Pharmacology and Phytochemistry of Ecuadorian Medicinal Plants: An Update and Perspectives

The use of plants as therapeutic agents is part of the traditional medicine that is practiced by many indigenous communities in Ecuador. The aim of this study was to update a review published in 2016 by including the studies that were carried out in the period 2016–July 2021 on about 120 Ecuadorian medicinal plants. Relevant data on raw extracts and isolated secondary metabolites were retrieved from different databases, resulting in 104 references. They included phytochemical and pharmacological studies on several non-volatile compounds, as well as the chemical composition of essential oils (EOs). The tested biological activities are also reported. The potential of Ecuadorian plants as sources of products for practical applications in different fields, as well the perspectives of future investigations, are discussed in the last part of the review.


Introduction
The geographic location of Ecuador, together with its geological features, makes the country's biodiversity one of the richest in the world. Ecuador is, indeed, considered among the 17 megadiverse countries, accounting for about 10% of the entire world plant species, and every year new plants are discovered and added to the long list of the species already known. This fact makes Ecuador an invaluable source of potentially new natural products of biological and pharmaceutical interest, such as carnosol, tiliroside [1], and dehydroleucodine (DL) [2]. Moreover, most plants are considered to be medicinal, where they are a fundamental part of the health systems of several Ecuadorian ethnic groups [3]. The knowledge of traditional healer practitioners has been maintained over hundreds or even thousands of years [4]. Therefore, herbal remedies have gained acceptance thanks to the apparent efficacy and safety of plants over the centuries [5]. As a result, several doctors, especially in government intercultural health districts, practice integrated forms of modern and traditional medicine nowadays.
Scientific evidence of the therapeutic efficacy and absence of toxicity in Ecuadorian medicinal plants and their products has started to be collected only in the last few decades by the researchers of several groups in different Ecuadorian Universities. This scientific activity has increased dramatically in recent years, thanks to the support of the Ecuadorian people and government authorities, who consider the sustainable use of biodiversity resources a possible source of economic wealth.
This review gives a comprehensive analysis of recent phytochemical and biologically oriented studies that were carried out on Ecuadorian medicinal plants and is focused on the potential relationships between traditional uses and pharmacological effects, assessing the therapeutic potential of natural remedies. This review completes the information that was provided by our group in 2016 [3]. Since then, more than 100 scientific articles have information that was provided by our group in 2016 [3]. Since then, more than 100 scientific articles have been published concerning phytochemical and pharmacological studies of more than 120 plants belonging to 42 different botanical families. In addition, a few naturally derived products have been patented [6]. Moreover, traditional natural preparations, such as colada morada, which is consumed on the Day of the Dead (Día de los Muertos) [7], and horchata lojana, which is a typical beverage that is made of a mixture of medicinal and aromatic plants consumed by the people of southern Ecuador [8][9][10], have received great attention. Other typical preparations are an infusion of guaviduca from Piper carpunya Ruiz & Pav. [11], which is a traditional drink of the Amazonian people, and the infusion of Ilex guayusa Loes., which is an emblematic tree of the Amazon Region of Ecuador that is widely used in folk medicine, ritual ceremonies, and for making industrial beverages [12,13].
Many of the scientific articles mentioned in this review refer to studies that were carried out on plants and traditional preparations from southern Ecuador, especially from the province of Loja (Figure 1), which has a long tradition in exporting medicinal plants of great importance for human health, such as quina (Cinchona spp.) and condurango (Marsdenia condurango Rchb.f.).
Possible future research directions are also discussed in this review. In addition, the therapeutic potential of some herbal products for the development of new drugs was indicated.  Possible future research directions are also discussed in this review. In addition, the therapeutic potential of some herbal products for the development of new drugs was indicated.

Literature Search Strategies and Sources
Relevant data on medicinal plants from Ecuador were retrieved using the keywords "medicinal plants from Ecuador," "pharmacology," "toxicity," "phytochemistry," and "biological studies" in different databases, including Pubmed, SciFinder, Springer, Elsevier, Wiley, Web of Science, and Google Scholar. The search range was 2016-July 2021. The plant names and authorities were checked with the database WFO (2021): World Flora Online, published on the Internet at http://www.worldfloraonline.org (accessed on 25 September                    Figure 13. Structures of compounds 88-110 from Arcytophyllum thymifolium and 111 from Siparuna echinata. To alleviate toothache and labor pain; as an anti-inflammatory, antiviral, antiseptic, antifungal, analgesic remedy; and to treat a supernatural ailment known by native people as "bad air." The essential oil (EO) was rich in p-cymene (40.0%), limonene (19.5%), myrcene (7.7%), and camphene (5.6%) [14].
The EO exhibited an important acaricidal effect: at a concentration of 2%, it was lethal to R. sanguineus larvae [14].

Annonaceae
Annona montana M. Guanabana de monte or guanabana (false graviola) The plant is used to treat lice, influenza, and insomnia; immature fruits are used to treat dysentery.

Amarryllidaceae
Crinum × amabile Donn Lirio de araña púrpura (purple spider lily) or lirio de araña gigante rosada (pink giant spider lily) in the Ecuador continent and lirio de cinta in the Galapagos Islands It is used in the Esmeraldas province to treat hemorrhoids.
Alkaloids, flavonoids, glycosides, and carbohydrates were determined as the main compounds in leaves and bulbs using phytochemical screening [16].
The anti-inflammatory and cytotoxic activities were evaluated using isolated neutrophils and the tetrazolium salt method (WST-1), respectively [16]. The alkaloid profile of each species was analyzed using GC/MS [17,18]; a high content of lycorine-type alkaloids was found in P. dubia and P. brevifolia bulbs [18].

Phaendranassa brevifolia
The in vitro inhibitory activity of P. cinerea, P. cuencana, P. dubia, P. glauciflora, and P. tungurague was evaluated against the enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), which are considered important targets in the mechanism of Alzheimer's disease. Docking studies indicated that cantabricine (1) (Figure 2), which is an alkaloid present in most species under investigation, was active on both enzymes. However, this compound was not present in the extracts of the two plants that exhibited the highest in vitro inhibitory activity, namely, P. cuencana (IC 50 = 0.88 ± 0.11 µg/mL) against AChE and P. dubia (IC 50 = 14.26 ± 2.71 µg/mL) against BuChE; instead, the two species were rich in galanthamine-type alkaloids [17]. The alkaloid profiles of P. dubia and P. brevifolia bulbs were investigated and significant inhibitory activities on both enzymes were determined [18]. The IC 50 values of the activity against AChE were 25.48 ± 0.39 and 3.45 ± 0.29 µg/mL, respectively, whereas the IC 50 values against BuChE were 96 ± 4.94 and 58.89 ± 0.55 µg/mL, respectively. A high content of lycorine-type alkaloids was found in both species [18]. The potential antidiabetic properties were evaluated by measuring the α-amylase and α-glucosidase inhibitory activities. No activity was reported on α-amylase, whereas the percentages of α-glucosidase inhibition were significant only at the high concentrations of 500 and 1000 µg/mL, with values of 73.02 ± 0.2 and 91.0 ± 1.0%, respectively. The IC 50 values (µg/mL) of the antiradical and antioxidant activities, as determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH), showed that the Trolox (a water-soluble derivative of vitamin E) equivalent antioxidant capacity (TEAC) and the β-carotene-linoleic acid model system (β-CLAMS) assays were 31.6 ± 0.2, 23.0 ± 1.93, and 43.1 ± 0.81, respectively [19].

Ilex guayusa Loes. Guayusa
Widely used in the Amazon region of Ecuador in ritual ceremonies; moreover, the traditional use for treating various ailments and diseases was well documented by several recent reviews [22].
The content of polyphenols, alkaloids, and the health benefits of a tea drink prepared with guayusa leaves together with beverages from other Ilex species was discussed [23]. The optimization of the ultrasound-assisted extraction of phenolic antioxidants from the leaves using response surface methodology was described [24].
Strong inhibition of the enzyme hyaluronidase indicated an interesting anti-inflammatory activity; however, no antibacterial effects were observed from Staphylococcus aureus and Escherichia coli [25]. In an attempt to validate the traditional use of guayusa and alfalfa for the treatment of female infertility, the estradiol levels in blood samples were measured after administration of the plants to rats, which showed high in vivo estrogenic effects [26]. A methanolic extract of guayusa exerted a significant inhibitory effect on α-glucosidase (IC 50 value = 176.5 ± 1.50 µg/mL), while it was inactive against α-amylase. In antiradical and antioxidant assays, the IC 50 values (µg/mL) were 14.2 ± 0.99, 11.8 ± 1.01, and 13.0 ± 0.85 in DPPH, TEAC, and β-CLAMS assays, respectively. it is employed as an anti-inflammatory and antibacterial remedy [20].

Oreopanax ecuadoriensis
Seem. Pumamaky (puma paws) Quichua people use it as a sacred plant in rituals to protect and purify people. Traditional medical treatments also include its use in postpartum baths and to cure flu and headaches.
At a concentration of 1.25% in DMSO, the average halos of growth inhibition (mm) that were shown by the EO were 6.0 ± 0.0 for Candida albicans, indicating no activity, 6.14 ± 0.09 for  [28].
The popular name of the tree varies depending on the region; in Ecuador, it is known by the names canagucho and morete The edible fruits are widely consumed in the palm-growing regions.
The content of flavones, flavonols, flavanones, phenolic acids, and carotenoids in extracts of fruits collected at three different altitudes were compared using HPLC/MS. Most flavonoid glycosides [29] contained quercetin as the aglycone.
A high antioxidant capacity, as well a good protective effect against lipid oxidation were determined, and a direct correlation between the concentration of bioactive compounds and antioxidant capacity was found [29].
The antibacterial and antifungal activities were evaluated using the microdilution technique against the Gram-negative bacteria Pseudomonas aeruginosa, Klebsiella pneumonia, Proteus vulgaris, Salmonella typhimurium, and Escherichia coli; the Gram-positive bacteria Enterococus fecalis and Staphylococcus aureus; and the fungi Trichophyton rubrum and T. mentagrophytes. A moderate inhibitory activity was observed only toward T. rubrum (MIC = 125 µg/mL) and T. mentagrophytes (MIC = 250 µg/mL) [32].
Chuquiraga jussieui J.F. Gmel. Chuquiragua To cure kidney and liver diseases and as a diuretic.
Carotenes, vitamin C, and polyphenols were the main compounds that were identified in extracts of specimens collected at different locations [33].
High antioxidant properties of the extracts; they were higher for the leaf than for the flower extract. No quantitative data were determined [33].
Antimicrobial and antifungal activities were reported for samples of the plant collected in countries that were different from Ecuador, whereas the antioxidant activity and the chemical profile of different organic extracts, determined using GC/MS, were described for a sample that was collected in Ecuador. The EtOAc fraction from a leaf methanolic extract showed the highest DPPH radical scavenging activity (90.69 ± 3.16% at 500 µg/mL) and reducing activity of the ferric tripyridyltriazine complex (Fe 3+ -TPTZ) with a value of 2.355 mg Trolox equivalent (TE)/g dry fraction. These effects could be mainly related to the presence in the fraction of eugenol, trans-isoeugenol, lucenin-2, methyl salicylate, and syringic acid [34].  [35].

Coreopsis venusta Kunth
Ñache leñoso (woody ñache) To relieve inflammation to women's bellies and during labor caused by cold.
The antioxidant capacity of a plant methanolic extract, expressed as Trolox equivalents (µM TE) per milligram of extract, was 790.7 ± 1.4 in the ABTS test and 869.8 ± 15.4 in the DPPH assay [20].

Guángalo
It is used in southern Ecuador to treat skin problems.
Dehydroleucodine (5) was active against an entire panel of eight different acute leukemia cell lines with an average LD 50 value of 9.4 µM [6].

Schltld. Arquitecta
To treat venereal diseases and prostate inflammation and used as a diuretic.
Sacha anis (fake anise) or chilchil wandura Tagetes are used as medicinal plants, as well as ornamental plants, food additives, biopesticides, and for dyeing clothes.
Experiments on a carrageenaninduced acute inflammation model showed the anti-inflammatory activity of aqueous and ethanolic extracts.
In general, the analysis of samples from Peru and Ecuador gave similar results [39]. In healing ceremonies and shaman rituals in the Amazon region, in treatments against rheumatism and atherosclerosis, and an analgesic and antipyretic remedy.
The most important compounds that occur in the plant are sulfur derivatives, such as diallyl disulfide, diallyl trisulfide, alliin, allicin, allyl propyl sulfide, divinyl sulfide, diallyl sulfide, and dimethyl sulfide. The presence of a few sterols, iridoids, flavonoids, and alkaloids was also reported [40].
The radical scavenging effect of the stem EO was only moderate in a DPPH test (22.9 ± 2.3 mg/mL) and a value of 179.5 ± 23.4 µM ascorbic acid equivalents was determined using a ferric reducing antioxidant power (FRAP) assay [43]. The EO from mature fruits that were mixed with the EO from Schinus molle showed potential acaricidal activity against larvae of the cattle tick Rhipicephalus (Boophilus) microplus [44].
Twenty-five compounds, including the main one, α-phellandrene (50.32%), were identified using GC/MS in the EO that was hydrodistilled from the fruits [45].
The EO was tested using the microdilution method against the bacteria Proteus vulgaris, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumonia, Salmonella typhimurium, Staphylococcus aureus, and Enterococcus faecalis, and the fungi Trichophyton rubrum and T. mentagrophytes. The oil exhibited a modest activity against S. aureus (MIC = 625 µg/mL), while the MIC values against the remaining microorganisms were, on average, above 2500 µg/mL. Furthermore, the oil was a potential source of a repellent product against mosquitoes [45].

Cactaceae
Hylocereus megalanthus (K. Schum. ex Vaupel) Ralf Bauer Yellow pitahaya or dragon fruits The edible fruits are exported from Ecuador to different countries.
A direct relationship between the antioxidant capacity and the α-glucosidase inhibitory activity was demonstrated for the EtOAc extract. This extract exhibited the highest antioxidant activity while producing the strongest enzyme inhibitor with an IC 50 = 0.90 µg/mL [50].

Pena de cerro
It is used by Saraguros as a first-aid treatment of ailments, such as liver diseases, cancer, swollen wounds, and inflammation of the genital organs.
Isolated compounds and an aqueous extract were tested (MTS assay) against MCF-7 (breast carcinoma), PC-3 (prostate carcinoma), RKO (colon cancer), and D-384 (astrocytoma) human tumor cells. The aqueous extract was active against all these lines, except against MCF-7 cells, whereas ursolic acid (11) was active against all these lines with IC 50

Mosquera
To heal wounds and to treat inflammation, toothache, bronchitis, gout, and rheumatism.

Croton thurifer Kunth
Mosquera (the name originates from the resin that exudes from the tree) The exudate latex of the stem bark is used to eliminate warts and to treat wounds, sores and ulcers (20), β-sitosterol (21), trans-tiliroside (22), and sparsifol (23) (Figure 4) were isolated from the plant [53].
Moderate antioxidant activity was determined for the EO, with a percentage of DPPH radical scavenging activity of 79.5 ± 2.4% and a ferric-reducing antioxidant power (FRAP) of 292.3 ± 24.0 µM as ascorbic acid equivalents [54]. Fabaceae To treat pneumonia.
Otholobium mexicanum (L. f.) J.W. (Grimes) Culen To treat diarrhea and gastric problems, and as a contraceptive and antibacterial remedy.
Several popular names, depending on the place of growth: chuillur, cugur, rosa, achiotico, achacapuli, and campano are the most common ones A remedy against gastritis, inflammation, scurvy, and rheumatism.
The flavonoid glycoside trans-tiliroside (22) (Figure 4) was isolated from the leaves [1]. (22)   Research was performed with the aims to (i) develop a predictive model for the antibacterial potential of the genus Hypericum using HPLC fingerprints of H. laricifolium, H. quitense, and H. decandrum that were collected in the Andean regions of Azuay, Loja, and Cañar (Ecuador); and (ii) evaluate the influence of natural variables, such as the altitude and soil composition on the pharmacological effect of lipophilic extracts of H. laricifolium. They exhibited high antibacterial activity, with the pH, soil components, and organic matter as the main factors that influenced the activity; furthermore, no relationship was found between altitude and the antibacterial effects. The prediction model that was obtained did not have predictive ability for different Hypericum species, which could be explained by the differences in the chemical compositions of the three species [57].
The leaf EO exhibited moderate in vitro activity against five fungal strains, with it being especially effective against Microsporum canis, which is a severe zoophilic dermatophyte that is a causal agent of pet and human infections [60]. The diterpene carnosol (30) (Figure 6) exhibited high activity against the "blast disease" that is caused by the fungus Pyricularia oryzae [61]. The minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) values of carnosol (30) against this fungus were very close to those of the well-known pesticide flutriafol [61]. Moreover, carnosol (30) showed a promising selective inhibitory activity of the enzyme BuChE (5.15 M, in comparison with 8.568 ± 0.570 M of the positive control donepezil) [1].

Lepechinia paniculata (Kunth) Epling Yayllon or llanllum in Kichwa
The buds are tied at the forehead for treating the "mal de aire", a sort of evil eye, and against headache, while flower infusions are used to treat nervous diseases.

Melissa officinalis L. Toronjil Relaxant, insomnia
The ethanol extract, which was obtained via maceration of the leaves, was a rich source of essential fatty acids and derivatives, benzenoids, phytosterols, and pentacyclic triterpenes [64].
On the basis of the literature, most constituents identified using GC/MS showed interesting biological activities, including antimicrobial and antitumor properties [64].

Albahaca (basil) or albahaca blanca (white basil)
This plant is used by indigenous population both for culinary and medicinal purposes The volatile fractions from the methanol and the 70% aqueous ethanol extracts of the aerial parts of the plant were chemically characterized using GC/MS and HPLC-DAD-MS techniques [65].
The EO, the raw extracts, and the main constituents, namely, eugenol and rosmarinic acid, showed significant IC 50 values in the DPPH and ABTS assays. The EO and eugenol also showed remarkable activity against Pseudomonas syringae pv.
syringae and moderate effects against Candida spp. clinical isolates, with a possible antimicrobial synergy in association with fluconazole. The extracts and isolated compounds were weakly cytotoxic against a HaCaT cell line (keratinocytes) and non-mutagenic against Salmonella typhimurium TA98 and TA100 strains, indicating safety. The EO was weakly active against human adenocarcinoma alveolar basal epithelial cells (A549 cell line). This evidence suggests a potential use of the crude drug, extracts, and the EO as antioxidant agents in cosmetic formulations and food supplements. In addition, the EO may also have potential applications in plant protection and anti-Candida formulations [65].
In an in vitro assay, the EO exhibited interesting inhibitory activity of the enzyme BuChE, with an IC 50 = 32.60 µg/mL, which was the best value that was determined for an oil from a Salvia species. In contrast, the oil was weakly active against AChE, with an IC 50 > 250 µg/mL [66].
The EO showed interesting selective inhibitory activity against the enzyme BuChE (IC 50 = 50.70 µg/mL) and only low inhibitory activity against AChE (IC 50 = 117.60 µg/mL) [67]. SSEE did not adversely affect the cellular viability at any tested concentration. No significant change was observed in the cell cycle. The anti-inflammatory effects of SSEE on pAECs were analyzed using a lipopolysaccharide (LPS) as the inflammatory stimulus. Different markers that were involved in the inflammatory process, such as cytokines and protective compounds, were evaluated using real-time quantitative PCR and Western blots. SSEE showed the ability to restore pAEC physiological conditions by reducing interleukin-6 and increasing heme oxygenase-1 protein levels. The phytochemical composition of SSEE was also evaluated via HPLC/DAD and spectrophotometric assays. The presence of different phenolic acids and flavonoids was revealed, including rosmarinic acid as the most abundant component. SSEE possessed an interesting antioxidant activity, as assessed using the oxygen radical absorbance capacity (ORAC) and DPPH assays. In conclusion, SSEE was suggested to have in vitro anti-inflammatory effects. This finding represents the initial step toward possible scientific support for the traditional therapeutic use of the plant [68]. Statistical analysis suggested the existence of two EO chemotypes and a direct correlation between the environmental conditions and the chemical composition of the oils [70].
The EO showed moderate antioxidant activity in the DPPH and the FRAP assays. Concerning the oil antimicrobial activity, the MICs were 0.5 µL/L for Staphylococcus aureus, 0.05 µL/L for Bacillus subtilis, 5 µL/L for Escherichia coli, 0.05 µL/L for Salmonella enteritidis, 0.5 µL/L for Aspergillus niger, and 0.5 µL/L for Pennicillium citrinum [69]. In another investigation, the leaf EO was used to predict the termiticidal and repellent effects on termites Nasutitermes corniger using a one-factor response surface methodology design. The variable that was analyzed was the concentration of the EO in EtOH at an interval of 0.05-0.3% for the anti-termite activity and between 0.01 and 0.12% for the repellent action. A 100% mortality rate was found at oil concentrations > 0.12%, while the effect was 22.2% at the minimum concentration analyzed. Moreover, 100 and 48.9% of the termites were repelled by the oil at concentrations of 0.12 and 0.01%, respectively. Forty-two compounds, 39 of which were identified, were detected in the leaf EO, which was analyzed using GC/MS. The cytotoxic effects of leaf, seed, fruit, stem, and bark extracts on colon carcinoma cells RKO (normal p53) and SW613-B3 (mutated p53) were investigated. The stem bark methanolic extract exhibited the highest cytotoxic potential. Moreover, the cytotoxic effect was similar on both cell lines, indicating that it was independent of the status of p53. However, RKO cells were more sensitive than SW613-B3 cells.
No evidence for apoptotic markers was recorded; nevertheless, both cell lines showed signs of autophagy after the treatment, including increased Beclin-1 and LC3-II and decreased p62. Lupeol  Five quercetin glycosides and one kaempferol glycoside were isolated from hydroalcoholic extracts of leaves and flowers. In addition to nicotiflorin (40) from flowers, rutin (41) from flowers and leaves, and artabotryside A (42) from leaves, three novel quercetin glycosides were isolated: hecpatrin (43) and gaiadendrin (44) from the leaves, and puchikrin (45) from the flowers (Figure 7) [73].

GC/MS analysis of the volatile alkaloidal fractions led
to the identification of a few lycodine-type and lycopodine-type alkaloids (46)(47)(48)(49)(50) (Figure 8 In addition, the presence of unprecedented high-molecular-weight alkaloids was determined. An analytical UHPLC-UV-MS method for the quantification of tricin (52) in the extracts of Huperzia plants was also described [74].

The significant AChE and monoamine oxidase A (MAO-A)
inhibitory activity of the alkaloidal fractions from H. brevifolia, H. compacta, H. espinosana, and H. tetragona may support the use of these plants to prepare brews that induce psychoactive effects in participants in magical-religious ceremonies [4]. The unusually high amount of tricin (52) in H. brevifolia and H. compacta is remarkable, where this flavone is considered a potent selective inhibitor of different cancer cell lines and a potential colorectal cancer chemopreventive agent [74].

Mucolytic
The hexane and the 80% hydroalcoholic extracts of the leaves were analyzed using GC/MS. The phytochemical contents of the two species were similar and included fatty acids, diterpenes and triterpenes, phytosterols, and abundant amino acids [75].
The leaf aqueous extracts of the two species showed an important mucolytic effect, confirming the traditional use. Thus, the two Malva extracts are potential sources of vegetable material for research and development of phytotherapeutic products with mucolytic and gastroprotective activities [75]. Two EOs were isolated, with yields of 0.17 and 0.15% (v/m), respectively, via hydrodistillation of leaves collected in the canton Cañar, in the regions Moyancón and Chorocópte at altitudes of 1347 and 3191 m above sea level, respectively. Ninety-nine compounds were identified and quantified in the oils using GC/MS and GC/FID. The compositions of the two EOs were not significantly different, with 1,8-cineole and α-pinene being the main components [76].
The EO from the Moyancón region showed moderate antibacterial activity against Staphylococcus aureus, Streptococcus pyogenes, and Escherichia coli [76].
The EO cytotoxic activity was tested (MTT) against MCF-7 (breast), A549 (lung) human tumor cell lines, and a HaCaT (human keratinocytes) non-tumor cell line. A promising selective and efficient activity was observed against the MCF-7 cell line (IC 50 = 5.59 ± 0.13 g/mL at 48 h), which was mainly due to the high content of α-bisabolol in the oil. Weak antibacterial effects against Gram-positive and Gram-negative bacteria were observed using a high-performance thin-layer chromatography (HPTLC) bioautographic assay and the microdilution method; trans-nerolidol and β-cedren-9-one were mainly responsible for the activity. Equally negligible was the radical scavenging activity, which was measured using the HPTLC bioautographic and spectrophotometric DPPH tests. In contrast, the minimum inhibitory concentration (MIC) values against some phytopathogen strains were remarkable [78]. (Fl), and 29.7 and 24.3% (Fr), respectively. The high concentration of the mixture of the two aldehydes (citral) makes the aroma of colada morada prepared in southern Ecuador quite different from the aromas of the same beverage made in other regions of the country [7].
The pleasant aromatic properties and the good in vitro antimicrobial activity of arrayán suggest a plausible scientific explanation for the use of the plant to aromatize a traditional beverage and as a natural anti-infective and anti-yeast agent.
The EO may become a novel rich source of the important industrial chemical citral [7].

Myrcianthes hallii (O. Berg) McVaugh Arrayán or arrayán de Quito As an antiseptic
Thirty-eight compounds were identified in the hydro-methanol extract using ultra-high-performance liquid chromatography (UHPLC) that was hyphenated to heated electrospray ionization MS and UV detectors.
They included polyphenols and organic acids [79].
The hydro-methanol extract showed modest antibacterial activity against methicillin-resistant and methicillin-susceptible Staphylococcus aureus and multidrug-resistant and susceptible Pseudomonas aeruginosa, Enterococcus spp., and Streptococcus pyogenes strains, with the exception of E. coli, which was found to be less sensitive. Interestingly, no relevant differences were observed between methicillin-susceptible and methicillin-resistant strains.
Orchidaceae Maxillaria densa Lidl. Orquídea de mandíbulas Antispasmodic and antidiarrheal remedy, and to treat stomach pains; also used as an ornamental plant.
Phenanthrene derivatives were found in methanol and chloroform extracts [81].

Oxalis tuberosa Molina Oca
Remarkable anti-inflammatory properties; used to treat fever, earache, and dermatitis.
Ludwigia peruviana (L.) H. Hara Mejorana de campo Diuretic and part of a treatment for kidney problems.
Extracts of species belonging to this family showed antifungal, antioxidant, and antibacterial activities.

Peperomia inaequalifolia
Ruiz & Pav. Congona, conguna, tigresillo Analgesic, antiparasitic, and sedative effects. When mixed with other plants, it is used to make a traditional drink called horchata.

Piper barbatum Kunth Cordoncillo allupa
Used by Quichua communities as an antibacterial agent.

Piper lanceifolium
Kunth Matico, hoja de platanillo A leaf aqueous infusion is taken as a bath to treat skin infections and a leaf decoction mixed with a little alcohol is drunk to treat headache and body pain.

DC. Matico
Used by the indigenous communities living in the Morona Santiago province as an antirheumatic and analgesic remedy, and as an antidote for snake bites.
Called omentaca by the Huaorani people To prevent tooth decay.

Anku yuyu lutu yuyu
To treat kidney diseases and toothache, and as an anti-inflammatory agent in combination with other plants.

Roupala montana Aubl. Palo de zorrilo
The infusion is used to treat nervous diseases.
Hexane extracts of the stems and leaves showed antiradical capacities with values of 58.6 ± 20.6 and 68.5 ± 15.1 µM TE/mg extract in ABTS and DPPH assays, respectively [20].

Canllye
Aerial parts are used in the Andean region to treat indigestion and colics.

Manzana de mono (monkey apple)
Analgesic and anti-inflammatory remedies.
Two oils were extracted with hexane from the seeds of green and ripe fruits in a Soxhlet apparatus. Four fatty acids were identified using GC/MS in the saponifiable fraction, among which, 9-octadecanoic acid predominated (61.05%). The main constituents of the unsaponifiable fractions were squalene (81.26%) from green fruits and 3-oxo-urs-12-en-24-oic acid methyl ester (45.13%) from ripe fruits, respectively. Thirty-one compounds, including phenolic derivatives and triterpene saponins, were identified using LC-MS in the hydroalcoholic extracts of green and ripe fruits [97].
Solanaceae Datura stramonium L. Chamico or estramonio (stramonium) To treat asthma, toothache, and Parkinson's disease; it is also used as an antiparasitic and analgesic remedy.

Mashua or cubios
To cure kidney and prostate disorders, liver pain, and skin eczemas.
The alkaloidal extract of leaves and stems showed an IC 50 = 364.8 ± 18.9 µM TE/mg extract in an ABTS assay and an IC 50 = 258.2 ± 38.0 µM TE/mg extract in a DPPH test [20]. To flavor drinks, desserts, salads, and as a food seasoning agent; infusions of the leaves and flowers are used to treat respiratory and digestive problems.
Phytochemical screenings indicated the presence of tannins, polyphenols, triterpenes, and unsaturated sterols in the leaves, stems, and flowers; phenylpropanoids and catechins in the stems and flowers; alkaloids in the leaves and flowers; saponins in the leaves and stems; and coumarins and methylene ketones in the flowers.
The ethanolic extracts showed high antibacterial activity against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The flower extract was moderately active against S. aureus. The flower and stem extracts showed high antifungal activity against Candida albicans, while the leaf extract was only moderately active. All the extracts were significantly lethal against Artemia salina after 24 h of exposure; the stem extract presented the highest activity (82.19 µg/mL), followed by the leaf extract (168.77 µg/mL) and the flower extract (172.76 µg/mL) [100].
Zingiberaceae Curcuma longa L. Turmeric, curcuma, or safran Turmeric extracts have shown hepatoprotective, antiparasitic, antifungal, and insect repellent activities; the plant is traditionally known for its fungicidal and bactericidal properties, and as a food seasoning agent.
Low antioxidant activity was detected for the EO using DPPH and FRAP assays; instead, the EO exhibited good antibacterial activity against Bacillus subtilis, Staphylococcus aureus, and Penicillium citrinum [101].

Renealmia thyrsoidea (Ruiz & Pav.) Poepp. & Endlicher
Shiwanku muyu A wide range of pharmacological properties, including antimalarial, antipyretic, analgesic, and anti-flu effects, and antidote activity against snake bites. A dye is extracted from the fruits, which is used in rituals by ethnic groups in the Amazon region.
The EO exhibited immunomodulatory and bronchodilatory effects. In vitro assays showed that the EO was active against the hydroxyl radical (IC 50 = 0.0065 µg/mL), ABTS cation radical (IC 50 = 3.94 µg/mL), oxygen radical (IC 50 = 404.0 µg/mL) and DPPH radical (IC 50 = 675 µg/mL); moreover, it had Fe(III)-chelating activity (IC 50 = 0.822 µg/mL) and exhibited xanthine oxidase inhibitory activity (IC 50 = 138.0 µg/mL). In vivo studies with Saccharomyces cerevisiae showed that the oil blocked the oxidation processes in yeast cells and significantly increased the antioxidant marker enzymes, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in a dose-dependent manner. In addition, at a concentration of 1.6 mg/mL, the EO increased cellular viability under H 2 O 2 -induced oxidative stress. Thus, the antioxidant ability of ginger EO demonstrated its potential as a food additive and a phytotherapeutic remedy [103].

Conclusions and Perspectives
The criteria for investigating most of the 120 species cited in this review appeared to be based mainly on an ethnobotanical and ethnopharmacological approach. Indeed, scientific evidence has often confirmed traditional uses; however, not rarely, tested biological activities were not strictly related to the traditional uses. On the other hand, plants were not collected with the aim of including extracts or products in high throughput screening programs. This strategy should, instead, be involved in future research projects since it is the only investigational system that is available for discovery programs that addresses the effects of natural products on selected enzymes and receptor targets emanating from molecular biology.
Essential oils (EOs) were the most frequently investigated products. In general, oil compositions were fully determined using GC/MS and GC/FID analyses; in addition, the oil enantiomer composition and odorant characteristics were often established. As regards the biological activities of the EOs, the activity of Renealmia thyrsoidea EO against Escherichia coli and Pseudomonas aeruginosa [102], as well as the antifungal activity of Lepechinia radula [63], Ocimum campechianum [65], Piper ecuadorense [88], and Piper pubinervulum [90] EOs against Candida and Trichophyton strains, which are common causes of severe forms of candidiasis and dermatophytosis, are of great interest. Moreover, it is important to underline the strong acaricidal activity of a mixture of Bursera graveolens and Schinus molle EOs [44], the repellent effects of Dacryodes peruviana EO against mosquitoes [45], and the anti-termite properties of Ocotea quixos EO [70].
Thus, many EOs have the potential to be used not only as components of new perfumes due to the pleasing organoleptic properties but also as ingredients in the formulations of phytocosmetics, as well as antiseptic and insect repellent products. Moreover, essential oils should be screened in the future against clinically important bacteria and strains that are resistant to common antibiotics.
Alzheimer's disease is the most common cause of dementia affecting elderly people and it is associated with a loss of cholinergic neurons in parts of the brain. Cholinesterase inhibitors (ChEIs) delay the breakdown of acylcholine that is released into synaptic clefts and so enhance cholinergic neurotransmission; thanks to these effects, ChEIs are considered efficacious at treating mild-to-moderate AD. In this context, the study of EO cholinesterase inhibitory activity is a relatively new area of research; in particular, the oil mechanisms of action have been poorly investigated so far. It is, therefore, of great interest that several EOs described in this review exhibited such inhibitory effects; in particular, the highly selective BuChE inhibitory activity exhibited by Clinopodium brownei [58], Coreopsis triloba [35], Myrcianthes myrsinoides [77], and Salvia leucantha [66] EOs is worthy of further studies. Equally interesting is the ChEI activity that was found for the flavonoid tiliroside, the diterpene carnosol (30) [1], and the alkaloids found in a few Phaedranassa species [17,18].
Concerning the non-volatile fractions and isolated compounds, the studies were less systematic and the compounds that are responsible for many plants' activities are still unknown. Isolated compounds belonged to different biosynthetic families, including new ones, such as the high-molecular-weight alkaloids occurring in some Huperzia species, whose complete structures are, however, still unknown [4]. Extracts and isolated metabolites were subjected, almost routinely, to antiradical, e.g., DPPH, ABTS, and antioxidant (e.g., β-CLAMS and FRAP) assays. These tests are expected and, therefore, of little scientific significance for extracts containing phenolic compounds, unless high antioxidant products may be developed as phytotherapeutic agents or food supplements with health-promoting activities through the in vivo reduction of the oxidative stress. In this context, the high antioxidant activities of Baccharis obtusifolia [20], Oreocallis grandiflora [94], and Zingiber officinale [103] are worthy of note.
Oxidative stress induces the activation of pro-inflammatory cytokines and subsequent inflammation; therefore, the in vitro antioxidant activity of a product is often considered good evidence of its anti-inflammatory property. However, a more scientifically sound approach should require the study of the molecular mechanisms that underline anti-inflammatory activities. In this context, the expression of mitogen-activated protein kinases (MAPKs) or the release of numerous pro-inflammatory mediators, such as COX-2, the inducible nitric oxide synthase (iNOS), and interleukins IL-1β and IL-6, play a major role in the pathogenesis of various inflammatory disorders and, thus, serve as significant biomarkers for the assessment of the inflammatory process. The investigation of the antiinflammatory effects of Salvia sagittata ethanolic extract [68] is a significant example of such an approach.
Several extracts and isolated compounds that were discussed in this review showed interesting inhibitory activity of the enzymes α-glucosidase and/or α-amylase. Indeed, pancreatic and intestinal glucosidases are the key enzymes of dietary carbohydrate digestion, and inhibitors of these enzymes may be effective in slowing glucose absorption to suppress postprandial hyperglycemia. In this context, it is significant to mention that the extracts and phenolic or flavonoid contents of Gaiadendron punctatum [73], Muehlenbeckia tamnifolia [93], Oreocallis grandiflora [19], and Otholobium mexicanum [56], as well as trans-tiliroside (22) [53], prenyloxy eriodictyol (92), and rhamnetin (101) [96], showed enzymatic inhibitory activity that was comparable or superior to acarbose, which is a drug that is currently used in the treatment of diabetes mellitus. Therefore, these results should promote studies on determining whether these hypoglycemic products can become sources of new antidiabetic drugs.
It is very well known that some of the most used drugs in cancer chemotherapy derive from natural products. In this context, the high antiproliferative effects shown by the extracts of some plants, such as Annona montana [15] and Grias neuberthii [72], against several human tumor cell lines are of great interest. Isolated compounds with potent in vitro cytotoxic properties include the flavonoid tricin (52) from Huperzia spp. [74], the triterpene ursolic acid (11) from Bejaria resinosa [51], and the sesquiterpene lactones onoseriolide (6) from Hedyosmum racemosus [48] and dehydroleucodine (5) from Gynoxis verrucosa [2]. The antileukemic properties of dehydroleucodine (5) and some derivatives were the objects of patents [6]. These findings should stimulate more systematic screening of the cytotoxic effects of Ecuadorian plants' metabolites and the investigation of the mechanisms of the cell antiproliferative effects.
Considering the overall research activities that has been carried out so far in Ecuador on natural products, it can be concluded that little or scarce attention has been dedicated to the semi-synthesis of derivatives of isolated bioactive compounds with the aims to increase their activity, to study the structure-bioactivity relationships, and to explore the mechanisms of action and the signaling pathways that are involved in the biological activities. Even fewer efforts have been put into the synthesis of new chemical entities using computational approaches (in silico) to model the structures of natural products or to design completely new molecules. Indeed, research activities on these themes should be encouraged because they were demonstrated to be highly successful in the discovery of new bioactive compounds.
Finally, further studies, including those in vivo, are required to understand the relevance and selectivity of biological effects that have only been demonstrated in vitro so far. It is also important for practical applications to know potential acute and chronic toxicities, risks, and side effects of the plant-derived products. In fact, even raw extracts can be used as food additives and therapeutic remedies once the absence of toxicity has been demonstrated, the contents have been standardized, and the efficacy has been scientifically shown.
In conclusion, this review has clearly demonstrated the great potential of Ecuadorian plants as sources of products for different purposes and applications. Moreover, some guidelines for future research programs concerning possible sustainable uses of local therapeutic resources were indicated.
Ultimately, an important purpose of this paper is to stimulate more extensive studies on the rich medicinal flora of Ecuador.