In the quantitative estimation of A. chinense bulb and leaf, high content of saponin was observed. Saponin possesses antibiotic, insecticidal, and fungicidal activity [16]. Steroidal saponins isolated from A. chinense bulb possess anti-tumor property [7]. Saponins are cytotoxic and inhibit the migration ability of B16 and 4T1 cells [4]. Laxogenin a saponin isolated from A. chinense bulb have anti-tumor property in stage-two lung carcinogenesis [8]. Therefore, A. chinense can be used as a potential plant for the extraction of saponin for medicinal and pharmaceutical use.
Alkaloids have been reported to have anticancer, antibacterial, antiviral, and antifungal activity [17]. Aclidinium bromide a drug from alkaloid is used to treat chronic obstructive pulmonary disease; atropine and scopolamine are alkaloid derivatives used in traditional medicine for treating asthma [18]. A. chinense showed a moderate content of alkaloids which could be exploited for their pharmacological properties.
Low content of phenols [19] and flavonoids [20] indicate low antioxidant activity. Phenols are known to have anti-inflammatory, antimicrobial, anesthetic, antioxidant, anti-tubercular, anticancer, analgesic, and anti-Parkinson activity [21]. Flavonoids are known to have antioxidant effects and have been shown to inhibit the initiation and progression promotion of tumors [22]; consumption of flavonoids decreases coronary heart disease [23].
DPPH is a stable free radical with absorption spectra at 517 nm and loses its ideal absorption accepting an electron, resulting in a change from purple to yellow color, displaying the scavenging potential [24]. The low or negligible antioxidant capacity in the hexane leaf and bulb extract may be due to the low content of phenol [19] and flavonoid [20]. Our findings correlate with the previous report by Lin in A. chinense bulb [25].
The leaf extract showed higher antibacterial activity (20 mm) than the standard (18 mm) against P. aeruginosa, it is known that gram-negative bacteria are highly resistant to many antibiotics. The absence of ZOI was interpreted as the absence of activity. The activities are expressed as resistant if ZOI was less than 7 mm, intermediate (8–10 mm), and sensitive if more than 11 mm [26]. On observing the zone of inhibition, the bulb exhibited resistant activity whereas leaf was highly sensitive as an antibacterial. In A. niger, bulb extract showed intermediate (7 mm) activity whereas sensitive activity with 14 mm ZOI was observed in the leaf extract. The high composition of terpene, viz. phytol (35.76%) and perhydrofarnesyl (14.7%) in the leaf and 2-methyl octacosane (21.30%) in the bulb exhibited antimicrobial activity [19, 24, 27]. The leaf extract has an outstanding antibacterial activity against gram-negative bacteria P. aeruginosa.
The result of the current study supports the use of both bulb and leaf hexane extracts as a potential antibacterial and antifungal; the leaf extract presented as a wide antimicrobial spectrum compared to the bulb.
The GC-MS characterization revealed that the compounds found in both the bulb and leaves extract were not reported earlier in this plant. The difference in results reported in essential oil [6] may be due to the extraction method, soil pH, seasonal variation, climatic conditions, and many other factors.
In the leaf extract, phytol was the major component identified with a concentration of 35.76% and retention time of 20.475 min which is an acyclic diterpene with anticancer, anti-diuretic, nematicide, hepatoprotective, hypocholesterolemic, anticoronary, anti-androgenic antimicrobial, antioxidant, antiarthritic, anti-inflammatory, antidiabetic, and immunostimulatory [27] followed by tetratetracontane with a peak area of 18.49% appeared at 33.630 min is a long chain alkane, having antibacterial activity [28]. Perhydrofarnesyl acetone with 14.76% was the first compound detected in the leaf at 17.148 min and is a sesquiterpenoid that has extensive biological activities such as, antimicrobial, allelopathic, cytotoxic, and antifeedant activity [29].
The GC-MS analysis of the bulb displayed alkane as the major group. In the 28 compounds revealed, the dominance of compounds such as 2-methyloctacosane with the peak area of 21.30% appeared at 27.601 min which is an alkane with antimicrobial [30]. Tetratetracontane with a peak area of 14.05% which appeared at 30.497 min is an alkane having antibacterial property [28]. Eicosane, 10-methyl with a peak area of 12.06% appeared at 24.850 min, an alkane which has high antioxidant [31]. Heneicosane with a peak area of 8.46% reported at 33.939 min is an aliphatic hydrocarbon; it belongs to the higher alkane group having bio pesticidal property [32].
The GC-MS revealed that the bulb and leaves have a different bio-constituent; only three compounds tetratetracontane, nonadecane, and 2-methyl-octadecyl trifluoroacetate appeared in both the extract. Our findings on the chemical composition of hexane bulb and leaf extract did not correlate with the previous reports on the essential oil [5, 6] and no sulfide-containing compounds were identified in the crude extract.