Effect of chlorambucil on
potato subnormal germination and quality

Pro-Xylane is a sugar-protein hybrid made from xylose with anti-aging activity, which can induce the
biosynthesis of glycosaminoglycans in the superficial epidermis of the skin, promote the regeneration of collagen, and
is widely used in the cosmetics industry. In this paper, the preparation methods, biological activities and applications
of Pro-Xylane in cosmetics industry are reviewed.

Key words:

Pro-Xylane; biological activity; cosmetics

The structure of hydroxypropyl tetrahydropyranitol, a xylose derivative with anti-aging actives, is shown in Figure 1. glycosaminoglycan (GAG) secretion, induce GAG and proteoglycan (PG) biosynthesis in superficial epidermis, promote collagen synthesis, effectively promote epidermal-dermal tight junctions, and make the skin stronger and more elastic. Moreover, PX is non-toxic, easily biodegradable and does not accumulate in living organisms, so it is commonly used in cosmetics. In this paper, we review the preparation, biological activity and application of PX in cosmetics in recent years, in order to provide information and reference for the research and development and utilization of PX.

1.Preparation of PX

1.Preparation of PX
There are two main methods for the preparation of PX, one is the biosynthesis method, which has only been reported in a small amount of literature at home and abroad. Eddie Li, Gao-Gao disclosed a method for the preparation of PX by a one-pot method using biological enzymes, using xylose and isopropyl alcohol as substrates, under the catalytic action of isopropyl alcohol dehydrogenase, PX synthase, carbonyl reductase and coenzyme nicotinamide adenine dinucleotide to produce PX. Although the enzymes are specific and the purity of the products is high, the enzymes are difficult to select. The selection of enzymes is difficult, and enzyme proteins may be introduced during the reaction. The enzymes are difficult to select and may introduce enzyme proteins during the reaction, and some biocolloids may be produced.

A large number of production methods reported in the literature are chemical synthesis methods. cavezza et al. used xylose as raw material, condensation reaction with acetylacetone in alkaline aqueous solution, and then reduction of ketone carbonyl by the action of sodium borohydride to obtain PX. to avoid the complicated procedure of removing borates, Philippe et al. used D-xylose as raw material, condensation reaction with acetylacetone in the presence of sodium bicarbonate, conversion to C glycoside, and then the reduction of the carbonyl group by catalyst Ru/C to synthesize PX, the synthetic route is shown in
D-xylose can be sustainably sourced from beech trees, and the synthesis process is mainly a two-step process of C-glycosylation and catalytic hydrogenation, with environmentally friendly and low toxicity reaction conditions, which is regarded as the first successful example of green chemistry applied to cosmetics. This method realized the industrial development of PX, a new environmentally friendly active ingredient in cosmetics, and became the main production method of PX at present .

2.Biological activity of PX

In the literature, PX is reported to be a structure-specific compound  with the (β, S) conformation as the dominant conformation and its biological activity is much greater than that of the mixture of (β, S) and (β,R) conformations. Its steric structure has become the focus of current attention and research.

2.1 Promotion of GAG synthesis

GAG is a long-chain linear polysaccharide composed of repeating disaccharide units. GAG is a long-chain linear polysaccharide composed of repeating disaccharide units and is commonly found in the intracellular GAG is a long-chain linear polysaccharide composed of repetitive disaccharide units and is commonly found in the intracellular, cell surface and extracelluar matrix (ECM) of skin, including (HA), chondroitin sulfate (CS), dermatan sulfate (DS), keratin sulfate (DS), keratin sulfate (KS), acetyl heparin sulfate (HS) GAG absorbs moisture and GAG can absorb moisture and prevent the loss of moisture from the skin.
GAG can also form GAG-PG conjugates with PG, which affect cell proliferation, differentiation and the biological functions of different growth factors and functional proteins. GAG can also form GAG-PG conjugates with PG, affecting cell proliferation, differentiation and the biological functions of different growth factors and functional proteins. It can also form GAG-PG conjugates with PG and affect cell proliferation, differentiation and the biological functions of different growth factors and functional proteins, and is therefore important for skin repair and regeneration.

PX consists of xylose attached to a glycosidic ligand, which provides a binding site for soluble GAG and can initiate GAG production and assembly without relying on endogenous core proteins, greatly increasing free GAG levels. Pineau et al  found in an in vitro 3D reconstructed skin atrophy model induced by corticosteroids that PX induced an increase in the expression of the cell membrane HA receptor, CD44, in atrophic human skin. PX also acts on keratinocytes, enhancing their GAG synthesis and promoting fibroblast growth factor.
PX also acts on keratinocytes, enhances their GAG synthesis, promotes proliferation and migration of fibroblast growth factor 10 (FGF-10)-dependent cells, and has a positive role in epithelial repair. Emilie et al. used reconstructed dermal tissue as a model to demonstrate that PX increases GAG synthesis, which is beneficial for maintaining skin homeostasis and promoting skin tissue regeneration.

2.2 Promoting collagen regeneration

The junction between the epidermis and dermis of the skin is called the dermal-epidermal junction (DEJ), and aging of the skin leads to degradation of the ECM and changes in the DEJ, causing degradation of the mechanical properties of the skin and dermal damage.
PX acts at the DEJ to induce protein deposition and expression of DEJ structural function proteins, as well as to increase collagen type IV and VII expression, allowing GAG to populate the type IV collagen network, improving skin laxity due to aging and thus reducing wrinkles.
Juliette et al  evaluated the effect of PX on key proteins of DEJ and upper dermal components in an in vitro 3D reconstruction of a whole skin model. It was found that PX upregulated the deposition of key DEJ proteins such as type IV collagen, laminin 5, and type VII collagen. Type IV collagen is a major component of the BMZ dense plate, which enables the basement membrane to maintain normal nutrient and water transport.
Type VII collagen is the main component of the BMZ anchor fibers, which serve as an accessory structure connecting the dermis to the epidermis. In addition, type I procollagen and protofibrillar protein 1 were also observed to play an important role in protein and protofibrillar protein 1 was also observed to be upregulated. It has been shown that PX, in addition to stimulating GAG PX stimulates the expression of GAG and acetyl heparan sulfate proteoglycan (HS-PG) in addition to stimulating the expression of GAG acetyl heparan sulfate proteoglycan (HS-PG), PX induced a more regular morphological structure of DEJ, thus contributing to endogenous and exogenous skin aging. In addition to stimulating the expression of GAG and acetyl heparan sulfate proteoglycan (HS-PG), PX induced a more regular morphological structure of DEJ, thus improving endogenous and exogenous skin aging.

3.Application of PX in the field of cosmetics

PX is applied to the skin with three major effects: anti-aging, moisturizing, and repair. The biological phenomena of skin aging can be divided into two categories: endogenous aging and exogenous aging. Endogenous aging is caused by internal physiological factors and manifests as fine lines, epidermal thinning, and dermal atrophy caused by aging. Extrinsic aging is the effect of all external factors on the skin, such as UV light, pollution, and cigarette smoke exposure leading to deep wrinkles, skin laxity, and capillary dilation. Over the past 20 years years, aesthetic medicine has made significant progress in the field of combating age-related skin aging. significant progress has been made in the past 20 years in the field of age-related skin aging, and effective treatments now include botulinum injections, skin laser treatments, Botulinum toxin injections, skin laser treatments, and topical skin treatments. The latter focuses on small molecules or natural extracts such as retinol, estrogen, growth factors, and antioxidants.
PX is a cosmetic product synthesized from natural xylose as a starting material. xylose as the starting material for cosmetic products, PX is widely used in many skin care products, including common creams and special nanoformulations. The effectiveness of PX has been proven in several studies.

3.1 Moisturizing and repairing effect of PX

In addition to natural skin aging in postmenopausal women, estrogen deficiency leads to decreased collagen synthesis, skin atrophy [19], decreased skin elasticity, and increased skin dryness [20]. Anne et al. prepared a cream containing 3 % PX, 1 % hexanedione, 5 % hydroxyethyl urea (hydromancy), 5 % 4-hydroxyethyl piperazine ethanesulfonic acid (HEPES), and moisturizing ingredients (water, glycerol, Cyclopentasiloxane, stearic acid, butylene glycol). Butylene glycol), menopausal women used this combination product with the moisturizing ingredients alone
The clinical evaluation was performed after 60 d. Lee et al. found that a significant decrease in GAG and PG levels was strongly associated with skin wrinkle development and that PX stimulated GAG production and HS-PG expression to promote dermal repair, improve skin elasticity, and increase skin firmness.

3.2 Anti-aging effects of PX

Claire et al. applied a placebo and a cream containing 10 % PX on the lateral forearm of postmenopausal women aged 60-75 years, and skin biopsies were collected from the foreskin biopsies were collected from the forearm after 3 months, and the dermis was observed by transmission electron microscopy skin ultrastructural changes were observed by transmission electron microscopy, and it was found that the skin area treated with 10 % PX cream compared with the placebo dense plate of the true-epidermal junction compared to the placebo-treated skin area became more uniform and regular, and the morphological appearance of the DEJ showed a significant The morphological appearance of the DEJ showed a significant improvement.

Pineau et al investigated the role of PX in the synthesis of sulfated GAG and HS-PG through human skin cell cultures or exosome models. In human dermal fibroblast cultures, PX increased the synthesis of GAG to an extent that correlated with its dose. Studies using PX in a corticosteroid atrophic skin model showed a significant increase in HS-PG expression and synthesis in model skin, approaching normal skin levels, and increased cohesion at the epidermal and dermal-epidermal junctions, thereby alleviating signs of aging and maintaining a youthful appearance. Zoe et al. studied the use of a PX-containing product on the hand, arm, and facial skin of 20 women over 55 years of age with type II diabetes mellitus twice daily for 12 weeks. The study found that subjects with mild to moderate fine lines, wrinkles, and hyperpigmentation on the face and hands showed significant increases in skin thickness on the face and arms, and significant improvements in fine lines, firmness, skin tone, skin smoothness, and overall appearance with significant anti-aging efficacy of the product. Ning Jibin et al. prepared the product containing PX, HA and/or its salt, hydrolyzed HA and/or its salt, acetyl chitosan amine (HA precursor), de-
The complexes containing PX, HA and/or its salt, hydrolyzed HA and/or its salt, acetyl chitosan amine (HA precursor), deionized water, and ingredients with antiseptic effect or preservatives were prepared, and the synergistic effects of each component in terms of efficacy were fully utilized through appropriate proportioning, so that the complexes could strengthen skin DEJ, enhance the expression and content of ECM components such as collagen, PG, GAG by fibroblasts in the dermis, and improve skin elasticity and firmness, thus realizing the anti-aging function of the skin. Huang Wei prepared a PX-containing skin care cream with stable properties, excellent affinity to skin, and fast absorption, which can improve skin elasticity, reduce fine lines and improve overall skin aging with long-term use.
It can improve skin elasticity, reduce fine lines and improve overall skin aging with long-term use. Nanotechnology can reduce the particle size of cosmetic ingredients to facilitate their penetration into the deeper layers of the skin and thus better utilize their efficacy. Wei Wei et al. prepared nanoformulations containing active ingredients such as PX, retinyl retinoate, and soy isoflavones. The preparation exhibited significant anti-aging and wrinkle-removing effects. Eddie Li et al. prepared a nanoemulsion with a particle size of less than 200 nm, which could improve the bioavailability of PX. In addition, as PX was encapsulated by lipids and in the presence of collagen peptides
conditions, nanoliposomes were formed, which reduced the active ingredient’s contact with skin enzymes in the skin, making it less susceptible to hydrolysis and improving its action This reduces the contact between the active ingredient and the enzymes in the skin, making it less susceptible to hydrolysis and increasing its duration and effect.

4.Outlook

At present, with the rapid development of the cosmetics industry, safe and environmentally friendly cosmetic ingredients are receiving increasing attention. PX, as a kind of cosmetic raw material based on natural XXVI Food and Drug 2022, Vol. 24, No. 6 natural xylose as a starting material for cosmetic products, PX is widely used in It is widely used in a variety of skin care products. However, at this stage, the safety studies of PX Haudrey et al [29] reported a case of contact dermatitis caused by PX-containing anti-aging cream. The safety, efficacy, and biocompatibility of PX need to be more fully investigated. The safety, efficacy, and biocompatibility of PX need to be further and more comprehensively investigated with modern molecular The safety, efficacy, and biocompatibility of PX need to be further and more comprehensively studied. The research will be more perfect and its application prospect will be more broad.

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