ReviewBioactive compounds and health benefits of some palm species traditionally used in Africa and the Americas – A review
Introduction
Palms (Arecaceae/Palmae) have a pantropical distribution and inferred origins in the tropical rain forest (Baker and Couvreur, 2013, Dransfield et al., 2008). Their diversification started during the mid-Cretaceous period of Laurasia, about 100 million years ago (Couvreur et al., 2011), with recent (Miocene) increase in these diversification rates, mainly from a South American source of dispersing lineages (Baker and Couvreur, 2013). Among 760 palm species found in the Americas, the popular and traditional medicinal use of 106 species is known (Macía et al., 2011, Sosnowska and Balslev, 2009), while 23 species belonging to 11 genera were described in African palm ethno-medicine, especially against infections/infestations and digestive system disorders (Gruca et al., 2015).
Palms play a prominent role in the history of food and agriculture, from ancient times to the present. Many of these species are an important source of oils, and the oil palm (Elaeis guineensis Jacq.) is a major oil producer (May and Nesaretnam, 2014). As a portable source of both food and water, Cocos nucifera L. (coconut) has played a critical role in the ability of humans to voyage, establish trade routes and colonise lands, while it continues to have hundreds of commercial uses (Gunn et al., 2011). The earliest records of Phoenix dactylifera L. (date palm) cultivation date back approximately 7000 years in the lower Mesopotamian basin (Khelil et al., 2016, Terral et al., 2012), along with other long-domesticated perennial plants such as the fig tree, the olive tree and the grapevine (Terral et al., 2012). P. dactylifera is widely cultivated in arid and semiarid regions, where high temperature, intense light, ultra-violet radiation, salt and sand erosion provide stress conditions. An extremely xeric environment leads to the development of morphological, physiological and molecular strategies for the survival of these plants (Khelil et al., 2016), which may influence their metabolites and their bioactive composition.
The palms mentioned above, along with those cited in Table 1, have been widely used in traditional medicine on the African and American continents. Among American indigenous and non-indigenous peoples (Paniagua-Zambrana et al., 2015, Sosnowska and Balslev, 2009) and among African peoples (Gruca et al., 2015), the most common traditional uses were against infections/ infestations and digestive system disorders. On the African continent, the treatment of gastrointestinal worms, malaria, and bacterial infections (mainly related to sexually transmitted diseases and gastro-intestinal disturbances), along with genitourinary system disorders and rites/ magic (related with the stigma of infertility and its negative social repercussions, especially for women) have been well documented (Gruca et al., 2015). Among north-western South American peoples, the importance of the treatment of skin and subcutaneous tissue and the respiratory system have been described (Paniagua-Zambrana et al., 2015), while the preponderance of treatments for pain, injuries, disorders of the skin tissue and muscular-skeletal system among other American indigenous and non-indigenous peoples may be connected to everyday hunting activities, for which palms could provide emergency relief (Sosnowska and Balslev, 2009). Other African and American uses include the treatment of respiratory, endocrine, cardiovascular, mental and neural systems, of neoplasms, and for dental health, along with metabolic and nutritional disorders. The most used parts of the palm tree are the fruits (17–53%), especially their oils (33%), followed by roots (17–40%), seeds (10–16.5%), palm heart (9.5–18%), leaves (5–21%), flowers (3–8.5%) and flower sap (6%) (Agra et al., 2008, Dias, 2012, Gruca et al., 2015, Hoffmann et al., 2014, Macía et al., 2011, Paniagua-Zambrana et al., 2015, Sosnowska and Balslev, 2009).
Palms, in general, are rich in oils, terpenoids and phenolic compounds. The mesocarp and endocarp oils of many palms include a range of volatile compounds and other terpenoids that are mainly beneficial to health, such as phytosterols (Santos et al., 2013a), carotenoids and pro-vitamin A (Rodriguez-Amaya et al., 2008), tocols and vitamin E (Coimbra and Jorge, 2012, May and Nesaretnam, 2014, Siles et al., 2013) and triterpene pentacyclics (Bony et al., 2012a, Galotta and Boaventura, 2005, Goh et al., 1988, Koolen et al., 2012, Peng et al., 2015). Among the phenolic compounds, phenolic acids (Chakraborty et al., 2006), resveratrol and other stilbenes (Rezaire et al., 2014, Schauss et al., 2006b, Schulz et al., 2015), anthocyanins (Bicudo et al., 2014, Schauss et al., 2006b) (Gordon et al., 2012), flavones (Williams et al., 1983), flavonols (Williams et al., 1983), dihydroflavonoids (Chin et al., 2008, Kang et al., 2010), flavan-3-ol (Jaffri et al., 2011b), procyanidins (Williams et al., 1983) and lignans (Chin et al., 2008) have been described in different parts of the palm species, especially in fruit pulps, seeds and leaves.
The objective of the present study is to discuss the fatty and water-soluble bioactive compounds of commercial and wild palms and their related biological properties for human health in Africa and the Americas. The diversity of palm bioactive compounds is described, along with a critical evaluation of pharmacological studies and their relationship to the ethno-medicinal use of palms. The species selected in this review are the main palm trees evaluated so far, regarding the presence of bioactive substances and pharmacological studies, among those palms commonly used in traditional medicine on the African and American continents (noting that Areca catechu, for example, is by origin an Asian palm that has been introduced on the African continent, where it is traditionally used). In addition to the species presented in this review, many others are frequently used, but they are still little studied with respect to their phytochemical compounds and pharmacology, and these topics should therefore be the subject of increasing study due to the importance they exert.
Section snippets
Material and methods
This study was based on a survey of the most widely used palms in the world (which are also the most studied, such as C. nucifera, P. dactylifera, A. catechu, E. guineensis), along with other native and wild ones (Euterpe species such as açaí; Attalea species such as babassu; Acrocomia aculeata - macaúba; Mauritia flexuosa - buriti; Butia species - jelly palm; Bactris gasipaes - peach palm; Astrocaryum species such as tucumã), with studies on bioactive substances and pharmacological assessments
Fat-soluble healthy compounds
Fruits of many species of palm are a source of oil, and pulp of Mauritia flexuosa, Astrocaryum vulgare, Oenocarpus bataua and Attalea maripa showed oil contents between 31% and 42% (Rodrigues et al., 2010), Attalea speciosa (as O. phalerata) nut provides 63–68% oil (Santos et al., 2013), while Elaeis guineensis contributes significantly to the world's oils and fats market, especially for food (May and Nesaretnam, 2014). The fatty acid composition of the pulp and kernel oils of many palms often
Water-soluble healthy compounds
Phenolic compounds were associated with total antioxidant capacity of fruits, such as P. dactylifera (Amira et al., 2012), E. guineensis (Rodriguez et al., 2016), Euterpe edulis (juçara, also known as açaí-da-mata Atlântica) (Bicudo et al., 2014, Schulz et al., 2015) and M. flexuosa (Candido et al., 2015). Variable but significant values of total vitamin C, phenolic compounds and in vitro antioxidant activity were reported in several palm fruits, leaves and seeds (Table 4). In vitro antioxidant
Geographic and ripening variations
Along with the effect of genetic factors, healthy compounds from palms can also vary due to environmental and ripening conditions. A study of the geographical provenance of crude oil from the E. guineensis showed that its volatile fingerprint and some fatty acids (lauric, palmitic and monounsaturated from the n-9 series, such as oleic acid) varied significantly among the three continents of origin - South-east Asia, Africa and South America (Tres et al., 2013). M. flexuosa fruits from the
Biological properties
Biological studies have been validating the traditional use of tropical palm species against several infectious and degenerative diseases (Table 6) and adding new contributions by evidencing anti-microbial, antioxidant, anti-inflammatory, hypoglycaemic, hypolipidemic, hypocholesterolemic, anti-thrombotic, anti-proliferative and other properties of these plants.
Toxicity
A. catechu nut chewing has been associated with aggravation of disease in asthmatic patients (Taylor et al., 1992), with down-regulation of cell-mediated immunity (Wang et al., 2009, Wang et al., 2007), inducing DNA damage (Rehman et al., 2016) and carcinogenic effects (Hernandez et al., 2017, So et al., 2015). However, considering that A. catechu was commonly considered to be a safe traditional medicine in China for thousands of years, future studies could devote more efforts to establishing a
Conclusion and prospects
Palms are generally rich in oils, terpenoids and phenolic compounds. Commercial palms such as E. guineensis, P. dactylifera and C. nucifera have been consumed worldwide throughout human history, while the deepening of phytochemical and pharmacological studies associated with their ethno-pharmacological information confirm the extensive functional and medicinal value of these species. Scientific studies on other wild palms have been expanded in recent years, while some of these fruits are
Acknowledgements
The author thanks Embrapa, Brazil for support through project PC 11, Palm Germplasm Bank (01.15.02.002.11.00).
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2022, Journal of Functional FoodsCitation Excerpt :Recent studies revealed that this oilseed is rich in omega-3 and −6 PUFAs as well as flavonoids, especially anthocyanins, with its effects concentrating on inflammatory processes control, cardiovascular protection, and oxidative stress control (Nascimento et al., 2019; Pinto et al., 2018). Besides anthocyanins, bacaba also contains carotenoids (around 1.4 mg 100 g−1 of oil), vitamin C (30 mg 100-1 of pulp) and other flavonoids (close to 36 mg 100-1 of pulp), such as quercetin (Agostini-Costa, 2018). A derivate from this compound, quercetin glycosylated derivate was found to have angiotensin-converting enzyme type 1 and 2 inhibitor activity (ACEIn and ACE2In), which are the main action searched in the development of anti-COVID-19 therapies (Antonio, Wiedemann, & Veiga-Junior, 2020).