**4.4 Antioxidants**

Free radical theory is an important theory of aging [7]. Oxidative stress significantly influence the aging process and longevity. The use of antioxidants to combat aging has received considerable interest [16]. Several antioxidants (e.g., resveratrol and curcumin) are currently under investigation.

#### **4.5 Autophagy inducers**

Defects in autophagy have been linked to several diseases that can impact aging and lifespan. Maintenance of a proper autophagic activity with autophagy inducers has the potential to extent longevity [16, 20, 21]. Autophagy inducers include nonpharmacologic tools (e.g., caloric restriction and exercise) and several nutritional supplements and approved drugs (e.g., vitamin D, resveratrol, metformin, and rapamycin) (non-exhaustive list). Novel and more specific autophagy-inducing drugs are under investigation.

#### **4.6 Senolytic drugs**

Senescence is a common feature occurring in several tissues and organs during the aging process. Senotherapy represents a promising new therapeutic area [16, 19, 22, 23]. Senolytics are a class of drugs (e.g., dasatinib, quercetin, fisetin, and navitoclax) that selectively clear senescent cells. Several clinical studies are currently planned or ongoing. Results from early pilot studies suggest that senolytic drugs can decrease senescent cells, reduce inflammation, and alleviate frailty.

#### **4.7 Stem cell therapy**

Stem cell therapy represents a new emerging era in medicine (**Figure 14**) [16–18]. It has the potential to delay the aging process and, therefore, extend longevity, by better treating chronic diseases and degenerative conditions that impact lifespan.

#### **Figure 14.**

*Stem cell therapy has the potential to delay the aging process and extend longevity (Picture downloaded from the internet "Google Images").*
