Scientific validation of the traditional knowledge of Sikta ( Tabernaemontana sananho , Apocynaceae ) in the Canelo-Kichwa Amazonian community

Tabernaemontana sananho is a tree member of the Apocynaceae family referred to as sikta in Kichwa language. It is widely used in northern South America as painkiller, stimulant, antiseptic and is also highly valued as a sacred plant. In this work, we report the traditional knowledge and uses of sikta by the scarcely contacted Kichwa community of Pakayaku (Pastaza province, Ecuador) and further provide a scientific framework for its scientific validation. A review of the available literature revealed the presence of a wealth of biologically active indole alkaloids that potentially account for the great number of medicinal uses of sikta. This case study is illustrative of the importance of scientific validation of traditional knowledge (i) for indigenous communities —as empowering tool—, (ii) for the sake of scientific knowledge and (iii) for plant conservation.


Introduction
Traditional indigenous knowledge has been often disregarded as unscientific due to its alleged insufficient repeatability, inability to provide data for quantitative analysis and intrinsic lack of tools to measure confidence (Ragupathy & Newmaster, 2009).As a result, indigenous communities have been often sidelined in the political decision-making process, alienating its members from the management of natural resources within their own traditional realms.Studies that validate traditional indigenous knowledge are therefore necessary as tools to empower indigenous peoples, to incorporate their knowledge to the mainstream scientific system and provide a framework for sustainable natural resource management (Gratani & al., 2011).
Despite the lack of recognition of traditional indigenous knowledge, an increasing body of research is raising its credibility through scientific studies.
Validation of indigenous knowledge can use quantitative (Ragupathy & Newmaster, 2009), qualitative (Fassil, 2003) or both methods (Macía, 2004).In this study, we present a qualitative contribution to the validation of traditional knowledge in a scarcely contacted Canelo-Kichwa Amazonian community in Pastaza, Ecuador, of Tabernaemontana sananho Ruiz & Pav.(Apocynaceae), referred to as sikta in Kichwa (Quechua) language.Sikta is a highly symbolic plant species widely used in northern South America as a medicinal drug.
Sikta is a widespread small tree in the understory layer of the lowland evergreen rainforests across northern South America, from the Brazilian Amazon basin to Panama including Colombia, Ecuador, the Guianas, Peru, Surinam and Venezuela.Within Ecuador, it is cited in the provinces of Napo, Orellana, Pastaza, Morona-Santiago, Zamora-Chinchipe, the northern Sucumbíos, Carchi and Esmeraldas, so it is mostly distributed over the Noroccidental province of the Amazonian biogeographical Region; this species shares its habitat with abundant and diverse Eschweilera (Lecythidaceae), Iryanthera (Myristicaceae) and Protium (Burseraceae) tree species (Borgtoft & al., 1998;Anon., 2012;Tropicos.org;Globalbioclimatics.org).
They are shrub-like small trees, repeatedly dichotomously branched, with l-2 pedunculate inflorescences in the forks.Their leaves are opposite, petiolate or less often sessile, those of a pair being equal or subequal, thick and coriaceous.They have pentamerous sympetalous white flowers; corolla lobes overlapping to the left; anthers mostly narrowly triangular, partly sterile; ovary with two open sincarpic carpels, subglobose at fructification, with a mostly fleshy, often thick wall and two narrow ridges; and fruits with many ellipsoid seeds deeply grooved on one side.The species was firstly described in Peru by Ruiz & Pavón (1798-1802; Plantillustrations.org; Figure 1).The interest of this tree resides in its use as a multipurpose remedy and symbolic plant that is "only recognized by selected persons from ancestral cultures" (Van Beer & al., 1984).The sikta tree produces a number of biologically active substances as byproducts of its secondary metabolism.Most of them belong to the chemical family of the indole alkaloids (Van Beer & al., 1984), substances whose effect is known since early times in history and that have proved highly valuable in western medicine (Monachino, 1954).Sikta is reported to act as a stimulant, be used as cureall and bears a high symbolic value, as many indigenous peoples consider it sacred (for a summary of previously reported uses see Appendix 1).In Colombia it has been used to cure eye wounds, while in Brazil, a concoction of the roots is used against rheumatic pains (Van Beer & al., 1984).Leaves are used against syphilis, fever, and as a heart tonic.Roots allegedly work against abscesses, skin pathologies and colds, while the bark is employed as a contraceptive and painkiller plus as a stimulant for hunting dogs.A wide array of indigenous peoples uses the sikta tree, among them, to cite some examples, the Aguaruna of Peru (Brack Egg, 1999) and the Awa, Cofan, Secoya, Shuar, Wao or Kichwa from Ecuador (De la Torre & al., 2008;Luzuriaga, 2017), where sikta is in addition regarded as a highly valued sacred plant.
The Kichwa community of Pakayaku (Bobonaza river, Pastaza, Ecuador) includes approximately one thousand inhabitants widely spread over their ancestral territory, where they live in open wood cottages scattered through the forest.The community makes contact with the rest of the country only occasionally by radio or by rafting the river Bobonaza for five hours to the closest village connected by road (Canelos).Pakayaku lacks electric supply, medical attention, running water and sewage network, and therefore also TV, connection to the Internet or mobile phones.Labor division in Pakayaku is based on sex: men work as hunters and warriors, and fell trees to open a forest clearing or chakra where women later cultivate the land and prepare the staple food, the yucca.The children learn Spanish at an elementary school, while the elderly speak only Kichwa.School absenteeism is unfortunately rife.
This study aims to report the traditional knowledge and uses of sikta by the Pakayaku community and lay a framework for its scientific validation, with the objective of incorporating the indigenous knowledge to the global scientific network, raising the awareness of the nonindigenous peoples and legitimate the traditional uses of the sikta on the basis of scientific evidence.

Study area and voucher collection
The  A bibliographic study was performed to provide scientific evidence for the medicinal uses of the plant.

Results and Discussion
Our survey recorded twelve uses of sikta tree.Most of them involve the use of the plant or plant drug as an ethno-medicine to treat a series of conditions in human patients, but other uses such as to deliver strength and as a stimulant for hunting dogs were also recorded.A list of plant drugs, uses and preparation by ethnopharmacological techniques is provided in Appendix 2.
The capacity to improve dog hunting skills is of particular interest.To our knowledge, this is the first report for Kichwa peoples of the Bobonaza river basin.Similar uses are reported from the Awaruna in Peru, an indigenous group sharing a Shuar common ancestry with the Kichwas (Luzuriaga, 2017).
Sikta trees are considered sacred by the Kichwas.The trees bear high symbolic meaning and are regarded as a bridge that links the person with the hidden forces of Nature.This high symbolic meaning attributed to sikta is also reflected in the fact that trees are not felled by the men when clearing the forest.Moreover, the location of the individual sikta trees used by the initiated adults is kept under secret.To our knowledge, this is the first time such an elevated cultural status is attributed to a Tabernaemontana species among the Kichwa peoples.
We documented rituals aimed to cleanse the body and soul of evil spirits.These treatments and rituals are conducted by an informed person who prescribes a series of indications that the patient must observe to eventually recover health.Most requirements involve strict fasting, with later controlled intake of a certain food such as roasted banana prepared without any salt or peppers.Fasting can endure from two weeks to three months.
The high symbolic status of sikta in the Kichwa community contrasts with the more mundane uses of Tabernaemontana reported for other native peoples of the northern Amazon basin (summarized in Appendix 1).The Cofan, Awa, Secoya, Wao, and Shuar of the northern provinces of Ecuador principally use the plant as a sedative, vulnerary and tonic, or as a stimulant and hallucinogenic brew in concoction with species of Osteophloeum (Myristicaceae) and Brugmansia (Solanaceae).Other uses such as animal feeding and as building material are also reported.Anti-parasitic activity is reported in the literature but was not recorded in our survey.
Ethno-medicinal preparations vary in their formulation across indigenous communities.Plant drugs employed change from one community to another as well.For instance, while the Canelo-Kichwa community of Pakayaku employs sikta roots for digestive or respiratory conditions, the Kichwas of Orellana use sikta bark or leaves to treat colds.Similarly, the Canelo-Kichwa people of Pakayaku use sikta leaves as vulnerary in post-delivery bleeding while the Kichwas of Napo employ sikta latex for the same purpose.
A series of contributions report biological activity that can potentially explain the widespread uses of sikta by indigenous peoples across the northern Amazon basin to treat a wide range of conditions (Appendix 1).Van Beer & al. (1984) and references therein reported coronaridine activity on the autonomous and central nervous systems as a painkiller and respiratory depressant, as well as estrogenic activity that could account for the use of sikta as a contraceptive.3-hydroxycoronaridine is reported to show antibiotic activity, while ibogamine is apparently a powerful stimulant of the central nervous system.Voacangine exhibited a slight central nervous stimulant effect.
Regarding other species of Tabernaemontana, Rizo & al. (2013) found promising antitumoral activity in coronaridine and heyneanine from T. catharinensis.Rohini & Mahesh (2015) obtained successful results when evaluating the anti-inflammatory and antinociceptive activity of TS1 and TS2.Pratchayasakul & al. (2008) found that ibogamine from T. divaricata and ibogaine presented a similar effect.The revision of Dos Santos & al. (2017) described the anti-addictive action of these alkaloids, which opens a window for prospecting their use in drug detoxification programs.Similar activity for voacangine from T. corymbosa was reported by Xuan & al. (2006).
Indole alkaloids are reported to possess antiinflammatory and anti-nociceptive activity (Van Beer & al. 1984).This could account for the relief of abdominal pain and respiratory conditions attributed to sikta by the Shuar, Wao, Cofan, and Kichwa peoples.Shuars and Kichwas brew concoctions of diverse sikta drugs to relief pain due to muscular and skeletal injury as well as general discomfort.
The combined anti-microbial and anti-parasitic activity of coronaridide from T. divaricata reported by Pratchayasakul & al. (2008) and Estevez & al. (2007) (leishmanicidal activity) could account for the traditional use of sikta in the treatment of infections, parasitosis and parasitic diseases, as well as for the use of sikta concoctions as a birth aid (potential effect on uterine contractions), as a vulnerary and in the puerperal hygiene of mother and child.Bennett & Alarcón (2015) reported that the administration of stimulant substances to hunting dogs can enhance their sensory perception and therefore improve the detection and capture of prey, which opens a window for use in specialized training programs for police dogs.
The scientific validation of traditional knowledge is an important step towards the legitimization of indigenous culture in the global society.It is empowering for the indigenous people as well as a valuable contribution to contemporary science and a promotion of environmental conservation.*Roots of three plant species ("three trees that are well nailed the root") are collected and "thin barks are scraped and thrown".Then left during the night in an open space (referred to as "enserenar").The next morning at four the person takes a glass of the resulting concoction, and rests during the following day, being only allowed to move once to go to the bathroom.If not getting better, repeat.At four in the afternoon a bath in the river is taken, and the next day, the person is required to fast, eating only roasted banana, without mayto nor any chili or salt.This diet must be followed for fifteen days or more, up to three months ("well endured three months, our body is getting better").
Catharsis 1 *Same procedure as for rituals of body cleansing with roots Physical discomfort 1 *Bark *A concoction of ten plant species, "taking into account the sunrise and the sunset".Plant drugs are poured into a pot and covered with water, then boiled until dry.The resulting mixture is taken on an empty stomach when returning from work, and before eating chicha.The first day a strict diet must be observed, "eat neither pepper nor salt", but after that "we de".
Kichwa community of Pakayaku (Bobonaza River, Pastaza, Ecuador) lies in a fairly isolated region where bio-and ethnodiversity studies are still lacking.One of us (CXLQ) was based in the Biological Station Pindo Mirador in the northern Bobonaza river basin (1º27'09''S-78º04'51''W), and since 2008 in charge of environmental monitoring and education programs involving the local population (Figure 2).

Figure. 2 .
Figure. 2. Location of the study area.The Ecuadorian province of Pastaza is highlighted.
Specific ethnobotanical uses in Pakayaku in Tabernamontana sananho.*Ancestral utilizations, aspects or facets not previously published.Data procedence: Informants n1 and n2.Root is scraped and brewed in a liter of liquid.It is taken three times a day for fifteen days.Treatment is resumed after a pause.Root is scraped and brewed in a liter of liquid.The leaves are boiled in the afternoon and the next day at four in the morning the pregnant woman is bathed.
discomfort 2VeterinarySense organ Bark Five bushes are scraped in virgin forest.They are planted to be able to take power, and finally they are given to the dogs This plant is regarded high cultural value "we value it is secret we do not mistreat; we do nor cut at work we take good care"