**8. Natural antioxidants: role against aging**

Role of antioxidants in quenching ROS has been appreciated for a long time. Recently, a 15 yearlong study showed that ROS formation could be lessened by 10% in people aged 45 or above by simply having an antioxidant rich diet [71].

Antioxidants are compounds that quench the free radicals by providing an electron and generating stable compounds that are less harmful to a cell. In this manner they inhibit the train of events that occur when free radicals oxidize other biomolecules. Antioxidants can be classified into different categories based on enzymatic/ non-enzymatic activity, occurrence, solubility although other miscellaneous molecules displaying antioxidant properties have also been reported. Examples of certain regular antioxidants found in a cell involve Superoxide dismutase (SOD), Glutathione peroxidase (GPx) and Catalase (CAT). Non-enzymatic antioxidants include Vitamin E, C, thioredoxin, glutathione and melatonin. Further antioxidants such as minerals (Cu, Zn, Mn, Se), other vitamins, polyphenols and carotenoids are also derived from regular diet [72].

Usually, cells maintain a fine balance between ROS formation and their quenching by resident antioxidants. But, UVR shift the balance towards ROS formation resulting in a phenomenon called 'Oxidative stress', where resident antioxidants become incapable of quenching the high amount of ROS formed [73]. This state can however be circumvented by additional antioxidant supplementation. Drawbacks of synthetic antioxidants such as toxicity, low solubility, cost and a presumed negative outlook towards chemical products have increased the demand for natural antioxidants [74]. These antioxidants are naturally available in numerous sources like vegetables, fruits, spices, herbs, edible mushrooms among others [75]. Furthermore, beverages derived from these sources are also rich in antioxidants and have gained increased populace especially among younger generation.

Till date, several pure phytochemicals and plant-based compounds have been reported for their antioxidant and anti-photoaging activity. We have tried to summarize some important phytochemicals as potential antioxidant and anti-photoaging agents in **Tables 1** and **2**.

### **8.1 Beverages as source of antioxidants**

Various beverages, specifically mixed juices have abundant antioxidants as they are made using various fruits and vegetables [86]. Other beverages like coffee and


*Skin Aging: Implications of UV Radiation, Reactive Oxygen Species and Natural Antioxidants DOI: http://dx.doi.org/10.5772/intechopen.100102*

#### **Table 1.**

*Pure phytochemicals and their anti-photoaging properties.*

tea also include antioxidants and can help alleviate photoaging signs. Green tea is enriched in bioactive compounds like methyl-xanthins, flavon-3-ols and catechins such as (−)-epicatechin (EC), (−)-epicatechin-3-gallate (ECG), (−)-epigallocatechin (EGC) and (−)-epigallocatechin-3-gallate (EGCG). EGCG can inhibit erythema and neutrophil infiltration in the skin induced by UVR [87]. Drinking Green tea can ameliorate other photoaging markers like increased numbers of dermal cysts, sebaceous glands enlargement, vacuole formation and increased epidermal thickness. Green tea polyphenols are also elemental in decreasing MMP-2, 3, 7 and 9 levels along with reduced oxidation and carbonylation of proteins upregulated under UVR [88, 89]. Polyphenols and Chlorogenic acid found in coffee can help avoid free radical associated diseases. Reduction in pigmentation spots induced under UV was seen in Japanese women who consumed coffee at a higher rate [90]. *Coffee Arabica* leaf extracts are rich in caffeic acid, chlorogenic acid and phenols. These bioactive compounds help lower MMP-1, 3 and 9 expressions while elevating type I procollagen production. Further, a decrease p-ERK, p-JNK and p-p38 levels has also been shown thereby effectively blocking UV induced activation of key signaling pathways [91].


**Table 2.**

*Plant-derived phytocompounds having antioxidant and anti-photoaging activity.*

A diterpenoid, Atractyligenin found in Coffee silverskin has been shown to decrease ROS levels by 62% post UV treatment, modulate MMP-1, 2, 3 expressions, inhibit activation of MAPK pathways and increase Endo180 receptor expression [92].
