PV Sindhu failed to better World No.10 Chen Yufei of China to go down fighting 17-21, 21-23 in a 43-minute match.
Saina, who won a bronze in the Glasgow World Championship, defeated Marin 22-20 21-18 in a hard-fought battle.
Title-contenders Sindhu and Srikanth would look to put behind the disappointment of an early exit from Japan Open and make a positive start to their campaign at the USD 750,000 Denmark Open Super Series Premier, which begins on Monday.
Top Indian shuttlers PV Sindhu and Saina Nehwal were retained by their respective franchises at the players auction of the Premier Badminton League (PBL) on Monday.
As many as 10 Olympic medalists and eight medalists from the recently concluded BWF World Championships have confirmed their presence in the PBL league, which will be held in December.
Kidambi Srikanth, who lost in the quarterfinals in Japan Open, remains the highest-ranked Indian male player at eighth.
In March 2015, PV Sindhu became the youngest recipient of the Padma Shri.
Pranaav Chopra and Sikki Reddy, who had clinched the Syed Modi Grand Prix Gold title at Lucknow this year, squandered the opening game advantage to go down 21-14, 15-21, 19-21.
With this victory, Axelsen enjoys a 3-2 head-to-head lead over Srikanth in five meetings, having won the last three duels.
Olympics medallists PV Sindhu and Saina Nehwal crashed out of the USD 325,000 Japan Open Superseries after suffering straight-game defeats in second round on Thursday.
Saina took 39 minutes to dispatch Thailand's Pornpawee Chochuwong 21-17 21-9 in the women's singles opening round.
Sindhu might meet world champion Okuhara for the third straight tournament if she can get past Mitani and the Japanese does the same against Hong Kong's Cheung Ngan Yi in their respective openers.
After lifting the title, Sindhu dedicated her victory to Prime Minister Narendra Modi on his birthday.
P V Sindhu said the heart-breaking World Championship final loss was not on her mind when she was plotting the downfall of Japan's Nozomi Okuhara en-route to her Korea Open title.
Sindhu defeated the eighth seed Okuhara 22-20 11-21 20-18 in an energy-sapping contest that lasted an hour and 23 minutes to exact sweet revenge of her heart-wrenching World Championship final loss to the Japanese at Glasgow last month.
Rio Olympics silver medallist Sindhu won 22-20, 11-21, 21-18 in an hour and 22 minutes at the SK Handball Stadium.
PV Sindhu vs Nozomi Okuhara Highlights, Korea Open Final: World Championship silver medallist PV Sindhu made history by becoming the first Indian to win the Korea Open.
PV Sindhu came into the match with a 3-5 head to head count, having lost to the Chinese at the Asia Badminton Championship in April this year.