4. Natural compounds in solar radiation protection: current knowledge

In recent years, many plant species have been investigated for their potential uses in the field of solar radiation protection, but much remains to be accomplished. As stated above, this depends on both a large number of under-investigated species and the lack of an official standard in vitro SPF evaluation method, to speed up the screening procedure. Depending on this, and on the many different and incomplete approaches led by different research groups, it is also complex to have a general picture of the existing knowledge. In the aim to achieve a "state of the art," we conducted a detailed bibliographic research on the plants already investigated in biological activities useful for sunscreen products.

In our previous investigation [2], we identified 54 plants, 5 lichens, and 14 pure molecules which have been studied in order to obtain herbal sunscreen products. It is remarkable how many plant extracts showed preliminary natural UV filter activity and, in the same manner, antioxidant properties and/or synergistic photoprotective effects.

Table 1 summarizes a selection of the abovementioned plants, lichens, and pure molecules which have been mentioned at least in two different types of research.


damages of the skin

Lichens are mentioned by several types of research [18–23] as natural sources of photoprotective compounds and phytocomplexes. Some examples of bioactive compounds obtained by lichens are epiphorelic acid I and II, salazinic acid, usnic acid, secalonic acid, and calycine. According to the studies regarding lichens, the main highlighted activities were antioxidant properties and broad-spectrum UV-absorbing capacity. Regarding pure molecules, quercetin and resveratrol have been widely investigated [7, 24–30] for their antioxidant, antiproliferative, and anti-inflammatory properties, including also UVA and UVB filter

UV light is recognized by the US National Institute of Environmental Health Sciences, as the main etiological agent of a large number of skin cancers, sunburns, and oxidative stress (US Tenth Report on Carcinogens). Despite controversial data about photo-irritation, photosensitization, and contact dermatitis, synthetic and mineral sunscreens are used to prevent UVinduced skin damage and are very common in several skin care formulations. More often than not, the etiology of a skin disease is multifactorial and includes DNA damages, inflammatory

enhancer activity.

n.r.—not reported.

Plant name Plant

Punica granatum Fruits,

Vaccinium myrtillus L. part(s) used

peel

Plant extract Type of

Silybum marianum Seeds n.r. Flavonolignans Silymarin, Silybin,

Vitis vinifera Seeds n.r. Polyphenols Flavan-3-ol derivatives,

methanol extract

Fruits n.r., water-

soluble extract

Table 1. Selection of plant extracts useful for sunscreen application.

compound(s)

Pongamia glabra Seeds n.r. n.r. Pongamol, karanjin UV absorber

Polyphenols, anthocyanins

Anthocyanidins, hydrolyzable tannins

Major constituent(s) Main effect(s)

Guidelines for the Development of Herbal-Based Sunscreen

http://dx.doi.org/10.5772/intechopen.72712

n.r. Reduction of UV

Decreases in the number of UVB-induced dimers in the human skin, synergic photoprotective activity in nanostrustured lipid

51

Inhibits UVB-induced damage, antioxidant

A-stimulated ROS formation, attenuation of UVA-caused peroxidation of membrane lipids, and depletion of intracellular

Free-radical-scavenging effect, prevents UVB- and UVC-induced lipid peroxidation, reducing the oxidative stress and

carrier

GSH

apoptosis

Delphinidin, cyanidin, and pelargonidin

silydianin, silychristin,

catechin, epicatechin, oligomeric proanthocyanidins

isosilybin

5. Strategies and solutions


Table 1. Selection of plant extracts useful for sunscreen application.

Lichens are mentioned by several types of research [18–23] as natural sources of photoprotective compounds and phytocomplexes. Some examples of bioactive compounds obtained by lichens are epiphorelic acid I and II, salazinic acid, usnic acid, secalonic acid, and calycine. According to the studies regarding lichens, the main highlighted activities were antioxidant properties and broad-spectrum UV-absorbing capacity. Regarding pure molecules, quercetin and resveratrol have been widely investigated [7, 24–30] for their antioxidant, antiproliferative, and anti-inflammatory properties, including also UVA and UVB filter enhancer activity.
