M. Sarwar Alam

Oleanen and stigmasterol derivatives from Ambroma augusta

Abstract Augustic acid, a new oleanane derivative, and a stigmasterol glycoside were isolated from the roots of Ambroma augusta. Their structures were established as olean-12-en-2β,3β-diol-28-oic acid and stigmast-5,22-dien -3-O-α- d -glucopyranoside respectively, on the basis of full spectral analyses and chemical methods.

D-Limonene modulates inflammation, oxidative stress and Ras-ERK pathway to inhibit murine skin tumorigenesis.

d-Limonene, a common monoterepene has been shown to have antiproliferative, apoptosis-inducing and chemopreventive effects. In the present study, we have investigated the effects of d-limonene on the growth of 7,12-dimethylbenz[a]anthracene (DMBA)-initiated and 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted skin tumor development. We found that d-limonene (50 and 100 mg/kg body weight) treatments to the mouse skin significantly reduced the TPA-induced (a) edema and hyperplasia (p < 0.001); (b) expression of cyclooxygenase-2; (c) ornithine decarboxylase activity (p < 0.001); and (d) [3H] thymidine incorporation into DNA (p < 0.001). In addition, treatment of d-limonene effectively restored the level of reduced glutathione, glutathione peroxidase, glutathione reductase, glutathione S-transferase, catalase and malondialdehyde production in TPA-treated mouse skin. In a two-stage skin tumorigenesis study, d-limonene significantly reduced the tumor burden (p < 0.005) and tumor incidence as compared to DMBA/TPA-treated mice. d-Limonene treatment also extended the latency period of tumor development from 4 to 9 weeks. d-Limonene treatment decreased the expression level of Ras, Raf and phosphorylation of extracellular signal-regulated protein kinase 1/2 in DMBA/TPA-induced tumors. A decrease in the expression of Bcl-2 and an increase in Bax expression were also observed in tumor tissues of mice treated with d-limonene. Taken together, our findings suggest that d-limonene may exert its chemopreventive activity through the inhibition of inflammation, oxidative stress and Ras-signaling as well as the induction of pro-apoptotic state during TPA-mediated promotion of DMBA-induced skin cancer in mouse model.

Perillyl alcohol attenuates Ras-ERK signaling to inhibit murine skin inflammation and tumorigenesis.

In the present study, the chemopreventive effect of topical application of perillyl alcohol (POH) on 9,10-dimethylbenz(a)anthracene (DMBA)-initiated and 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted skin tumorigenesis and its possible mechanisms of action in Swiss albino mice were investigated. We evaluated the effect of pretreatment of POH (6 and 12 mg/kg body weight) on TPA (2 microg/200 microl of acetone)-induced skin edema, hyperplasia, peroxidase damage and modulation in activities of catalase, glutathione reductase, glutathione peroxidase, glutathione-S-transferase and reduced glutathione contents. Application of POH 30 min prior to TPA treatment, showed a protective effect in almost all the investigated parameters. Additionally, pretreatment with POH showed a significant inhibition of ornithine decarboxylase (ODC) activity and [(3)H] thymidine incorporation into epidermal DNA. In promotion phase, a significant reduction was found in tumor incidence and tumor burden in mice pretreated with POH (12 mg/kg body weight) with extension of the latency period from 4 to 8 weeks as compared to those treated with TPA alone. POH significantly suppressed the Ras/Raf/ERK pathway and induced apoptosis in Swiss albino mice skin. Our findings suggested that the chemopreventive efficacy of POH is probably due to the inhibition of oxidative stress responses, inhibition of the Ras cell proliferation pathway and induction of apoptosis in murine skin tumor promotion phase.

24β-Ethylcholest-4-en-3β-ol from the roots of Lawsonia inermis

Abstract A new sterol, namely lawsaritol, has been isolated from the roots of Lawsonia inermis. Its structure has been elucidated as 24β-ethylcholest-4-en-3β-ol on the basis of spectral analysis and chemical reactions.

Synthesis of novel steroidal D-ring substituted isoxazoline derivatives of 17-oxoandrostanes

A facile synthesis of isoxazoline derivatives of 17-oxoandrostane at the side chain of D-ring is reported. The scheme involves the transformation of the starting dehydroepiandrosterone acetate (ketone) to the Knoevenegel product, reduction to the nitrile, and elimination to the carboxaldehyde. Cycloaddition of nitrileoxides across olefinic aldehyde intermediate led to the synthesis of novel side chain isoxazoline derivatives.

Synthesis of novel 1,2,3-triazole based benzoxazolinones: their TNF-α based molecular docking with in-vivo anti-inflammatory, antinociceptive activities and ulcerogenic risk evaluation.

A library of novel bis-heterocycles containing benzoxazolinone based 1,2,3-triazoles has been synthesized using click chemistry approach. The compound 3f exhibited potent selective COX-2 inhibition of 59.48% in comparison to standard drug celecoxib (66.36% inhibition). The compound 3i showed significant (p < 0.001, 50.95%), TNF-α inhibitory activity as compared to indomethacin (p < 0.001, 64.01%). The results of the carrageenan induced hind paw oedema showed that compounds 3a, 3f, 3i, 3o, and 3e exhibited potent anti-inflammatory activity in comparison to Indomethacin. The molecular docking studies revealed that 3i exhibits strong inhibitory effect due to the extra stability of the complex because of an extra π-π bond. The histopathology report showed that none of the compounds caused gastric ulceration.

Progressive iron overload enhances chemically mediated tumor promotion in murine skin.

Iron overload has been shown to enhance chemically mediated cutaneous tumor promotion in animals. However, the majority of these animal studies have used high concentrations of iron before initiating tumor development. The current study was designed to evaluate the effect of small doses of iron on the promotion stage of chemically mediated cutaneous carcinogenesis. We found an increased tumor response in mice initiated with dimethylbenz(a)anthracene (DMBA) when iron at the dose levels of 0.5, 1.0, and 1.5mg/mouse was injected (intramuscularly) once a week into mice at the promotion stage of skin carcinogenesis, employing 12-O-tetradecanoyl phorbol-13-acetate (TPA)/benzoyl peroxide (BPO) as tumor promoter. The appearance of first papilloma and the number of tumors/mouse were recorded weekly. When compared to the control (non-iron-treated) group, the iron-treated groups showed an augmented incidence of tumors and number of tumors/mouse. In iron-treated mice, tumors appeared earlier than in the control group. TPA/BPO treatment resulted in a significant decrease in the activities of antioxidant enzymes and depletion in the level of epidermal reduced glutathione (GSH). TPA treatment in non-iron-treated mice resulted in approximately 20-40% decrease in GSH level and in the activities of antioxidant enzymes, whereas 1.5-mg iron treatment along with TPA treatment resulted in about approximately 30-70% decrease in GSH level and in the activities of antioxidant enzymes. Similarly, treatment of iron along with BPO treatment resulted in a dose-dependent higher depletion of GSH and the antioxidant enzymes as compared to non-iron-treated animals treated with BPO. Further, TPA/BPO-mediated induction in ornithine decarboxylase activity and [3H]thymidine incorporation in cutaneous DNA was approx two- to threefold higher in mice treated with iron as compared to non-iron-treated mice. Cutaneous lipid peroxidation and iron levels were also higher in mice treated with iron as compared to non-iron-treated mice. These data suggest that progressive iron overload can enhance the tumor promotion ability of TPA/BPO in DMBA-initiated murine skin.

URSANE AND STEROL DERIVATIVES FROM PLEUCHEA LANCEOLATA

Abstract Pleuchioside, a new ursane derivative and pleuchiol, a new stigmastanol derivative were isolated from the leaves of Pleuchea lanceolata . Their structures have been established as urs-3α,19α,20β-triol and stigmasta-5,11 12-dien-3p-ol, respectively, on the basis of full spectral analyses and chemical methods.

Isolation and Characterization of a Dihydroxysterol from Lawsonia inermis

Abstract A new dihydroxysterol, named Lawsaritol A (1), has been isolated from the roots of Lawsonia inermis and its structure has been elucidated by spectral analysis and chemical evidences.

Normethyl pentacyclic and lanostane-type triterpenes from Adiantum venustum.

Phytochemical studies on the aerial parts of Adiantum venustum resulted in the isolation of normethyl lupane-type, a normethyl oleanane-type and a lanostane-type triterpene. Structures of these triterpenes have been established as 30-normethyl lupane-20-one, 30-normethyl olean-3-one-30 beta-ol and lanost-20(22)-ene-30-ol on the basis of spectral data analyses and chemical methods.