[a]pyrene- and cyclophoshamide-induced mutagenicity by Cinnamomum cassia.

Inhibitory effect of Emblica officinalis on the in vivo clastogenicity of benzo[a]pyrene and cyclophosphamide in mice.

In vitro inhibition of carcinogen-induced mutagenicity by Cassia occidentalis and Emblica officinalis.

Evidence that ferric nitrilotriacetate mediates oxidative stress by down-regulating DT-diaphorase activity: implications for carcinogenesis.

Protective effect of Cassia occidentalis extract on chemical-induced chromosomal aberrations in mice.