The demands of human beings are increasing continuously for phytomedicine due to its accuracy and consistency, leading to an emphasis on plants and their role in phytomedicine bioactivity. A large number of plant species are slowly evolving due to many reactions, including environmental impact on habitat loss, destructive collection, etc. The overall effects endanger plant populations, and most of them are poorly explored and less studied. Therefore, such plant species need greater attention for their industrial use and effective conservation with the screening of the newer secondary metabolites. Various chromatographic techniques had provided us with a broad notion to explore the biochemical composition of plant and plant parts.
Considerable effort has been made to isolate and determine the metabolites available in the species from the genus
Decalepis. The earliest intervention in this regard was available by Murti and Seshadri [
29], who claimed the presence of Inositol, saponins, tannins, phenolics, alkaloids, flavonoids, etc. in root tuber of
D. hamiltonii. Nagarajan et al. [
30] have reported a few specific metabolites, i.e., 2-hydroxy-4-methoxy benzaldehyde (2H4MB), from volatile oils (96%), which is found to be an important constituent in
D. hamiltonii. Further work has been done to investigate the metabolic content by George et al. [
31] and confirmed the presence of 2H4MB in the tuberous root of
D. hamiltonii as major metabolites. They have also found some other minor metabolites of pharmacological value, namely 2-hydoxybenzaldehyde (31.01%), 4-O-methylresorcylaldehyde (9.12%), benzyl alcohol (3.16%), etc. The GC-MS analysis of tuberous root extract of
D. hamiltonii by Nagarajan et al. (2001) observed the presence of benzaldehyde (0.01%), salicylaldehyde (0.01%), methyl salicylate (0.04%), 2-phenylethyl alcohol (0.08%), ethyl salicylate (0.03%), and vanillin (0.45%) in minor amounts that are biologically significant. Nagarajan and Rao [
32] developed a chromatographic technique in which they used gas as a mobile phase and found varying combination of the aromatic compound in
D. hamiltonii. Other compounds, such as 4-hydroxyisopthalic acid, 14-aminiotetradecanoic acid, 4-(1-hydroxy-1-methylethyl)-1-methyl-1,2-cylohexane diol, 2-(hydroxymethyl)-3-ethoxybenzaldehyde, bornerol, and ellagic acid have also been reported in
D. hamiltonii root [
33,
34]. Moreover, α-atlantone (2.06% v/w of oil) and β-pinene (2.01%) have been isolated by Thangadurai et al. [
35].
Table 1 represents the GCMS analysis of methanolic root extract of
D. hamiltonii. This table shows the presence of bioactive constituents in methanolic root extract of
D. hamiltonii with their retention time and area percentage.
Some studies on the determination and evaluation of phytocompounds in
D. arayalpathra also revealed the presence of a compound similar to that reported in
D. hamiltonii. Ahmad et al. [
16] performed the screening of metabolites for methanolic extract of tuberous root of
D. arayalpathra and its successive fractions that revealed the presence of the alkaloid, phenolics, tannins, carbohydrate, flavonoids, terpenoids, etc. Further GC-MS analysis enabled the identification of furaneol, 2H4MB, 4H3MB (4-hydroxy-3-methoxybenzaldehyde), nerol acetate, diazoacetone, benzoic acid, neryl acetate ester, hexacontane, mome inositol, inositol, tetrapentacontane, diethyl phthalate, 4-ethoxy-ethyl, hexacontane, methyl commate D, diazoacetone, squalene as a major metabolites with chromelin, anhydride, alcohol, myristate, Benzoic acid, Lup-20(29)-en-3-yl acetate, 2,6-Octadiene-1-ol, phthalic acid, and steraloids as minor metabolites [
16]. The high-performance liquid chromatography (HPLC) studies of methanolic extract of
D. arayalpathra confirmed the presence of 2H4MB as the major constituents with chlorogenic acid having potential biological activity [
16,
17,
18]. George et al. [
36] also noted the presence of 2H4MB in the root of
D. salicifolia as major metabolites in their early work. A recent report by Das et al. [
37] witnessed the occurrence of phenolic and flavonoids compounds on
D. nervosa phytochemical screening.