Efficacy and Tolerability of Topical Polyphenon E in Multiple "Seborrheic Keratosis-Like" Lesions of the Groin in an Immunocompetent 26-Year-Old Man

Injectable catechin-based supramolecular hydrogel for highly efficient application in HPV-associated OSCC

Catechins are a group of natural polyphenols extracted from green tea. Notably, they have been proven to have excellent anti-HPV and anti-tumour properties and to be effective against some HPV-related diseases, showing great potential in the treatment of HPV-associated oral squamous cell carcinoma (HPV⁺ OSCC). However, the poor bioavailability, short half-lives, and stability issues of catechins hamper their clinical application. To overcome these shortcomings of catechins, we innovatively synthesised an injectable supramolecular hydrogel, namely catechin-phenylenebisboronic acid-isoguanosine (CPBisoG), with catechin (one of the simplest catechins) and isoguanosine (isoG), another natural product with self-assembly ability, via dynamic phenylborate diester bonds. The biodegradation and sustained-release time of the CPBisoG hydrogel in mice lasted up to 72 h. This supramolecular hydrogel not only functioned as a good local drug delivery platform with good stability, injectability, self-healing properties, biocompatibility, biodegradability, but also exhibited therapeutic effects toward HPV⁺ OSCC in vitro and in vivo. And interestingly, it also showed selective inhibition against HPV⁺ OSCC cells. In all, these results demonstrate that this catechin-based hydrogel could sustainedly and highly effectively treat HPV⁺ OSCC topically, which could also provide a promising strategy for the management of other HPV-associated diseases in the future.

Nanoencapsulation of Tea Catechins for Enhancing Skin Absorption and Therapeutic Efficacy

Tea catechins are a group of flavonoids that show many bioactivities. Catechins have been extensively reported as a potential treatment for skin disorders, including skin cancers, acne, photoaging, cutaneous wounds, scars, alopecia, psoriasis, atopic dermatitis, and microbial infection. In particular, there has been an increasing interest in the discovery of cosmetic applications using catechins as the active ingredient because of their antioxidant and anti-aging activities. However, active molecules with limited lipophilicity have difficulty penetrating the skin barrier, resulting in low bioavailability. Nevertheless, topical application is a convenient method for delivering catechins into the skin. Nanomedicine offers an opportunity to improve the delivery efficiency of tea catechins and related compounds. The advantages of catechin-loaded nanocarriers for topical application include high catechin loading efficiency, sustained or prolonged release, increased catechin stability, improved bioavailability, and enhanced accumulation or targeting to the nidus. Further, various types of nanoparticles, including liposomes, niosomes, micelles, lipid-based nanoparticles, polymeric nanoparticles, liquid crystalline nanoparticles, and nanocrystals, have been employed for topical catechin delivery. These nanoparticles can improve catechin permeation via close skin contact, increased skin hydration, skin structure disorganization, and follicular uptake. In this review, we describe the catechin skin delivery approaches based on nanomedicine for treating skin disorders. We also provide an in-depth description of how nanoparticles effectively improve the skin absorption of tea catechins and related compounds, such as caffeine. Furthermore, we summarize the possible future applications and the limitations of nanocarriers for topical delivery at the end of this review article.

Applications of a Standardized Green Tea Catechin Preparation for Viral Warts and Human Papilloma Virus-Related and Unrelated Cancers

Most cell-based and animal experiments have shown that green tea catechins (GTC) exhibit various health benefits. In human experimental and epidemiological studies, there are conflicting results, and more precise investigations are required. One of the most effective ways to prove beneficial health effects in humans might be clinical intervention studies. Polyphenon^®E was developed as a standardized GTC preparation, which was approved by Food and Drug Administration of US in 2006 as a medication to treat genital warts (Veregen^® or sinecatechins). Positive efficacy of Polyphenon^®E/sinecatechins/Veregen^® (PSV) on anogenital warts has been demonstrated in several epidemiological studies and there have been several case reports to show the clinical effectiveness of PSV. In addition, several studies have provided evidence to suggest that PSV is effective in other human papillomavirus (HPV)-related diseases, although some studies failed to show such effects. Since (−)-epigallocatechin gallate (EGCG) is the major component of PSV, the mechanism of the action of PSV might be deduced from that of EGCG. The microarray analysis of the biopsy samples from the patients suggested that apoptosis induction and the downregulation of inflammation are involved in the mechanism of the action of PSV in the clearance of anogenital warts. Cell-based and animal experiments using PSV also demonstrated effects similar to those elicited by EGCG, explaining how PSV works to induce apoptosis and exert anti-inflammatory actions in HPV-related diseases. Future studies would clarify what kinds of diseases respond effectively to PSV, showing health benefits of GTC and EGCG in humans.

Great green tea ingredient? A narrative literature review on epigallocatechin gallate and its biophysical properties for topical use in dermatology

The purpose of this review is to examine epigallocatechin-3-gallate (EGCG) regarding its stability in different conditions (pH-value, concentration, temperature), its interactions with common cosmetic ingredients, and its application in the dermatological field. The literature research considered published journal articles (clinical trials and scientific reviews). Studies were identified by searching electronic databases (MEDLINE and PubMed) and reference lists of respective articles. Higher concentrations of EGCG were reported to correlate with better stability and the same can be said for low temperatures and pH values. The interaction between EGCG and hyaluronic acid strengthens its antioxidant activities. Titanium dioxide coated with EGCG proved a suitable ingredient in sunscreens. The polyphenol possesses antioxidant properties, which proved effective in the prevention of UV-induced skin damage and to alleviate the symptoms of Imiquimod-induced psoriasis. The three endpoints of this review not only showed interesting results but also highlighted some limitations of EGCG. Studies show that the molecule is unstable, which may hinder its dermatological and cosmetic applications. The reported interactions with cosmetic ingredients were limited. As the health aspects of EGCG are well-reported, ECGC has become a focus of interest for health professionals trying to treat common dermatological diseases.