Pharmacognostic evaluation and TLC/HPTLC analysis of Nimba flowers (Azadirachta indica A. Juss) used in Ayurveda

Abstract BACKGROUND: Azadirachta indica A. Juss belonging to family Meliaceae is a fast-growing, large-sized evergreen tree, distributed throughout warmer parts of India, Myanmar, and tropical Africa. The leaves, bark, flower, fruit, and root are widely used in traditional medicinal systems. It has various pharmacological activities owing to its anti-inflammatory, antipyretic, analgesic, antibacterial, antifungal, antimalarial, antiviral, and antioxidant properties. The present study focuses on pharmacognostic details and thin layer chromatography (TLC) chromatographic analysis for development of quality standards of dried flowers used in Ayurveda. MATERIALS: Flowers of A. indica A. Juss were collected from Jammu and dried. Dried flower and fine powder of flowers were used for macro- and microscopic study and physicochemical variable analysis, like loss on drying (LoD), ash value, aqueous and alcohol-soluble extractive value, acid-insoluble ash, and pH, as prescribed in the Ayurvedic Pharmacopeia of India. Different combinations of solvents were also used to develop a fingerprint profile for this: A Camag high-performance TLC Linomat 5 applicator, a twin-trough TLC chamber, a TLC densitometer, Visioncat software (CAMAG, Muttenz, Switzerland), and a 100- µL Hamilton syringe (Bonaduz, Switzerland) were used. RESULTS: The microscopic study of the flower of A. indica A. Juss shows that the epidermis of the pedicel is composed of papillose cells covered by a thick cuticle. The ground tissue cells are oval–polygonal with intercellular spaces. Numerous crystals of calcium oxalate are present in cortical cells. The vascular bundle is covered by a sclerenchymatous pericycle. Similar features were observed in the perianth. The stigma is sticky and papillose, the style thin, and the ovary superior and trilocular. The microscopic analysis shows the presence of numerous unicellular uniseriate, glandular trichome, and epidermal cells with thick papillate cuticles, vessels, and pollen grains with a distinct exine and intine. The physicochemical analysis shows 0.47%, 7.5%, 0.58% 17.3%, and 24% for LoD, ash value, acid insoluble ash, alcohol extractive, and water extractive value, respectively. Fingerprint developed in the selected mobile phase, that is, toluene: ethyl acetate: chloroform: formic acid (6:1:2.5:0.5), results in the best resolution with maximum 06 black color band under UV254, 07 fluorescent blue, and red colored bands under UV366 (ethanol), and after derivatization, maximum 08 bands were observed when visualized under visible light (hexane). CONCLUSION: The standardization of dried Nimba flowers, utilized for their medicinal properties in herbal pharmaceuticals, is essential for ensuring accurate authentication, consistency, and quality control for its therapeutic applications. The pharmacognostic parameters of the dried flower of A. indica A. Juss laid down in the present study will serve to establish its identity and purity and strength (extractive value), particularly for the herbal drug industry. The chromatographic analysis provides a unique pattern of resolution of components (phenolic, flavonoids and triterpenoids) that can be used for assessment of the quality of the Nimba flower.