Biological activity of Boswellia serrata Roxb. oleo gum resin essential oil: effects of extraction by supercritical carbon dioxide and traditional methods

Figures & data

Figure 1. Percentage yield of Boswellia serrata oleo gum resin essential oils isolated through different extraction methods.

Table 1. Total phenolic, total flavonoid contents, DPPH free radical scavenging, hydrogen peroxide scavenging, and total antioxidant/FRAP activities of Boswellia serrata oleo gum resin essential oils isolated through different extraction methods.

Extraction methods	Total phenolics (mg/L)^A	Total flavonoid contents (mg/L)^B	Inhibition in linoleic acid system (%)	DPPH free radical scavenging activity (%)	Hydrogen peroxide scavenging (%)	Total antioxidant contents/FRAP^C
Hydro-distillation	581.88 ± 12.57^b	328.22 ± 8.20^b	68.56 ± 1.16^d	53.39 ± 0.43^d	56.71 ± 0.5^c	91.66 ± 1.05^b
Steam distillation	400.42 ± 10.01^c	202.66 ± 5.06^c	71.37 ± 1.61^c	59.39 ± 0.73^c	50.74 ± 0.68^d	94.39 ± 1.04^a
Supercritical fluid CO2	598.24 ± 13.15^a	376.18 ± 7.42^a	94.18 ± 1.47^b	96.16 ± 1.57^b	68.25 ± 1.02^b	56.74 ± 0.79^c
BHT	–	–	98.85 ± 1.89^a	97.92 ± 1.92^a	–	–
Ascorbic acid	–	–	–	–	85.57 ± 1.14^a	–

Values are mean ± standard deviations of three separate determinations.

Different letter in superscripts represent significant difference among Boswellia serrata oleo gum resin essential oils isolated through different extraction methods.

A = Total phenolic contents (mg/L of essential oil, measured as gallic acid equivalent).

B = Total flavonol contents (mg/L of essential oil, measured as catechin equivalent).

C = Total antioxidant contents/FRAP (mg/L of essential oil, measured as gallic acid equivalent).

Table 2. Antimicrobial activity of Boswellia serrata oleo gum resin essential oils isolated through different extraction methods.

	Essential oils isolated through different extraction methods
Microorganism	Hydro-distillation	Steam distillation	Supercritical fluid extraction	Positive control^A
Inhibition zone (mm)
Escherichia coli	15.10 ± 0.30^c	16.80 ± 0.33^b	7.57 ± 0.19^d	21.11 ± 0.20^a
Staphylococcus aureus	12.90 ± 0.17^c	14.15 ± 0.27^b	9.87 ± 0.18^d	24.38 ± 0.40^a
Pastrulla multocida	21.07 ± 0.29^c	24.21 ± 0.34^b	10.79 ± 0.14^d	28.53 ± 0.52^a
Bacillus subtilis	14.22 ± 0.28^b	14.47 ± 0.25^d	8.47 ± 0.15^e	22.32 ± 0.45^a
Fusarium solani	12.37 ± 0.32^c	23.00 ± 0.46^b	10.12 ± 0.24^d	24.36 ± 0.42^a
Aspergillus niger	10.70 ± 0.25^c	12.08 ± 0.30^b	8.80 ± 0.21^d	22.61 ± 0.74^a
Alternaria alternata	21.64 ± 0.34^b	16.73 ± 0.18^c	16.24 ± 0.32^c	24.82 ± 0.62^a
Aspergillus flavus	13.64 ± 0.42^b	12.71 ± 0.33^c	11.62 ± 0.18^d	23.32 ± 0.70^a
Minimum inhibitory concentration (µg/mL)
Escherichia coli	98.52 ± 1.96^b	70.36 ± 1.82^c	337.78 ± 4.52^a	5.83 ± 1.16^d
Staphylococcus aureus	112.58 ± 2.76^b	98.52 ± 1.96^c	168.88 ± 1.96^a	2.92 ± 0.84^d
Pastrulla multocida	70.36 ± 0.14^b	35.18 ± 0.77^c	281.47 ± 2.19^a	8.33 ± 0.95^d
Bacillus subtilis	112.58 ± 2.76^b	98.52 ± 1.96^c	281.47 ± 1.96^a	13.33 ± 2.17^d
Fusarium solani	281.46 ± 3.04^b	56.29 ± 2.40^c	337.12 ± 2.42^a	5.88 ± 0.16^d
Aspergillus niger	562.94 ± 8.07^a	281.46 ± 7.03^c	478.49 ± 6.40^b	8.42 ± 0.21^d
Alternaria alternata	79.36 ± 1.34^b	140.74 ± 2.81^a	140.74 ± 2.81^a	5.00 ± 0.10^c
Aspergillus flavus	281.46 ± 3.62^a	225.17 ± 3.50^c	267.39 ± 2.80^b	6.66 ± 0.13^d

Values are mean ± standard deviations of three separate determinations.

Different letter in superscripts represent significant difference among Boswellia serrata oleo gum resin essential oils isolated through different extraction methods.

A = Positive control for bacteria and fungi was amoxicillin and fluconazole (25 µg/disc), respectively.

Table 3. GC–MS analysis of Boswellia serrata oleo gum resin essential oils isolated by different extraction methods.

		% Composition of essential oils
Components^A	RI^B	Hydro-distillation	Steam distillation	Supercritical fluid CO2 extraction	Method of identification
Monoterpene hydrocarbon
α-Thujene	931	4.43 ± 0.11^b	5.24 ± 0.23^a	2.06 ± 0.09^c	a, b
α-Pinene	939	80.86 ± 1.09^a	74.2 ± 0.72^c	76.63 ± 0.89^b	a, b
Camphene	953	0.47 ± 0.01^b	1.66 ± 0.03^a	0.3 ± 0.00^c	a, b
2,4(10)-Thujadiene	957	0.76 ± 0.20^a	0.15 ± 0.01^c	0.24 ± 0.00^b	a, b
Verbenene	967	0.43 ± 0.01^c	0.78 ± 0.02^b	1.48 ± 0.03^a	a, b
Sabinene	976	1.27 ± 0.02^a	0.57 ± 0.00^b	0.18 ± 0.00^c	a, b
β-Pinene	980	1.48 ± 0.03^b	3.3 ± 0.07^a	0.94 ± 0.02^c	a, b
Myrcene	991	1.05 ± 0.03^b	1.25 ± 0.03^a	0.85 ± 0.01^c	a, b
Limonene	1031	0.10 ± 0.00^c	1.93 ± 0.05^a	0.45 ± 0.01^b	a, b
m-Cymene	1082	0.14 ± 0.00^c	1.55 ± 0.03^a	0.86 ± 0.01^b	a, b
α-Terpinolene	1088	0.32 ± 0.00^c	0.37 ± 0.00^b	0.42 ± 0.00^a	a, b
Oxygenated monoterpene
4 Methyl-anisole	1020	1.98 ± 0.25^a	0.31 ± 0.03^c	0.96 ± 0.03^b	a, b
1,8-Cineole	1032	0.14 ± 0.00^c	0.20 ± 0.01^b	0.80 ± 0.03^a	a, b
α-Thujone	1102	2.46 ± 0.12^a	0.55 ± 0.03^c	1.12 ± 0.09^b	a, b
α-Campholenal	1125	1.64 ± 0.15^b	0.44 ± 0.06^c	2.10 ± 0.21^a	a, b
Isothujol	1133	0.10 ± 0.00^c	0.16 ± 0.01^b	0.24 ± 0.01^a	a, b
trans-Pinocarveol	1139	0.37 ± 0.01^c	2.25 ± 0.21^b	5.31 ± 0.34^a	a, b
cis-Verbenol	1140	0.17 ± 0.00^c	2.09 ± 0.39^a	0.47 ± 0.01^b	a, b
Pinocarvone	1162	0.24 ± 0.02^b	0.11 ± 0.00^c	0.78 ± 0.01^a	a, b
α-Phellandren-8-ol	1166	0.07 ± 0.00^b	0.16 ± 0.00^a	0.02 ± 0.00^c	a, b
Isopinocamphone	1173	0.25 ± 0.01^a	0.25 ± 0.00^a	0.14 ± 0.00^b	a, b
Terpinene-4-ol	1177	0.44 ± 0.03^b	0.22 ± 0.02^c	2.28 ± 0.49^a	a, b
Myrtenol	1194	0.16 ± 0.02^b	0.72 ± 0.01^a		a, b
Verbenone	1204		0.87 ± 0.01		a, b
p-Cymen-7-ol	1287	0.67 ± 0.00^a	0.41 ± 0.00^c	0.51 ± 0.00^b	a, b
Bornyl acetate	1285		0.26		a, b

a = Identification based on retention index.

b = Identification based on comparison of mass spectra.

A = Compound listed in order of elution from a DB-5 capillary column.

B = Retention indices on the DB-5 capillary column.

Figure 2. Variations in chemical components of Boswellia serrata oleo gum resin essential oils extracted through different extraction methods.