This page follows a source whose reuse terms permit translation, preserving its structure and line of argument in English.
About this resource
This resource closely follows a 2018 article that documented knowledge and use of Tabernaemontana sananho, called sikta, in the Canelo-Kichwa community of Pakayaku in Pastaza Province, Ecuador, and compared it with existing phytochemical and pharmacologic literature. Rather than excluding Indigenous knowledge from science, the authors presented a case study connecting it with the community’s cultural values, transmission of knowledge, and conservation of biodiversity.
“Scientific validation” in the title does not mean that the therapeutic efficacy of sikta or sananga eye drops was tested in a human clinical trial. The study centered on qualitative ethnobotany recording uses described by 2 community elders and comparison with published literature. Eye-related use is mentioned in literature from other regions, but the researchers did not administer eye drops in Pakayaku or measure visual acuity, eye disease, infection, pain, or another outcome. The paper contains no comparative trial establishing clinical efficacy of sananga eye drops in humans.
Study design
The research site was the Pakayaku community in the Bobonaza River basin. 1 author had participated in local environmental monitoring and education and conducted planned household visits and walking surveys with residents and a Kichwa interpreter. The paper reports written collective consent from community representatives and prior oral consent from participants.
The plant was collected on November 28, 2015 in the Aychatambo area of Pakayaku, in lowland evergreen forest at 425 m elevation, and deposited as specimen QAP 92980 in the José Alfredo Paredes Herbarium in Quito. Identification was rechecked by a coauthor. Retaining the plant name and specimen makes the record more open to reexamination than one based only on a vernacular name.
The principal informants in the ethnobotanical study were 2 community elders knowledgeable about sikta. Semi-structured interviews encouraged open narration and recorded the Kichwa name, plant parts used, explanations of use, collection time, storage, preparation, purposes, and related information. Recordings were organized in spreadsheets, uses were categorized through an existing classification, and findings were compared with Ecuadorian ethnobotanical literature. The authors also reviewed literature on constituents and biological activity.
Content
The paper locates sikta within relationships between the community and forest, rather than treating it only as a candidate natural product. In Pakayaku, the sikta tree carries high symbolic value and is described as connecting people with unseen powers of nature. Men reportedly do not cut it when clearing forest, and the locations of particular trees are known only to adults entrusted with that knowledge. According to the authors, this is an example of especially high cultural standing for Tabernaemontana in a Kichwa community.
The study documented 12 uses of sikta. Many concerned ethnomedical uses involving the body or ritual, and they included accounts of gaining strength and stimulating hunting dogs. The plant parts used for particular purposes do not agree across communities. Records from Pakayaku, Orellana, Napo, and other locations, for example, assign different roles to roots, bark, leaves, and latex. A single word, “sikta,” therefore cannot be assumed to identify a uniform product or practice.
The authors compared Pakayaku records with literature concerning other Indigenous groups in the northern Amazon. Reports included sedation, tonics, wounds, hunting, and symbolic uses. A use for eye injuries in Colombia was introduced from published literature, but this was an ethnobotanical use record rather than a treatment study with clinical diagnosis, standardized eye drops, a control group, and follow-up.
Comparison with phytochemistry notes that indole alkaloids including coronaridine, 3-hydroxycoronaridine, heyneanine, ibogamine, and voacangine have been reported for T. sananho, and that another study reported TS1 and TS2 from a leaf extract. The authors argue that previously reported pharmacology might explain some traditional uses, but their evidence includes isolated constituents, other Tabernaemontana species, and animal models. It is not equivalent to effects of the whole plant or an eye preparation.
Results
The central direct achievements were confirming the target species through a botanical specimen; recording 12 uses from 2 elders; and preserving in text and supplementary material the high symbolic standing of sikta in the community and regional variation in parts and purposes of use. This is ethnobotanical evidence relevant to knowledge preservation, community self-determination, and plant conservation.
The literature comparison organized multiple indole alkaloids and reported biological activities of those constituents or extracts. The authors positively interpreted these correspondences as possible scientific explanations for traditional knowledge. The presence of indole alkaloids, however, does not verify all ethnomedical claims together. Molecular activity, animal responses, community use, and human clinical outcomes are separate stages of evidence.
“12 uses were confirmed” therefore does not mean that 12 treatment effects were confirmed. What was confirmed was the record of knowledge and practices described by the informants. The study performed no constituent analysis, sterility assessment, ocular toxicity test, prospective administration to humans, controlled comparison, or clinical-outcome assessment of sananga eye drops.
Limitations
There were 2 principal informants, not a sample designed to quantify frequency or agreement across the whole community. The authors’ long-term relationship with the community supports contextual understanding, while researcher interpretation also enters interviews, translation, and classification. Some knowledge is intentionally restricted, and the published record may not represent all of it.
The literature-based “scientific examination” was not a systematic review with a prespecified search, quality assessment, and pooled effect sizes. Findings from other species, other plant parts, isolated compounds, crude extracts, and animal studies cannot be transferred directly to human effects of T. sananho. Reducing cultural and symbolic value to clinical efficacy—or rejecting that cultural value because a clinical trial is absent—would both fall outside the study’s scope.
Safety
This was not a safety trial and did not systematically collect adverse events, perform eye examinations or blood tests, or measure exposure. Reports that the plant contains multiple bioactive alkaloids are also a reason not to assume traditional use is automatically safe. Constituents may vary with plant part, botanical identity, extraction method, and concentration.
In particular, a historical record of eye-related use is not proof of a safe ophthalmic product. Culture assays and oral animal experiments do not substitute for ocular-surface safety. This resource gives no preparation or administration procedure and is not intended to be used alone for diagnosis, treatment, or decisions about self-administration.
Source and rights
Original source: Luzuriaga-Quichimbo CX, Ruiz-Téllez T, Blanco-Salas J, Cerón Martínez CE. Scientific validation of the traditional knowledge of Sikta (Tabernaemontana sananho, Apocynaceae) in the Canelo-Kichwa Amazonian community. Mediterranean Botany. 2018;39(2):183–191. DOI: 10.5209/MBOT.60073.
The article page at Mediterranean Botany states that the content is distributed under Creative Commons Attribution 4.0 International (CC BY 4.0). This source-aligned resource names the original authors, journal, DOI, and license and distinguishes observations from the authors’ interpretations. Tables, figures, and extended interview quotations are not reproduced.