Bioactive Compounds, Antioxidant, and Antimicrobial Activity of Seeds and Mucilage of Non-Traditional Cocoas

Abstract

The biodiversity of the Amazon rainforest includes little-known cocoa species, which are essential resources for local communities. This study evaluated the bioactive compounds and antioxidant and antimicrobial activity of seeds and mucilage of four non-traditional cocoa species (Theobroma subincanum, T. speciosum, T. bicolor and Herrania nitida). Physico-chemical properties, minerals, vitamin C, organic acids, phenolics, and carotenoids were analysed by spectrophotometric and chromatographic techniques. The antioxidant activity was measured by ABTS and DPPH, along with the antimicrobial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Streptococcus mutans, as well as Candida albicans and Candida tropicalis. T. subincanum seeds scored high in titratable acidity, magnesium, sodium, syringic acid, chlorogenic acid, caffeic acid, rutin, and quercetin. In contrast, the mucilage scored high in calcium, m-coumaric acid, ferulic acid, kaempferol, quercetin glycoside, and antimicrobial activity against Streptococcus mutans. T. speciosum mucilage excelled in malic acid, tartaric acid, naringenin, and antioxidant capacity. T. bicolor seeds excelled in lutein and antimicrobial activity against Staphylococcus aureus and Candida albicans, and mucilage in iron, potassium, vitamin C, citric acid, gallic acid and 4-hydroxybenzoic acid, zeaxanthin, β-carotene, and antioxidant capacity by ABTS. The mucilage of H. nitida has a high soluble solids content. These results highlight the potential of these species as sustainable sources of functional compounds and nutraceuticals.

Keywords: Amazon rainforest; carotenoids; in vitro; microextraction; organic acid; phenols.

Figure 1

Photograph of different types of cocoa. Note: (A) Theobroma subincanum Mart. (Identification code: 4747, Herbario QUPS-Ecuador); (B) Theobroma speciosum Wild. Ex Spreng (Identification code: 4751, Herbario QUPS-Ecuador); (B-1,B-2) T. speciosum flowers; (C) Theobroma bicolor Bonpl. (Identification code: 4752, Herbario QUPS-Ecuador); (D) Herrania nitida (Poepp.) R.E.Schult. (Identification code: 4784, Herbario QUPS-Ecuador).

Figure 2

Antimicrobial activity of cocoa species: (A) Escherichia coli; (B) Staphylococcus aureus; (C) Pseudomonas aeruginosa; (D) Streptococcus mutans; (E) Candida albicans; and (F) Candida tropicalis. Note: T.su-PU, pulp of T. subincanum; T.bi-PU, pulp of T. bicolor; T.su-SE, seeds of T. subincanum; T.bi-PU, seeds of T. bicolor; Con, control.

Figure 3

Exploratory multivariate analysis using Pearson correlation. (A) All variables including total bioactive compounds; (B) bioactive compounds and antioxidant activity; (C) bioactive compounds, antioxidant, and antimicrobial activity; (D) correlation matrix considering all variables in study. Note: Ws, seed weight; DLs, seed longitudinal diameter; DEs, seed equatorial diameter; SS, soluble solids; AT, total titratable acidity; AS, ash; Hu, humidity; OA, total organic acid; PT, total phenolics; TC, total carotenoids; ChT, total chlorophyll and their derivatives; DPPH, antioxidant activity by DPPH; ABTS, antioxidant activity by ABTS; Ca, calcium; Fe, iron; K, potassium; Mg, magnesium; Na, sodium; CV, vitamin C; Sau, Staphylococcus aureus; Smu, Streptococcus mutans; Cal, Candida albicans; CiA, citric acid; MaA, malic acid; TaA, tartaric acid; GaA, galic acid; 4HA, 4-hydroxybenzoic acid; mCA, m-coumaric acid; SiA, syringic acid; ChA, chlorogenic acid; CaA, caffeic acid; NaA, naringenin; FeA, ferulic acid; Rut, rutin; Kam, kaempferol; GIQ, quercetin glucoside; Que, quercetin; Lut, lutein; Zea, zeaxanthin; Aca, α-carotene; Bca, β-carotene; ChB, chlorophyll b; PhA, pheophytin a; PhB, pheophytin b.

Figure 4

Exploratory multivariate analysis using principal component. (A) PCA with distribution of fractions under study; (B) contribution of each variable to PCA. Note: Ws, seed weight; DLs, seed longitudinal diameter; DEs, seed equatorial diameter; SS, soluble solids; AT, total titratable acidity; AS, ash; Hu, humidity; OA, total organic acid; PT, total phenolics; TC, total carotenoids; ChT, total chlorophyll and their derivatives; DPPH, antioxidant activity by DPPH; ABTS, antioxidant activity by ABTS; Ca, calcium; Fe, iron; K, potassium; Mg, magnesium; Na, sodium; CV, vitamin C; Sau, Staphylococcus aureus; Smu, Streptococcus mutans; Cal, Candida albicans; CiA, citric acid; MaA, malic acid; TaA, tartaric acid; GaA, galic acid; 4HA, 4-hydroxybenzoic acid; mCA, m-coumaric acid; SiA, syringic acid; ChA, chlorogenic acid; CaA, caffeic acid; NaA, naringenin; FeA, ferulic acid; Rut, rutin; Kam, kaempferol; GIQ, quercetin glucoside; Que, quercetin; Lut, lutein; Zea, zeaxanthin; Aca, α-carotene; Bca, β-carotene; ChB, chlorophyll b; PhA, pheophytin a; PhB, pheophytin b; MU1, mucilage T. subincanum; MU2, mucilage T. speciososum; MU3, mucilage T. bicolor; MU4, mucilage H. nitida; SE1, seed T. subincanum; SE2, seed T. speciososum; SE3, seed T. bicolor; SE4, seed H. nitida.