In this study, we propose ultra-performance liquid chromatography coupled with quadrupole/time-of-flight mass spectrometry (UPLC-QToF-MS/MS)-guided metabolite isolation as a choice analytical approach to the ongoing structure–activity investigations of chemical isolates from the edible lichen, Ramalina conduplicans Vain. This strategy led to the isolation and identification of a new depside (5) along with 13 known compounds (1–4, 6–14), most of which being newly described in this lichen species. The structures of the isolates were established by detailed analysis of their spectral data (IR, NMR, and Mass). The acetone extract was further analyzed by UPLC-Q-ToF-MS/MS in a negative ionization mode, which facilitated the identification and confirmation of 18 compounds based on their fragmentation patterns. The antioxidant capacities of the lichen acetone extract (AE) and isolates were measured by tracking DPPH and ABTS free radical scavenging activities. Most isolates displayed marked radical scavenging activities against ABTS while moderate activities were observed against DPPH radical scavenging. Except for atranol (14), oxidative DNA damage was limited by all the tested compounds, with a marked protection for the novel isolated compound (5), as previously noted for the acetone extract (p < 0.001). Furthermore, compound (4) and acetone extract (AE) have inhibited intestinal α-glucosidase enzyme significantly (p < 0.01). Although some phytochemical studies were already performed on this lichen, this study provided new insights into the isolation and identification of bioactive compounds, illustrating interest in future novel analytical techniques.

Three new saxicolous species of the lichen genus Buellia De Not. from India are described here, namely Buellia austroindica, B. subhemispherica and B. vizagensis. All the three species are characterized by an amyloid medulla and contain xanthones, connorstictic, and norstictic acid. The species B. austroindica is distinguished by its brownish yellow, rimose-areolate, UV+ pale white thallus, and orange pruina on the apothecial disc. Buellia subhemispherica is characterized by a pale grey to ivory white, rimose-areolate, UV+ orange thallus and an exciple that is aeruginose-pigmented with a paler middle layer. Buellia vizagensis is characterized by a warm white to white-grey, rimose areolate, UV+ orange thallus and yellowish brown pruina on the apothecial disc. Buellia cinnabarina and B. spuria are reported for the first time from India. Detailed descriptions, figures and distribution maps of all the species are provided.