Radical scavenging, prolyl endopeptidase inhibitory, and antimicrobial potential of a cultured Himalayan lichen Cetrelia olivetorum

Figures & data

Figure 1. Factors involved in the initiation and progression of neurodegenerative diseases.

Figure 2. (a) Natural thallus of lichen Cetrelia olivetorum; (b) culture of C. olivetorum grown in MS medium; (c) symbionts observed as blue-colored fungal hyphae and dark green algal cells from the same culture.

Figure 3. TLC of C. olivetorum showing the production of olivetoric acid.

Figure 4. Culture biomass of lichen C. olivetorum obtained from various nutrient media over 60 d.

Table 1. Radical scavenging, prolyl endopeptidase inhibitory activity and phytochemical content of lichen Cetrelia olivetorum at 25–100 µg/mL concentration.

	Radical scavenging activity			Prolyl endopeptidase inhibition	Phytochemical content
	100 µg/mL			50 and 25 µg/mL
	DRS (%)	ALP (%)	TEAC (mM)	PEPI (%)	Total polyphenol content (g/g dry wt)	Polysaccharide content (g/g dry wt)	Protein content (g/g dry wt)
Lichen material
Natural	98.98	96.90	7.21	17.33	1.30	2.36	2.51
Culture	93.05	89.21	7.99	6.66	0.22	21.30	0.97
Standard PEP inhibitor (10 µg/mL)
Z-pro-prolinal				8.66
Standard antioxidants (20 µg/mL)
BHA	76.0	35.4
BHT	85.4	47.0
Quercetin	63.0	40.8
Trolox			3.6

PEP, prolyl endopeptidase; PEPI, prolyl endopeptidase inhibitory activity; DRS, DPPH radical scavenging activity; ALP, anti-lipid peroxidation; TEAC, trolox equivalent antioxidant capacity; BHA, butylated hydroxyl anisol; BHT, butylated hydroxyl toluene.

Table 2. Half-inhibiting concentration (IC₅₀) of methanol extracts of C. olivetorum for radical scavenging and the prolyl endopeptidase inhibitory activity.

	IC50 values (µg/mL)
	PEPI	DRS	ALP
Lichen material
Natural	144.25	50.51	51.59
Culture	187.68	57.73	56.04
Standard PEP inhibitor
Z-pro-prolinal	57.73
Standard antioxidants
BHA		12.9	28.2
BHT		12.0	23.0
Quercetin		15.8	24.9

Data presented are the mean of three consecutive readings of sample in the assay performed. PEP, prolyl endopeptidase; PEPI, prolyl endopeptidase inhibitory activity; DRS, DPPH radical scavenging activity; ALP, anti-lipid peroxidation; BHA, butylated hydroxyl anisol; BHT, butylated hydroxyl toluene.

Table 3. Minimum inhibitory concentration (MIC, µg/mL) of C. olivetorum against clinical isolates.

	Lichen extracts		Standard antimicrobials
Clinical isolate	Natural	Culture	Erythromycin	Streptomycin	Tetracycline
E. cloacae	104	50.35	104	4.97	4.94
K. pneumoniae	101.99	50.11	102.47	4.98	24.91
P. aeruginosa	51.17	103.44	114.18	5.00	25.03
S. marcescens	50.92	103.23	101.58	50.32	50.39
S. epidermidis	103.04	102.89	4.93	4.95	4.94
			Nystatin	Ketoconazole	Fluconazole
C. albicans	26.24	105.67	68.36	54.50	7.58