Biological Activities of Alkaloid Fraction of Fritillaria karelinii (Fisch. ex D. Don)

Abstract

Background: Fritillaria karelinii (Fisch. ex D. Don) belongs to the lily family (Liliaceae) and grows in Central Asia, Iran, Pakistan, and the Xinjiang Autonomous Region of China. The underground bulbs of this plant are traditionally used as both food and medicine, especially within the framework of traditional Chinese medicine (TCM). Although earlier studies reported promising antioxidant activity, comprehensive investigations combining morpho-anatomical, phytochemical [high-performance thin-layer chromatography (HPTLC) and gas chromatography-mass spectrometry (GC-MS)], and biological analyses are lacking. This study addresses this gap by providing an integrative characterization of F. karelinii bulbs.

Objectives: The present study aims at a comprehensive characterization of the bulbs of F. karelinii, including their morphological, anatomical, and chemical features. The chemical profile of the samples was studied using HPTLC and GC-MS. Additionally, the complete extract was analyzed for antioxidant, antimicrobial, and cytotoxic activity to assess its biological potential.

Methods: Histochemical analysis was performed to localize alkaloids and other metabolites in the parenchyma cells of F. karelinii bulbs. To obtain a characteristic chromatographic profile and identify the main alkaloids, HPTLC was applied as a fingerprinting tool. The GC-MS was used primarily for profiling fatty acids and other volatile/semi-volatile compounds in the methanolic extract, while acknowledging that this method does not capture polar metabolites such as phenolics or flavonoids. The biological activity of the samples was evaluated through free radical scavenging (DPPH), ferric reducing antioxidant power (FRAP), antimicrobial assays, and cytotoxicity testing.

Results: Histochemical analysis confirmed the presence of alkaloids in the parenchyma cells of the bulbs, which also contained abundant starch granules. The HPTLC revealed a distinct fingerprint, highlighting the major alkaloids. The GC-MS profiling of the methanolic extract detected 16 fatty acids and other volatile components, with linoleic acid (40.86%) and palmitic acid (30.58%) as the dominant fatty acids, followed by linolenic acid (13.30%) and stearic acid (5.85%). The alkaloid-rich fraction contained 5α-cevan-3β,20-diol (19.65%) and fritillarin (18.86%) as prominent alkaloids. Their identification was confirmed by comparison with the National Institute of Standards and Technology (NIST) library, which showed high similarity scores [match factor (MF) = 890, reverse match factor (RMF) = 905 for 5α-cevane-3β, 20-diol; MF = 875, RMF = 900 for fritillarin]. The crude extract showed no detectable DPPH scavenging, antimicrobial, or cytotoxic activities under the tested conditions. In contrast, it demonstrated moderate ferric reducing capacity (1.0578), though lower than the reference standard gallic acid (1.8705).

Conclusions: The bulbs of F. karelinii were shown to contain diverse classes of secondary metabolites, as confirmed by histochemical analysis. The HPTLC and GC-MS profiling identified 5α-cevan-3β,20-diol and fritillarin as the predominant steroidal alkaloids, whose RMF and MF values confirm their structural reliability. However, under the tested experimental conditions, the methanolic extract did not exhibit significant antioxidant, antimicrobial, or cytotoxic activities. These findings indicate that while the species possesses a complex phytochemical profile, further investigations are required to clarify its pharmacological relevance. The present results highlight the need for more comprehensive studies, including the evaluation of other compound classes (e.g., phenolics, flavonoids, alkaloids) and optimized experimental conditions, before firm conclusions regarding its medicinal potential and traditional uses can be drawn.

Keywords: Alkaloids; Fritillaria karelinii; GC/MS; HPTLC; Kazakhstan; Liliaceae.

Figure 1.. A, external morphology of Fritillaria karelinii bulbs; B and C, transverse section; D, longitudinal section of bulbs stained with toluidine blue O, highlighting the internal structure composed of parenchymatous cells densely packed with starch grains; E – H, close-up view of starch grains; G and H, histochemical staining to identify starch grains and alkaloids in the cells; dark blackish-blue staining indicates the presence of starch grains, while yellow-orange coloration confirms the presence of alkaloids (scale bar: B and C = 200 μm, D = 50 μm, E and F = 20 μm, G and H = 10 μm).

Figure 2.. High-performance thin-layer chromatography (HPTLC) fingerprint profiles of the methanol extract and fractions of the bulb extracts: A, without derivatization; B, derivatized with vanillin-sulfuric acid; and C and D, derivatized with Dragendorff’s reagent [the tracks correspond to: RK-M1 (1), RK-M2 (2), RK-M3 (3), RK-M4 (4), and crude extract (5)].

Figure 3.. Mass spectra of A, 5α-cevane-3β,20-diol; and B, fritillarine

Figure 4.. Structural formulas of the main alkaloids identified in the bulbs of Fritillaria karelinii: 5α-cevane-3β,20-diol (19.65%) and fritillarine (18.86%)