This product is the dried fruit of the plant Forsythia suspensa (Thunb.) Vahl, belonging to the Oleaceae family. The fruit is harvested in the autumn when it is initially ripe and still green, impurities are removed, steamed, and dried, commonly referred to as "Qingqiao"; when the fruit is fully ripe, it is harvested, dried, and impurities are removed, commonly referred to as "Laoqiao".
【Characteristics】 This product is long oval to oval in shape, slightly flattened, measuring 1.5 to 2.5 cm in length and 0.5 to 1.3 cm in diameter. The surface has irregular longitudinal wrinkles and numerous small raised spots, with a distinct longitudinal groove on each side. The apex is sharply pointed, and the base has a small fruit stalk or has fallen off. Qingqiao is mostly uncracked, with a greenish-brown surface and fewer raised grayish-white spots; it is hard, with many seeds that are yellow-green, slender, and winged on one side. Laoqiao cracks from the apex or splits into two lobes, with a yellow-brown or reddish-brown surface, the inner surface mostly light yellow-brown, smooth, with a longitudinal septum; it is brittle; the seeds are brown and mostly fallen off. The aroma is slightly fragrant, and the taste is bitter.
【Identification】 (1) Cross-section of the fruit skin: The outer fruit skin consists of a single layer of flattened cells, with thickened outer and lateral walls covered by a cuticle. The outer side of the mesocarp contains scattered vascular bundles; the inner side of the mesocarp consists of multiple rows of stone cells, which are elongated, oval, or long oval in shape, with varying wall thickness, mostly arranged in a tangential mosaic. The inner fruit skin consists of a single layer of parenchyma cells. (2) Take 1 g of the powdered product, add 20 ml of petroleum ether (30-60°C), seal tightly, and sonicate for 15 minutes, filter, recover the solvent from the filtrate to dryness, and dissolve the residue in 5 ml of ethanol to prepare the test solution. Take 1 g of Forsythiae Fructus reference material and prepare the reference solution in the same manner. Perform thin-layer chromatography (TLC) tests according to the general rule 0502, applying 3 μl of each solution onto the same silica gel G TLC plate, using a developing agent of hexane-ethyl acetate-acetic acid (15:10:0.25), develop, remove, dry, spray with 10% sulfuric acid ethanol solution, and heat at 105°C until the spots are clearly visible. Examine under sunlight and ultraviolet light (365 nm). In the test solution, spots of the same color as those in the reference solution should appear in corresponding positions under sunlight, and fluorescent spots of the same color should appear under ultraviolet light. 【Examination】 Impurities: Qingqiao should not exceed 3%; Laoqiao should not exceed 9% (General Rule 2301). Moisture: Should not exceed 10.0% (General Rule 0832, Method 4). Total ash: Should not exceed 4.0% (General Rule 2302). 【Extractives】 Determined by the cold extraction method under the determination of alcohol-soluble extractives (General Rule 2201), using 65% ethanol as the solvent, Qingqiao should not be less than 30.0%; Laoqiao should not be less than 16.0%. 【Content determination】 Volatile oil: Determined by the volatile oil determination method (General Rule 2204, Method A). The volatile oil content in Qingqiao should not be less than 2.0% (ml/g). Forsythin: Determined by high-performance liquid chromatography (HPLC) (General Rule 0512). Chromatographic conditions and system suitability test: Using octadecylsilyl-bonded silica gel as the stationary phase; acetonitrile-water (25:75) as the mobile phase; detection wavelength at 277 nm. Theoretical plate number calculated based on the Forsythin peak should not be less than 3000. Preparation of the reference solution: Take an appropriate amount of Forsythin reference substance, accurately weigh, and dissolve in methanol to prepare a solution containing 0.2 mg per 1 ml. Preparation of the test solution: Take about 2 g of the powdered product (passed through a No. 5 sieve), accurately weigh, place in a sealed conical flask, accurately add 25 ml of methanol, weigh, sonicate (power 250W, frequency 40kHz) for 25 minutes, cool, reweigh, and use methanol to make up for the weight loss, shake well, filter, accurately measure 10 ml of the filtrate, place in a 25 ml volumetric flask, dilute with water to the mark, shake well, filter, and take the filtrate for testing. Determination method: Accurately take 10 μl of both the reference solution and the test solution, inject into the liquid chromatography system for measurement. The product should contain not less than 0.15% Forsythin (C27 H34 O11) based on the dried product. Forsythin A: Determined by high-performance liquid chromatography (HPLC) (General Rule 0512). Chromatographic conditions and system suitability test: Using octadecylsilyl-bonded silica gel as the stationary phase; acetonitrile-0.4% glacial acetic acid solution (15:85) as the mobile phase; detection wavelength at 330 nm. Theoretical plate number calculated based on the Forsythin A peak should not be less than 5000. Preparation of the reference solution: Take an appropriate amount of Forsythin A reference substance, accurately weigh, and dissolve in methanol to prepare a solution containing 0.1 mg per 1 ml (prepared as needed). Preparation of the test solution: Take about 0.5 g of the powdered product (passed through a No. 5 sieve), accurately weigh, place in a sealed conical flask, accurately add 15 ml of 70% methanol, seal tightly, weigh, sonicate (power 250W, frequency 40kHz) for 30 minutes, cool, reweigh, and use 70% methanol to make up for the weight loss, shake well, filter, and take the filtrate for testing. Determination method: Accurately take 10 μl of both the reference solution and the test solution, inject into the liquid chromatography system for measurement. The product should contain not less than 3.5% Forsythin A (C29 H36 O15) in Qingqiao; Laoqiao should contain not less than 0.25% Forsythin A (C29 H36 O15). 【Properties and Channels】 Bitter, slightly cold. Enters the Lung, Heart, and Small Intestine meridians. 【Functions and Indications】 Clears heat and detoxifies, reduces swelling and disperses nodules, disperses wind-heat. Used for abscesses, scrofula, mastitis, erysipelas, wind-heat colds, initial stages of warm diseases, heat entering the nutritive level, high fever with thirst, delirium with rashes, and painful heat dysuria. 【Dosage】 6-15 g. 【Storage】 Store in a dry place.2. Authenticity Identification 1. Forsythia: This product is the dried fruit of the plant Forsythia suspensa (Thunb.) Vahl, belonging to the Oleaceae family. Harvesting: The fruit is harvested in the autumn when it is initially ripe and still green, impurities are removed, steamed, and dried, commonly referred to as “Qingqiao”; when the fruit is fully ripe, it is harvested, dried, and impurities are removed, commonly referred to as “Laoqiao”.
Characteristics: This product is long oval to oval in shape, slightly flattened, measuring 1.5 to 2.5 cm in length and 0.5 to 1.3 cm in diameter. The surface has irregular longitudinal wrinkles and numerous small raised spots, with a distinct longitudinal groove on each side. The apex is sharply pointed, and the base has a small fruit stalk or has fallen off. Qingqiao is mostly uncracked, with a greenish-brown surface and fewer raised grayish-white spots; it is hard, with many seeds that are yellow-green, slender, and winged on one side. Laoqiao cracks from the apex or splits into two lobes, with a yellow-brown or reddish-brown surface, the inner surface mostly light yellow-brown, smooth, with a longitudinal septum; it is brittle; the seeds are brown and mostly fallen off. The aroma is slightly fragrant, and the taste is bitter.
Forsythia Products: Qingqiao, mostly uncracked, with a greenish-brown surface and fewer raised grayish-white spots; it is hard.
Forsythia Products: Laoqiao, cracks from the apex or splits into two lobes, with a yellow-brown or reddish-brown surface, the inner surface mostly light yellow-brown, smooth, with a longitudinal septum; it is brittle; the seeds are brown and mostly fallen off.
Inferior Forsythia Product 1: Extract residue, which is the residue after extraction, has little therapeutic effect due to the loss of active ingredients. This product resembles Forsythia but lacks the luster of the authentic product, has a dull color, and is often covered with a grayish-white powdery substance, is brittle, and easily breaks.
Inferior Forsythia Product 2: Early harvested goods, which are harvested too early during high price years, resulting in shriveled, seedless products that are easily crushed by hand.
This type of Forsythia, although authentic, has significant differences in characteristics and pharmacopoeia due to improper harvesting time. What is the content of this product? I found relevant data online for comparison (data source: Traditional Chinese Medicine Material Network Zhou Xing – Can Forsythia Leaves Replace Forsythia? Evaluation of Forsythia Content Differences from Different Regions).
2. Forsythia Imitation: The fruit of the plant Syringa vulgaris, belonging to the Oleaceae family, is a greening plant. It is long oval in shape, with almost no grayish-white spots on the surface, and is smaller than authentic Forsythia.
Processing of Forsythia: Due to the special substance on the surface of Forsythia, direct sunlight is not effective for rapid drying. Previously, it was common to sun-dry and then pile up to sweat, repeating several times until dry. This method has the disadvantage of easily causing mold during processing, and the Forsythin and Forsythin A contained in unsteamed Forsythia are easily decomposed by enzymes, leading to a decrease in content. Therefore, this method has been used less frequently in recent years.