From the Guidelines

Astringent toner has no therapeutic benefits.

The provided evidence does not mention astringent toner, instead, it focuses on the effects of various beverages and compounds on advanced glycation end-products (AGE) formation and accumulation.
There is no direct link between astringent toner and therapeutic benefits in the given text.
However, the evidence suggests that certain compounds, such as polyphenols found in tea, coffee, and some plant extracts, have anti-AGE activity and may have therapeutic benefits in reducing AGE formation and accumulation 1.
These compounds, including catechins, chlorogenic acid, and quercetin, have been shown to inhibit AGE formation, reduce oxidative stress, and have anti-inflammatory properties.
The evidence also highlights the importance of a healthy diet and lifestyle in reducing AGE formation and accumulation, and suggests that drinking no-added-sugar beverages enriched with inhibitors of the Maillard reaction may be a beneficial nutritional strategy 1.

From the Research

Astringent toner has been shown to have various therapeutic benefits, including improving skin hydration 2, reducing oiliness 3, and exhibiting antioxidant, anti-inflammatory, and antimicrobial activities 4, 5.
The use of a comprehensive skin care routine that includes a toner has been found to outperform a simple routine in improving superficial hydration, deep hydration, skin roughness, and reducing crow's feet wrinkle depth 6.
A study on the anti-sebum efficacy of guava toner found that it significantly reduced oiliness on the forehead and nose, making it a suitable daily application for improving skin efficacy 3.
Plant extracts, such as those found in astringent toners, have been found to have beneficial effects on the skin, including moisturizing, anti-aging, antimicrobial, antioxidant, anti-inflammatory, regenerative, wound healing, photoprotective, and anti-tyrosinase activity 4.
Gallic acid, a phenolic phytochemical found in some astringent toners, has been found to exhibit powerful antioxidant, anti-inflammatory, antimicrobial, and anti-cancer activities, making it a useful ingredient in cosmetic formulations 5.

The application of cream and toner successively has been found to have little effect on skin hydration, but repeated application of toner can be efficacious for skin hydration 2.
Astringent toner has been found to reduce oiliness on the forehead and nose, making it a suitable daily application for improving skin efficacy 3.

Plant extracts and gallic acid have been found to be useful ingredients in cosmetic formulations due to their beneficial effects on the skin 4, 5.
The use of astringent toner as part of a comprehensive skin care routine can provide various therapeutic benefits, including improving skin hydration and reducing oiliness 6, 2, 3.