## 5 Plant Compounds and Longevity  
Human longevity has dramatically increased during the last century thanks to the great health advances that have significantly reduced premature deaths. However, although the rate of aging of the population is high, life expectancy has not followed the same degree of improvement [162]. Aging is a multifactorial process that includes numerous mechanisms, such as the shortening of telomeres, systemic inflammation, oxidative stress, and a deficiency of cellular energy, mainly due to autophagy and mitochondrial dysfunction, causing cells to enter a state of senescence and cellular cycle arrest [163]. In fact, many of the molecular mechanisms underlying aging coincide with the same altered pathways responsible for diseases such as cancer, neurodegeneration, or cardiovascular disease [164]. Assessing the potential effects of plant compounds on longevity is complex, since the process requires the entire life cycle of the studied subjects to be followed, something which is difficult in the case of organisms with a high life expectancy, such as mammals. In the case of humans, various epidemiological studies have shown a direct relationship between the high consumption of plant products with a higher life expectancy and a lower prevalence of non-communicable diseases. In this sense, the Mediterranean diet has long been linked to healthy aging and greater longevity [165; 166; 167; 168]. A study conducted in an area of Sardinia, Italy, where there is one of the highest concentrations of centenarians in the world, related this fact to an improvement in the quality of the diet associated with the nutrition transition, maintaining, however, a high consumption of fruits and vegetables and a moderate meat intake [169]. In addition, a recent meta-analysis of prospective cohort studies has revealed significant inverse associations between the low consumption of fruits and/or vegetables with all-cause mortality [170]. Another interesting study analyzed the relation between food habits and all-cause mortality in the old Chinese population (\(\geq\)80 years) [171]. Similarly to the Mediterranean diet, the consumption of fruits and vegetables was inversely associated with higher mortality risk. Another fascinating case of study is the long life of the Hunza people, who live in a remote and pristine area of the Himalayas, north of Pakistan [172; 173]. This population lives in peace, happy and without stresses,and consumes a moderate quantity of fruits and vegetables. They do not consume any processed foods, which could be related to low levels of oxidative stress and oxidative-related disorders. Altogether, this could contribute to the good health and high life expectancy of this group of people. Most studies on the ability of different plant compounds to extend lifespan have been developed in a nematodal model organism for aging processes, specifically, using the roundworm _Caenorhabditis elegans_. In an interesting approach, the effects of the quasimoid (degraded triterpene lactone) glaucarubinone, which is present in several species of the plant family _Simaroubaceae_, were investigated [174]. Treatment with glaucarubinone significantly extended _C. elegans_ lifespan in a process mediated by induction of the mitochondrial metabolism and the reduction of fat accumulation. Concretely, glaucarubinone has been shown to increase oxygen consumption, as measured with a Clark-type electrode. The authors suggest that the increased oxygen consumption also increases the production of mitochondrial ROS, which can act as cellular messengers, inducing endogenous antioxidant defense and longevity. The effects of 4-hydroxy-E-globularinin (4-HEG), an iridoid present in _Premina integrifolia_, usually used in the Indian medicine, were assayed in _C. elegans_[175]. 4-HEG treatment increased longevity in the worm and improved the resistance to paraquat-induced oxidative stress.