An evaluation of the effectiveness of azelaic acid as a depigmenting and chemotherapeutic agent

Biosynthesis of Odd-Carbon Unsaturated Fatty Dicarboxylic Acids Through Engineering the HSAF Biosynthetic Gene in Lysobacter enzymogenes

Fatty dicarboxylic acids (FDCA) are useful as starting materials or components for plastics, polyesters, nylons, and fragrances. Most of the commercially available FDCA contain an even number of carbons, and there remain few sustainable methods for production of FDCA with an odd number of carbons (o-FDCA). In this work, we explored a novel biosynthetic route to unsaturated o-FDCA. The approach was based on genetic modifications of hsaf pks-nrps, encoding a hybrid polyketide synthase-nonribosomal peptide synthetase (PKS-NRPS) in Lysobacter enzymogenes, an environmental bacterium emerging as a new biocontrol agent. This single-module PKS-NRPS catalyzes the biosynthesis of lysobacterene A, a polyene-containing precursor of the antifungal natural product Heat-Stable Antifungal Factor (HSAF). We genetically removed the NRPS module from this gene and generated a new strain of L. enzymogenes, in which the PKS module was fused to the thioesterase domain of hsaf pks-nrps. The chimeric gene was verified by DNA sequencing, and its expression in L. enzymogenes was confirmed by reverse transcription-polymerase chain reaction (RT-PCR). The total fatty acids were extracted, esterified, and analyzed by GC-MS. The results showed that the engineered strain produced new fatty acids that were absent in the wild type. The main product was identified as hepta-2,4-dienedioic acid, an unsaturated o-FDCA. This work sets the foundation to explore a sustainable and environment-friendly approach toward unsaturated o-FDCA, which could be used as precursors for new compounds that can serve as versatile feedstock for industrial materials.

Cosmeceutical Aptitudes of Azelaic Acid

BACKGROUND

Azelaic acid (AZA) is a white crystalline dicarboxylic acid naturally found in grains, rye and barley. AZA has substantial biological and therapeutic abilities (viz a viz) its anti-inflammatory, anti-oxidant, anti-keratinizing, anti-microbial properties, etc. which contribute to its applicability in the management of mild to harsh dermatological complications (acne, rosacea, dermatitis, hyper-pigmentation, carcinomas, etc.). AZA has shown its effectiveness against varied non-inflammatory and inflammatory lesions by normalizing the hyper-keratinization statie and attenuating the increased levels of microbial content. Topically AZA, either alone or in conjunction with other active moieties, has proved to be effective in preventing acne and several other hyper-pigmentary conditions.

OBJECTIVES

Chronic applicability of AZA has been evidenced with the effects like itching, burning, stinging, redness, etc. To deal with the former issues, research is being conducted to substitute the conventional formulations with novel preparations (liposome's, niosomes, micro sponges, lipid nanocarriers, etc.), which could enhance the overall pharmaceutical and pharmacological profile of the drug.

CONCLUSION

This article is an attempt to highlight the basic physiochemical properties of AZA, its physiological role (especially in dermatology), various commercial preparations and recent novel approaches that are in research with an aim to augment the therapeutic and safety profile of AZA.

The combination of 2% 4-hydroxyanisole (Mequinol) and 0.01% tretinoin is effective in improving the appearance of solar lentigines and related hyperpigmented lesions in two double-blind multicenter clinical studies

BACKGROUND

Solar lentigines are a chronic condition of the aging population resulting from years of cumulative sun exposure. A topical treatment that is both safe and effective would be welcome and useful. Combinations of therapeutic agents are often used and allow synergy of mechanisms with tolerability. A tyrosinase inhibitor in use in Europe, 4-hydroxyanisole (Mequinol), and the retinoid tretinoin have been used singly as depigmenting agents.

OBJECTIVE

The efficacy and safety of the combination product of 2% 4-hydroxyanisole (4HA [mequinol]) /0.01% tretinoin solution (tradename Solagé) were evaluated in two phase III, randomized, controlled, double-blind trials.

METHODS

Subjects were randomized to treatment with 4HA/tretinoin solution, one of the active components (4HA or tretinoin), or vehicle. Subjects applied the test solution with a wand applicator twice daily to all solar lentigines and related hyperpigmented lesions on the face, forearms, and backs of hands for up to 24 weeks. Trial 1 had a 24-week no-treatment regression phase and trial 2 had a 4-week no-treatment regression phase. Information collected included clinical assessments of Target Lesion Pigmentation, Physician's Global Assessment of Improvement/Worsening, an Assessment of Overall Cosmetic Effect, and a Subject's Self-Assessment Questionnaire.

RESULTS

The 4HA/tretinoin combination was clinically superior to each of its active components and to the vehicle in the treatment of solar lentigines. At the end of treatment, in trial 1 and trial 2, 4HA/tretinoin was statistically superior to each of its active components and vehicle on the forearms and face (P </=.03), except versus tretinoin on the face in trial 2 (P =.2). In trial 2, a trend toward greater efficacy of 4HA/tretinoin over tretinoin on the face was demonstrated at the end of treatment (P =.2), which was also increasingly evident at the end of the 4-week follow-up (P =.06). Most skin-related adverse events were mild and were similar for both the 4HA/tretinoin and tretinoin treatment groups.

CONCLUSION

For the treatment of solar lentigines and related hyperpigmented lesions, the topical combination product containing 2% 4HA/0.01% tretinoin solution is well tolerated and superior to either active component.

Inhibitory effect of azelaic acid on neutrophil functions: a possible cause for its efficacy in treating pathogenetically unrelated diseases

It has been shown that acne, hyperpigmentation and lentigo malignant are more or less related pathogenetically to reactive oxygen species (ROS). It has recently been reported that azelaic acid is effective in treating these conditions and that it possesses anti-enzymatic and antimitochondrial activity, including cytochrome-P450 reductase and 5 alpha-reductase in microsomal preparations with nicotinamide adenine dinucleotide phosphate (NADPH). We therefore investigated the effects of azelaic acid on human neutrophil functions, such as chemotaxis, phagocytosis and ROS generation. ROS generation in a cell-free system was also assessed. The results revealed that neutrophil chemotaxis and phagocytosis as well as ROS generated in a xanthine-xanthine-oxidase system were not significantly changed in the presence of azelaic acid. However, azelaic acid markedly decreased O2- and OH. generated by neutrophils. It may be concluded that the reported clinical effectiveness of azelaic acid is partly due to its inhibitory action on neutrophil-generated ROS, leading to a reduction both in oxidative tissue injury at sites of inflammation and in melanin formation.

Azelaic acid. A review of its pharmacological properties and therapeutic efficacy in acne and hyperpigmentary skin disorders

Azelaic acid is a naturally occurring saturated dicarboxylic acid which, on topical application (usually as a 20% cream), has been shown to be effective in the treatment of comedonal acne and inflammatory (papulopustular, nodular and nodulocystic) acne, as well as various cutaneous hyperpigmentary disorders characterised by hyperactive/abnormal melanocyte function, including melasma and, possibly, lentigo maligna. In addition, azelaic acid has an antiproliferative and cytotoxic effect on the human malignant melanocyte, and preliminary findings indicate that it may arrest the progression of cutaneous malignant melanoma. The mechanism of this selective cytotoxic action of azelaic acid is unclear, but may possibly be related to its inhibition of mitochondrial oxidoreductase activity and DNA synthesis. In controlled studies, topical azelaic acid demonstrated comparable anti-acne efficacy to topical tretinoin, benzoyl peroxide, erythromycin and oral tetracycline, while in patients with melasma azelaic acid proved at least as effective as topical hydroquinone. On topical application azelaic acid is well tolerated, with adverse effects apparently limited to a generally mild and transient local cutaneous irritation. Thus, topical azelaic acid, employed either as monotherapy or in combination with other treatments, is likely to prove of value in the management of acne and several hyperpigmentary disorders, most notably melasma.

Azelaic acid

This review is an update on the literature accumulated over the past 10 years following the original observation that azelaic acid, a naturally occurring and nontoxic C9 dicarboxylic acid, possesses significant biologic properties and a potential as a therapeutic agent. These studies have shown that azelaic acid is a reversible inhibitor of tyrosinase and other oxidoreductases in vitro and that it inhibits mitochondrial respiration. It can also inhibit anaerobic glycolysis. Both in vitro and in vivo it has an antimicrobial effect on both aerobic and anaerobic (Propionibacterium acnes) microorganisms. In tissue culture it exerts a dose- and time-dependent cytotoxic effect on malignant melanocytes, associated with mitochondrial damage and inhibition of deoxyribonucleic acid (DNA) synthesis. Tumoral cell lines not containing tyrosinase are equally affected. Normal cells in culture exposed to the same concentrations of the diacid that are toxic for tumoral cells are in general not damaged. Radioactive azelaic acid has been shown to penetrate tumoral cells at a higher level than normal cells of the corresponding line. Topically applied (a 20% cream), it has been shown to be of therapeutic value in skin disorders of different etiologies. Its beneficial effect on various forms of acne (comedogenic, papulopustular, nodulocystic) has been clearly demonstrated. Particularly important is its action on abnormal melanocytes, which has led to the possibility of obtaining good results on melasma and highly durable therapeutic responses on lentigo maligna. It is also capable of causing regression of cutaneous malignant melanoma, but its role in melanoma therapy remains to be investigated.(ABSTRACT TRUNCATED AT 250 WORDS)

Pigment change and melanocyte distribution in guinea pig skin after cutaneous freeze injury

Cryosurgery has been recommended for the treatment of cutaneous neoplasms, including benign and malignant melanocytic tumors. The main side effect of this treatment is pigment disruption which may be prolonged. There are no quantitative studies on melanocyte distribution after freeze injury. In this study the effect of standardized freeze times on melanocytes in guinea pig skin (tricolored) is described at the anatomic level and at the light and electron microscopic level. Melanocytes are quantified in epidermal sheets following dopa staining at 1-, 2-, and 3-month intervals after freezing. All the lesions were initially hypopigmented with a peripheral rim of hyperpigmentation. This was a transient phenomenon associated with an absence of melanocytes. Pigment migrated into the lesions so that after 3 months all the lesions on black skin were diffusely hyperpigmented. Pigment was slower to return to the red skin. Hair follicles were destroyed in the center of the lesion. The epidermal sheets demonstrated that the hyperpigmentation was an epidermal phenomenon and was associated with increased numbers of melanocytes (p less than 0.001). These melanocytes were distributed evenly throughout the lesion in contrast to the irregular distribution in normal skin.