Flavonoid Content During the Growth and Floral Development of Calendula officinalis L.

Summary

Here, we present the aluminum chloride colorimetric method, a direct analytical technique to determine flavonoids in calendula quantitatively. This approach utilizes a straightforward chemical reaction involving treating the calendula extract with an aluminum chloride reagent, forming a colored complex. The color intensity, assessed using spectrophotometry, correlates with the flavonoid concentration.

Abstract

Pot marigold (Calendula officinalis L.) with multiple uses, notably its medicinal applications due to its richness and diversity in secondary metabolites, such as flavonoids, which possess anti-inflammatory and antioxidant properties.This study analyzed plant growth and biomass distribution, as well as total flavonoid concentration in tubular, ligulate flowers, and flower heads throughout floral development. Floral initiation and differentiation occurred five weeks after transplantation, following a sigmoid pattern of biomass accumulation in its organs as well as in plant height. Aerial organs reached a maximum biomass of 76 g/ g/plant on day 69. The maximum absolute growth rate was 2.38 g/day at 62 days, while the highest relative growth rate was recorded in reproductive organs on day 48 (0.137 g/g/day). Flavonoids, expressed as quercetin equivalents, showed higher concentrations during stages ranging from flower buds to fully opened flower heads (145-177 mg/g of dry matter). These findings emphasize the importance of harvesting at optimal stages to maximize flavonoid content and leverage their potential for therapeutic and commercial applications.

Introduction

The growing interest in secondary metabolites from medicinal plants is driven by their diverse applications in pharmaceutical, therapeutic, cosmetic, and other industries. Among them is Calendula officinalis L., an annual herbaceous plant of the Asteraceae family native to the Mediterranean region¹ but widely cultivated worldwide, has gained recognition due to the various uses of its flowers, including ornamental, medicinal, industrial, and culinary applications². Currently, England is the world's largest producer of C. officinalis³.  

The flo....

Protocol

1. General materials and methods

1. Field experiment for detecting floral initiation
   1. Set up the experiment under field conditions. Transplant calendula seedlings over an area of 153 m² with a planting density of plants per square meter, spaced 60 cm apart.
   2.  Establish the localized drip irrigation system with 16/8000-gauge NOTE: The seed lot used in this experiment was harvested  from a single genotype,then selected by the  mass selection breeding method across  three previous cultivation cycles. For a temperate climate, sowing time is best at the Spring season, followed by  transplant....

Results

Growth of C. officinalis exhibited sigmoid biomass accumulation kinetics throughout the plant and its organs. This observation aligns with reports from other authors, which consistently display a sigmoid growth curve. Among the aerial organs, stems accumulated the most biomass (Figure 3). Initial growth in all aerial organs was slow, with flowering and bud development starting on day 41. The plant reached its maximum dry biomass on day 69, averaging 76 g per plant.

Discussion

Two types of flowers, ligulate and tubular, were identified (Figure 5). We found that ligulate flowers contain a lower concentration of flavonoids than tubular flowers, with differences ranging from 11% to 53%. This indicates that tubular flowers accumulate more flavonoids than ligulate flowers, because the tubular flowers have more biomass and a higher concentration of these compounds.

When the stages of floral development were compared, it was found that the fla.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Air-circulating oven	Precision 17 GCA Corp.	N/A	Equipment
Bug clean	Alternagro	N/A	Control of agricultural pests with plant oils and extracts
Methanol analytical grade	merck	822283	Reagent
Nitrofoska special 12+12+17+2 MgO+8 S	EUROCHEM	7/548/CEE,1999/45/CE	NPK - granular fertilizer contains: ammonium nitrate, ammonium salts, phosphates, calcium salts, potassium, in some cases magnesium and trace elements. 1H-Pyrazole, 3,4-dimethyl-,phosphate (1:1)
PHC Healthy Start	PHC Mexico	N/A	PHC Healthy Start 12-16-12 is a fertilizer to improve plant nutrition, color and vigor.
Quercetin	Sigma-Aldrich	204-187-1	Standard substance