Honeysuckle Berries Research Articles

Variation of Fruits Morphometric Parameters and Iridoid Content of Lonicera caerulea L. Germplasm Collection

The dark-blue, fleshy berries of Lonicera caerulea L. are used as fresh or processed in many products such as juice, smoothie, wine, compote, jam, marmalade, candies, chocolate, cake, or extracts. L. caerulea fruits are appreciated in the food industry and medicine mainly due to a high content of biologically active phenolic compounds, especially anthocyanins and vitamin C – in the amount up to 186 mg.100 g-1, and health-promoting properties. Thirty-four genotypes of Lonicera caerulea species originated from germplasm collection of the Forest-Steppe of Ukraine in M.M. Gryshko National Botanical Garden of NAS of Ukraine (NBG) (Kyiv, Ukraine) and were characterized by using the morphometric traits and iridoids content. Differences between the genotypes were significant in all observed parameters. The fruits of L. caerulea collection varied in evaluated morphometric parameters as follows: fruit weight 0.70–1.54 g, length 15.33–26.52 mm, diameter 7.12–13.10 mm. The shape indexes of fruits varied from 1.42 to 3.65. Our results showed that the content of iridoids ranged from 97 to 314 mg.100 g-1 of fresh L. caerulea fruits. Interestingly, L. caerulea berries taste differs between the varieties, those with bitter or sour-bitter taste are distinguished by the highest content of iridoids (225–314 mg.100 g-1), while berries without bitter taste were characterized by significantly lower contents. Thus, honeysuckle berries should be selected preferentially regarding their bitterness, due to the anti-inflammatory and antioxidative properties of iridoids.

Polyphenols Content, Antioxidant Properties and Allergenic Potency of Organic and Conventional Blue Honeysuckle Berries

Blue honeysuckle berries are a rich source of polyphenols with strong antioxidant properties. The purpose of this research was to determine the effect of organic and conventional cultivation on the polyphenols, antioxidant and allergenic potency of blue honeysuckle berry cultivars: ‘No 30’, ‘Jolanta’ and ‘Indygo’ in two growing seasons. Identification of individual polyphenols was performed using the HPLC method; the total polyphenols content and antioxidant activity were determined by spectrophotometric methods. The determination of allergic potency was tested by ELISA. In the second year of the study the total polyphenols were significantly higher in organic blue honeysuckle than in the conventional blue honeysuckle. In both growing seasons, the ‘Indygo’ cv. was characterized by the highest concentration of all bioactive compounds 3241.9 mg and 3787.2 mg per 100 g−1 D.W. A strong correlation was found between the polyphenol content and the antioxidant activity for organic fruit in both years, as well as for allergenic potency. Contrary to the best bioactive properties was ‘Indigo’ cv., with the highest allergenic potency (108.9 and 139.2 ng g−1 D.W.). The lowest content of specific allergens was found in the ‘No 30’ cv. Since honeysuckle is still a new cultivated plant, information about its allergenic potency is insufficient.

The impact of ultrasound-assisted thawing on the bioactive components in juices obtained from blue honeysuckle (Lonicera caerulea L.)

Ultrasound (US) assisted thawing of blue honeysuckle berry was utilized in order to reduce the losses of bioactive components (ascorbic acid, anthocyanins, phenolic acids, iridoids, proanthocyanins) and increase the extraction efficiency during juice processing. It was analysed whether it was more beneficial to apply US (alone or with enzymatic treatment) to the frozen state, until reaching the cryoscopic temperature or thawed state. Both the US and enzymatic treatment significantly increased the extraction efficiency, extract content, acidity and the content of iridoids and chlorogenic acid in juices, especially if the US was applied to 50 °C. It was probably due to a higher extractivity by the greater damage of the tissue and detexturation. Enzymatic treatment due to long heating contributed to a higher degradation of anthocyanins, ascorbic acid and proanthocyanidins, which are more heat-sensitive. The results of the study mainly indicated the possibility of including ultrasound-assisted thawing in the fruit processing before pressing the juices. This may replace costly enzymatic treatment.

Honeysuckle Berry (Lonicera caerulea L.) Inhibits Lipase Activity and Modulates the Gut Microbiota in High-Fat Diet-Fed Mice.

Honeysuckle berry (HB, Lonicera caerulea L.) is an oriental herbal medicine reported to have beneficial effects on metabolic disorders, such as obesity and non-alcoholic fatty liver disease. The fruit part of HB is rich in anthocyanin, a type of polyphenol. Most studies credit the antioxidant and anti-inflammatory properties of HB as the mechanisms of its effectiveness. This study investigated the inhibitory effects of HB on lipase using an in vitro assay and the modulatory effect of HB on gut microbiota in high-fat diet (HFD)-fed mice. HB inhibited pancreatic lipase activity with IC50 values of approximately 0.47 mg/mL. The fecal triglyceride (TG) levels were higher from the HFD of the HB-fed mice than they were for the control mice. Moreover, the fecal microbiota from the HFD of the HB-fed mice had relatively lower Firmicutes and higher Bacteroidetes than that from the HFD-only mice. These results suggest that HB modulates gut microbiota composition, which may contribute to body fat reduction. Hence, HB could present a useful agent for treating metabolic diseases through lower TG uptake and the regulation of gut microflora.

Evaluation of Immunotropic Activity of Iridoid-Anthocyanin Extract of Honeysuckle Berries (Lonicera caerulea L.) in the Course of Experimental Trichinellosis in Mice.

Our experiment determined the immunotropic activity of a natural, iridoid-anthocyanin extract from honeysuckle berry (Lonicera caerulea L.) (LC). The extract was administered to mice infected with Trichinella spiralis, orally at a dose of 2 g/kg bw, six times at 24 h intervals (from day 3 prior to the infection to day 3 post-infection (dpi) with T. spiralis. At 5, 7, 14, and 21 dpi, samples of blood, spleen, and mesenteric lymph nodes (MLN) were collected, and isolated lymphocytes were analyzed by flow cytometry. The splenocyte proliferation was estimated with MTT testing, and the intensity of intestinal and muscle infection was also studied. LC stimulated the local immune system by inducing lymphocyte proliferation in the spleen 7 dpi and altered the percentage and absolute count of B (CD19+) and T (CD3+, CD8+) cells 7, 14, and 21 dpi in the peripheral blood. LC extract affected the dynamics of expulsion of adult Trichinella from the intestines and prolonged the intestinal phase of the infection but did not change the number of larvae in the muscles. These results suggest that Lonicera caerulea L. fruit extract modulates murine cellular immune response during intestinal phase of T. spiralis infection but shows no antiparasitic activity.

Phenolic Compounds, Vitamins C and E and Antioxidant Activity of Edible Honeysuckle Berries (Lonicera caerulea L. var. kamtschatica Pojark) in Relation to Their Origin.

Honeysuckles are frost tolerant plants providing early-ripening fruits with health-promoting properties which have been used in traditional medicine in China. This study evaluates the impact of the climatic conditions of two areas on the chemical composition and antioxidant activity (AOA; by DPPH—2,2-diphenyl-1-picrylhydrazyl and photochemiluminescence assays) of eight cultivars of honeysuckle berries (Lonicera caerulea L. var. kamtschatica Pojark) of various ripening times. Expectedly, chemical composition and AOA values varied depending on the cultivars, locality and selected methods. Berries from Lednice (the area with more sunshine) showed higher average contents of total monomeric anthocyanins (TMAC; pH differential absorbance method), vitamins C and E and total phenolics (high-performance liquid chromatography). In contrast, berries from Žabčice (the area with more rain) performed higher average contents of total phenolics and flavonoids (UV/VIS spectroscopic analyses). Interestingly, fundamental amounts of chlorogenic acid were determined irrespective of the locality. Regarding TMAC and vitamin C content, early ripening Amphora from both areas has been assessed as the best cultivar; concerning the content of phenolic compounds, Fialka from both areas and Amphora from Lednice is considered as the most valuable. The obtained results may facilitate the selection of the most valuable cultivars for both producers and consumers.

Diet-Related Plumage Erythrism in the Western Tanager and Other Western North American Birds

Consumption of the berries of two exotic bush honeysuckles (genus Lonicera) containing the red carotenoid pigment rhodoxanthin has resulted in abnormal erythristic plumages in several species of birds in eastern North America. Here we report 12 examples of plumage erythrism in the Western Tanager (Piranga ludoviciana), in both live birds (5) and museum specimens (7), that we suspect have the same etiology. The erythristic tanagers feature overtly orange to red feathers variously scattered on the head, rump, wing coverts, and/or underparts, areas of the plumage normally colored by carotenoid pigments. All were in their year of hatching, so the reddened feathers, including replaced median coverts with orange tips, represent formative plumage grown on or near the breeding grounds where berries containing rhodoxanthin are available. By contrast, adult Western Tanagers undergo body molt primarily in the Mexican monsoon region in fall and on their winter grounds in early spring where bush honeysuckles are nonexistent. We also report examples of Red-breasted Sapsuckers (Sphyrapicus ruber) with anomalous red pigmentation on their backs and of Cedar Waxwings (Bombycilla cedrorum) with orange tail bands, as previously documented in the East. In these species, the reddened areas are typically yellow or green, colors based on carotenoid pigments that can be altered through the consumption of fruits containing rhodoxanthin. We conclude that these reddened feathers are the result of the consumption of honeysuckle berries or possibly the red arils of the Pacific Yew (Taxus brevifolia), representing a first report of diet-related erythrism in western North America.

Особенности культивирования российских и зарубежных сортов жимолости съедобной (Lonicera edulis Turcz.) in vitro

Introduction. The demand for honeysuckle berries and planting material is growing. Clonal micropropagation is the most effective method for industrial plantations. The research objective was to study the effect of cytokinins and auxins on Russian and Canadian honeysuckle microshoots and roots.
 Study objects and methods. The study featured regenerated honeysuckle (Lonicera edulis Turcz.) of three Russian cultivars (Bakcharsky Velikan, Doch Velikana, Yugana) and two Canadian cultivars (Boreal Beauty, Boreal Beast). The experiment focused on the effect of sterilizing agents and sterilization time on the viability of honeysuckle explants at the stage of culture introduction in vitro. The effect of the growth regulator Cytodef in the QL nutrient medium on organogenesis was studied at the stage of micropropagation proper, the effect of auxin IBA on plant root formation – at the stage of rooting in vitro.
 Results and discussion. The greatest viability of honeysuckle explants (80–94%) was registered in the samples affected by Lizoformin 3000 (5%) and silver nitrate (0.2%) as sterilizing agents with a sterilization time of 10 min at the stage of in vitro culture introduction. The biggest quantity (8.8 pcs.) and total length (40.1 cm) of microshoots were observed when the content of cytokinin Cytodef in the culture medium QL was 0.3 mg/L at the stage micropropagation proper. The Boreal Beast cultivar had the largest total length of shoots (29.0 cm). The biggest quantity (5.5 pcs.) and total length (30.8 cm) of roots resulted from 0.5 mg/L of auxin IBA at the stage of rooting in vitro. Coconut substrate produced the highest survival rate (92–99%) at the stage of adaptation to non-sterile conditions in vivo, with the greatest number of leaves (8.1–10.2 pcs.) observed in Canadian cultivars.
 Conclusion. Cytodef and IBA proved to be effective growth-regulating substances for microplants of Russian and Canadian honeysuckle cultivars in vitro, which makes them promising for berry plantations.

Lonicera caerulea L. as a Source of Biologically Active Compounds for the Enrichment of Fermented Milk Product

Abstract Lonicera caerulea L., also known as honeysuckle berries, are rich in biologically active compounds, which makes them a valuable raw material for the development of functional foods. The objects of the research were three honeysuckle cultivars (‘Zoluška’, ‘Siņaja Ptica’, ‘Goluboje Vereteno’), four genotypes (No 2A; No 3; No 5; No 8) and kefir, enriched with various amounts (3–10%) of fruit puree. Physical and chemical analyses to determine the qualitative indicators of raw materials and products were performed. The degree of liking of kefir was assessed using sensory analysis: hedonic and line scales. The results obtained showed that among the cultivars the highest content of anthocyanins (1103.5 mg·100 g−1), total phenols (693.3 mg·100 g−1), flavonoids (753.9 mg·100 g−1), and tannins (1.6 mg·100 g−1), were found in ‘Siņaja Ptica’ berries, while among the genotypes, berries of No 8 had the highest concentration of the aforesaid compounds. Both samples also showed the highest antiradical activity: ABTS+• on average by 71.7% and DPPH− by 43.7%. According to the sensory evaluation, kefir with 10% honeysuckle puree was rated the highest. Honeysuckle berries could be used as a promising source of natural anti-oxidants in future research aimed at developing different new products that could meet consumer expectations.

Biochemical value of berries of promising edible honeysuckle varieties for the production of functional food products

Lonicera edulis L. occupies a special place among sparsely distributed garden crops in the middle horticulture zone of Russia. The main advantages of the culture are its long maturation period, long fruiting period, high plasticity, value of the biochemical composition of berries. The paper presents experimental data on the biochemical composition of honeysuckle berries of the new generation introduced under the conditions of the Central Chernozem Region. Varieties with high levels of soluble dry substances, sugars, ascorbic acid, flavonols are noted. Prospects of obtaining functional food products using fresh honeysuckle fruits are considered. “Honeysuckle” fruit drink and low-calorie jams with high antioxidant activity are obtained.

Effects of process parameters on texture quality of blue honeysuckle berry snack under continuous microwave puffing conditions

To improve the texture quality of blue honeysuckle berry (BHB) snack under continuous microwave puffing and obtain suitable process parameters, the effects of technology parameters, such as microwave intensity, ventilation velocity, and puffing time, on the objective indexes in terms of temperature, moisture content, expansion ratio, porosity, hardness, and brittleness of BHB snack were investigated via response surface method and pore distribution analysis. The results showed that microwave intensity and puffing time had the highest effects for the objective indexes. The formation of texture quality of snack depended on the structure and distribution of internal pores inside the product. The optimal parameters for continuous microwave of snack were obtained as the microwave intensity of 9.23 W/g, ventilation velocity of 0.76 m/s, and puffing time of 3.26 min to produce a desirable texture quality. This study may provide guidance for the industrial production development of novel snack products for berry fruits like BHB. Novelty impact statement This work investigated the puffed BHB snack under continuous microwave puffing and optimized the process parameters to achieve a desirable texture quality. Microwave intensity lower than 10 W/g achieved desired texture quality with suitable hardness and brittleness of BHB snack. The size and distribution of internal pores determined the formation of texture quality of BHB snack.

Anti-Sarcopenic Obesity Effects of Lonicera caerulea Extract in High-Fat Diet-Fed Mice.

Sarcopenic obesity is a combination of sarcopenia and obesity. Although several herbal extracts showed improvement on sarcopenia and obesity, respectively, there are few studies on sarcopenic obesity. Lonicera caerulea (honeysuckle berry, HB) can ameliorate metabolic disorders including obesity. However, its effects on sarcopenic obesity have not been reported yet. Thus, the aim of this study was to investigate whether HB extract might have any beneficial effects on sarcopenic obesity in high-fat diet-induced mice. Forty-eight mice were classified into six groups and treated for eight weeks: (1) NC, normal diet control; (2) HC, high-fat diet control; (3) PC, high-fat diet with orlistat; (4) HB100, high-fat diet with HB extract at 100 mg/kg; (5) HB200, high-fat diet with HB extract at 200 mg/kg; and (6) HB400, high-fat diet with HB extract at 400 mg/kg. Body weight, fat accumulation, muscle mass, muscle strength, and mRNA expression of muscle atrophy were monitored. Compared with the HC group, HB administration showed anti-obesity properties. It reduced body weight gain and modulated serum biochemical parameters and tissue antioxidant enzymes. HB also increased muscle strength and muscle mass of hind legs. In addition, it decreased mRNA expression levels of Atrogin1 and MuRF1 as markers of muscle atrophy but increased PGC1α and SIRT1 as markers of muscle growth. These results suggest that HB might be effective in preventing sarcopenia associated with obesity.

Polyphenols from blue honeysuckle (Lonicera caerulea var. edulis) berry inhibit lipid accumulation in adipocytes by suppressing lipogenesis

Ethnopharmacological relevanceBlue honeysuckle (Lonicera caerulea var. edulis) berry has been used in folk medicine for the treatment of bacterial infections, gastrointestinal disorders, and metabolic diseases. There is evidence to support its pharmacological effects in improving diabetes, fatty liver, and obesity. Aim of studyTo investigate the effect of blue honeysuckle berry extract (BHBE) on lipid accumulation in adipocytes and the underlying mechanism. Materials and methodsHigh-performance liquid chromatography (HPLC) coupled with mass spectrometry (MS) was applied to analyze the polyphenolic compounds in BHBE. 3T3-L1 cells were used to induce into adipocytes. Oil Red O staining combined with triglyceride (TG) content determination were carried out to evaluate intracellular lipid accumulation. Western blot was used to determine the expression of lipogenic enzymes and transcription factors. Real-time PCR was used to determine the expression of lipolytic enzymes and adipocyte markers. ResultsThe primary polyphenols in BHBE are flavonoids (mainly flavonols and anthocyanins). BHBE dose-dependently inhibited lipid accumulation in adipocytes by reducing the expression of fatty acid synthase (FAS) and increasing the phosphorylation level of acetyl-CoA carboxylase (ACC). Moreover, BHBE was found to promote the phosphorylation of AMP-activated protein kinase (AMPK) and further reduce the expression of lipogenic transcription factors (PPARγ, C/EBPα, and SREBP-1c), while the selective AMPK inhibitor attenuated the suppressive effect of BHBE on lipogenesis. In addition, BHBE increased the expression of beige adipocyte markers (Cd137 and Tmem26) and uncoupling protein 1 (UCP1) without affecting the expression of brown adipocyte markers (Ebf3 and Eva1). ConclusionBHBE inhibits lipid accumulation in adipocytes by suppressing lipogenesis via AMPK activation as well as by promoting beiging of adipocytes, which supports the anti-obesity potential of blue honeysuckle berry.

Effect of Two Combined Functional Additives on Yoghurt Properties.

The aim of the research was the analysis of yoghurts enriched with blue honeysuckle berries dry polyphenolic extract and new preparation of resistant starch. The additives were introduced individually at concentration 0.1% (w/v) and in mixture at final concentration of 0.1 and 0.2% of both components. Yogurt microflora, pH, and its physicochemical and antioxidant properties were examined over 14 days of storage under refrigerated conditions. Studies showed that both substances can be successfully used in yoghurt production. Yoghurt microflora es. S. thermophilus and Lb. delbrueckii subsp. bulgaricus counts appeared to be higher in samples supplemented with these additives comparing to control yoghurt by 3–8%. More stimulating effect on their growth, especially on S. thermophilus, revealed resistant starch. Addition of this polysaccharide improved also the rheological properties of yogurts, which showed higher viscosity than samples produced without it. Addition of honeysuckle berries preparation significantly influenced the yogurts’ color, giving them deep purple color, and their antioxidant potential. During storage, contents of anthocyanin and iridoid compounds were decreasing, but antioxidant activity in the products remained stable.

Honeysuckle storage in modified atmosphere

Honeysuckle is a natural source of the most important physiologically valuable nutrients but has a short period of storage. The experiments were carried out on variety Zymorodok. Freshly picked berries (600-700gr.) were placed in perforated plastic containers, cooled down to +0,50C and stored in “Xtend” bags. The concentrations of oxygen, carbon dioxide and ethylene in the bags were regularly measured. The berries were also visually inspected. After 5 days of storage, the levels of concentrations of gases inside the packages stabilized and for the next 35 days were in the range of 1,2-2,1% for CO2 and - 19,2-18,8% for O2. The ethylene production was insignificant. The storage of cooled berries in MA significantly reduce berry losses induced by microbiological diseases (up to 2,2%) and better maintain the quality of honeysuckle (87,5% standard berries). Thus, using MA (“Xtend” bags), it is possible to prolong the period of storage of honeysuckle berries up to 28 days.

Influence of storage conditions on selected quality characteristics of blue honeysuckle berry juice

Influence of storage conditions on selected quality characteristics of blue honeysuckle berry juice

Optimization of processing technology for blue honeysuckle berry snack: From microwave vacuum concentration to freeze‐drying

To enrich the berry product variety and improve the edible quality of blue honeysuckle berry (BHB), on the basis of determining the mixture recipe of the BHB pulp, fructose, and yoghurt (BHBY), the combined technology of microwave vacuum concentration (MVC) and freeze-drying (FD) was proposed to produce novel BHBY snack. The results showed that the highest retention rate of anthocyanin content was 94.83% under a vacuum pressure of −0.05 MPa and a temperature of 50°C. The optimal FD parameters for the concentrated BHBY were determined as critical moisture content of 1.89 g/g (dry basis), material thickness of 13 mm, and desorption temperature of 36.9°C with a snack of hardness of 1,943.9 g, brittleness of 604 peaks, L* value of 36.7, and a* value of 20.7. The final BHBY snack presents acceptable taste with crispy texture and desired color. The developed processing technology is feasible for BHB snack. Practical applications This work developed a novel BHB snack by the application of MVC followed by FD technology and optimized the processing technology to achieve the desired product with high drying efficiency, preferable texture taste, and considerable retention of anthocyanin content. The recipe of BHBY and the processing technology proposed was beneficial for improving the edible quality of BHB. Further, it may provide guidance for the development of novel snack and deep processing of berry fruits like BHB.

Influence of microbiological fertilizers on yield and general condition of plants of perspective blue honeysuckle varieties

The purpose of the research was to study the infl uence of microbiological nitrogen and phosphorus fertilizers on the yield and general condition of blue honeysuckle plants on sod-podzolic soils in the conditions of the Republic of Mari El. The experiment was conducted according to the following scheme – factor A– varieties: Goluboye Vereteno (control), Elite form No. 50, Pamiati Silaeva, Nizhegorodsky Dessert, Elite form No. 81, Podarok Dergunovu, Lakomka; factor B – fertilization: control (without fertilizer), bacterial fertilizers Azotovit, Phosfatovit, Azotovit + Phosfatovit, the rate of application in each option was 14 l/ha, water – 3000 l/ha, ammofoska (N12, P15, K15), the application dose was 300 kg/ha. The repeatability of the experiment was 3-fold, the placement of plots was rendominized, the term for applying microbiological and mineral fertilizers was the fi rst decade of May, once. The application was superfi cial. Joint application of “Azotovit” and “Phosphatovit” as an early spring top dressing, it allows to signifi cantly increase the yield of blue honeysuckle berries, the increase was 0.4 t/ha with a yield of 2.0 t/ha. The use of bacterial fertilizers Azotovit and Phosphatovit in the initial period of growth of honeysuckle plants has a positive eff ect on their further development and general condition, as well as increases the potential yield. The highest average annual increase was obtained in the option of joint application of bacterial nitrogen and phosphorous agrochemicals in the elite form No. 81 variety (36 cm), which exceeded the control (Goluboye Vereteno variety on an unfertilized background) by 2.1 times.

Characterization and inhibitory activities on α-amylase and α-glucosidase of the polysaccharide from blue honeysuckle berries

An acidic heteropolysaccharide HEP-2 was obtained from blue honeysuckle berry extracts after purification using Sepharose 6B and Sephadex G-200 column chromatography. The molecular weight of HEP-2, determined with high-performance gel permeation chromatography, was 3.01 × 106 Da. Fourier transform infrared spectroscopy, gas chromatography and nuclear magnetic resonance analyses revealed the presence of α-, β-pyranose ring and six sugar residues in HEP-2. Amorphous aggregates of HEP-2 with irregular shape and lacking the triple helical structure were detected using the Congo red test, scanning electron and atomic force microscopy, and X-ray diffraction studies. Rheological characterization showed typical shear-thinning behavior and viscoelastic property of the polysaccharide. HEP-2 exerted significant inhibitory effects on α-amylase and α-glucosidase and displayed competitive inhibition kinetics. The collective results support the potential utility of HEP-2 as a hypoglycemic agent for enzyme-targeted treatment of diabetes or functional food.

Rhodoxanthin synthase from honeysuckle; a membrane diiron enzyme catalyzes the multistep conversation of β-carotene to rhodoxanthin.

Rhodoxanthin is a vibrant red carotenoid found across the plant kingdom and in certain birds and fish. It is a member of the atypical retro class of carotenoids, which contain an additional double bond and a concerted shift of the conjugated double bonds relative to the more widely occurring carotenoid pigments, and whose biosynthetic origins have long remained elusive. Here, we identify LHRS (Lonicera hydroxylase rhodoxanthin synthase), a variant β-carotene hydroxylase (BCH)-type integral membrane diiron enzyme that mediates the conversion of β-carotene into rhodoxanthin. We identify residues that are critical to rhodoxanthin formation by LHRS. Substitution of only three residues converts a typical BCH into a multifunctional enzyme that mediates a multistep pathway from β-carotene to rhodoxanthin via a series of distinct oxidation steps in which the product of each step becomes the substrate for the next catalytic cycle. We propose a biosynthetic pathway from β-carotene to rhodoxanthin.