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Product Description

L-Borneol, also known as Ai Pian in Chinese, is a naturally occurring crystalline compound extracted from the fresh leaves of Blumea balsamifera (Asteraceae). The primary active component is L-Borneol, which is one of the three major sources of "Borneol" (the other two being synthetic borneol and natural D-Borneol). It is the levorotatory isomer of D-Borneol, possessing distinct physical properties, pharmacological activities, and applications. Below is a detailed overview:

Source and Preparation

Plant Source:
Blumea balsamifera is a perennial herb or subshrub mainly distributed in Yunnan, Guizhou, and Guangxi provinces of China. Its fresh leaves are the sole raw material for producing natural L-Borneol.

Extraction Process:
L-Borneol is obtained by steam distillation of the essential oil from Blumea balsamifera leaves, followed by cooling crystallization and recrystallization for purification. The resulting product appears as semi-transparent, whitish crystals with a strong, refreshing aroma. When burned, it emits dense smoke and a bright flame.

Quality Standards:
According to the Chinese Pharmacopoeia, L-Borneol content must not be less than 85.0%, while Isoborneol must not exceed 5.0% and Camphor must not exceed 10.0%.

Composition and Structure

Primary Component:
L-Borneol (C₁₀H₁₈O, molecular weight: 154.25) is a levorotatory monoterpenoid alcohol. Its chemical structure is the mirror image of D-Borneol.

Melting Point: 201–205°C

Specific Rotation: [α]ᴅ²⁰ = –37.74° (in ethanol)

Minor Components:
Contains trace amounts of eucalyptol, L-camphor, and sesquiterpene alcohols, which together contribute to its characteristic fragrance and supplementary biological activities.

Comparison with Other Types of Borneol

Feature	L-Borneol (Ai Pian)	D-Borneol (Natural Borneolum from Cinnamomum camphora)	Synthetic Borneol (Racemic Borneol)
Source	Extracted from leaves of Blumea balsamifera (Asteraceae)	Extracted from resins or branches of Cinnamomum camphora	Chemically synthesized from turpentine or camphor
Optical Activity	Levorotatory ([α]ᴅ²⁰ = –37.7°)	Dextrorotatory ([α]ᴅ²⁰ = +37.7°)	Racemic (optically inactive)
Main Component	L-Borneol (≥85%)	D-Borneol (≥99%)	Racemic Borneol with isoborneol and impurities
Melting Point	201–205°C	208°C	210.5°C
Odor	Strong and refreshing aroma	Mild and pleasant aroma	Sharp, chemical-like odor with residual synthetic notes
Safety	Naturally derived, low toxicity	Naturally derived, high safety	May contain toxic impurities such as Isoborneol
Pharmacological Focus	Strong anti-inflammatory and analgesic activity	Prominent resuscitative and awakening effects	Weaker efficacy, more irritative

Pharmacological Actions and Clinical Applications

Central Nervous System Stimulation (Resuscitative Action): L-Borneol rapidly crosses the blood–brain barrier and enhances central nervous system function. It is used to treat conditions such as stroke-induced coma, febrile delirium, and other "closed syndromes." Its mechanism is associated with GABA receptor modulation and inhibition of neuronal apoptosis.

Anti-Inflammatory and Analgesic Effects: Studies show that L-Borneol significantly reduces carrageenan-induced rat paw edema and acetic acid–induced writhing in mice, demonstrating superior anti-inflammatory effects compared to synthetic borneol. Clinically, it is used for oral ulcers, pharyngitis, and arthritis.

Transdermal Absorption Enhancer: As a natural penetration enhancer, L-Borneol improves stratum corneum permeability and boosts the efficacy of topical formulations (ointments, patches, etc.). Compound formulations containing L-Borneol enhance the local anesthetic effect and drug delivery depth.

Antimicrobial and Antiseptic Activity: Exhibits inhibitory effects against Staphylococcus aureus, Escherichia coli, and Candida albicans, making it useful in treating skin infections, otitis media, and similar conditions.

Other Applications

Ophthalmology: Used in eye drops (e.g., Ba Bao Eye Drops) to relieve redness, swelling, and corneal opacity.

Dermatology: Applied for corns, burns, eczema, and wound healing.

Personal Care and Fragrance Industry: Serves as a premium fragrance ingredient in cosmetics and perfumes, providing a long-lasting, refreshing scent.

Identification and Quality Evaluation

Authentic Product Characteristics:

Appearance: Semi-transparent, whitish crystalline flakes; hard and brittle, not easily crushed.

Aroma: Refreshing and natural without any pungent odor.

Burning Test: Produces dense smoke with a bright flame and no black residue.

Common Adulterants:

Synthetic Borneol: Colorless transparent crystals, soft and crumbly, burn with yellow flame and turpentine-like odor.

Mixed Products: May contain camphor or menthol-component analysis (e.g., GC-MS) is required for accurate identification.

L-Borneol (Ai Pian), as a traditional Chinese medicinal and natural aromatic compound, possesses unique optical activity and pharmacological functions. Its natural origin, safety, and therapeutic versatility make it irreplaceable in both medical and cosmetic applications. Modern pharmacological studies have validated its efficacy and safety, and future innovations are expected to further expand its role in advanced formulations and precision medicine.