shikonin and naphthazarin

Pathological scarring is an intractable problem for both patients and clinicians. A major obstacle for the development of scar remediation therapies is the paucity of suitable in vivo and in vitro models. The "Scar-in-a-jar" model was previously established by our colleagues based on the principle of "Macromolecular crowding". This has been demonstrated to be an extracellular matrix-rich in vitro model offering a novel tool for studies related to the extracellular matrix. In the study reported herein, we have optimised this approach to model human dermal fibroblasts derived from hypertrophic tissues. This optimised in vitro model has been found to hold similar properties, such as increased collagen I, interleukins and transforming growth factor beta-1 expression, compared to that observed in hypertrophic scar tissue in vivo. In addition, Shikonin has been previously demonstrated to hold potential as a novel hypertrophic scar treatment due to its apoptosis-inducing property on hypertrophic scar fibroblasts. Other Shikonin analogues have also been reported to hold apoptosis-inducing properties in various cancer cell lines, however, the effects of these analogues on hypertrophic scar-related cells are unknown. We therefore evaluated the effects of Shikonin and its analogues on hypertrophic scar-derived human fibroblasts using the optimised "Macromolecular crowding" model. Our data indicates that Shikonin and Naphthazarin are the most effective molecules compared to related naphthoquinones. The data generated from the study offers a novel in vitro collagen-rich model of hypertrophic scar tissue. It also provides further evidences supporting the use of Shikonin and Naphthazarin as potential treatments for hypertrophic scars.

Topics: Animals; Apoptosis; Cell Line; Cicatrix; Cicatrix, Hypertrophic; Collagen; Extracellular Matrix; Fibroblasts; Humans; Models, Biological; Naphthoquinones; Skin

To minimize the cytotoxicity of shikonin and alkannin that arises through the generation of reactive oxygen species (ROS) and alkylation of the naphthazarin ring, two series of novel core-scaffold-modified shikonin and alkannin derivatives were designed. These derivatives, which differ in their configurational and positional isomerism (R-, S-, and 2- and 6-isomers) were synthesized in high enantiomeric excess (>99 % ee). The selectivity of the dimethylated derivatives was significantly higher than the parent shikonin in vitro, but some side effects were still observed in vivo. Surprisingly, the dimethylated diacetyl derivatives with poor anticancer activity in vitro showed tumor-inhibiting effects similar to paclitaxel without any toxicity in vivo. The anticancer activity of these derivatives is in agreement with their low ROS generation and alkylating capacity, emphasizing their potential as prodrugs. This strategy provides means to address the nonspecific cytotoxicity of naphthazarin analogues toward normal cells.

Topics: Alkylation; Animals; Antineoplastic Agents; Cell Line, Tumor; Cell Survival; Drug Design; Female; Male; Mice; Microsomes, Liver; Naphthoquinones; Neoplasms; Prodrugs; Rats; Reactive Oxygen Species; Stereoisomerism; Structure-Activity Relationship; Transplantation, Heterologous; Transplantation, Homologous

Naturally occurring gums and resins with beneficial pharmaceutical and nutraceutical properties were tested for their possible protective effect against copper-induced LDL oxidation in vitro. Chiosmastic gum (CMG) (Pistacia lentiscus var. Chia resin) was the most effective in protecting human LDL from oxidation. The minimum and maximum doses for the saturation phenomena of inhibition of LDL oxidation were 2.5 mg and 50 mg CMG (75.3% and 99.9%, respectively). The methanol/water extract of CMG was the most effective compared with other solvent combinations. CMG when fractionated in order to determine a structure-activity relationship showed that the total mastic essential oil, collofonium-like residue and acidic fractions of CMG exhibited a high protective activity ranging from 65.0% to 77.8%. The other natural gums and resins (CMG resin 'liquid collection', P. terebinthus var. Chia resin, dammar resin, acacia gum, tragacanth gum, storax gum) also tested as above, showed 27.0%-78.8% of the maximum LDL protection. The other naturally occurring substances, i.e. triterpenes (amyrin, oleanolic acid, ursolic acid, lupeol, 18-a-glycyrrhetinic acid) and hydroxynaphthoquinones (naphthazarin, shikonin and alkannin) showed 53.5%-78.8% and 27.0%-64.1% LDL protective activity, respectively. The combination effects (68.7%-76.2% LDL protection) of ursolic-, oleanolic- and ursodeoxycholic- acids were almost equal to the effect (75.3%) of the CMG extract in comparable doses.

Topics: Cholesterol, LDL; Dose-Response Relationship, Drug; Gum Arabic; Humans; Karaya Gum; Mastic Resin; Naphthoquinones; Oils, Volatile; Oxidation-Reduction; Pigments, Biological; Pistacia; Plant Extracts; Resins, Plant; Structure-Activity Relationship; Triterpenes

Alkannin and shikonin, two natural products from Alkanna tinctoria and Lithospermum erhythrorhizon (Boraginaceae), are used in folk medicine where they are claimed to possess, among other properties, wound healing and anti-inflammatory activity. We investigated, together with the structurally related naphthazarin, their in vitro antioxidant and hydroxyl radical scavenging activity as well as their in vivo antiinflammatory activity. I was found that all examined compounds significantly inhibited in vitro lipid peroxidation of ra hepatic microsomal membranes, competed with DMSO for free hydroxyl radicals, and reduced inflammation (mouse paw edema induced by FCA) very efficiently. The examined compounds proved equal or superior to the common reference compounds for each of these properties. I is concluded that the claimed and/or proven actions of alkannin and shikonin are attributable at least partly to their intervention in free radical processes.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Dimethyl Sulfoxide; Edema; Female; Free Radical Scavengers; Freund's Adjuvant; Lipid Peroxidation; Naphthoquinones; Rats; Rats, Inbred F344

beta-Alkannin (shikonin), a compound isolated from the root of Lithospermum erythrorhizon Siebold Zucc., has been used as a purple dye in ancient Japan and is known to exert an anti-inflammatory activity. This study aimed to understand the biological activity in terms of physico-chemical characteristics of beta-alkannin. Several physico-chemical properties including proton dissociation constants, half-wave potentials and molecular orbital energy of beta-alkannin were elucidated. This compound shows highly efficient antioxidative activities against several types of reactive oxygen species (ROS), such as singlet oxygen ((1)O2). superoxide anion radical (.O2), hydroxyl radical (.OH) and tert-butyl peroxyl radical (BuOO.) as well as iron-dependent microsomal lipid peroxidation. During the reactions of beta-alkannin with 1O2, .O2- and BuOO., intermediate organic radicals due to beta-alkannin were detectable by ESR spectrometry. Compared with the radicals due to naphthazarin, the structural skeleton of beta-alkannin, the beta-alkannin radical observed as an intermediate in the reactions with (1)O2, and .O2- was concluded to be a semiquinone radical. On the other hand, during the reactions of beta-alkannin and naphthazarin with BuOO., ESR spectra different from the semiquinone radical were observed, and proposed to result from the abstraction of hydrogen atoms from phenolic hydroxyl groups of beta-alkannin by BuOO.. Based on the ROS-scavenging abilities of beta-alkannin, the compound was concluded to react directly with ROS and exhibits antioxidative activity, which in turn exerts anti-inflammatory activity.

Topics: Acetonitriles; Anti-Inflammatory Agents, Non-Steroidal; Deuterium Oxide; Electron Spin Resonance Spectroscopy; Free Radical Scavengers; Free Radicals; Lipid Peroxidation; Molecular Structure; Naphthoquinones; Peroxides; Plants, Medicinal; Potentiometry; Reactive Oxygen Species; Spin Trapping